$15.00
Audio System Design
and Installation
FUNDAMENTALS
OF AUDIO TECHNOLOGY,
SOUND SYSTEM DESIGN
AND INSTALLATION
Rev. 3
Leviton Integrated Networks: Audio System Design and Installation
Table of Contents
Level 1: Fundamentals of audio technology
Overview: Fundamentals of Audio Technology, Sound System Design and
Installation ....................................................................................................................................1
Part 1: Fundamentals of Sound, Electronics and Audio Systems
Basics of audio reproduction .................................................................................................3
Basics of electronics ..................................................................................................................6
What makes a sound system? ............................................................................................ 10
Part 2: Basics of Multi-Room Sound
System types ............................................................................................................................. 13
System layout ........................................................................................................................... 15
System elements and components .................................................................................. 16
Part 3: Basics of Home Theater
System topology ...................................................................................................................... 28
System elements ..................................................................................................................... 29
Level 2: System design and specification
Part 4: Design and Installation Planning
Working in production home construction .................................................................... 32
Blueprints, floor and electrical plans ................................................................................ 32
Design tools .............................................................................................................................. 33
Power requirements .............................................................................................................. 34
Location strategies .................................................................................................................. 35
The walk-through .................................................................................................................... 36
Part 5: Developing the Bill-of-Materials
Bill-of-Material considerations ............................................................................................ 37
Examples .................................................................................................................................... 38
Level 3: System installation and set-up
Part 6: Pre-Wire/Rough-In
Scheduling ................................................................................................................................. 39
Tools and materials ................................................................................................................ 39
Review of wiring practices ................................................................................................... 39
Wiring the premise ................................................................................................................. 41
Preliminary wiring check ...................................................................................................... 44
Part 7: Trim-Out
Scheduling ................................................................................................................................. 45
Tools and materials ................................................................................................................ 45
Preparation ................................................................................................................................ 46
Installing and connecting speakers ................................................................................... 46
Installing and connecting volume controls .................................................................... 48
Connecting the distribution module (Impedance Matching with Auto-Surge) . 49
Making the amplifier connection ....................................................................................... 50
Installing and connecting the home theater .................................................................. 51
Part 8: Equipment Set-Up and Troubleshooting
Activating the multi-room system and the Home Theater system ......................... 52
Basic troubleshooting ............................................................................................................ 53
© 2005 Leviton Mfg. Co. All rights reserved. Rev. 3.
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Leviton Integrated Networks: Audio System Design and Installation
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Overview: Fundamentals of Audio
Technology, Sound System Design
and Installation
Program goal: Leviton has created complete, easy-to-install and use, high performance
audio systems targeted toward the “Bell curve:” the 90% of residential construction
currently missed by the audio installation business.
Program structure: This is a three-subject (organized into 5 interdependent proficiency
levels) audio system design, specification, installation and marketing program for
contractors currently in the installed multi-room audio business as well as those looking
to add this service to their portfolio.
This is the Leviton Integrated Networks Audio 1 course.
Audio 1 contains three “foundation” training levels: Fundamentals of residential audio
technology, system design and specification, and system installation and set-up. The
course includes basics of acoustics and electronics, along with audio system design and
installation, as a subset of structured cabling. Contractors completing Audio 1 will have
the ability to configure, install and activate a multi-room audio system and home theater
system using industry-standard components.
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Part 1: Fundamentals of Sound,
Electronics and Audio Systems
Basics of Audio Reproduction
Whether it’s a thunderclap or a whisper, every sound is the result of acoustical energy.
This acoustical energy is generated by a “source” and moves through a medium (air,
liquid, or a solid material) in the form of sound waves. The sound waves received by the
human ear and converted into electrical impulses for our brain to process and store.
Indeed, we actually hear with our brain; our ears simply collect and convert the sound.
For our purposes, a sound wave can be measured by its frequency (how many times the
wave occurs each second) and by its intensity, or level.
A 20 Hz bass note
is roughly
55 feet long.
Frequency is measured in cycles per second, or Hertz (Hz). A 20 Hz bass tone, for
example, which is the lowest frequency humans can detect, means that the sound wave
is repeating 20 times each second.
To give you a notion of what a 20 Hz bass note actually is, if we use 1100 feet/second as
approximately the speed of sound at sea level, and divide that distance by 20 (as in 20
Hz, or 20 cycles per second), we can picture a sound wave that is roughly 55 feet long.
Using the same type of calculation, since the upper end of human hearing is 20,000 Hz
(20 kHz), a sound wave at this frequency is barely half an inch long.
Tech Note: The long and short of sound waves.
Sound is easy to imagine because it moves relatively slowly (compared to light
and other forms of energy)—a pokey 1,100 feet per second. That’s why when you
count the seconds between a lightning flash and the thunderclap during a storm,
you can tell how far away the strike was (it takes sound 5 seconds to travel about
a mile at sea level). As anyone in aviation knows, the speed of sound changes
depending on altitude.
It is important to note that although speakers do an amazing job of sorting out every
sound wave length between 55 feet and half an inch, larger speakers are (generally)
better at reproducing longer (deeper) sounds and smaller speakers better at shorter
(higher) frequencies. This is why most home-entertainment speaker systems (with a few
notable exceptions) consist of multiple, purpose-built drivers such as a woofer (a large
speaker for reproducing the longer, lower frequencies) and a tweeter, a very small speaker
for reproducing short high frequencies.) If the woofer is larger than 8-inches, sometimes a
third driver called a mid-range is used to fill in the middle frequencies. To make sure the
right frequencies get to the right driver, multi-driver speakers typically use a crossover
network to direct different ranges of frequencies to the right driver. Otherwise, a tweeter
would be quickly burned-out trying to reproduce bass frequencies.
It is also important to understand that sounds are made up of complex mixtures of
frequencies called fundamentals and harmonics. To help us understand the concept of
fundamentals and harmonics, let’s consider several musical instruments, such as the
piano, pipe organ, clarinet and accordion. All are capable of producing the same range of
frequencies (that is, they have the same fundamental (bass) frequency range within the
frequency spectrum); however, they all sound different. This is because they each produce
a unique set of overtones and undertones, or other frequencies, which are called
harmonics.
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
Tech Note: The sound is in the details.
20kHz
10kHz
9kHz
8kHz
7kHz
6kHz
5kHz
4kHz
3kHz
2kHz
1kHz
900Hz
800Hz
700Hz
600Hz
500Hz
400Hz
300Hz
200Hz
100Hz
90Hz
80Hz
70Hz
60Hz
50Hz
40Hz
20Hz
In an audio system,
doubling the
electrical power
increases volume
by just 3dB.
30Hz
If you look at a simple frequency response chart, instruments such as the piano,
pipe organ and others seem nearly identical—they cover relatively the same
spectrum of sound. The reason they sound so different and distinct are the myriad
acoustical overtones and details, or harmonics, that these instruments produce.
BASIC PRINCIPLES OF SOUND
AM RADIO
FM RADIO–MAGNETIC TAPE RECORDING
DISC RECORDING
33MM FILM RECORDING
16MM FILM RECORDING
PIPE ORGAN
HUMAN EAR
WIDE–RANGE SPEAKER SYSTEM
MALE SPEAKING VOICE
FEMALE SPEAKING VOICE
KEY JINGLE
HAND CLAPPING
BASS VIOL
TIMPANI
HARMONICA
ACCORDIAN
FOOTSTEPS
BASS DRUM
CHIMES
PIANO 88 NOTE
PICCOLO
CYMBALS
TUBA
XYLOPHONE
CELESTA
TRIANGLE
TRUMPET
CLARINET
OBOE
CELLO
VIOLIN
TROMBONE
Frequency Range of Instruments
In sound reproduction, when harmonics interact in a way that degrades the original
sound, it is called harmonic distortion.
Intensity is measured in energy units called Bels, named in honor of the inventor of the
telephone. Because the intensity of sound influences the height of the sound wave,
intensity is usually referred to as amplitude.
The Bel is mathematically related to power ratios. But because Bels are unwieldy for
expressing sound amplitude relative to human hearing, the standard in audio is to use
one-tenth of a Bel, or a decibel (dB). Mathematically, three decibels, or 3dB, is considered
the smallest increment in volume that the ear can detect.
Sound(s)
Decibel Level
Power Level
Saturn rocket at lift-off
195 dB
25 - 40,000,000 Watts
120-130 dB
1 - 10 Watts
100 dB
0.01 Watt
Average conversation
60-70 dB
0.0001Watt
Whispering voice
30 dB
0.000000001 Watt
Film soundstage
20 dB
0.00000000001 Watt
Full orchestra
Boiler shop
Highway traffic
Subway station
Average traffic
Average office
The mathematical relationship between volume (dB) and power (watts) is complex. In an
audio system, doubling the electrical power increases volume by just 3dB (the smallest
increase one can hear). However, to double the volume, the electrical power must be
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
increased by 10 times. The preceding table puts the relationship between volume (dB)
and electrical power (Watts) in perspective relative to human hearing.
Frequency and intensity should be considered together. When we say that a typical
speaker has a frequency response from 40 Hz to 20 kHz, it does not mean much unless
we also know how relatively loud the speaker is at those frequencies. That is why the
speaker’s frequency response is also referenced at 0 db. If that speaker’s intensity varies
very little, this might be specified as 40 Hz to 20 kHz +/- 3 dB. A speaker rated at 40 Hz
to 20 kHz +/- 10 dB, on the other hand, could be missing significant parts of the sound
(likely low bass and high treble).
60 Hz – 20 kHz
100
90
80
A: Frequency response, Magn dB re 7.080p
88
86
84
82
70
60
50
20
20
40
50 60 70
200
80
90
100
1K
300 400 500 600
700
Hz 800
900
2k
3k
4k
5k 6k 7k
20k
8k
9k
10k
Frequency response of a typical in-wall speaker. The y-axis scale, in decibels, provides critical information as to how “flat” the
speaker actually measures.
Frequency and intensity are only part of the acoustical mechanism that makes sound
“sound” natural to the human ear. The field of psychoacoustics, which deals with how the
brain perceives sound, shows that sound’s spectral component (frequency realm) is only
part of the story. Equally important are the direction from where the sound appears to
come (known as the spatial realm) and exactly when in time it reaches us (known as the
temporal realm). Without these other audio cues, sound “sounds” dead, as anyone who
has spent time in an acoustical “dead” room (anechoic chamber) can attest to.
We depend on
temporal (time)
and spatial
(directional)
acoustical cues
to tell us where
a sound is.
For example, we depend on frequency response and harmonic information to tell us that
a piano sounds “like a piano.” But, we depend on temporal (time) and spatial
(directional) acoustical cues to tell us where and how far away that piano is. This would
also be true of the locations of a singer and the orchestra that make up the performance.
Sound arrives from different directions and at different times.
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
Reproducing sound
requires electronics
to amplify the sound
from a source, and
energize or drive a
loudspeaker to
reproduce it.
This is easily proved through a very simple psycho-acoustical experiment: sit in a chair,
cover your eyes, and have someone serve as a moving sound source by walking around
the room while talking constantly (or ringing a bell or jangling keys). The fact that you can
tell almost exactly where the sound is coming from even when you can’t see the source
proves how sensitive your ear/brain hearing apparatus is to space and time acoustical
cues. Since the direction and timed arrival of sounds changes depending on the ratio of
direct and reflected sound we hear, all these parameters are crucial in determining how
realistically a sound system can reproduce music.
Tech Note: The math behind sound.
Sound reproduction concepts are usually expressed in logarithmic, rather than
linear, terms. An example is the fact that doubling sound volume requires a ten
times increase in power. Another example is found on most commonly-used
frequency response graphs, where the “benchmark” frequencies are double the
value of those preceding them: 62Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kH, etc. It is
not critical to master the math—just to know that this is why response curves and
power graphs look the way they do.
Basics of Electronics
While producing sound is a mechanical process, with few exceptions, reproducing sound
requires electronics to amplify the sound from a source, and energize or drive a
loudspeaker to reproduce it. Let’s examine a few basic electronic concepts which may be
helpful in understanding audio systems.
Flow: Cu.In./sec.
Amperage is similar to the
volume of water in a pipe
Voltage is similar to the
pressure behind the the
water pushing it through
Amperage X Voltage
= Power (Wattage)
Volume X Pressure
Power. All audio systems require electrical power to run, as speakers are essentially AC
linear motors (but instead of moving a shaft or object, the speaker moves back and forth,
which imparts pressure on the air in front of it to propagate sound waves).
Power is measured in watts (W) and is expressed in several ways. Peak power is the
maximum power that might be used over any given time interval (usually of a very short
duration), while continuous or RMS (Root-Mean-Square) power is the average power that
is used over the same period. This is why a speaker might be rated as 120 W continuous/
60 W RMS. Incidentally, “Root Mean Square” power is the most mathematically correct
way to express “real-world,” useable average or continuous power.
Current, Voltage and Resistance. Electrical elements might be easier to understand in
terms of plumbing. Current is the rate of electron flow through a conductor. Current is
measured in amperes (A), which is like the volume or amount of water flowing in a pipe.
Voltage (V) is the pressure pushing the electrons along, just like the pressure behind a
water system. Resistance can be anything that slows the flow, such as a blockage in the
pipe, or reducing the diameter of the pipe and consequently reducing the water flow.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Ohm’s Law. George Ohm didn’t set out to make life miserable for audio installers. Mr.
Ohm is simply the gentleman who first noticed that the amount of voltage and amperage
changed when he used different types and lengths of conductors. In the process, he
figured out the physics at work behind these changes. For example, Ohm found that while
20 V produced 1 A of current in a 1 meter wire, when he doubled the wire length to a 2
meters, the same 20 V source only produced 0.5 A of current. However, when he doubled
the thickness (diameter) of the wire, the same 20 V now produced 4 A of current.
Furthermore, when he changed the wire type from copper to gold, the resistance
increased, but when silver was used, the resistance decreased.
The Ohm, named in his honor, is the measure of resistance that allows one volt to push
one ampere of current through a conductor. Based on this relationship between voltage,
current, and resistance, Mr. Ohm devised a law which stated that in any circuit, current is
directly proportional to voltage and inversely proportional to resistance.
Using Ohm’s Law, several formulas can be derived:
Ohms (resistance)
Voltage / Amperage
Amperage (current)
Voltage / Resistance
Voltage (pressure)
Resistance x Amperage
Watts (power)
Voltage x Amperage
Mechanical
impedance exists
in a speaker, which,
as a motor, has
moving parts that
must be pushed into
action by the audio
signal.
Impedance. Resistance in direct current (DC) electrical circuits is relatively simple, but in
alternating current (AC) circuits, resistance gets more complex. This is because various
components react to alternating current (but not to direct current), which further resists or
impedes the current. Therefore, AC resistance is typically referred to as impedance (Z)
(literally, anything that impedes the flow of electricity). Impedance can be defined as “the
total opposition to current flow in any circuit,” regardless of whether the opposition
results from electrical, mechanical, and/or acoustical forces. In fact, in an audio system, all
three forms of impedance are present.
Tech note: Related but not necessarily interchangeable.
Impedance and resistance, while often used interchangeably, are not exactly the
same thing. Electrical resistance refers to the extent to which a material resists
current flow in a direct current (DC) application, expressed as a ratio of a
conductor’s potential difference to current flowing through it. Electrical
impedance refers to all the factors that can oppose (or impede) non-direct or AC
(alternating) current, including capacitance and inductance—it is more complex as
a result.
Acoustical impedance takes into account pressure against a speaker’s diaphragm,
while mechanical impedance addresses the moving parts of a loudspeaker. In
real-world audio systems, this is why calculating system impedance must take
into account speakers, volume controls and cabling. In any electronics system,
matched impedances are a prerequisite of high performance.
Electrical impedance exists in the wiring, volume controls and at the amplifier
itself. Recall that Mr. Ohm became famous for observing that just by changing a
wire’s length or diameter, the resistance changed dramatically. Likewise, in a multiroom audio system, with potentially a half-dozen volume controls and hundreds of
feet of cabling, electrical impedance becomes a factor.
© 2005 Leviton Mfg. Co. All rights reserved.
7
Audio System Design and Installation: Fundamentals of Audio Technology
Both mechanical and electrical impedance exist in the speaker, which, as a motor, has
moving parts that must be pushed into action by the audio signal. The moving parts
naturally “fight back” when the AC electrical signal tells them to get moving. Speaker
impedances quickly add-up in a multi-room system.
Acoustical impedance exists at the interface between the speaker and its environment
(the listening room) – a speaker must work much harder to push a 55-foot bass note into
the air in a room than it does to push a half-inch treble sound.
