REVISION(S)
Octave Filter Set Type 1624 (English DK BE 0563-12)
A revision of the previou$ Instruction Manual (English DK BE 0563-11) to comply
with new instruments:
•
Level Recorder Type 2317;
•
Power Supply ZG 0254;
Curves on Inherent noise and Phase shift have been included.
Dept.3, June 1985
"•
31 ...
OCtave Filter set
The selectable centre frequency range is
from 31 ,5 Hz to 16 kHz and a linear position
gives a frequency band from 5 Hz to 75
kHz. The analysed signal may also be
weighted by selecting "A" or "C" frequency
weightings on the Sound Level Meter.
+
Brliel & Kjmr
Instruction Manual
Octave Filter Set Type 1624
aro.aaaq.,
Type 1624
Rudy for
nut:Filtet
•
An Octave Filter Set primarily intended for
use with Precision Integrating Sound Level
Meter Type 2230 or 2233. Used with either
of the Sound Level Meters, it forms a compact and portable lightweight unit enabling
in situ octave acoustic analysis. Semi-automatic recording of the analysis is possible
using either Level Recorder Type 2317, 2306
or Type 2309. Manual stepping of the filter
is indicated by a green LED.
The selectable centre frequency range is
from 31 ,5 Hz to 16 kHz and a linear position
gives a frequency band from 5 Hz to 75
kHz. The analysed signal may also be
weighted by selecting "A" or "C" frequency
weightings on the Sound Level Meter.
+
Bri.iel & Kjc:er
OCT AVE FILTER SET
TYPE 1624
From serial no.1 032482
Revision May 1985
CONTENTS
1.
INTRODUCTION AND SPECIFICATIONS (PRODUCT DATA) ............................................................................ 1
2.
CONTROLS .................................................................................................................................................................. 5
3.
OPERATION ................................................................................................................................................................. 7
3.1.
3.2.
3.3.
PRELIMINARY ........................................................................................................................ 7
POWER SUPPLY .................................................................................................................... 8
Battery check .......................................................................................................................... 8
Battery replacement .............................................................................................................. 8
Mains Supply and Charger ................................................................................................... 8
FREQUENCY ANALYSIS ....................................................................................................... 9
Introduction ............................................................................................................................. 9
Frequency Analysis ................................................................................................................ 9
Frequency Analysis with Level Recorder .......................................................................... 10
Frequency Analysis with earlier Level Recorder ............................................................. 13
4.
APPENDIX ................................................................................................................................................................. 14
5.
SERVICE AND REPAIR ........................................................................................................................................... 16
types 1624 and 1625
Octave Filter Set and
Third Octave/Octave Filter Set
USES:
• Filter Sets for Sound Level Meters
• Semi-automatic octave noise analysis (Type 1624)
• Loudness evaluation in accordance with ISO R
532 (Stevens and Zwicker)
• Noise checking to octave and third-octave limiting
curves
• Automatic 1f3 octave and octave (with 1f1 or 1f3
oct. step) noise analysis (Type 1625)
• Building acoustic measurements
• Attenuation of background noise
• Sound power measurements on machines
• Distortion measurements
FEATURES 1624:
FEATURES 1625:
• 10 octave filters in accordance with IEC
R 225-1966, DIN 45651 and ANSI S1.11-1966
Class II requirements; and unweighted linear
response
• 31 third-octave and 31 overlapping octave filters
in accordance with IEC R 225-1966, DIN 45651,
DIN 45652, and ANSI S1.11-1966 Class II & Ill
requirements; and unweighted linear response
• Centre frequencies from 31 ,5Hz to 16kHz,
frequency range 22Hz to 22kHz (octave), 5Hz to
75kHz (Lin)
• Centre frequencies from 20Hz to 20kHz,
frequency range 18Hz to 22kHz (1/3 oct.)
and 14Hz to 28kHz (oct.), 3Hz to 75kHz (Lin)
• 0 dB nominal filter attenuation
• 0 dB nominal filter attenuation
Octave Filter Set Type 1624 and
Third Octave/Octave Filter Set Type
1625 are primarily designed for use with
Sound Level Meters Types 2230, 2231
and 2233 for in situ octave and 1/3 octave
acoustic analyses. The Type 1624 enables octave analysis to be carried out,
while Type 1625 offers 1/3 octave analysis and octave analysis in octave or 1/s
octave steps. Both filters are compatible
with either of the Sound Level Meters,
forming a complete, compact and portable, lightweight unit. Semi or fully automatic analysis recording is possible with
a portable Level Recorder Type 2317 or
2309.
BP 0106-14
Bruei&KJType 16.2 4
Centre frequency
Hz
Recording
On ...
lin•
18 k.
Reset
8k •
R..dyfor
4k •
next filter
•
--Bruel & Kjmr
Type 1625
(Pr&$01 Enablol
Filter Step
(Preset)
Stan
260.
1211.
Stop
Recording
Step Size
63 •
1/ 3 1 / 3
31.5 .
'Reco~;:;
Octave filter Set
Fast
1 / 1 Oct .
Slow
Recording Speed
1/ 3 -
1/ 3
1 11 1 / 1 Oct.
Bandwidth
1 / 1 Octave Filter Set
- :--8 60
10 dB
6 45
-
- - 105
2
5
0
0
Rec . No.: _
Date: _ _
Sign.; _ _ 0
QP 1124
0
10
20
Hz
50
100
200
2
500
kHz
10
400ABCL•n.
20
(1612/2112)
Zero Level:
Mulliply Frequency Scale by :
A B C lin.BJ0067
Fig. 3. Frequency characteristics of the 10 octave filters in Type 1624
Sound Level Meter. The analysis can
be recorded semi-automatically with
the Level Recorder Type 2317 or 2309.
Fig. 1. Sound Level Meter Type 2230 with
1f3-1f1 Octave Filter Set Type 1625
The Octave Filter Set Type 1624
and the Third Octave/Octave Filter
Set Type 1625 are both active filters,
which are small in size and light
weight. Both are easily fitted to the
bottom of the Sound Level Meter
Type 2230, 2231 or 2233, ensuring
both mechanical and electrical connections with proper matching of input and output impedances.
Adding a Filter Set to a Sound Level Meter greatly extends the uses of
the instrument, enabling detailed frequency analysis to be carried out.
For semi-automatic recordings, the
Filter Set is connected to the Level
Recorder by the control cable AQ
0034. The ground connection is ensured by cable AO 0173 used to connect the Sound Level Meter to the
Level Recorder. See Fig.4. The SPL
for the selected frequency band is obtained from the Sound Level Meter
Output, and the start/stop of paper
movement is controlled by the Filter
Set. The recording is made on graduated paper with a scale of 15 mm/octave, such as QP 0124 for Type 2317.
The Type 1624 contains 10 active
octave filters with centre frequencies
from 31,5 Hz to 16kHz. Each octave
filter satisfies the requirements of IEC
Recommendation R 225-1966, DIN
45651 and ANSI Sl.ll-1966 Classll,
see Fig.2. The total frequency range is
from 22Hz to 22kHz as can be seen in
Fig.3. A linear position is also available covering the frequency range
from 5Hz to 75kHz (-1 dB).
IX)-2
"0 -1
g0
·.p t
~ 2
Level Recorder
2317
a; 3
t:: 4
<( 5
The overall frequency range of both
filters sets covers the entire audio-frequency range with the centre frequencies arranged according to the preferred frequencies of ISO R 266, DIN
45401 and ANSI S 1.6-1960. The filters may be switched in successively
manually (Type 1624 or 1625), or
automatically (Type 1625). The level
in each frequency band is displayed on
the Sound Level Meter and may be
noted in a measurement report or
plotted on graph paper. For greater
convenience the analysis can be recorded in situ, either semi-automatically (Type 1624) or automatically
(Type 1625) using one of the portable
B & K Level Recorders Type 2317 (one
channel) or Type 2309 (two channels).