30
B: Impedence, Magn (Ω)
Loudspeaker parameters
25
Ω
20
15
Re
5.50 Ω
fo
50.48 Hz
Qm
2.91
Qc
0.69
Qt
0.56
Zmax
28.580
10
5
20
200
Hz
2k
20k
Impedance curve for a typical in-wall speaker. The speaker’s actual impedance is highly dependent on the frequencies being reproduced.
Note that a speaker’s impedance can vary greatly from its “nominal” rating.
Leviton understands
that the Contractor’s
Law (Time = Money)
is just as critical to
success as Ohm’s
Law.
Why must impedances be matched? In electrical circuits, impedance matching is
essential to maximize power transfer, minimize distortion, and improve performance.
Audio is no exception, which is why amplifiers have nominal impedance ratings. If an
amplifier is connected to a low-impedance load, it can become unstable and even selfdestruct. Likewise, if an amplifier is connected to a high impedance load, it may not be
able to “drive” the speakers adequately. This is why amplifiers and speakers have nominal
impedance ratings – their stated electrical “comfort zone.”
To explain the difference between “nominal” and “minimum” impedances, think of the
speaker as a dynamic (as opposed to resistive) load. The speaker presents a higher
impedance to the amplifier when it is “pumping” sound at some frequencies than at
others; that is, the actual impedance of the speaker will change or “swing” depending on
the frequencies it is reproducing. This is why a speaker might be rated at 8 Ohms
nominal/6 Ohms minimum.
How do impedances add up? It depends on the circuit. In a series circuit – similar to a
“daisy chain” – the speaker impedances simply add. For example, two 8 Ohm speakers
present a total impedance of 16 Ohms (Z1 + Z2 = Z total). However, in a parallel circuit –
the (the type used in star-topology wiring) the calculation involves reciprocals and is more
difficult to use. With two resistances, a simplified formula is: (Z1 X Z2) / (Z1 + Z2) = Z
total. For example, two 8 Ohm speakers in parallel will have 4 Ohm total impedance.
With more than two speakers, we must use another version of the impedance formula,
which involves summing up the reciprocal of each impedance, then taking the reciprocal
of the sum: 1 / Z total = 1 / Z1 + 1 / Z2 + 1 / Z3 …1 / Zn.
Ultimately, you want to ensure that the total speaker impedance stays within the typical
amplifier’s “comfort zone,” which is generally between 4-8 Ohms.
Isn’t there an easier way? Absolutely! Build the audio system around a centralized
impedance-matching distribution device. This is exactly how the Leviton Integrated
Networks audio systems are designed, with speakers, volume controls and distribution
components all matched to ensure perfect impedance matching in systems covering up to
six rooms/zones.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Leviton understands that the Contractor’s Law (Time = Money) is just as critical to success
as Ohm’s Law. That is why all Leviton Integrated Networks audio systems are based on
the “No Math Required” principle. Although we took a little time to explore impedance to
help you to understand its role in audio systems, you shouldn’t have to deal with it. The
Leviton solution is engineered for the needs of production building and contracting, as
you would expect from a leader in electrical devices.
Tech Tip: don’t spend valuable time doing the math.
In multi-room audio calculating audio system impedances is time consuming
and error-prone, and a mistake can even result in amplifier damage or system
malfunction. It’s a lot easier to use a centrally-located impedance-matching
device, and there are a number of good ones on the market. Usually an extra
audio component, an impedance-matcher is wired between the amplifier’s
outputs and the volume control/speakers in each room. It presents a stable 8Ohms to the amplifier regardless of what’s hooked up on the other side (the
trade-off is sensitivity; the impedance-matcher consumes quite a bit of audio
output power—but amplifier power is relatively cheap). An impedance-matcher
also takes up room as another audio component (Leviton’s System Matching
Module approach eliminates that problem—it mounts right in the structured
cabling enclosure).
Leviton uses
transformer-free
volume control
technology
incorporating
aero-space grade
resistors.
Some common electronic terms and components based on these concepts: a resistor
is a device that opposes (but does not completely block) electric current. It does this by
being made of carbon or another material that is only a partial conductor.
Anything that passes current is a conductor. Metals such as silver, copper and aluminum
are good conductors (silver has a resistance of 0.00000001 Ohms, which for practical
purposes is non-existent). Materials like glass and wood are such poor conductors (glass
has a resistance of 1 trillion Ohms!) that they are effectively insulators. Between the
category of good and poor conductors are the semi-conductors, which includes
germanium and silicon.
Semi-conductors include transistors and other solid-state devices. Transistors are used to
amplify voltage or current in audio amplifiers and are sometimes called output devices or
drivers, and – in combinations of millions – as switches in PC’s.
Inductors are simply coils of wire. Inductors have the interesting property of producing a
magnetic field when alternating current is passed through the inductor. Transformers are
related to inductors in that they change the voltage or current level from the source side
to the load side.
Capacitors are commonly found in audio applications. A capacitor stores and releases an
electrical charge at a predetermined rate.
In an amplifier, large storage capacitors and transformers form the power supply, which
delivers the voltage and current (as directed by the output devices) needed to drive the
speakers. In speakers, capacitors (along with inductors and resistors) form part of the
crossover network, a built-in passive circuit that properly assigns the sound to the right
individual drivers.
In conventional volume controls, a special audio-transformer or autoformer is used to
change the sound level without changing the sound (in practice, autoformers tend to filter
some of the low and high frequencies, which is why Leviton uses transformer-free volume
control technology incorporating aero-space grade resistors.
© 2005 Leviton Mfg. Co. All rights reserved.
9
Audio System Design and Installation: Fundamentals of Audio Technology
What Makes a Sound System?
Any system reproducing sound, including music, is made up of the same five parts –
regardless of its size, cost or complexity.
Sources can have
both analog and
digital outputs, but at
some point the digital
sound signal must be
converted back to
analog to be
processed by our
hearing.
Sound source: this is a low-level sound signal (also known as a “pre-amp level” or “linelevel” in the audio world, although the latter is very different from the electrical meaning!)
containing necessary music and entertainment information for reproduction. Sound
sources include compact discs, analog and/or digital radio stations (AM/FM, XM and
satellite, and internet radio), digital formats such as MP-3 and Wave files, and older
formats such as records and tapes.
Source components include CD changers and jukeboxes, PC’s, digital and analog radio
tuners, and internet-enabled audio appliances.
A system’s listening options are usually expressed as either single-source (which means it
plays one type and content at a times throughout the house) or multi-source (which
allows listeners to switch between different types and content in different listening areas
known as “rooms” or “zones”).
Sources can have both analog and digital outputs, but at some point the digital sound
signal must be converted back to analog to be processed by our hearing.
Tech Note: Digital demystified.
While there is a lot of mystique around digital and analog reproduction, the
technology is easy to understand.
In analog sound reproduction, an “image” or replica of the sound waves is stored
in a record groove or on magnetic tape. Later, this replica is tracked or read, and
reproduced. In digital sound reproduction, sound is broken into slivers through
sampling by a computer (using an analog-to-digital converter), with each sliver
assigned an individual binary number that is stored on a CD or MP-3 file. Later,
those numbers are reconstructed back into the original sound waves and are
reproduced by another computing chip (a digital-to-analog converter).
For a good analogy, use a home improvement project such as replacing a front
door. You could take a picture or make a scale drawing of the door in order to
order the right size, but that might cause some error (just as a phonograph record
always has some noise). The better method would be to precisely measure the
door, write down just those measurements, and have the replacement door cut
to that exact set of measurements. The second method is much like the concept
behind digital sound reproduction—by only copying and playing back the
numbers that “measure up” to the original sound, it leaves behind any noise—
which is why CD’s don’t have the clicks and pops associated with LP records or
the hiss associated with magnetic tape. With either mode, the audio the signal
must eventually be converted back to analog AC and amplified in order to drive
speakers and be heard.
The process of assigning numbers to sound is called sampling. A chip-based
computer called an analog-to-digital converter essentially dissects or “slivers” the
incoming sound into thousands of tiny impulses each second, assigning a digital
binary number to each. Those numbers are all that are stored on a compact disc
(or in an MP-3 file). When it comes time to play the digital music back, these
numbers are “read” by another specialized computer, in this case a digital-toanalog (DAC) converter, which reassembles them into coherent sound waves.
10
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
One problem is size—these millions of numbers take up a lot of storage space (a
single second of CD-quality music would require over 50 pages of sheet-fed
computer paper, for example!). To reduce the size of digital sound, digital
systems employ Codecs (literally compression/decompression) to essentially
“dehydrate” the sound, throwing away all but the essentials. Inaccurately termed
“compression,” this process is described as “lossy” because it is a close, but not
exact, replica of the original. Coming up with digital coding systems that can
satisfy the human eye and ear was one of the primary missions of the Moving
Pictures Experts Group, who set the MPEG video standards that make DVD’s
possible. Their MPEG-2 system’s audio layer 3, more commonly known as MP-3,
is now the foundation for the entire internet and PC-based music industry.
A. Waveform
B. Sampled
C. Each sample is
assigned a binary
A single stereo
amplifier of
sufficient power
can run left and
right speakers
throughout an
entire house.
number and the
numbers are
stored
ie:
1100111100111000
In the digital process, the analog sound waveforms (A) are sampled some 44,000 times each second (B). Each sample is assigned a
binary number (C). During playback, those numbers provide all the necessary information for reconstructing the original sound.
Amplification: by itself, a sound source does not have enough power to “drive” speakers.
The signal must be electronically boosted, or amplified, in order to be heard. An amplifier
takes the signal and provides the necessary gain for that purpose.
Since nearly all music listening is done in stereo over two speakers, nearly every amplifier
system assigns two separate channels of amplification to speaker pairs – one for left and
one for right. In a multi-room system, this does not necessarily mean that each room has
two dedicated channels. In fact, a single higher-powered stereo amplifier of sufficient
power can run left and right speakers throughout an entire house—the two stereo
channels are simply split between the multiple rooms or zones.
Either way, the preferred method is to have a separate amplifier dedicated to powering
the multi-room sound system (either with two high-powered channels or multiple lowerpowered paired channels), rather than playing everything off of the AV receiver or
entertainment center (although the dedicated whole-house amplifier may be located in
the same stack of components).
Amplifier power is stated in watts per channel (WPC), which is simply an expression of
the amplifier’s ability to do work based on its voltage and current capabilities.
Tech note: on rooms and zones
You’ll hear both terms used in multi-room audio, somewhat interchangeably. A
zone, which is a listening area, may refer to one or several rooms. A master
bedroom with an attached bathroom might be a zone, for example. So would a
kitchen with an adjacent dining area and/or family room, or an outside patio
area. Generally a zone will have more than two speakers, but it will usually have a
common volume control.
© 2005 Leviton Mfg. Co. All rights reserved.
11
Audio System Design and Installation: Fundamentals of Audio Technology
While every room
is different,
installing built-in
sound systems
in production
construction has
the advantage
of the rooms
being consistent
from building to
building.
Volume Control: every system must be controlled. Imagine a
listening system with no volume control, running at “full tilt” all the
time. A level, or volume, control is essential. In a single-room stereo
system, the amplifier’s volume control is used. In a multi-room
system, each room/zone has at least one control, which is usually
mounted on the wall and/or is accomplished using a remote
control device. If remote control is used, some kind of method to
“repeat” its commands back to the amplifier and source
components is required. Typically, infrared (IR) repeating is used.
Additionally, multi-room systems may include other control features such as source
selection (AM/FM, CD, PC, etc.), operational functions (fast forward, rewind, skip, and
stop), and equalization (bass, treble, and more advanced functions)
Speakers: the amplified and controlled source signal must be
converted from electrical to acoustical energy in order for us to
hear it. This requires a transducer (a device designed to convert
one form of energy to another). A speaker is an audio transducer
(as is a headphone and a microphone).
In a multi-room system, speakers are usually built into the wall or
ceilings. Unlike shelf or floor-standing speakers, which have their
own acoustically-tuned box or enclosure – which maximizes their
efficiency (their use of the amplifier’s power), most in-wall
speakers and ceiling speakers must use the wall or ceiling itself
as an enclosure. This can become an issue when in-wall speakers
are used with limited-power amplifiers.
Listening room. Sometimes considered the fifth component, the listening environment is
part of the acoustical circuit – through sound reflection, absorption and diffraction, the
room itself has the capacity to greatly affect the sound. Sound actually behaves much like
light, and, like light, dictates much of the room’s character or ambience. While every room
is different, installing built-in sound systems in production construction has the advantage
of the rooms being consistent from building to building. This is similar to factory-installed
automotive music system, which have the advantage of being located in a predictably
consistent acoustical environment, since each car on a particular production line has the
same interior.
12
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Part 2: Basics of Multi-Room Sound
System Types
Centralized, localized, or modularized system architecture? While there is an almost
infinite variety of combinations of types and brands of speakers, sources components,
controls and amplifiers available, there are three common methods, or system
architectures, in which they can be organized.
MR/MS hub
SGC65
SGC65
SGC65
SGC65
Localized Systems
SGC65
SGC65
SGC65
SGC65
Multi-Room/Multi-Source
Control and Amplifier Center
SGI65
SGI65
SGI65
SGI65
AV Reciever "Front End"
(and can serve as multi-room amplifier)
SGI65
SGI65
SGI65
SGI65
SGI65
SGI65
AV Reciever "Front End"
Multi-Room Multi-Source
Multi-Room Multi-Source
Multi-Room Single-Source
Multi-Room Single-Source
SGI65
SGC65
SGI65
SGC65
SGC65
Audio Sources
SGC65
Audio Sources
SGC65
SGC65
MR/SS hub
Dedicated Multi-Room Amplifier
(if required)
SGI65
SGI65
Centralized System
Localized System
In a centralized system amplified music is distributed over speaker wire run from a central amplifier (either stereo or
multichannel) to speakers and volume controls in each room In a localized system a low-level music signal is distributed
over communications cabling (usually Category 5 UTP) to “satellite” amplified volume controls in each room.
Centralized Systems: A centralized system is similar in concept to a mainframe
computer – all of the intelligence and power are in one central location, with connected
“terminals” (speakers and controls) located throughout the premises.
In a centralized audio system, the amplifier is usually located in a stack along with the
other audio components (sources, equalizers, etc.) with all the multi-room speaker wires
and infrared repeating control cables terminating at that point. Speakers, volume controls
and/or keypads, and IR receivers are all located at the other end of the wiring
infrastructure. Between them is the whole-house structured cabling panel (or a second
panel dedicated to audio components), through which all speaker wire are “home run”
for easy access and configuration changes. Using a wallplate location to consolidate all
cabling is not recommended.
In this architecture, the amplifier may be the big two-channel stereo variety or even an AV
receiver, with the multi-room system connected to the “speaker B” terminals. But since
this means that whatever is being listened to in the main system room will also be heard
around the entire house, most system designers either use a separate amplifier or
separated amplifier stage of an AV receiver. Better receivers are equipped with multiroom/multi-source capability or a dedicated stereo or multi-room amplifier to drive the
whole-house system, which allows the playing of a different source or sources throughout
the room.
The main advantage
of any centralized
system is high
performance.
Some amplifiers are modular and consist of “mono-blocks,” which allows extra channels
to be added by plugging in more mono-blocks. The main advantage of any centralized
system is high performance, because larger (20-50 Watts per channel typically) amplifiers
may be used since size, heat and voltage issues are not a concern with these “outboard”
amplifiers. While some power is lost over the longer wire runs, the relatively low “watts© 2005 Leviton Mfg. Co. All rights reserved.
13
Audio System Design and Installation: Fundamentals of Audio Technology
per-dollar” ratio of these amplified systems overcomes that issue, making centralized
systems a great overall value.
Localized systems: Localized Systems are much more like communications systems
(such as telephone and intercom) – the cabling carries the basic signal, but all the
amplification and controlling is done by a dedicated component in the room itself, with
that component simply plugged-into the signal cable.
In a localized system,
the amplifier itself is
right in the listening
room and usually
built right into the
volume control or
keypad
In a localized system, the amplifier itself is in the listening room and usually built right into
the volume control or keypad, which theoretically should provide an advantage since the
amplifier is much closer to the speakers. The concept is simple: either single or multisource audio signals are sent from the centralized main system over low-voltage cabling
to each room-located volume control/amplifier unit, which powers the individual speaker
pair in that room or zone. Simplicity is the main advantage here – the requirement is
simply Category-5/5e cabling to each planned volume control/amplifier location, which
connects to the speakers via speaker wire.
The main drawback is an inherent power restriction caused by current limitations over
Category-5/5e cabling. Just by looking at the difference in size and capacity between
speaker wire and Category-5 UTP cable, you can easily grasp the concept. Electrically,
Category- 5 cable is a very small “pipe” as compared to 14 AWG stranded speaker cable.