0.5
0.6
0.7 0.8 0.9 1D
1.2
1.4
1.6 1.8 2.0
2.5
Frequency relative to centre frequency f/fm
Two Channel Level
Recorder 2309 8502l6
170125/2
Fig. 2. Top of an octave filter characteristic from the Filter Set Type 1624
Fig. 4. Set-ups for semi-automatic octave
analysis and recording with T y pe
2317 or 2309
oooooooooooooooooooooooooooooooooooooooooooooooooo
Bri.iel & Kjar
RecOI"ding Mode· DC Lin Cl!l
DC Log 0
AC Log 0
AC A'ler..ing _ _ Range : 2.Q__(d8)
Paper Speed: _ 3 _ mmts
Wr
Speed :~mm/s
Aec . No.: _ _ dB
The signal fed to the Filter Set is
also weighted as selected on the Sound
Level Meter ("A", "C", "Lin. 20Hz to
20kHz" or "All Pass 10Hz to 50 kHz").
Octave Filter Set Type 1624
The Type 1624 permits octave frequency analysis when used with a
2
dB
oate:_ _ 10
Time: _ _
Sign.: _ _
Zero Levei ;_§Q_ 0
~~':;'~~ oo;.: _
9
~
analysis
20
with 1624
and 2317_ 30
St•rl Lin. Oct aft--}---"
QP 0151
St•rt Line- t il ()day•- 20
31,5 Hz
25
40
63
SO
125
80 100
250
160 200
500
315 400
630 800
1kHz
1.25 1,6
2
16
2 ,5 3,15
10 12,5
lin.
20 !2s
3,15
1613/ 161
83031912
Fig. 5. Octave analysis of machine noise using the set-up in Fig.4
When recording each octave, the filter output is disconnected from the
Sound Level Meter during the first
millimetre which corresponds to the
settling time. Once the recording of
one octave is completed, the paper
stops and the indicator READY FOR
NEXT FILTER lights up. At the end
of the analysis the SPL with the linear
weighting (or "A" or "C" if applied on
the SLM) is recorded.
co -2
"'0
c:
0
·.::;
"'
c:
s
:::l
:(
Max. Ripple
(peak-to-valley)
0
2
0,5 dB
4
6
8
10
12
14
16
1/3 _111 Oct. Filter Set Type 1625
18
The Type 1625 permits 1/3 octave
and octave frequency analysis. Octave
frequency analysis can be made with
octave or l/3 octave step size. An unweighted frequency response (Lin)
from 3 Hz to 75 kHz is also available.
20
The Type 1625 contains 31 active 1/3
octave filters and 31 overlapping 1/1
octave filters at 1/3 octave intervals
covering 11 octaves. Centre frequencies are from 20Hz to 20kHz. Each
filter fulfils the requirements of IEC
recommendation 225-1966, DIN 45652
and ANSI Sl.11-1966 Class III for 1/3
octave filters; and DIN 45 651 and
ANSI Sl.11-1966 Class II for 1/1 octave
filters, see Fig.6. The total frequency
range is from 18Hz to 22kHz (1/3 oct.)
and from 14Hz to 28kHz (1/1 oct.).
The level in each frequency band
can be read on the Sound Level Meter's digital display, the centre frequency of the filter being displayed on
the Filter Set. The filter centre frequency being selected manually by
push button.
22
0,4
0,6
0,5
0,7
0,8 1
1,4 1 ,8
2,5
0,9 1,2 1,6 2,0
Two Channel Level
Recorder 2309
Frequency relative to centre frequency f/fm
850217
17 124 1
Fig. 7. Automatic lj3 octave analysis and
recording with Type 2317 or 2309
Fig. 6. Top of a lj3 octave filter characteristic from the Filter Set Type 1625
oooooooooooooooooooooooooooooooooooooooooooooooooo
BrUel & Kjar
~ordlng Mode: DC Lin. t8 DC Log. 0
AC log. 0
AC Av.,..i,.. _ _ Range : _
(dB) Paper Speed : ~mmls
Wr. Speed: ~mm/a
20
Roc. No. , _ .dll
Date: _ _
10
Ttme
~::' Leve1 ,_§Q_ ~
~~~~rneob;.:_ 1o
1/3 octave
analysis
2c
with 1625
[j]Jli_[]JI!li[Ji[l l!lil l l il il l lilil l t~![ j_[j [ij
and 231:,,., L~~ Octo~-f-
OP0151startlln~~ti3 0c.'•.,.-~2s
31,5Hz
63
.. oso
125
eotoo
250
160200
500
3ts•oo
630800
1kHz
usu
2
2.S3,ts
The filter scanning is electronically
programmed and controlled to obtain
an RMS read out error less than 0,5
dB over the whole analysis range. The
settling time and the paper drive
speed are controlled by the Filter Set
to ensure a precise recording in a
minimum time.
The filter scanning is electronically
controlled and programmed to optimise the recording. The Filter Set increases the Level Recorder paper
speed as the analysis band centre frequency is increased. Thus, an accurate
recording is obtained in a minimum of
time.
16
zoJ~~Cin.l.§15=a_=~=~.,.,~,..,31=
1 ~J
112
Fig. 8. Third-octave analysis of machine noise using the set-up in Fig. 7
oooooooooooooooooooooooooooooooooooooooooooooooooo
Recording Mode: DC lin. lliO
BrUel & Kjar
DC Log. 0
AC Log. 0
AC Aver-.ging - - Range : _§Q_(dB)
Paper Speed: ~mm/s
Wr. Speed : __g§.Q_mm~
20
Rec. No.: _ _ dB
oate:_ _
Time: _ _
dll
10
Sign .: _ _
Zero Level :~ 0
M~~ht~re Obj.:_ 10
~
~~~·~~~)l
10
(1625!@TIT 30
Start Line Oct•,.____.:f--'
31,5 Hz
63
125
250
500
1kHz
2
QP 0151 Start Line 113 Oct~•- 20 25
40 SO
80 100
160 200
315 400
630 800
1,2 5 1.6
2 .5 3,15
When the Filter is connected to a
Level Recorder Type 2317 or 2309 the
recording of the analysis and the filter
stepping is carried out automatically.
The Level Recorder is connected to
the Sound Level Meter using cable AO
0173, and to the Filter Set using control cable AQ 0034. See Fig.7.
wt2.s
10
~
16
10 12,5
20
!r.;;.:::.:in.3,-;:.15---=--:-;::-,;o.61""31'"'t~]
~2
Fig. 9. Octave analysis with 1/3 oct. step size of machine noise using the set-up in Fig. 7
The starting frequency is selectable
to eliminate low frequency components and the analysis can be interrupted and restarted during recording
with the "Start/Stop" push button. An
analysis can also be stopped before
completion and the paper automatically moved to the next start position,
ready for a new run.
Recording of octave analysis with 1/3
octave or 1/1 octave step size is also
automatic. For octave analysis with
octave step size, a choice between
three series of centre frequencies is
offered (lowest frequencies 20, 25 or
31,5 Hz).
Two analysis recording speeds
("Fast" or "Slow") are available to allow for stabilization of the Sound Level Meter detector depending on
whether a "Fast" or "Slow" time
weighting is selected on the Sound
Level Meter.
Power supply
The active filters contained in the
Filter Sets are powered from the
Sound Level Meter through the 15 pin
connector, provided the EXT. FILTER switch on the Sound Level Meter
is set to "In". The battery pack in the
Filter Set contains 4 cells IEC LR 6
(B&K No. QB 0013) and is always
connected in parallel with the battery
pack in the Sound Level Meter. The
battery life (alkaline cells) of the
Sound Level Meter/Filter Set is approximately 12 hours with the Type
1624 and approximately 8 hours with
the Type 1625. The Mains Power Supply and Charger ZG 0254, including a
drawer with rechargeable cells can be
used to power the Filter Set.