In such systems, the Category-5 cable has to deliver the amplifier’s electrical power as
well as the audio signal. While the line-level audio signal from the entertainment center is
perfectly suited for Category-5 distribution, these localized systems also must power the
individual room amplifiers with 24 Volts DC over the same Category-5 cable. This restricts
their total power delivery capability, although such systems are fine for casual listening.
Given that the per-room cost of a localized system is equal to or higher than the per-room
cost of a centralized system (with a multi-room amplifier that can deliver 20-75 Watts per
channel to the same room), on a watts-per-dollar basis, the two types are not always
“apples to apples.”
Modular systems: A third type of system architecture is starting to appear. In a modular
system, all of the amplification is located right at the speaker itself, with the speaker
functioning as a “node” on an audio network.
Some early systems have debuted with speakers networked by speaker wire, Category-5
cable, and even wireless cards that are IP-addressable to function as part of an Ethernet
network. This area is still in the research and development stage, and because the
amplifiers are buried in the wall with the speakers, all the same power limitations of
localized systems also apply to analog-powered modular systems.
14
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
System Layout
Specifics on control and speaker location are covered later, but the overall plan should
assume that the system will have three “layers:”
Multi-Room/Multi-Source
Control and Amplifier Center
AV Reciever "Front End"
(and can serve as multi-room amplifier)
B. Central
Consolidation
Point
C. Back End
Audio Sources
A. Front End
System Block Diagram
A. The front end includes the AV receiver or entertainment center with associated source
components (tuner, CD changer, etc.). It is important to note that a QuickPort™ wall plate
should be installed behind the front-end location to allow for four speaker binding posts
(2 red/positive and 2 black/negative) for connecting the audio amplifier at the front end
with the central consolidation point.
B. The central consolidation point, such as a structured cabling panel. This panel may
either be the whole-house panel or a second, dedicated AV panel. All system wiring
(amplifier feed, speaker wires, and control cables) would be “home run for easy access
and configuration. The panel will also house any centralized audio distribution
components, such as multi-room connection blocks.
C. The back end, which includes from two to more than six rooms, each with one or more
speakers and a volume control.
It is important to note
that a QuickPort wall
plate should be
installed behind the
front-end location to
allow for four speaker
binding posts.
The system topology for communications wiring also applies to audio systems.
© 2005 Leviton Mfg. Co. All rights reserved.
15
Audio System Design and Installation: Fundamentals of Audio Technology
System Elements and Components
Speakers
Speaker types: the vast majority of installed multi-room and home theater systems
involve just three types of installed speaker:
Ceiling-mounted: Unless it is difficult to access, for music and background/foreground
entertainment, the ceiling is the best place for sound as they can cover the entire room
and remain out of “line of sight.”
Ceiling speakers are usually co-axial in design, which means the tweeter is in front of, and
mounted on axis with, the woofer. The most popular ceiling speaker size is 6.5 inches.
In-wall: While in most new construction the ceiling is very accessible, in retrofit situations
and special circumstances it may be easier to access the wall. And, for home theater
listening, the wall location is preferred for flanking the viewing area for a proper theatrical
presentation. 6.5-inch in-wall speakers are the most commonly used size with the 8-inch
speaker being the second most popular.
Outdoor: The growing popularity of developed outdoor entertainment areas (decks,
patios, spas, pools, etc.) has popularized the outdoor speaker. These speakers usually
resemble small indoor “monitor” speakers, with a smaller metal or plastic enclosure,
mounting bracket, and weatherized grille and connectors.
Each individual
speaker driver
is really an
electro-acoustic
linear motor.
Surround
Dust Cap
Terminals
Basket
Center
Voice Coil/Former
Magnet
Back Plate
Vent
Cutaway of a typical speaker
Speaker design and technical features: Typical in-wall and ceiling speakers are usually
of multi-way design, which means they are comprised of:
• A low-frequency driver (woofer) for reproducing bass
• A high-frequency driver (tweeter) for reproducing the treble range
• An optional mid-frequency driver (midrange) to reproduce the middle, or “vocal,”
region of the sound spectrum
• A crossover network to make sure that low, mid and high frequencies each reach
their assigned driver
Each individual speaker driver is really an electro-acoustic linear motor. All dynamic
speakers consist of three basic elements: a voice coil which sits suspended in a magnetic
gap surrounded by a magnet, and a cone or diaphragm which is attached to the voice
coil. When AC current from an amplifier is applied to the voice coil, it moves back and
forth in the magnetic gap, driving the cone/diaphragm and imparting acoustical energy
into the air in the listening room.
As a moving system, speakers have a natural resonance point, a certain frequency (usually
in the bass region) where they are the most efficient (where they produce a maximum
amount of sound with very little power applied). While resonance is easily managed and
can even be put to work in enclosed speakers, it can create acoustical problems with inwall and ceiling speakers.
16
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Tech Note: The “moving air” myth.
You may hear some custom installers boast of a speaker’s ability to “move air,”
which is inaccurate and misleading. In reality, speakers generate sound waves
which are a form of energy propagating through the air in the room, which is the
medium of their transmission. Speakers convert electrical energy into acoustical
energy and impart that energy into the air in the listening room; fans and blowers
“move” air. Sound waves behave just like ocean waves, which are the result of
energy moving through the water and not the water itself moving.
Speaker materials: There is a great deal of variation (and potential for confusion) in
speaker design and materials, and not all of that variation is for purely scientific reasons.
Given the amount of competition, a lot of brands resort to marketing “designer” materials
whose mere presence is no guarantee of improved performance.
Generally, all that is important is for the individual drivers to respond quickly to audio
signals in order to faithfully reproduce them, while not deforming in the process (which
would add distortion).
As a moving system,
speakers have a
natural resonance
point, a certain
frequency (usually
in the bass region)
where they are the
most efficient.
For woofers, that means constructing them out of materials that are as light and rigid as
possible. Treated paper, which has been used to form woofer cones since the 1920’s, is
now joined by materials such as polypropylene, aluminum, titanium and Kevlar. Kevlar,
which is a trademark of DuPont, has excellent characteristics – strong enough to stop a
bullet, yet light enough, as a fiber, to easily work with. However, even the most exotic
plastic or metal is still out-classed by old-fashioned paper when it comes to strength/
weight ratios. Paper is cellulose, an ultralight and rigid natural fiber. That’s why some of
the best woofers are a layered hybrid of paper and an exotic material, to get the best of
both worlds.
Tweeters can be made out of a wide variety of simple and exotic materials including
fabrics (silk, nylon), plastics (kapton, polymers) and metals (aluminum, titanium, even
beryllium). But, their final form – usually an ultra-light, micro-thin, dome-shaped
diaphragm – is dictated by the need to move at rates of up to 20,000 times per second in
order to faithfully reproduce high frequencies. Because the faster, shorter and higher
frequencies are much more directional (resembling a flashlight compared to the woofer’s
floodlight pattern), tweeter shapes take into account dispersion characteristics in order to
reproduce sound more evenly. While some in-wall and ceiling speakers feature directable
or swiveling tweeters to compensate, this can actually impair the stereo image (the
proper placement of the apparent source of sound in the room). A better approach is to
correctly engineer the speaker for even, wide dispersion at all audible frequencies.
© 2005 Leviton Mfg. Co. All rights reserved.
17
Audio System Design and Installation: Fundamentals of Audio Technology
▼
Tweeter
Speaker polar response
(Looking down at the
speaker)
Speakers are
rated in several
ways, power
handling,
impedance,
and frequency
response.
Midrange
Bass
Tech note: polar response is important—and swiveling tweeters can ruin it.
Because a woofer might be reproducing a sound wave over 50’ long while a
tweeter is dealing with sounds as small as half an inch, they do not radiate sound
the same way. A speaker’s polar response indicates how evenly the speaker
distributes, or disperses, sounds at different frequencies. As frequencies get
higher, the sound gets more directional. While bass notes are smooth and omni
directional in pattern (like a floodlight), midrange frequencies tend to “beam”
more like a spot light, and treble can behave like a flashlight. To overcome this in
in-wall and ceiling speakers, some speaker companies build a swivel point into
the tweeter so it can be aimed into the listening area, setting up a “sweet spot.”
Speaker specifications: As we have already discussed, speakers are rated in several
ways, power handling, impedance, and frequency response. Other factors include:
Open and enclosed designs: Most in-wall and ceiling speakers are open-backed. That is,
they are like a shelf speaker’s front baffle without the enclosure, similar to automotive
speakers.
The role of a baffle (either
an enclosure or a wall/ceiling)
By using the wall or ceiling cavity as an enclosure, this type of speaker offers relatively
high value and efficiency, which are useful advantages in whole-house multi-room
systems. But what if the wall or ceiling itself is not acoustically ideal? The fact is that
architects and builders do not make wall/ceiling design and material decisions based on
acoustics. The characteristic “hollow” sound heard in many in-wall systems is the result of
backward-radiating sound, often excessive mid-bass resulting from the speaker’s resonant
point, reflecting from the back wall and passing again through the cone and the wall itself.
The listener is actually hearing the reflected sound trapped inside the wall through the
thin cone.
18
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
In fact, a speaker mounted in a wall or ceiling can actually turn that wall or ceiling into a
transducer. Composite or hybrid cones, with their layers of materials, provide one level of
defense by minimizing the effect, and placing insulation behind the speaker can certainly
help.
Tech Tip: for liability reasons, any insulation materials must be suitably fire
and safety-rated for in-wall use! Carefully check the ratings and specifications
of any audio installation accessories, especially in production construction.
The best solution is to use an in-wall or ceiling speaker featuring a precisely-tuned subenclosure, which eliminates the wall or ceiling from the acoustic circuit altogether. This is
actually the preferred method in commercial and professional audio systems, and is
catching on in residential systems.
Speaker location: The listening room is a critical part of the acoustical circuit, and is
essentially a speaker enclosure in its own right. While it can’t be easily changed, there are
some guidelines to working with it.
Preliminary speaker location: In selecting speaker locations, the goal is two fold:
1. The locations should ensure even, smooth sound coverage in the primary
occupancy space for the room, and
2. The locations should be as unobtrusive as possible, out-of-the-way of furnishings
and not taking up any valuable decorating “real estate.”
Speaker considerations: Conforming to the location guidelines just mentioned is always
easier with ceiling speakers, which can effectively cover the entire room and do not take
up any living or decorating space. Ceiling mounted speakers are usually a close match to
the ceiling in color, and are not as likely to require wallpaper or color-matching.
Just as the vast majority of primary lighting fixtures are ceiling mounted, speakers, which
are really “sound fixtures,” should be similarly considered. Sound, like light, is reflected,
diffused and absorbed by room treatments.
As well, selling builders, architects, sales agents and ultimately end-users is much easier
when sound system components are out of the “line-of-sight.” Consumer preference for
ceiling speakers runs very high, which is why ceiling speakers account for two out of every
three speakers sold for professional installation.
Always consider the ceiling your primary solution, with in-wall speakers your back-up for
the following situations:
• Ceiling access is difficult or not advised for construction or other reasons (in a small
bathroom, for example, where they may be too asymmetrical or close to a ceiling
fan/light fixture
When specifying
volume controls, the
most important thing
to consider is not
speaker power but
rather the amplifier’s
output power.
• The room is so low and wide that too many ceiling speakers would be needed to
provide effective coverage throughout the room
• Home Theater applications, where in-walls are better-suited for front and center
sound reproduction (however, ceiling speakers are also suitable for surround
applications)
• Soffit situations, when taking advantage of a particular room design detail (archway,
niche, alcove, fireplace, etc.) is desired
Location basics: A low-ceilinged room is ideal for multiple ceiling speaker pairs, while a
higher-ceilinged room can get away with fewer speakers. The reason is that the sound
coverage fans out as the distance increases from the speaker, so the higher the speaker,
the wider and broader the coverage (the sound has more time to spread out).
© 2005 Leviton Mfg. Co. All rights reserved.
19
Audio System Design and Installation: Fundamentals of Audio Technology
Always consider the
ceiling your primary
solution, with in-wall
speakers as your
back-up.
If using the walls instead of the ceiling, in-wall speakers should be located on the longer
wall if possible. With in-walls, the best height is as close to (standing) ear-level as practical
given the room’s intended use. (Obviously, this must be compromised by furniture and
décor, and aesthetic considerations.) If the speakers must be mounted higher than earheight, they should be inverted to place the tweeters on the bottom and take advantage
of their extra directionality.
Design note: Ceilings rule.
While an in-wall location will rarely please everyone, few people object to ceiling
speakers—which is why most lighting is placed in ceilings instead of on walls.
Using the ceiling as the primary installed speaker location is always the path of
least resistance. While harder to access in a retrofit, ceiling speaker wiring is no
more difficult in new construction than in-wall. Take advantage of it!
Location specifics: The best horizontal speaker location can be determined by measuring
the speaker surface twice. First, divide the surface in half, and divide each half again (this
divides the wall into quarters). Note the two lines marking the divisions between the two
left quarters and the two right quarters (this is the outermost desirable speaker
placement). Next, divide the same surface into thirds, and note the two lines marking the
boundary of the first and third division. The difference between the lines from the quarters
and the lines from the thirds are the ideal range for placing a left or right speaker, with the
final locations dictated by room use and symmetry considerations. The same exercise can
also be used to plan speaker locations in a ceiling.
With either ceiling or wall placement, it is important to note that a speaker’s bass
response dramatically increases when the speaker is closer to one or more room
boundary. This phenomenon is called doubling. While shelf and floor-standing speakers
can be easily moved, in-wall and ceiling speakers are fixed and the mistakes are
permanent. Staying within the boundaries of the “Quarter/Third” method effectively pulls
the speaker locations sufficiently from the room boundaries to avoid bass doubling.
However, final placement will depend on the room’s sound “signature.”
2. Redivide into thirds
B
C
B
Axis A
A
Axis C
1. Divide surface
into half and quarters
Axis B
A
Axis B
B
C
B
3. "Boundary difference is
optimum for speaker location
4. Ceiling optimization
axis "A" is prefered
Quarter/Third Speaker Placement Method
Tuning the speaker locations to the room: This is much simpler than it sounds: simply
stated, rooms have different acoustic “signatures” that can be optimized by carefully
choosing the final speaker locations. Depending on construction and materials, and
furnishing and intended use, a room is either: hard (live) with a lot of sound reflections or
soft (dead) with fewer reflections.
In a hard room, sound appears to come from different locations and arrives at the ear at
different times, so the ear hears it as emanating from points beyond the room itself. This
makes the room sound larger-than-life.
20
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Because the majority of sound reaching the listener in a soft or dead room is direct
sound, the room sounds smaller since it lacks the multiple reflections that seem to
emanate from points beyond the room.
The following table illustrates sound absorption coefficients for particular building
materials in three frequency ranges (low frequencies, midrange and high frequencies).
Note: the higher the number, the more sound absorbed by the material.
Room Surface
Material:
Low Frequency
125Hz
Midrange
1000Hz
High Frequency
4kHz
Brick
.03
.04
.07
Acoustic ceiling tile
.76
.99
.94
Carpet
.02
.37
.65
Glass
.35
.12
.04
Drywall on studs
.29
.04
.09
Concrete block (painted)
.10
.07
.08
A carpeted, drywalled room with an acoustic tile ceiling is pretty “dead,” while the brick
room with large windows or patio doors is pretty “live.” But a live room may benefit from
a slight increase in bass to balance out the room’s inherent “brightness” and to minimize
reflections and irregularities, which is what moving the speakers closer to the boundaries
will do. This also reduces the “larger-than-life” sound of a live room.
As a rule, kitchens,
baths and dining
rooms tend to sound
“live,” and bedrooms,
family rooms and
dens tend to
sound “dead.”
Conversely, the “dead” room will benefit from speakers located further from the
boundaries and closer to each other, which will make the room sound more “live” and
slightly larger at the same time. As a rule, kitchens, baths and dining rooms tend to sound
“live,” and bedrooms, family rooms and dens tend to sound “dead.”
The rules to use:
1. in soft/dead rooms, speakers should be closer together (and further from room
corners/boundaries) to maximize reflections and minimize bass response
2. in hard/live rooms, speakers should be further apart (and nearer to room
corners/boundaries) to minimize reflections and maximize bass response
Transmission:
Sound penetrating
room boundries and
affecting adjacent
rooms.
Absorption:
Sound energy that
is diminished by room
surfaces or objects
in the room.
Reflection:
Sound literally
reflecting from room
surfaces.
Diffusion:
Sound reflected in
a random fashion
throughout the room.
Single speaker applications—a growing category, since stereo
speakers are useful in small rooms such as master bathrooms,
where there is a need for high-quality sound but not enough room
for two speakers. In this case, follow the same placement
guidelines for a room interaction with a more symmetrical location
(such as axes “A” or “C”).
© 2005 Leviton Mfg. Co. All rights reserved.
21
Audio System Design and Installation: Fundamentals of Audio Technology
Volume Controls
Types: The vast majority of installed sound systems use passive volume controls in each
room or zone (a zone is a listening area, which may be a room, or it could be several
room combined such as master bed and bath, or family/kitchen
area, or outdoor).
A passive control is in-line between the amplifier and speakers, and
attenuates the sound (it cannot amplify it). Although one still hears
antiquated terms surfacing in volume control discussions (such as
“rheostat” and “L-Pad”), since the 1970’s volume controls have
used autoformers (audio transformers) for more efficient signal
management and better performance.
Ratings and specifications: Volume controls usually have one
salient specification: power handling. Like speakers, they should
A sliding volume control
offer a peak and a continuous/RMS rating. And, like speakers, a lot
of volume controls out there just use the highest number. Insist on both for your own
peace of mind and your customer’s.
Tech note: don’t underrate the job of the volume control.
Remember that both the speaker and volume control are directly “in the line of
fire” with the amplifier’s output power. A high-power rated speaker connected
to a low-powered volume control forms a chain with a dangerously weak
link—and sets the stage for an expensive call back!
When specifying
volume controls, the
most important thing
to consider is not
speaker power but
rather the amplifier’s
output power.
Choosing the right power: When specifying volume controls, the most important thing to
consider is not speaker power but rather the amplifier’s output power. For example,
consider a whole-house system being driven by a high quality 150 Watt RMS stereo
amplifier. This is like a water system with a lot of potential pressure on one side, but it
needs fixtures on the other end equal to the task. That amplifier, under peak power
conditions and under high-demand conditions, can deliver almost twice its rated output
power for an instant. That amounts to 300 Watts Peak per channel. Divided over a fourroom system, each room must be prepared to handle at least 75 Watts RMS/channel, and
more is always better here. So, that “moneysaving” 100 Watt peak/50 Watts RMS control
is simply not going to be up to the job.
On the other hand, a 60 Watts RMS/channel amplifier could comfortably operate with
lower-powered controls. Multi-channel amplifiers for multi-room systems usually have
multiples of lower-powered amplifiers, and are more suited for lightweight controls.
Note: amplifier, volume control and speaker power-matching is thoroughly
covered in Part 4: System Design and Installation Planning.
Choosing the right type of volume control: A volume control must handle all the voltage
and current produced by the amplifier. As well, it must pass every audible frequency, from
20Hz to 20 kHz, to the speakers. This makes the volume control the weakest link in the
audio chain and often results in compromises that can be heard in the bass and treble
ranges. In fact, volume controls can contribute to the distinctive “nasal” sound associated
with in-wall and ceiling speakers, which is the result of filtering out some of the bass and
treble.
This is something that autoformer volume controls simply cannot avoid. Even the best
autoformers filter some low and high end sound, and lower-powered lightweight controls
are even more likely to do so (their lighter transformers can more easily “saturate” with
electromagnetic force/EMF). Leviton Integrated Networks also offers transformer-free
technology controls, which, as a purely “resistive” load, leave audio signal frequency
response untouched.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Tech note: To get rid of “in-wall sound,” first replace the volume control!
The muffled sound many people associate with installed speakers may actually be
coming from the volume control. Autoformers filter sound by nature—they
essentially create the same effect as turning down an amplifier’s bass and treble
controls would. Going to a non-transformer volume control can dramatically
improve the sound.
Both stereo volume
control inputs
0 dB
Transformer free
volume control
output
- 10 dB
- 20 dB
- 6 dB @ 58 Hz
- 6 dB @ 11.5 kHz
- 30 dB
- 40 dB
Major brand top of
the line transformer
control output.
- 50 dB
1Hz
10Hz
100Hz
1kHz
10kHz
100kHz
Autoformer versus transformer-free volume control.
Volume control locations: These should be planned for convenient access and based on
room use. For example, a kitchen area is also a communications center in the typical
home (most phone calls take place in the kitchen unless there is a home office). Having
the volume control relatively close to the phone/PC area is more convenient for adjusting
the sound level before making or taking a call. Bedroom and bathroom volume controls
should be easily accessible (some installers locate bedroom volume controls next to the
bed itself).
In a centralized
system architecture,
the first decision is
whether to use a
legacy amplifier
(one already owned
by the end-user),
or to provide the
end-user with a new
amplifier dedicated
to multi-room
sound.
Special features: Some volume controls enable IR routing (being able to receive
commands from infra-red remote controls and repeating them to the entertainment
center) and/or other major features. Leviton’s Decora Digital Chopin™ Volume Control
provides three-way room volume control much like a three-way light circuit lets you
control lights from different locations.
Amplifiers
Amplifier location: As mentioned previously, the amplifier will be located at the system’s
front end and connect to the central consolidation point using a wired QuickPort wall
plate with two pair of speaker binding posts.
Amplifier types and features: In a centralized system architecture, the first decision is
whether to use a legacy amplifier (one already owned by the end-user), or to provide the
end-user with a new amplifier dedicated to multi-room sound. Given the variables in
production residential construction and home sales, the best course will be to engineer a
system to accept a legacy amplifier while also accommodating a dedicated amplifier if
practical.
© 2005 Leviton Mfg. Co. All rights reserved.
23
Audio System Design and Installation: Fundamentals of Audio Technology
There are three types of amplifiers to consider:
AV Receiver: Many higher-end AV receivers have sufficient output power to drive a multiroom system, and some have multi-room/multi-source capability which allows using
some of the amplifiers in a surround receiver to drive multi-room speakers. As the most
popular category in consumer AV, the AV receiver is likely to be the amplifier of choice in
three out of four multi-room installations (and it does “double duty” running a built-in
home theater).
Two-channel amplifier: Also known as a stereo amplifier, this can work in place of or
alongside an AV receiver. Any higher-output stereo amplifier with a robust power supply
(at least 50 Watts RMS/channel) can power a properly designed multi-room system.
Multi-room amplifier: This is similar to a stereo amplifier, except it may have four, six,
eight or even twelve channels, with channel pairs assigned to different rooms/zones.
Because these designs have a lot more amplifier output devices (transistors) connected to
the power supply, each channel is usually lower-powered than a two-channel amplifier
(multi-channel amplifiers generally produce 20-40 Watts RMS/channel). Their main
advantage is flexibility in more complex (and custom) multi-room systems using keypad
control and separate functions and sources for different rooms.
Tech note: high current facts.
On that “high current” phrase: during the 1990’s, the phrase “high current” came
into wide usage. In audio, having sufficient current (amperage) does matter, but
only if both voltage and impedance are taken into consideration as well. In “realworld” audio systems, voltage, current and impedance are interdependent
concepts.
Other amplifier types to be aware of: Commercial amplifiers for music distribution use a
different amplification method called 70 Volt, which requires speakers with
complementary transformers for correct operation (you CANNOT use them without the
right speakers). 70Volt amplifiers are most often encountered in business, hospitality and
office venues. Do not confuse this with “audiophile” tube amplifiers which also have
transformers – these are autoformers more closely related to the ones used in volume
controls. You can treat an “audiophile” tube amplifier as you would a solid-state design
(tube amplifiers are rarely used in multi-room systems). A few solid-state amplifiers use
autoformers as well.
Amplifier features to look for: Some features and technologies are very useful for multiroom system operation.
a.
Music sensing – this automatically turns the amplifier ON when a musical signal is
present, allowing the amplifier to idle when not in use, which saves electricity and
minimizes wear and tear. On the downside, a long pause between songs (such as
a cycling CD changer can create) can send the amplifier back to idle mode, and
cause the first second or two of music to be dropped.
b. Impedance matching – yes, amplifiers have impedance issues as well, and some
of them offer switchable 4/8 Ohm operation for adjusting the output devices to
the load present. This helps maximize performance and prevent “overdriving.”
c.
Switchable speaker outputs – some amplifiers allow A and B speaker switching,
which helps set up dedicated audio zones.
d. Variable input/output – being able to adjust the volume of the amplifier itself is
extremely useful. It lets the installer and user set a maximum sound level for the
entire multi-room system.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Amplifier power: Power is one of the most misunderstood concepts in audio system
design. In fact, far more speakers are damaged more by too little power than by too much
power, which is why commercial sound system professionals usually increase the power
amplifier size when a client is “blowing” speakers frequently. The reason is that amplifiers
being grossly overdriven will clip (literally, clip-off part of the music waveform), producing
aberrant waveforms and excessive distortions. Because an amplifier can produce about
twice its rated output power in “clip” mode, this can easily result in thermal damage to a
speaker’s voice coil and mechanical damage to its moving parts. The most effective way
to minimize the chance of expensive (and time-consuming) damage is a two-stage
approach: Power and Protection.
Power – be conservative but “aim high.” Skimping on power can be expensive in the
long run, and tough on both amplifiers and speakers. There is a lot of copper in a multiroom system, possibly more than 1,000 feet of speaker cabling alone. Professional sound
engineers assume that a speaker is safe with a power amplifier with a Peak power rating
that is roughly twice the speaker’s RMS power rating, which means a speaker with a 60
Watt RMS rating can be used with an amplifier delivering up to a 120 Watts Peak/channel.
Next, they consider the user’s requirements for the sound system – a recording studio or
cinema, for example, might require sustained peak capability while more routine
applications may demand stronger continuous operation.
Far more speakers
are damaged more by
too little power than
by too much power.
For residential applications, the available Peak power in each room/zone should be no
lower than 50% of the speaker’s rated RMS wattage specification, and no higher than
150% of the speaker and volume control’s RMS specification to ensure an adequate
safety margin.
Tech note: calculating power often means adding apples and oranges!
To ensure an adequate safety margin, always compare the speaker and volume
controls RMS rating (continuous, minimum and more conservative) with the
amplifier’s available Peak power rating (more dynamic and “real-world).
Protection: Most amplifiers are designed to shut down if they encounter problems such
as shorts, low impedance, overdriving, etc. Leviton Integrated Networks highly
recommends protecting both distribution components and speakers.
Centralized protection at the point of distribution can shut down a speaker if it receives a
potentially damaging power surge. This is why Leviton is now building its AutoSurge™
protection technology into selected speakers and distribution components. The Leviton
Spec-Grade system is centrally wired through an Impedance Matching module with
AutoSurge technology, which ensures correct system matching and maximum overdrive
protection.
AutoSurge uses some of the same technology proven in Leviton’s Transient Voltage Surge
Suppression line (TVSS) for commercial and institutional use, effectively providing audio
surge protection as a built-in system component. AutoSurge-equipped speakers and
distribution components will briefly shut-down in the presence of damaging power, and
will automatically reset once the danger has passed.
Tech note: to protect speakers, increase the power.
It may seem counter-intuitive, but clean, ample power is less likely to damage
speakers than inadequate power. The reason is that a chronically underpowered
system is constantly running at “clipping,” where the amplifier is actually
chopping-off the audio waveforms due to its power limitations. A higher
powered amplifier is less likely to “clip,” and the clipping is what ultimately
damages speakers.
Note: amplifier, volume control and speaker power-matching is thoroughly covered
in Part 4: System Design and Installation Planning.
© 2005 Leviton Mfg. Co. All rights reserved.
25
Audio System Design and Installation: Fundamentals of Audio Technology
Cabling
Cable performance: most distributed audio signal travels over speaker wire, which is
multi-stranded two-conductor. The best wire to use will be between 12-16 gauge (AWG,
the lower the number the heavier the wire), with the strands themselves of a very light
gauge (165/34 wire means that each conductor is made up of 165 separate 34 gauge
strands). Most wire in this class will meet essential specifications for loop resistance (less
than .2 Ohms), inductance (less than .25 microHenries/foot) and capacitance (less than
50 picoFarads/foot). But don’t worry about these specs! They are simply there to
demonstrate that there is some science to proper cable design, contrary to most
audiophile cable marketing claims.
Cable ratings: It is critical to use and install only UL-rated cables specified for in-wall and
ceiling use, according to local wiring codes and the National Electrical Code (NEC). If you
use cabling not rated for in-wall and ceiling use, you expose yourself to a significant
liability risk.
Cable types: There are three types of cable used in multi-room sound and home theater
installations:
• Speaker level cable: Every speaker must be connected to an amplifier, usually
through a volume control, with cable designed for the job. Recall that cable length is
increased, its resistance also increased. And, when the cable diameter is increased,
cable resistance is decreased. In distributed audio systems, it is a good idea to keep
cabling impedances to a minimum, which is why speaker cable is multi-stranded.
These bundles of wires present the signal with a large overall diameter, thereby
providing a path of lower resistance for electron flow.
It is critical to use
and install only
UL-rated cables
specified for in-wall
and ceiling use.
Speaker cable, or wire, is measured in gauge. The smaller the number, the heavier
the cable. 14 gauge (14 AWG) wire, because it is easy to manage, terminate, and
has low impedance, is considered standard for multi-room. However, ensure that
the speaker wire is UL Class 2 or 3 (CL-2 or CL-3) rated for in-wall use. CL-3 rated
cable has an extra insulating (usually grey) sheath around the two insulated (red
and black) wires, and the designation “CL-3” will be printed on the cable. Note that
the main advantage of using a smaller cable is that it is easier to terminate. If you
want to use heavier “audiophile”-type cabling, you may need to terminate it using
special adapter tips in order to fit the cable into volume control connectors and
amplifier terminals. Note: in a plenum application (such as an air return), installed
speakers and cabling must be rated for plenum use (cable for this purpose will be
designated CL-3P). This, however, is rare in residential installations.
• Line level/pre-amp level cable: A large class, this includes everything from AV
component interconnect cables to specialized video cables for projection use.
Generally these are “shielded” cables, which means they have a grounded layer of
metal mesh or foil around the conductor(s) to prevent interference from outside
sources (such as speaker cables and AC wiring). In an installed system, the most
likely application for in-wall shielded cabling is connecting a receiver to an amplified
subwoofer, as both the AV receiver and subwoofer will have RCA-type inputs/
outputs. Again, if the cable is going into the wall it must be rated for in-wall use.
Note that the shielded coaxial cable recommended for distributed video
applications (RG-6 Quad shield) may be used in these applications with F-RCA
adapters.
Unshielded Twisted Pair (UTP): Also known as Category-5 or 5e cabling, UTP is gaining
ground as an accepted cable for line-level and preamp-level applications. UTP cable
protects the signal, without shielding, through a series of mathematically-correct twists in
the wire pairs, which neutralize any interference. (The technology dates back to the mid20th century, when rural telephone lineman started noticing that when they twisted cables
between long runs they got noticeably less static and noise at the ends.)
26
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
In multi-room audio and home theater, UTP cable is used for both line-level signal
distribution and control features, including IR routing. Because UTP is so inexpensive, it’s a
good idea to run it along with the speaker wiring to volume controls for any future
applications or upgrades (refer to Level 3/Part 6 for cable distance reommendations).
Most Category-5 UTP is rated for in-wall use, but check the jacket or box to be sure.
Tech Note: cable marketing—separating fact from fiction.
There is very little science in the ‘art and science’ of audiophile cables, and
electrons are notoriously brand-agnostic. Innumerable “double blind” tests have
proven that while listeners can detect a difference between adequate and
inadequate cabling, they cannot discern any differences between generic and
designer-branded versions of the same basic cable types.
Some essential specifications for speaker wire are:
1. loop resistance (less than .2 Ohms)
2. inductance (less than .25 microHenries/foot)
3. capacitance (less than 50 picoFarads/foot)
Most Category-5 UTP
is rated for in-wall
use, but check the
jacket or box to be
sure.
The important thing here is that most installer-grade CL-3 rated 14AWG stranded
speaker cable actually meets these specifications in the lengths typical of multiroom runs, and any cable that meets these specifications will not affect the sound
quality more than .5dB, which is less than 1/6th the minimum sound difference
detectable by the human ear (3 dB)! Given that even a significant deviation from
these specs might at worst affect sound by 1 or 2 dB which is still well below the
threshold of human hearing, it becomes apparent that the cable “debate” is more
Shakespearian than scientific—in other words, “much ado about nothing.”
Cabling should be the least expensive part of an audio system. Upgrading volume
controls, speakers and amplifiers is a much better investment.
© 2005 Leviton Mfg. Co. All rights reserved.
27
Audio System Design and Installation: Fundamentals of Audio Technology
Part 3: Basics of Home Theater
System Topology
Home theater planning and installation is very different (and usually less complicated)
than a multi-room system, for three reasons:
Side surround locations in side walls
Ceiling surround locations
Fronts
Center
Media Screen
Subwoofer locations
Back surround locations
in rear wall
Note: Expanded surround systems may require additional rear and side
speaker locations.