3
Specifications 1624 and 1625
1624 Octave
Filter Set Type
1625 Third-Octave and Octave
Frequency Range
Selective
22 Hz to 22 kHz
18 Hz to 22 kHz (113 oct.), 14 Hz to 28 kHz (111 oct.)
Linear
Typical 5Hz to 75kHz (-1 dB)
Typical 3Hz to 75kHz (-1 dB)
10 active 6-pole Butterworth octave filters
31 active 6-pole Butterworth third-octave filters and
31 overlapping 111 oct. filters at 1fs oct. intervals
covering 11 octaves
In accordance with standard
IEC R 225-1966, DIN 45 651 and
ANSI S 1.11-1966, Class II
IEC R 225-1966, DIN 45 652, DIN 45 651 and
ANSI S1.11-1966, Class II & Ill
Centre Frequencies
31,5 Hz to 16kHz
20 Hz to 20 kHz
Attenuation at Centre Frequency
0 dB ± 0,5 dB
0 dB ± 0,5 dB
Peak-to-valley Ripple
< 0,5 dB
< 0,5 dB
Attenuation outside Pass Band
See Fig.2 & 3, > 60 dB at 8 f 0 and 1/s f 0
See Fig.6, > 75 dB at 5 f 0 and 1/s f 0 (1/s oct.)
> 60 dB at 8 f 0 and 1fs f 0 (111 oct.)
Filter Shift
Slider switch
Green lamp indicates time for filter switching
when used with Level Recorder
Manual or Automatic with Level Recorder. 1fs oct. or
111 Oct. steps for 111 oct. analysis
Remote Control
Semi automatic of Level Recorders Types 2317 and Automatic to/from Level Recorders Types
2317 and 2309 via cable AQ 0034
2309 via cable AQ 0034
Band-Pass Filters
Input Impedance
10 kn in series with 5 J.LF
10 kn in series with 15 J.LF
Input Terminating Impedance
~
~
100 n
100 n
Max. 2 V sinus (2,8 V peak)
Input Voltage
Max. 2 V sinus (2,8 V peak)
Output Impedance
< 5 n in series with 15 J.LF
< 5 n in series with 2,2 J.LF
Output Terminating Impedance
~ 10k Q //1nF
~ 10k11//1nF
Inherent Noise
f 0 Hz
max.J.LV
31 ,5 Hz
63Hz-16kHz
Lin
Magnetic Sensitivity (50 Hz)
200 (typ. 140)
150 (typ. 70)
250 (typ. 120)
f 0 Hz (oct. or 1/s oct.)
20Hz-40kHz
50Hz-10kHz
12,5 kHz-20 kHz
Lin
Approximately 1 mV output for 100 A/m field strength
Operating Temperature
-10 to + sooc (+ 14 to +122 ° F)
Storage Temperature
-20 to +50° C (-4 to +122°F)
Batteries Removed
Influence of Temperature on Attenuation
Influence of Humidity on Attenuation
Batteries
Dimensions
Weight
max. J.LV
250 (typ. 170)
150 (typ. 80)
200 (typ.110)
250 (typ. 120)
< 0,5 dB (-10 to +50B C)
0
< 0,5 dB for 0 to 90% relative humidity at ~ 40° C without condensation
4 x 1,5 V IEC Type LR6 (QB 0013). Batteries used as extra supply for SLM
Length 105 mm (4,1 in)- Width 85 mm (3,3 in)- Height 47 mm (1 ,8 in)
450 g (1 lb) including batteries
Accesso,ies Included
4 Alkaline batteries
1 Plug
Accessories Available
1 ,5 m control cable
AQ 0034
1 ,5 m control cable
AQ 0182
Mains Power Supply and Charger ZG 0254
QB 0013
JP 0802
T00517GB1
2.
CONTROLS
Brilel & KJ8!tr
Centre Frequency
Ty~MJ 1624
H.i!:
lin •
11H•
8k.
Ready~r
4 k.
neKt Filter
63 •
31 ,6.
y f!IIC:.:~,:
Octave Filter Set
Fig. 2. 1. Front view of the Filter Set
READY FOR NEXT FILTER:
A green LED lit to indicate that the measurement at the selected frequency band has been completed and another frequency band may
now be selected.
Note: This facility functions only when the filter is synchronised for
operation with Level Recorder Type 2317, 2306 or 2309.