Self-contained: Home Theater systems are always confined to a single room. The home
theater receiver or amplifier outputs may also be used to drive a multi-room system, but
that will be through a connection from the AV receiver or entertainment center back to
the centralized structured cabling panel.
Wiring simplicity: No audio controls are required; the AV receiver or entertainment center
directly drives and controls the speakers. Moreover, the home theater system does not
“home run” back to a central panel. All wiring is located in the listening/viewing room,
and home run back to the entertainment center or AV receiver area. Finally, a modern
surround-sound receiver or amplifier has five or more built-in amplifiers designed to drive
speakers, so there is no impedance matching required.
Location: The main purpose of the system – audio enhancement and reinforcement of a
video experience – means that the layout and location of all audio components will be
dictated by the location of two elements: the viewing screen (TV or projector screen), and
the viewing area (usually couch or entertainment area). In production building, the
location for the screen/TV is determined by the location of AC and coaxial TV outlets, by
room fixtures (notably fireplaces) and where the rest of the furnishings are going to be
placed. Often, a simple review of building plans and discussion with the architect, builder
or decorator will provide all the necessary information to create an effective home theater
layout for production homes.
On-Wall vs In-Wall: Increasing in popularity are on-wall home theater systems using
small satellite speakers and dedicated subwoofers. The wiring plan is the same as in-wall/
ceiling systems, however.
28
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
System Elements
A home theater system will consist of the following:
Listening/viewing room: The same location considerations covered in Basics of MultiRoom Sound apply here, with one change: listening height should be determined by a
seated, not standing, listener, which will place the speakers slightly lower. If they must
remain high due to room considerations, it’s even more important to invert them to get
the tweeter location lower.
The same principles of hard/live and soft/dead rooms also apply. If the family room has a
large window area, you can almost count on it being live, while enclosed dens are usually
dead. Take into account that home theater rooms, by virtue of sofas, carpeting and usually
several people, are somewhat absorptive to begin with. Follow the same rule: increase
speaker distance from each other in hard/live rooms, and decrease speaker distance from
each other in soft/dead rooms.
Most rooms can be
adequately covered by
two properly-placed
speakers.
Design note: on surround-sound and speaker locations
While there are a number of standards out there, do not confuse the “channel”
designations with the number of speaker locations. Dolby Pro-Logic and Dolby
Digital, which account for virtually the entire market, both use five speakers. The
number designation in a surround technology usually refers to a particular
decoding format and not necessarily the number of speakers required. The trend
is actually toward fewer speakers. The new Dolby VS standard, for example, is
designed to reproduce full surround effects from only two speakers. Five speakers
plus a subwoofer location will cover most home theater requirements in
production building. Expanded home theater systems may add a rear center
channel (Dolby® 6.1) or additional surround speakers (Dolby® 7.1). While this is
outside the “Bell Curve”, it is a good idea to pre-wire for them for future
upgradability.
When placing surround-sound speakers, the preferred position is behind the
listeners. The next position is on the side walls flanking the listeners, and the third
position is in the ceiling above (and behind) the listeners. However, it’s important
to note that because most modern AV receivers with DSP (digital signal
processing) capabilities have a host of surround settings and room compensation
adjustments, speaker placement is not as critical as it used to be—when it comes
to adjusting a surround-soundfield, the modern AV receiver is both smart and
capable enough to do quite a bit of “correcting.”
Speakers and Speaker Locations:
Front left and right speakers: This pair or pairs will provide the main theatrical sound
image, and will flank the TV/screen area. An array system uses two pairs of front speakers,
with the top pair inverted so that the arrayed speakers’ tweeters are closest together.
Remember to plan for large entertainment center furniture. If this is likely in the viewing
location, position the speakers so they will not be obstructed.
Center channel speaker location: Leviton Integrated Networks recommends that you wire
a center channel speaker location but don’t install a speaker there. Moreover, that wired
location should be paralleled from a QuickPort wallplate with speaker binding posts near
the floor. The reason: It is almost impossible to correctly plan a center channel location in
production building because of the diversity in center channel arrangements and TV
design (a 50+inch large-screen TV, for example, will almost always block any installed inwall center channel!). By installing a speaker connection wallplate along with an in-wall
wire, the homeowner has the option for connecting-up his own enclosed or shelf centerchannel or having an in-wall center channel installed later.
Surround speakers: Properly-placed surround speakers can make the room appear larger.
© 2005 Leviton Mfg. Co. All rights reserved.
An in-wall and an enclosed
(shelf) center channel
speaker.
29
Audio System Design and Installation: Fundamentals of Audio Technology
Surround speakers
can be located above
the listeners, on
either side or rear
walls or in
the ceiling.
The trick is to remember that surround information is most convincing when not heard
directly, and that the surround-soundtrack is engineered to be reproduced as an “ambient
field” around and behind the listeners. This means that surround speakers can be located
above the listeners, on either side or rear walls or in the ceiling. While the preferred
placement is usually on the wall behind the listeners, this is not critical as final acoustical
adjustments can be made using the AV receiver or surround amplifier (all modern types
have reasonably sophisticated level-matching modes for fine-tuning a surroundsoundfield).
Tech tip: plan some additional surround options.
It’s not uncommon for installers to wire two or even three separate surroundsound speaker locations, such as ceiling, side wall and rear wall. It gives them a
lot of flexibility later, especially if the homeowner has space or decorating
requirements that rule out the first location.
Subwoofer location: Most AV receivers have an RCA (line-level) subwoofer output,
and a subwoofer is a common upgrade for many consumers. The Leviton
Integrated Networks recommendation is to install two QuickPort wallplates: one
behind the entertainment center, and the second in the likely subwoofer location
(usually a corner away from the sofa, and in proximity to AC power). Each
QuickPort plate will feature two RCA jacks (red and black), and will be connected
to each other using shielded in-wall audio cable so that the bass signal can be sent
from the AV receiver to the subwoofer. [Note: this is an excellent location for a
TVSS AC outlet to protect the subwoofer.]
AV Entertainment Center
Generally, the AV center will be close to the TV area with all AV components located
closely enough to use “patchcords” or interconnects. However, in some room designs the
TV location (possibly on top of a corner fireplace) may be some distance from the
component area (possibly built-in shelves or cabinets). In these situations a dual-gang
wall plate with two six-way QuickPort Decora inserts should be planned behind the TV.
An A/V entertainment center
Each should contain an F-connector (coaxial TV), left/right/video (red, black and yellow)
RCA jacks, and an S-video connector, with a corresponding dual-gang wallplate behind
the component area. This will enable multiple video sources (two RCA and two S-video)
to reach the TV; and the three RCA’s can be used for either composite audio/video or
component video.
30
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
The AV center is also the source for the speaker-level audio, which will require a second
two-gang wallplate with one six-way Decora insert and one four-way Decora insert. This
will accommodate five pairs of QuickPort speaker binding posts (each pair with one black
and one red), one pair for each of the five speaker locations: left front, right front, center
channel, left rear (surround) and right rear (surround).
The AV center area is another excellent candidate for a TVSS AC outlet to provide
protection for sensitive and expensive AV components.
Design note: planning for home theater and whole-house audio.
A lot of installers get confused when laying out an entertainment center.
Remember that there may be two concurrent functions in built-in home
entertainment: home theater and multi-room or whole-house audio. Remember
too that there are two ways of powering these functions:
1. The AV receiver is running both the home theater and the multi-room audio
package (in the multi-room/multi-source mode, a feature on a lot of higherend AV receivers).
Remember that
there may be two
concurrent functions
in built-in home
entertainment:
home theater and
multi-room or
whole-house audio.
2. The AV receiver is running the home theater, and a separate amplifier (either
two-channel or multi-channel) is running the multi-room audio package.
However, the AV receiver is connected to the separate amplifier (usually on
PREAMP or TAPE OUT) to provide sound source signals (CD, FM, etc.).
In either case, the components will usually be located in the same entertainment
center and connected to the centralized panel and distribution module in the
same way (through QuickPort wallplates and speaker cabling).
Cabling
The same three cable types used in multi-room sound and home theater installations are
also used in home theaters. Refer to the cabling section for specifications.
Design tip: subwoofer locations.
Installing a subwoofer wallplate means making a judgment call on subwoofer
location. Remember that because almost any modern amplified subwoofer is
equipped with adjustable gain, frequency and phase, placement is not as critical
as with passive subwoofers. A good rule-of-thumb is to locate the subwoofer in
the same general front plane as the left, center and right speakers, near one of
the room’s two front corners where it can be concealed.
The thing to avoid is putting the subwoofer in a location that may be a bass “null”
in relation to the listening area. Think of the room’s bass response as a
“checkerboard” pattern—moving a few feet may dramatically increase or decrease
the perceived bass. Moreover, many systems may sound fine while everyone is
standing—but when everyone sits down the bass drops away!
However, there is an excellent method of determining optimum locations in a
finished and furnished room. You can change places with the subwoofer—in other
words, place the working subwoofer itself in the listening location (such as on the
couch) and then move around the room listening to various locations. The
locations where you hear the bass sounding the best are the ideal places for the
subwoofer—when you trade places with it, the effect will remain the same.
© 2005 Leviton Mfg. Co. All rights reserved.
31
Audio System Design and Installation: Fundamentals of Audio Technology
Part 4: Design and Installation Planning
Working in Production Home Construction
Getting input from
builder sales agents
and even end-users
that can help you
fine-tune your
system plan.
The following information is geared toward new construction, where wiring and
component locations will be pre-determined based on the type of home and replicated in
multiple models. Making this successful will require close collaboration between the
contractor and the builder’s team (architect, interior designer, sales agents, and others),
and with end-users if possible. This is different from custom and retrofit installations,
where the relationship is generally directly between the contractor and end-user, and the
contractor has ample feedback on intended room use and living patterns.
You will encounter two production home scenarios (a new project and an existing
project), and based on that will want to adjust your system plan accordingly. Note that
while model homes are referenced below, keep in mind that some builders do not use
them, relying instead of centrally-located sales or design centers to feature options.
New project: In this scenario, you will be entering the development at the pre-production
stage, which also includes the model home(s). The advantage is twofold: you may be able
to influence a few of the audio-related final room parameters (such as TV location for a
family room), and will be able to perform a “from scratch” installation in the actual model
home(s). The latter is easier and gives you the opportunity to use that experience in finetuning the audio system plans for the production homes to follow. The disadvantage is
that you will have limited input from end-users and floor-plans (which may still be under
development) and will not be able to use an existing model home for review.
Existing project: This is when you are coming in after the model home is built and while
production homes are under construction. It gives you the advantage of working from
finished floor plans, and getting input from builder sales agents and even end-users that
can help you fine-tune your system plan and offering. The main disadvantage is that it will
be more difficult to retrofit a demonstration system in a model, and you will not have an
opportunity to influence any room options.
Review the builder’s product: Make sure you obtain complete plans for all home
models, as a builder may have many of them. You will want to prepare a complete AV
system plan (multi-room and home theater) for each. Also, make sure you review builderprovided plan options. Some builders allow their homebuyers to select different
entryways, staircases, and even number of bedrooms. Your audio system plans should be
flexible enough to accommodate these changes.
Blueprints, Floor and Electrical Plans
Multi-room system design: The purpose of reviewing these plans is to determine the
best locations for the following three multi-room system layers and the home theater
location. Note: while blueprints and electrical plans will contain the most technical detail,
the importance of floor plans cannot be overemphasized. More often than not, builderprovided floorplans illustrate room-use situations, which provides valuable information on
furniture locations (some plans even depict furniture), which is not easily discerned from
other types of building plans. The floor plan may be the most accurate information source
on how the room will actually be used.
Front end (source and amplifier component location): Note: if both a multi-room
system and home theater are being prewired, this may be the same location. As
mentioned in Sections 2 and 3, often home designs will feature a pre-determined media
center, identifiable by shelving and housing (alcove, niche, etc.) and proximity of AC and
low-voltage wallplates (especially coaxial F-connector plates for cable television).
32
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Centralized consolidation point: Since the premise will also have a structured cabling
system, the audio consolidation point will be either in or near the structured cabling
consolidation panel. This panel will be where the premises’ video, telephony, network,
and security wiring all converge. If a larger-scale audio system requires its own panel, it
should still be directly next to the structured cabling panel.
Tech tip: keep audio in its place.
It’s a good idea to use a second, dedicated structured cabling enclosure for audio
cabling and consolidation. Remember, speaker wires carry AC current which can
potentially interfere with communications and networking cabling. Some
installers use one enclosure for networking (Category-rated cabling and
distribution modules, LAN components, etc.) and a second for entertainment
applications (shielded coaxial video cabling and modules for satellite and CATV,
and audio wiring).
The floor plan may
be the most accurate
information source on
how the room will
actually be used.
Back end (room/zone locations): While these may differ between different home
models, within the same model they can be similar. It is essential to consult with the
builder/architect/designer to get the best idea of where furniture may go. For example, in
a bedroom or family/living room there is usually a bed/sofa orientation dictated by
windows, entry, AC outlets, and other features and consequently where speakers and
volume controls should be placed.
Home Theater location: While the room will likely be predetermined, it’s critical to learn
the ideal orientation of the home theater (viewing area related to seating, etc.).
Remember, speaker placement in home theaters is a performance decision dictated by
the geometry of the viewing area, as opposed to speaker placement for music listening
which is more of an aesthetic decision.
Design Tools
Along with building plans, there are PC-based AV system design tools available that
enable contractors to “drag and drop” components and systems into a presentable
document for planning, proposals and estimating. “D-Tools” is a prime example (and
contains Leviton Integrated Networks product data). While optional, these programs are
highly desirable business assets for audio/video system integration use.
Design note: preparing a PC generated professional-looking system plan
and proposal.
It’s easier than it looks, and can make a proposal look a lot more finished. Many
builders’ floorplans can be copied from their developments’ websites, or a
floorplan from a flyer can be easily scanned and saved as a digital file. Using
drawing software such as Microsoft’s’ Visio, it’s easy to build an audio component
placement and wiring plan over the floorplan (you can convert product photos of
speakers, volume controls and other audio components into icons and attach
“connection points” to them). The end result will be an audio system plan layered
over the builder’s own floorplan.
© 2005 Leviton Mfg. Co. All rights reserved.
33
Audio System Design and Installation: Fundamentals of Audio Technology
Power Requirements
Calculating system impedance and power requirements in unmatched systems:
Once a system is “mapped out” on paper, it is important to review the quantity of devices
comprising the system in order to make sure power and impedances are matched
(impedance-matching calculations will not be a factor when using the Leviton Integrated
Networks centralized impedance-matched systems). Remember, the entire system
impedance (volume controls, wiring and speakers) must present a load of no less than
four Ohms minimum and no more than eight Ohms maximum to the amplifier.
Remember the guidelines on power from Part 2:
For residential applications, the available Peak power in each room/zone should be no
lower than 50% of the speaker’s rated RMS wattage specification, and no higher than
150% of the speaker and volume control’s RMS specification to ensure an adequate safety
margin.
In other words, a speaker rated at 60 Watts RMS should have at least 30 Watts RMS
amplifier power available, and can safely operate with 60-90 Watts of Peak power
available (the speaker can, in fact, safely operate with even higher peaks, but this leaves
sufficient “headroom” for dynamic listening). Because impedance and other factors further
complicate the issue, dividing the amplifier’s power rating (which rises as impedance
drops) across a number of rooms/zones is not precise but does serve general planning
purposes.
The “right” amount
of power to use will
depend on the scale
of each system.
The “right” amount of power to use will depend on the scale of each system (how many
speaker pairs are being driven). A general planning rule is to assume that at least half of
the amplifier’s rated Peak and RMS power will be available to each room/zone at any
given time in a two room/zone system, a third to each area in a three- room system, a
quarter in a four-room system, and so on. Furthermore, as a safety margin you should
always match the speaker or volume controls RMS rating (continuous and more
conservative) with the amplifiers Peak rating. As an example, if you are dealing with a
100 Watt RMS/200 Watt peak amplifier, and follow the rule that the Peak power in each
room should be no greater than 150% of the RMS rating for speakers and volume
controls, that breaks down as follows:
Number of
rooms/zones
2
3
4
Approximate Potential Peak amp power
in each room/zone (each channel)
100 W
66 W
50 W
Approximate minimum speaker/
volume control RMS rating (each)
66 W
44 W
32 W
In rooms using two pairs of speakers (to cover a larger area, for example), both pairs of
speakers will usually be paralleled off a single control , which will lower overall
impedance and increase the amplifier’s available power to that room. Maintain the same
power handling requirements for four speakers as you would a pair (in other words, do
not “lighten up” on power handling just because you are using four speakers instead of
two).
Tech note: calculating power often means adding apples and oranges!
To ensure an adequate safety margin, always compare the speaker and volume
controls RMS rating (continuous, minimum and more conservative) with the
amplifier’s available Peak power rating (more dynamic and “real-world”).
34
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Location Strategies
When applying system components to a floor plan, remember that multi-room speaker
placement will be guided by aesthetic considerations (including furnishings and décor),
while home theater speaker placement will be dictated by performance needs (front and
surround-sound).
Speakers (indoor and outdoor): Refer back in this manual for placement guidelines
based on room geometry and composition. Using that information along with the floor
plan for each individual room/zone, select at least two ceiling or wall locations (and
alternates in case the walk-through identifies any installation conflicts).
Indoor locations: Most rooms can be adequately covered by two properly-placed
speakers, especially rooms under 400 square feet, as well as rooms with a very defined
listening area (such as bedrooms). For larger rooms, multiple speakers will ensure
thorough coverage (follow the power rating guidelines). In combination areas, remember
that each area should have at least one dedicated speaker pair – one pair for the kitchen
itself, and one for the family area, for example.
Most rooms can be
adequately covered by
two properly-placed
speakers, especially
rooms under 400
square feet.
Regardless of design or materials used , all outdoor speakers should be shielded
from direct exposure to the elements, if possible.
Outdoor locations: First, consider the primary area of use. If there is a deck or spa, the
speakers should be located where their sound can be directed toward that feature.
Second, consider long-term environmental effects. Outdoor speakers should be mounted
under an eave or overhang whenever possible to shield them from direct exposure to
rain, sun and snow.
Electrical considerations: Always cross-check the floor plan with the electrical plans,
especially when planning ceiling speakers, for proximity to lighting fixtures and junction
boxes. For planning sound locations in kitchen and bath areas especially, electrical plans
will show ventilation fans, heaters and other potential problems that floor plans will not.
To avoid heat and interference problems, keep speaker locations at least 12 inches away
from any motors or other AC-powered units, and lighting fixtures. As a general practice
always stay away from electrical wires whenever possible!
Volume Controls: Be sure to plan controls for easy accessibility based on room entry and
room use. Often, the lighting control location will be a tempting spot for a volume control
(again, cross-check the floor plan with the electrical plan). But remember that dimmers
are a potential source of interference—it is better to avoid getting close to them (if you
must mount an audio control near a dimmer, consider using a type which does not route
the audio signal through the control such as Leviton’s Decora Digital Volume Control or an
equivalent. In any case, low-voltage volume controls must be isolated from line voltage
devices (switches, dimmers and fan speed controls), either with a separate mounting
bracket or a rated divided box. As with speakers, it’s always good practice to select an
alternate location just in case.
System distribution components: In keeping with the star network topology used in all
structured cabling systems, the right location for audio distribution components is back at
© 2005 Leviton Mfg. Co. All rights reserved.
35
Audio System Design and Installation: Fundamentals of Audio Technology
the wiring consolidation point and in a structured cabling panel. These components
include simple speaker-level connecting blocks (where a left/right amplifier output is
divided into separate rooms/zones, combination speaker protectors/impedance matchers,
and IR-routing products.
Speaker wire should
be kept away from
both 120VAC
wiring and
communications
cabling
Cabling: This is the one element requiring a thorough integration with the electrical and
floor plans. As with communications and network wiring, audio cabling should not be run
in close proximity to AC wires. Rather, it should be kept at least 8 inches away (and if it
must cross an AC line, it should do so at a 90-degree angle). However, it is also important
to remember that signal and speaker-level audio cabling is AC wiring because the audio
signal uses alternating current measured in cycles per second, or Hertz. While speaker
wire operates at lower current and voltage levels than Romex, it also generates an
electromagnetic field (EMF), which can cause interference. For that reason, speaker wire
should be kept away from both 120VAC wiring and communications cabling (such as
Category 5 UTP).
Planning speaker wire runs: Remember that:
• Each room/zone will require two runs of twin-lead (positive and negative
conductors) or one run of four-conductor speaker wire, one for stereo LEFT and one
for stereo RIGHT. That is four conductors total. The two speaker wires/per room will
run from the central consolidation point to the volume control box, where it “splits,”
with a single speaker wire running to each individual speakers.
• There must be two twinlead or one 4-conductor speaker wire runs and a Category5/5e run from the “front end” amplifier location back to the central consolidation
point, in order to power the multi-room system. These will terminate in back of the
entertainment center or AV receiver using a Quickport wallplate and four speaker
binding posts (two for LEFT, two for RIGHT).
• You should avoid firebreaks and insulation and only use internal walls for speaker
and audio wiring. You can also use attics and crawlspaces or basements.
Other wiring: Plan on running Category-5/5e from the central consolidation point to each
volume control location, for any future repeater or signal transmissions applications, or if
planning a “localized” system with dedicated room amplifiers.
Home Theater variables: Home Theater is the exception to the star topology rule, as
that application is dedicated to a single room. However, the home theater entertainment
center will invariably need to communicate back to the centralized multi-room system,
which should be planned for in planning the layout. Remember to carefully review the
floor plans to determine likely seating locations for placing front and surround speakers,
and review the electrical plans to find the AC outlets and cable-TV jacks that will indicate
likely television placement and corroborate the seating arrangement assumptions.
The Walk Through
Working from the marked-up floor/electrical plans (or a separate audio system plan based
on them), calibrate the plan with a walk-through of the production home model frame. If
you are getting involved with an existing home development project after the builder’s
model home is constructed, you will want to use the model home as a guide for room
use and furniture placement.
Marking locations: Use the walk-through as an opportunity to mark-off primary and
alternate locations prior to rough-in. Take careful note of any challenges likely to come up
during installation.
Estimating the bill-of-materials (BOM): Use the walk-through to finalize a complete billof-materials (BOM) for a production home.
36
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Part 5: Developing the Bill-of-Materials
Based on the audio system plan, the next step is to prepare a complete bill-of-materials
which will include products from three categories and a fourth category of cabling and
labor:
Bill of Material Considerations
Control and distribution components
• Volume controls and color-change kits.
• Centralized distribution components, including impedance matching and basic
connection blocks
• AV media distribution, including Leviton’s Decora Media System (DMS), which
converts composite audio/video signals to Category-5 cabling. In Leviton Integrated
Networks Spec-Grade systems, the DMS is recommended for interfacing the PC to
the AV center for playing MP-3 music and internet-based entertainment on the
distributed audio system. (The DMS “receive” unit connects to the AV receiver as an
AUX input.) This category also includes any IR distribution for using infra-red
remote controls)
Speakers and mounting accessories
• Indoor speakers and rough-in kits. Remember, for both practicality and security
reasons during a rough-in you will not be leaving many products behind. Speakers,
for example, will be installed after the drywall is completed. You should plan on a
rough-in kit for each speaker pair, to reserve the location and make it easy to locate
wiring afterwards.
Remember, for both
practicality and
security reasons
during a rough-in you
will not be leaving
many products
behind.
• Volume control and wallplate “mud-rings.” For the same reason as with speakers,
plan on sufficient mud-rings to reserve low-voltage control and wallplate locations.
• Strike- and nail-plates. These will protect low-voltage wiring in situations where
you can’t wire through the center of a stud, make sure your BOM includes
strikeplates (also called nailplates) to prevent the drywallers and other contractors
from driving nails or holes through your audio wiring.
Installation accessories
• Wall plates. There are many different types. Nylon plates are tougher and more
flexible than plastic, and are recommended. Midway plates are about 25% larger
than ordinary plates, and are useful in covering-up any installation problems (make
sure you match them with other Midways). Leviton also makes blank inserts useful
for “future proofing” installations, as well as wall plate extenders that are useful
when a volume control needs some extra depth. For low-voltage connections,
Leviton offers the Quickport snap-in mounting system in two styles:
• Decora inserts (2-, 3-, 4- and 6-port Quickport inserts that fit into a standard
Decora wall plate)
• Traditional QuickPort (2-, 3-, 4- and 6-port wall plates).
Covers
• Protects the Strauss™ volume control in outdoor applications. Leviton has several
weather-resistant cover options. Most installations will have a simple wall-mounted
volume control and can use the basic Leviton 4998 cover. Some patios and decks
may call for a freestanding volume control (attached to a railing or post, possibly, or
the side of a gazebo). In this case, the volume control may be in an outdoor,
conduit-mounted box, and will be encased in a special Leviton outdoor box cover
with door (or equivalent).
© 2005 Leviton Mfg. Co. All rights reserved.
37
Audio System Design and Installation: Fundamentals of Audio Technology
Connectors
• Leviton makes a multitude of Quickport snap-in low-voltage connectors, but the two
that will comprise 99% of your audio installations are:
• Speaker binding posts (the standard connector for amplifier interfacing)
•
Home Theaters do
not use volume
controls or
centralized
distribution.
However, the types
of products are
the same.
RCA connectors (used for line-level audio and video, such as connecting
SUBWOOFER OUT on an AV receiver to a subwoofer wallplate elsewhere in the
room).
TVSS (transient voltage surge suppression) outlets
• Along with protecting speakers, it is also important to protect sensitive AV
components. All Leviton Structured Media Centers have a provision for TVSS outlets.
The same outlets can be installed behind a home theater system or entertainment
center to provide additional protection for AV receivers, DVD players, etc.
Cabling and Labor
• This should be based on both the plan and walk-through, to accurately anticipate
any additional requirements. Since you will be running speaker wire and other
audio wire through internal walls and not external walls to avoid insulation and
firebreaks, plan the lengths accordingly.
Home Theater BOM
There are a few differences: Home Theaters do not use volume controls or centralized
distribution. However, the types of products are the same.
BOM Examples
Leviton has provided a sample Spec-Grade Bill-of-Materials with typical quantities. By
using this format and pluging-in your product/cabling prices and labor rates, you can
estimate a job based on your audio plan, and then you are ready to proceed to the prewire rough-in stage.
38
© 2005 Leviton Mfg. Co. All rights reserved.
BILL OF MATERIALS
Leviton Spec-Grade Sound
Total
RESELL
PN
Dash
Color
option(s)
Strauss VC
SGVST
00W
W
Decora slider volume control with transformer-free technology
0
Decora slider volume control with transformer-free technology
VC color change kit
SGVCK
0IA
IA
Ivory & almond color change kit for Strauss
0
Ivory & almond color change kit for Strauss
System matching module
audio board
SGAMP
48211
000
06A
0
0
Module with Impedance-matching and AutoSurge protection (RMS)
Passive audio module
0
0
Distributes whole-house audio from structured media panel
Passive audio module
48210
48210
48210
48210
MCH
SRU
MSU
MRU
0
0
0
0
Decora Media System hub w/pwr supply
DMS Send & Receive units w/pwr supply
DMS Send unit only w/pwr supply
DMS Receive unit only
0
0
0
0
In-wall speaker
in-wall rough-in kit
SGI65
PCI65
00W
KIT
W
6.5-in in-wall speaker
6.5-in in-wall rough in kit
0
0
6.5-in in-wall speaker
6.5-in in-wall rough in kit
In-wall speaker
SGI80
00W
W
8-in in-wall speaker
0
8-in in-wall speaker
in-wall rough-in kit
PCI80
KIT
8-in in-wall rough-in kit
0
8-in in-wall rough-in kit
Ceiling speaker
SGC65
00W
W
6.5-in ceiling speaker
0
6.5-in ceiling speaker
ceiling rough-in kit
Outdoor speaker
PCC65
SG099
KIT
00W
W
6.5-in ceiling rough in kit
Environmental/Oudoor weather-resistant speaker
0
0
6.5-in ceiling rough in kit
Environmental/Oudoor weather-resistant speaker
screw-on wallplate
screw-on wallplate
designer wallplate
designer wallplate
midway wallplate
midway wallplate
special metal wallplate
wallplate accessory
outdoor cover
outdoor cover
outdoor cover
Quickport jack plate
Quickport jack plate
Quickport jack plate
Quickport jack plate
Quickport accessory
Decora Quickport insert
Decora Quickport insert
80401
80409
80301
80309
80601
80609
84003
6197
6196
4998
5977
40702
40803
40804
40806
40859
40850
40753
00*
00*
0S*
0S*
00*
00*
000
00*
VFS
00*
0**
0B*
0B*
0B*
0B*
0B*
0B*
0B*
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A,E
0
W,I,A
zinc
W
CL
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
Decora 1 gang plate
Decora 2 gang plate
Decora 1 gang snap-on plate
Decora 2 gang snap-on plate
Decora 1 gang oversized plate
Decora 2 gang oversized plate
1 gang metal surge protect label plate
Decora device wallbox extender
FS Box-type Decora device weather-resistant cover
Decora device weather-resistant cover
Decora device weather-resistant easy-mount cover
Quickport 2 port plate
Quickport 3 port plate
Quickport 4 port plate
Quickport 6 port plate
Quickport blanks
Decora 2-port inserts
Decora 3-port inserts
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Standard Decora plate
Decora Quickport insert
Decora Quickport insert
audio
video
audio
Quickport audio connector
Quickport audio connector
wallplate accessory
Surge receptacle
Surge receptacle
40754
40756
40830
40830
40830
40833
40833
80414
8280
5280
0B*
0B*
B*E
B*Y
B*R
B*E
B*R
000
000
000
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A
W,I,A, GY
I, W, R, B,
GY,W,A
Decora 4-port inserts
Decora 6-port inserts
black RCA
yellow RCA
red RCA
black binding post
red binding post
Decora blank insert plate
Hosp. grade surge receptacle w/ alarm
Industrial grade receptacle
0
0
0
0
0
0
0
0
0
0
Type
Description
Quantity
Price EA Total COST
Application Notes
1. Control & distribution
A/V media converter
A/V media converter
A/V media converter
A/V media converter
Brings PC-Based audio signal to AV receiver/entertainment center
2 SG speakers
3. Installation products
0
Installation (labor & cabling)
Labor (estimated)
Wire & Cable
Wire & Cable
Project Totals:
Low-voltage/hour
Low-voltage/foot
Low-voltage/foot
structured cabling, voice/data,
multimedia, security & communications
Cat 5/ multimedia
Speaker & AV special
Rate
Hours
Per foot
Total feet
Midways are larger plates that can cover installation problems
Used to identify AC surge outlet (below)
Used in patio and deck free-standing locations
Used in outdoor wall-mounted locations (typical)
Used in patio and deck free-standing locations
Four-way speaker plate (LEFT red & black, RIGHT red & black)
used to interface amplifier to multi-room audio distribution module
amplifier connector
amplifier connector
For protecting entertainment center (AC device)
Sub Total Product
0
0
0
0
Labor total
0
Product total
0
SYSTEM TOTAL
Total number of rooms/zones in project
#DIV/0!
PER ROOM/ZONE PRICE
Audio System Design and Installation: Fundamentals of Audio Technology
Part 6: Pre-Wire/Rough-in
Rough-In is the stage where the system infrastructure is laid into the premises, as a
“backbone” for all controls and speakers to be installed later.
Scheduling
Rough-in is usually during a time-sensitive stage in the construction cycle for two
reasons:
• It must be done after the premise is framed but before the walls, ceilings and other
access ways are “closed up,” and
• There are usually a number of other contractors working on the same project at the
same time, and often in the same space. You will want to communicate clearly and
frequently with any other incumbent contractors to make sure the job goes
smoothly.
• The best time to wire for audio is during the structured cabling prewire
The best time to
wire for audio is
during the structured
cabling prewire.
• The best window of opportunity is before drywall and insulation, but after AC wiring
and HVAC is in place.
Tools and materials
• All standard tools, which include drill and bits, pliers, strippers, etc.
• Special tools and items
• VOM (Volt/Ohm Meter)—used in checking electrical continuity.
• Measuring tape and carpenters’ level for ensuring straight mud-rings. Note: a
crooked mud-ring will yield a crooked wall plate and an unhappy builder and
ultimately customer. Take the time to do it right during the rough-in!
• Drill extensions. Although most useful in retrofit installations, drill extensions can
save time and make frame installations easier when reaching for hard-to-access
areas
• Strike- or nail-plates
• Speaker rough-in kits
• Mud-rings for mounting low-voltage devices
• Cable and cable management products, including wire-ties and wraps
Review of standard low-voltage wiring practices
• Low-voltage wiring is not as damage-resistant as Romex; handle it carefully.
• Only install UL-rated CL-2 or CL-3 cabling
• Speaker cable, or wire, is measured in gauge. The smaller the number, the
heavier the cable. 14 gauge (14 AWG) wire, because it is easy to manage,
terminate, and has low impedance, is considered standard for multi-room.
However, ensure that the speaker wire is UL Class 2 or 3 (CL-2 or CL-3) rated for
in-wall use. CL-3 rated cable has an extra insulating (usually grey) sheath around
the two insulated (red and black) wires, and the designation “CL-3” will be
printed on the cable. Note that the main advantage of using a smaller cable is
that it is easier to terminate. If you want to use heavier “audiophile”-type
cabling, you may need to terminate it using special adapter tips in order to fit the
cable into volume control connectors and amplifier terminals. Note: in a plenum
application (such as an air return), installed speakers and cabling must be rated
for plenum use (cable for this purpose will be designated CL-3P). This, however,
is rare in residential applications.
© 2005 Leviton Mfg. Co. All rights reserved.
39
Audio System Design and Installation: Fundamentals of Audio Technology
• Leviton recommends independent 1-inch holes drilled 1-1/4 inches from the edge
of the stud for running low voltage cable. If you must drill a shallower hole, use a
strike-plate to protect the wiring
Use appropriate
cable management
products (such as
Velcro straps, tie
wraps and other
mounting
accessories) for
securing audio
cable.
• Never run low-voltage cable in the same drill holes as AC wiring. Run low-voltage
wiring in a separate stud space whenever possible. Maintain at least an 8-inch
distance when running parallel to AC. If you must cross an AC line, do it at a 90degree angle to minimize interference
• Although it is tempting to locate audio controls near lighting controls, the latter is a
strong source of interference (especially Triac-equipped digital dimmers). If you
must use a volume control near a lighting control, consider using Leviton’s Decora
Digital Volume Control or an equivalent product that does not run any audio signal
through the control itself
• Remember that speaker wiring is also AC wiring—keep it separate from
communications cabling
• Avoid damage to UTP wiring and low-voltage cables in general by never exceeding
25-pounds of pulling force
• Maintain at lease a 1-inch bend radius for UTP wiring, and 3 inches for RG-6
quadshield, shielded audio cables and speaker wire. Use sweeping bends instead of
sharp turns that can damage cables
• Use appropriate cable management products (such as Velcro straps, tie wraps and
other mounting accessories) for securing audio cable. Never use staples.
• If running cable in conduit, leave a pull cord to access it later. Do not fill the conduit
past 40% of its capacity
• Install cabling in inner wall spaces to avoid wall insulation and firebreaks
• Keep cabling away from sources of heat such as hot water pipes and HVAC ducts
• Keep speaker cabling away from potential interference sources such as range
hoods, bathroom fans, central vacuums, etc.
• If you must run external wiring, use conduit.
The techniques for managing
communications and video
wiring are applicable for
multi-room audio—avoid
“pinched” cable bundles and
sharp cable bends, and always
use approved cable
management ties instead of
stapling cables.
40
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Wiring the Premise
At the volume
control locations,
make sure you leave
enough of a service
loop for later
access and
termination.
Review of audio wiring topology (working from the front end, or entertainment center):
1. From the entertainment center, TWO two-conductor speaker wires or one fourconductor MUST run to the central distribution point (usually a structured cabling
enclosure), for connection later to the distribution module. A Category-5 UTP cable
SHOULD be run from the entertainment center to the central distribution point for future
control and signal applications (the UTP does not need to be terminated at either end;
leave an appropriate service loop at each end for future access and termination). The
speaker wires will be terminated at the entertainment center with a stereo binding-post
QuickPort wallplate or equivalent.
2. From the central distribution point, TWO two-conductor speaker wires or one fourconductor (LEFT and RIGHT) MUST run to each volume control location to ensure that
BOTH left/right channels reach each room. A Category-5 UTP cable SHOULD be run from
the central distribution point to each volume control location for future control and signal
applications (the UTP does not need to be terminated at either end; leave an appropriate
service loop at each end for future access and termination) or for local room-based
amplification. At the volume control locations, make sure you leave enough of a service
loop for later access and termination.
3. Each speaker location in the room will get a SINGLE two-conductor speaker wire
coming from the volume control location in that room. It is not necessary for the speaker
wires to run together, and not always desirable—try to keep each speaker location’s wire
length matched to within 25% of the other to ensure that each speaker’s volume matches
the other (if this results in excess wire on one speaker, it can be run up and down a stud
in the prewire). Remember to leave an adequate service loop at the speaker location for
later access and easier termination.
© 2005 Leviton Mfg. Co. All rights reserved.
41
Audio System Design and Installation: Fundamentals of Audio Technology
Tech tip: plan some extra locations up-front.
Especially in a new project where end-user preference is still unknown, it may be
desirable to plan a second volume control location (this is most valuable in
master bedrooms). This is easier than it sounds: simply pass the TWO twoconductor wires through the first location and make a service loop, and then
route them onto the second (final) location for later “splitting” to the speaker
locations. Make a note of the both locations for later access, and use an “old
work” box for mounting the control in the drywall. Make sure you “zig-zag” the
paired wires between the paralleled studs for easy access later.
Wiring methodology:
1. Working from the central consolidation point, drill 1-inch holes in the center of each
stud through which the audio cabling will pass. If you must drill the holes off-center
and closer to the drywall side, use a strike- or nail-plate to protect the wiring
A digital camera is
extremely handy for
“remembering”
what’s inside the
wall later.
2. Maintaining the minimum bend radius, pull each room audio cable “bundle” through
the holes and to the volume control location. If you are pulling UTP cable along with
speaker wire, do not exceed 25 pounds of pulling force. A cable-pulling assistive tool is
very useful here
3. Make sure the ends of the wires pass through their respective mud-rings and speaker
rough-in kits, so that volume controls and speakers can be easily connected later. The
exception is if you are planning alternate volume control locations: both locations will
be loops inside the wall, and you will use an “old work” box later for mounting the
control—make sure you “zig-zag” the paired wires between the parallel studs for easy
access later. Each speaker rough-in kit will have individual instructions for a particular
model speaker; make sure you follow them. Make sure the mud-rings are straight to
avoid problems later
a. Use only approved cable management products to secure audio wiring – NEVER
staple it
b. Leave a service loop at each wire termination point. This ensures you’ll have
enough wire to work with later
4. Label each wire end for easy identification later
5. Install mud-rings or boxes for volume controls after you have completed the wiring run
to those locations (exceptions are multiple control locations, which will be marked for
later access and will get an “old work” box).
6. Install any required wall or ceiling rough-in kits for mounting speakers after you have
completed the wire run to those locations. Arrange the wires appropriately for the
particular kit.
7. Document your work for trim out. Make a note of any changes from your original plan.
A digital camera is extremely handy for “remembering” what’s inside the wall later.
Tech tip: don’t install speaker rough-in kits that may place the speaker too
close to a stud or floor joist.
If a speaker is too close to a stud or floor joist, the doglegs on that side may not
swing OUT properly—be careful not to get the mounting location too close.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Installing a rough-in kit during prewire “saves the space” for later installation.
Tech tip: how to make sure you can get at speaker wires later?
When you wire for extra or future speaker locations (especially in home theater
center channel and surround applications), the best way to ensure future wire
access is to make it easy to reach inside the wall. Many installers “zigzag” the wire
between the studs where the speakers may go, from outlet height to ceiling (or
zigzag inside the ceiling itself). This makes it a lot easier to find the wire later.
Document your
work for trim out.
A digital camera is
extremely handy for
“remembering”
what’s inside the
wall later.
Tech tip: watch those wire “bundles.”
Remember that speaker wire is not shielded. If you have an excess anywhere do
not get tempted to coil it—this can form an inductor and affect the sound quality.
Trim excess lengths accordingly (leaving short service loops is OK).
Wiring outdoor speakers:
Outdoor speakers will be surface-mounted instead of in the wall. Make sure the exit path
for the wire leaves room for the speaker and its mounting bracket, and make sure that the
wire and speaker/bracket assembly will be mounted away from direct exposure to the
elements (such as under an overhang).
Wiring the home theater:
The home theater wires using the same procedures and practices as multiroom sound,
with several differences:
Central consolidation point—the home theater speakers “home run” back to a two
or three-gang plate behind the entertainment center or wherever the AV receiver will
be located. Home theater speakers do not connect back to the structured cabling
enclosure.
Center channel location—this will be an option, wired through a floor (outlet level)
wallplate and then up the wall in a zig-zag pattern to provide an option for future
center installation in the wall. Leave a generous service loop at the floor location for
termination.
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
Give the end-user the
flexibility to install the
center speaker in a
variety of locations.
Subwoofer location—the subwoofer will also wire back to the entertainment center
or home theater receiver, but using shielded audio cable and/or UTP.
Alternate surround locations—because furniture placement may vary depending on
the homebuyer, it is an excellent idea to have two or even three surround locations
wired (back wall [preferred], side wall and ceiling).
Preliminary Premise Wiring Check
At this stage, it is preferable to check for cable continuity to identify any shorts or other
potential problems. This can save you considerable time later once the walls are closed
up.
It’s essential to
check for cable
continuity, to identify
any shorts or other
potential problems
before the walls are
closed up.
Preparing the wiring: To accommodate standard volume control and distribution
connectors, strip away about 1/4-inch of insulation from each conductor (the two speaker
wires and the four volume control wires). If using CL-3 (sheathed) cable or CL-3P
(plenum sheathed) cable, you will first remove the outer insulating sheath (usually grey)
before stripping the inner wires. Gently twist the copper strands slightly to smooth down
any stray ends.
Checking continuity in speaker wiring: First, return to the central consolidation point.
Each individual speaker wire will have two conductors (PLUS and MINUS, usually copper
and silver or red and black).
1. Gently tie the two bare ends of each wire together to deliberately make a “short”
2. Go to the volume control location and set the VOM to the “resistance” mode.
3. Take the other end of that wire and attach one of the probe tips from the VOM to
each wire.
4. If the wire is intact and current is flowing through the connected ends at the other
end of the run, you will get a reading
5. If you do not get a reading, first check the connection at the other end (it may
have come apart) and then inspect the cable run to find the cause. Pay particular
attention to any bends or kinks in the cable, and look for missing insulation.
Dressing the wires: Re-wrap the stripped wire ends with electrical tape to protect them
during the dry-walling stage.
Reading
Twist pair together
to create a short
VOM
Checking continuity on speaker and volume control wire runs.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Part 7: Trim-Out
Trim-Out is the phase when all installed system components are connected to the cabling
infrastructure laid in during rough-in.
Scheduling
Trim-out may occur in multiple stages:
• Speaker, control and distribution component installation
• System configuration and amplifier connection
Much of this will depend on the builder/homebuyer loop and when the installer is
actively engaged by the end-user.
Tech tip: don’t leave audio components in an unsecured location!
You will want to wait until the house is lockable and most other contractors are
done before installing high-value components such as speakers and controls.
You will want to
wait until the house is
lockable and most
other contractors are
done before installing
high-value
components such as
speakers and
controls.
Tools and Materials
Tools: Aside from standard tools, plan on having the following useful items:
• Set of jewelers’ screwdrivers (essential for connecting volume controls and
distribution blocks to speaker wire)
• Diagonal cutters (“dikes”)
• Multi-gauge wire-stripper
• VOM (Volt/Ohm Meter)
• AA, C or D 1.5 Volt battery (for the testing phase)
• Alligator clip-equipped insulated test leads
Materials: Refer to the BOM section of this manual for a complete list. Generally, except
for cabling, mud-rings and speaker rough-in kits, almost everything is installed during
trim-out. Make sure the premise is secure before undertaking this stage. Speakers and
volume controls are often “target” items on jobsites, as they have high value and are easy
to remove.
QuickPort Insert and
wallplate.
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
Preparation
It is a good idea to walk the premises before starting and inspect all mud-ring/speaker
rough-in kit locations to make sure the wire is still accessible. If the wires are not
accessible, correct the situation. Some installers prefer to lay out speakers and controls in
each room/zone, to avoid confusion when working with assistants.
An advantage of
specifying ceiling
speakers is that they
need painting far
less frequently than
in-wall types.
Installing and Connecting Speakers
If you start with the speakers, you can use the connected speaker to check continuity in
each room as you work back to the central consolidation point (structured cabling panel
location).
Preparing speakers: If the speakers need to be
matched to the ceiling or wall, this is the best time
to paint them (the speaker’s white color should
match the majority of ceilings and walls, making
this step optional). Refer to the instructions
published with the speakers if painting is required.
In general, use a template to protect the baffle area
(woofer and tweeter) so that just the frame gets
painted. If the grilles are fabric, avoid heavy
painting, as this will absorb the sound. With metal
grilles, make sure you remove any screening
material on the inside of the grille (many grilles
have a foam layer behind them, which will also
absorb paint).
The wired speaker fits the hole using the rough-in kit.
Tech tip: painting speakers.
An advantage of specifying ceiling speakers is that they need painting far less
frequently than in-wall types. If you are painting speakers, remove any cloth or
foam inserts behind the grille itself—they can become clogged with paint and
affect sound quality.
1. Remove any excess construction material from the rough-in kit area.
2. Using the template provided with the speaker, outline the size hole to be cut (if any) to
conform to the speaker mounting requirements. Make sure the hole is no larger than
the template requires; otherwise, the mounting “doglegs” may not have enough surface
to grab. Make sure both speaker holes are even and straight.
3. Using a jig or drywall saw, cut away any excess ceiling or wall material. You may want
to start the hole with a drill.
4. If you are planning on putting any insulation on the wall or ceiling area behind the
speaker, this is the best time. Insulation can reduce some “booming” and smooth bass
response, and also help reduce in-wall or ceiling “cavity” sound. You can use standard
wall insulation for this purpose: R-11 rock wool or fiberglass “blanket” insulation works
extremely well (observe all precautions when handling the material). There are also
speaker “back-boxes” on the market designed for this purpose, but always check for a
UL fire-ratings for in-wall, ceiling and plenum use.
5. The speaker will have a set of “doglegs”, which swing out behind the wall when the
front accessible screws are turned to lock the speaker in place. Make sure the doglegs
are in the “tucked” position (close to the speaker).
6. Take the wire from the rough-in, and remove the protective electrical tape from the
ends. Gently twist the copper to make sure there are no loose strands (these can cause
shorts).
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
If using sheathed CL-3 cable, it will have a RED and BLACK wire inside the (usually)
GREY outer sheath. Connect the RED wire into the RED terminal and the BLACK wire
into the BLACK terminal, by pushing the terminal button, inserting the wire into the
hole, and releasing the button.
If using other cable, check for a distinguishing mark on one of the twin leads: either the
wire may be copper (RED) or silver (BLACK), or the insulation on one side will be
ribbed or otherwise marked (use the marked side for RED and the other for BLACK).
Note: the important thing with speaker polarity is to ensure that each hook-up is
consistent. It is actually immaterial which color refers to which lead, as long as they are
the same in each room.
7. Making sure any excess wire is tucked back into the ceiling or wall cavity, gently slide
the speaker into the hole. If you use an electric screwdriver, use the lightest torque
setting and slowest speed possible – do NOT over tighten the doglegs as they easily
can be broken off. Take a screwdriver and tighten each of the front, or baffle, screws
until they resist (do this in opposing order, like changing a tire). Check to make sure
the speaker is secure (this means the doglegs are in the correct position). Tighten the
screws further, but not so tight that the speaker frame deforms.
It’s really easy to
forget to connect
the wires to the
back of the speaker
before installing it!
8. Repeat the process for the other speaker. Do not put the grilles on until you have
tested the system (you will need to remove them if there are any problems).
Tech tip: check and double check—and watch those studs!
It’s really easy to forget to connect the wires to the back of the speaker before
installing it! It’s also easy to miss a mounting dogleg that may be in the OUT
position and prevent the speaker from lining up properly. If a speaker is too close
to a stud or floor joist, the doglegs on that side may not swing OUT properly—be
careful not to get the mounting location too close.
Checking your work
Let’s briefly cover what is meant by “observing speaker and amplifier polarity.” Both the
amplifier and speaker, being AC devices, require a “return path” for current. When the
speakers receive the AC music signal, they must move in tandem: a base note should
make both woofer cones move outward first, then inward, for example. This is called
being in-phase. The amplifier, the speaker, and the volume control have a positive and a
negative terminal. The important thing is to make sure all positive terminals are
connected to each other, and all negative terminals are connected to each other.
Sound from one
speaker
Absorbed
by the other speaker
In Phase
Out of phase
Speaker phasing
If they are not, it will not cause damage but will greatly impair performance, as the system
would now be out-of-phase. With one speaker moving inward while the other is moving
outward, the net effect is severe cancellation of bass frequencies. If you run into a
situation where one room lacks deep bass and the vocals sound odd and distant, you
likely have wired the room out-of-phase. The situation is very easy to correct: simply turn
the system OFF, remove the volume control, and reverse the wires going to one of the
speakers.
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
If you suspect any wiring problems, you can easily and quickly check speaker polarity and
continuity before connecting the volume control.
1. Simply go back to the volume control location and identify the two conductors
going to each speaker.
2. Taking one of the two-conductor wires, separate the conductors.
3. Take a 1.5 Volt battery (size AA, C or D are useable) and connect the speaker wire
BLACK (or minus) lead to the MINUS, - or negative battery pole.
4. Momentarily touch the RED lead to the battery’s PLUS, + or positive pole.
5. If both wires are connected, you should hear a loud “tick” coming from the
speaker. Do not leave the battery connected for more than an instant, as
sustained DC voltage can damage speakers by causing their voice coils to
overheat.
6. If you suspect that you may have reversed some wires in the room, this method
can also be used to check polarity (whether or not the speakers are in-phase). If
the system is in-phase and correctly wired, each speaker cone should move the
same way when the battery is applied to either side. If not, the room is out-ofphase.
Installing Outdoor Speakers
Outdoor speakers
are a prime target
for jobsite thieves.
Remember to install outdoor speaker under an overhang or anywhere where they are not
directly exposed to rain or sun. Make sure the wire exit hole is sealed-up to prevent
moisture from entering the frame. It is a good idea to position and mount the brackets
before attempting to connect and install the outdoor speakers.
Tech tip: hang onto those outdoor speakers until the end!
Outdoor speakers are a prime target for jobsite thieves. A lot of installers prefer to
install the brackets and tape their business card to them, inviting the homebuyer
to make the call and get their speakers—it also provides an up-sell opportunity.
Installing and Connecting Volume Controls
The volume control has multiple connections: it takes in both stereo channels from the
amplifier, and sends them off to both speakers. This alone requires eight separate
connections (four inputs and four outputs).
1. Make sure any construction materials are removed from the mud-ring/mounting ring
or J-box where you intend to mount
the control.
2. Identify the four speaker signal twoconductor wires. Two wires will be
coming from the amplifier (actually
from the centralized distribution
module in a Leviton system), and two
will be connected to the room’s
speakers.
3. Remove the protective electrical tape
and twist the copper to smooth any
loose strands. This is especially
important with volume controls, as the
small, dense connection blocks make it
easy for loose strands to connect and
short.
48
The volume control wires using a modular connector.
© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
4. Make sure that only 1/4-inch of insulation is removed from the wire. Removing too
much insulation can leave exposed wire outside the connector (and jamming it in will
cause “bunching” inside the connector). Ideally, the bare wire should disappear into
the connector’s hole, leaving no unexposed wire.
5. Take the volume control’s removable connection block (standard on the Leviton
Strauss control). Loosen each of the eight connector securing screws.
6. Observing the connecting scheme outlined on the control, take each two-conductor
wire and insert its ends into the corresponding pair of holes.
7. Once both wire conductors are in their respective holes, keep gentle pressure on
them to keep the wire buried up to the insulator, and tighten their corresponding
screws until they can’t be turned anymore.
8. Repeat the process for the other three two-conductor wires.
It’s all too easy to
mount volume
controls upside
down—check the
orientation before
buttoning-up
your work.
9. Snap the wired connector back on the volume control’s circuit board. The control is
now ready for use.
10. Install the control into the mounting ring or J-box using the two long screws provided,
and install the wallplate. Make sure the control is right-side-up.
Tech tip: watch those volume controls!
It’s all too easy to mount volume controls upside down—check the orientation
before buttoning-up your work. There is usually a logo or icon on the front to help
identify direction.
Connecting the Distribution Module (for multi-room
audio distribution)
As mentioned earlier, a Leviton Integrated Networks Spec-Grade system is centrally wired
through a System Matching module with AutoSurge technology. This will ensure correct
system impedance matching and extra speaker overdrive protection. The System
Matching module is installed and wired during the trim-out phase.
1. At the centralized wiring point (in the main structured cabling panel or in a dedicated
audio panel), identify the paired two-conductor wires or single 4-conductor wire going
to each room (they should have been labeled in the rough-in stage). Note that the
System Matching module has similar connectors to those used on the Leviton Strauss
volume control, except that each one has four connectors instead of eight.
The main amplifier connects to the System Matching module, as will
each room.
© 2005 Leviton Mfg. Co. All rights reserved.
49
Audio System Design and Installation: Fundamentals of Audio Technology
2. Remove the protective electrical tape from the wire ends.
3. Connect each room’s two-conductor wire pair to the System Matching module using
the same procedure as the volume control. The two-conductor wire pair coming from
the amplifier/entertainment center location (LEFT and RIGHT) will connect to the INPUT
on the System Matching module.
4. Once connected, snap the module into the structured cabling panel’s mounting holes.
Gently pull any excess wire away from the module and use a cable management wrap
to dress the wire bundle. The System Matching module is now ready for use.
Tech tip: make the wiring easy on yourself.
It’s really easy to
create electrical
shorts on denselypopulated audio
connectors using
finely-stranded
speaker wires—
always check for
shorts!
It’s a lot easier to remove audio connectors and wire them off the device itself
(volume control and module). It is usually easier to connect the wired
connector(s) to the device first, and then mount the device as a final step. Finally,
it’s really easy to create electrical shorts on densely-populated audio connectors
using finely-stranded speaker wires—always check for shorts!
Making the Amplifier Connection
Back at the entertainment center or “front end,” identify the two-conductor wire pair (or
single 4-conductor run) going to the System Matching module at the consolidation point/
structured cabling center. The last step involves connecting those wires to a wall platemounted set of binding posts, so that by using that wallplate the amplifier can be
connected to the entire installed system.
1. Clear any excess construction material away from the mud-ring/mounting ring or
J-box.
2. Remove the protective electrical tape from the wire ends.
3. Select a QuickPort snap-in binding post (use RED for the positive wire conductor
and BLACK for the negative conductor).
4. Loosen the small screw on the back of the Quickport binding post and insert the
bare wire end up to the insulator. Tighten the screw.
5. Repeat the process for the other three conductors.
6. Snap the connected binding posts into a Leviton 4-port Decora insert in the
following order: the two LEFT conductors on the top (RED left, BLACK right) and
the two RIGHT conductors on the bottom (RED left, BLACK right).
7. Install the completed Decora insert in the mounting ring or J-box, and install a
Decora wall plate to finish the job. The amplifier interface is now ready for
connection.
Use wallplate mounted binding posts for all ampliffier connections.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Installing and Connecting the Home Theater
Follow the same speaker installation procedures and practices outlined earlier for multiroom audio, and observe the following differences:
• All speakers and connections are in the same room, which makes installation
and testing easier. Make sure each speaker two-conductor wire run has been
labeled: LEFT FRONT, CENTER (location only), RIGHT FRONT, LEFT REAR, and RIGHT
REAR (surrounds).
• Remember, the amplifier connection will be five channels instead of two channels.
You will use a two-gang Decora wallplate and two inserts: a 6-port for the LEFT,
CENTER and RIGHT FRONT channels and a 4-port for the LEFT and RIGHT REAR
(surround) channels.
Remember, for
home theater the
amplifier connection
will be five channels
instead of two
channels.
A home theater connector wallplate.
• Install a 5-channel speaker plate and terminate (that’s RED or + and BLACK or –
for each of five speakers, a total of TEN connections). Follow the procedures in the
last section “Making the Amplifier Connection.”
• Center channel location—install a QuickPort or equivalent single-speaker wallplate
(this will have one RED or + connector and one BLACK or – connector, usually a
binding post), preferably near the floor at standard outlet height for the room. Cut
the speaker wire at the service loop, and connect the run from the home theater
wallplate location to the two binding posts from the back of the wallplate. If the
consumer is going to use a stand-alone center channel (the majority of the market),
they can easily connect it to the terminated wallplate using the terminals. If the
consumer wants an in-wall center channel, simply remove the plate, disconnect the
two wires, and splice them into the rest of the wire run going up the wall (you can
use butt connectors or other suitable types for stranded copper wire). Finally,
connect the other end to the in-wall center channel speaker being installed.
• Subwoofer location—install two (stereo) RCA connectors on a wallplate behind the
subwoofer location, and connect to either the shielded cabling or UTP run
previously (shielded cable with usually require an RCA or F-RCA connector, UTP will
usually use a 110 connector). Install another stereo RCA connector pair behind the
entertainment center and terminate based on the style connector being used
(again, shielded cable with usually require an RCA or F-RCA connector, UTP will
usually use a 110 connector).
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
Part 8: Set-Up and Troubleshooting
The system should be interfaced and activated with an amplifier to determine any
potential problems. This is extremely important to assure the builder that the built-in
audio system was delivered in perfect working order. It is also highly recommended that
you leave behind documentation to that effect.
Activating the Multi-Room System
You will need a two-channel or multi-room amplifier to test the system and a sound
source (this can be a portable CD/MP-3 player or PC with MP-3 files and an RCA output
cable).
It is extremely
important to assure
the builder that the
built-in audio system
was delivered in
perfect working
order.
1. Make sure all volume controls are in the DOWN (off) position to avoid any
surprises. Also, make sure the VOLUME (gain) control on the sound source is
turned DOWN as well.
2. Make sure the amplifier is turned OFF. Connect the amplifier’s LEFT and RIGHT
output up to the QuickPort wall plate with the stereo speaker binding posts.
Observe polarity.
3. Connect the sound source’s OUTPUT to the amplifier’s stereo INPUT via an RCA
cable (on a personal stereo or PC, this may be a mini-stereo plug (headphone
type)-to-RCA LEFT/RIGHT adapter.
4. If the amplifier has any INPUT/OUTPUT or GAIN controls, turn them DOWN as
well.
5. Turn the amplifier ON. If it enters the protection mode after turn-on, turn it OFF
immediately and check the system for any shorts.
6. Raise the volume at the sound source to about 25%. If the amp has INPUT/
OUTPUT controls, raise them to 25% as well. You will now have audio streaming
from the source through the amplifier.
7. Go to the closest room and raise the volume control 25%. You should hear music
out of both channels. If you do, repeat the process for all the other rooms and
check to make sure both speakers are playing.
8. Go back to the “front end” where the amplifier is located, and raise the sound
source to 50% and the amplifier to 100%.
9. Go back to the closest room and raise the volume control. You should be able to
get room-filling sound without distortion, without raising the control all the way
UP.
10. Repeat the process for all the other rooms. The multi-room system is now ready
for use.
Activating the Home Theater System
You can also use a stereo amplifier to check a home theater system, which is actually
simpler given that there are no volume controls and the system and source are in the
same room.
1. While in the OFF position, connect the amplifier to any two of the five speaker
terminals on the five-channel QuickPort wall plate you installed earlier (behind
the AV receiver or entertainment center location).
2. Turn the amplifier ON with the sound source connected to it. Make sure the
VOLUME on the source is all the way DOWN.
3. Gently increase the volume level on the sound source. You should hear music on
two speakers.
4. Repeat the process for the other installed speakers. The home theater system is
ready for use.
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© 2005 Leviton Mfg. Co. All rights reserved.
Audio System Design and Installation: Fundamentals of Audio Technology
Basic Troubleshooting
The primary troubleshooting tool is logic in tracking down, locating and isolating
problems. For example, a problem affecting all rooms is probably occurring between the
amplifier and the consolidation point (the System Matching module in the structured
cabling center, for example). However, a problem occurring in only one or several rooms
is probably occurring at or near the room level (between the volume control and
speakers). Remember it is always easier to check (and eliminate as the trouble source)
cables, amplifiers and connections before pulling out volume controls and speakers!
Tech tip: the right way to troubleshoot.
Remember to always work backwards in troubleshooting—the fastest way to find
out what’s wrong is process of elimination while using logic to determine where
the problem can and can’t be.
An example: one channel out across the entire system (one speaker in EVERY
room) would have to be confined between the distribution module and the
amplifier. Always check the easy things first, and take nothing for granted: that
includes the audio patchcords connecting a source component to an amplifier, for
example.
The primary
troubleshooting tool
is logic in tracking
down, locating and
isolating problems.
Finally, you can reverse cables to see if the problem changes. For example, if you
have the LEFT channel out on the system and you reverse the LEFT and RIGHT
wires coming from the amplifier and the module and the problem reverses as a
result (the RIGHT channel is now out) then the problem is between the amplifier
and the source. If the problem does not reverse, then it is between the
connecting module and the rest of the system.
The following section covers some of the problems commonly found in multi-room
and home theater installations.
• If there is no sound anywhere
• First, make sure the amplifier and sound source are functioning (try using a pair
of outdoor speakers right off the amplifier.
• If the amplifier works, check the connections at the amplifier’s QuickPort wall
plate.
• Next, check the LEFT/RIGHT INPUT connection at the System Matching module in
the structured cabling center.
• If the connections seem OK, disconnect one of the room connections in the
panel and hook it up directly to the amplifier. Repeat the process. If the amplifier
can drive the rooms directly, the problem is between the structured cabling
center and the amplifier’s connection wallplate (or in the System Matching
module itself)
• If only one or several rooms are without sound
• The problem is between the central distribution point (System Matching module
and/or structured cabling center) and the room; or, within the room itself.
• To eliminate the System Matching module, repeat the procedure above with the
amplifier directly at the distribution center. If the affected rooms now play sound,
the problem is at the System Matching module or the structured cabling center.
If not, the problem is in the rooms.
• To check the rooms, bring the amplifier to each affected room. Disconnect the
volume control and remove it from the box. Pull off the connector. Remove the
LEFT and RIGHT two-conductor wires going to each speaker. Connect the
© 2005 Leviton Mfg. Co. All rights reserved.
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Audio System Design and Installation: Fundamentals of Audio Technology
installed speakers directly to the amplifier. Turn the amplifier ON, and gently raise
the sound source VOLUME. If you hear sound, the problem is at the volume
control. If not, it is at the speakers.
• If one or several rooms has sound in only one speaker
• Repeat the procedure just described, to identify whether the problem is at the
speaker or at the volume control (or in the wiring in-between).
• If the speakers make a “rattling” or “buzzing” sound
• Often, debris such as dust, drywall pieces and excess wire insulation can fall into
a speaker (this is most common in ceiling installations). Rather than remove the
speaker for cleaning, try this approach:
1. Make sure the amplifier’s VOLUME control is all the way DOWN.
2. Using an FM tuner, get some clean inter-station noise with the FM muting
turned OFF.
3. Turn the BASS control up.
4. Gently increase the amplifier’s volume until you get a mid-level “roaring”
sound like a waterfall. It should not be so loud that you can hear the speakers
popping or distorting. After 30 seconds of play, the movement of the cones
should have bounced all the debris from the back area. If the speaker
suddenly shuts OFF, it is likely that built-in protection has engaged. It should
reset in a minute or two.
• If a room (or rooms) lacks bass and/or vocals sound weak
• This usually indicates a phasing problem. If all the rooms suffer from this, the
problem is between the amplifier and the Impedance Matching module and/or
the structured cabling consolidation point. Simply switch one of the PLUS and
MINUS connections at the System Matching module’s input. (If you switch both,
the phase problem will not go away.) If a single or several rooms suffer from this,
the problem is at the room. Repeat this procedure at the SPEAKER connection at
the back of the volume control. Once the room is in-phase, the bass should be
restored.
• If channels are inverted (LEFT sounds come out of the RIGHT channel)
• The problem is that a LEFT and RIGHT connection was simply switched
somewhere. If it is in one room, check the volume control and speaker wiring. If it
is across the system, check the connections between the amplifier and the
System Matching module. While this situation may escape notice in multi-room
music, it is very noticeable and critical in home theater, where special audio
effects will appear in opposition to the video action.
• If the system shuts-down during operation
• This usually means two things:
• The System Matching module has been activated. Check the volume level,
and check the amplifier’s operation. If the amplifier is producing potentially
damaging current or transients, the protection will engage.
• The amplifier’s own protection circuit has been activated. If you are not using
a System Matching module, check all the volume controls (an impedance
mismatch will send the amplifier into protection). Check for shorts in the
system.
54
© 2005 Leviton Mfg. Co. All rights reserved.
Leviton Manufacturing Company, Inc.
59-25 Little Neck Parkway, Little Neck, NY 11362-2591
Telephone: 1-800-323-8920 Fax: 1-800-832-9538
For answers to technical questions, call the Tech Hotline toll-free at
1-800-824-3005, 8:30 AM to 6:00 PM E.S.T.
Visit Leviton’s website at http://www.leviton.com
© Copyright 2005 Leviton Manufacturing Co., Inc. All rights reserved.
S-739/F5