CENTRE FREQUENCY:
Slide switch with ten octave settings with centre frequencies from
31 ,5 Hz to 16 kHz and a setting for linear broad-band response from
5 Hz to 75 kHz.
To begin a recording of an analysis at the lowest centre frequency
when the Filter is synchronised with one of the above mentioned Level
Recorders, the switch should be moved to the "Start Recording" position and released.
15 PIN CONNECTOR:
15 pin connector for use with the Sound Level Meters Type 2230 or
2233. This connector ensures signal connection, connection between
the Sound Level Meter and Filter batteries, and power supply to the
Filter Set when the Filter Set is included in the measurement circuit
(i.e. EXT. FILTER "In" on the Sound Level Meter).
LOCKS:
Two spring loaded catches for securing the Filter Set to a Sound Level
Meter.
RECORDER CONTROL:
8 pin DIN socket for synchronization of the Filter Set with Level Recorder Type 2317, 2306 or 2309.
5
Filter
Output
-11 V
Not
used
OV
Not
used
+ 11 V
Signal
ground
Filter
Input
00888000
00
80800
ov
Not
used
+5V
+Batt .
-Batt .
Power
On/ Off
-5V
830457
Fig. 2.2. 15 pin connector for Sound Level Meter Type 2230 or 2233
Not used
Not used
Filter shift pulses
from Level Recorder
+ 6 V from
_.--+ollt--- Level Recorder
(indicates
Recorder "On")
0 V to stop
Level Recorder
immediately
Level Recorder
ground
830074
Fig. 2.3. Recorder Control socket
Battery drawer which accepts four 1,5 V alkaline cells (lEG type LR6,
AA size). These are connected in parallel with the batteries in the
Sound Level Meter (see section 3.2). This drawer can be replaced by
the drawer fitted with rechargeable cells supplied with the Mains Power Supply and Charger ZG 0254 (option).
BATTERY DRAWER:
1
Recorder Control
0
Fig. 2.4. Side view of the Filter Set
6
3.
OPERATION
3.1. PRELIMINARY
The Octave Filter Set Type 1624 employs only one active filter. The centre frequency can
be varied in nine steps from 31,5 Hz to 16kHz in accordance with national and international standards and recommendations.
Fig. 3. 1. Filter Set with the Sound Level Meter Type 2230
The Type 1624 is primarily designed for use with Sound Level Meters Type 2230 and
2233 to which it fits directly both mechanically and electrically. All electrical connections
between the Filter and the Sound Level Meter are made via the integral 15 pin connector
of the instruments.
To fit the Filter Set to the Sound Level Meter, remove the protective plastic plate at the
bottom part of the Sound Level Meter. Press the two side locks on the Fi Iter Set and
engage the connector. Push gently until the two side locks are fastened, ensuring that
the locks are again in their outer position. To insert the Filter Set in the measurement
chain, set the EXT. FILTER switch on the Sound Level Meter to "In". The measured
signal on the Sound Level Meter is now filtered in an octave band of centre frequency as
indicated by the CENTER FREQUENCY selector. The signal is also weighted as selected
on the Sound Level Meter, i.e. "A", "C" or "Lin". The SPL for the selected octave band
is displayed on the Sound Level Meter. Semi-automatic recording of the frequency analysis can be obtained using Level Recorder Type 2317, 2306 or 2309 (See section 3.3).
7
3.2. POWER SUPPLY
3.2.1. Battery check
The Filter Set is powered via the Sound Level Meter to which it is connected. The
batteries contained in the Filter Set are not used to power the Filter Set directly, but to
increase the life of the Sound Level Meter power supply. Life time with alkaline batteries
and Sound Level Meter Type 2230 or 2233 is approximately 12 hours.
To check the battery level of the Filter Set, connect the Filter Set to the Sound Level
Meter, remove the battery drawer from the Sound Level Meter and check the display on
the Sound Level Meter for "BAT" indication. If the "Bat" sign appears, approximately
half an hour operation time is left, when using these batteries alone. If the "BAT" sign,
and a non-resettable "t" appear, the Filter batteries must be replaced if they are alkaline
type, or recharged if Ni-Cd cells are fitted.
Note: Only one set of batteries, either in the Sound Level Meter or in the Filter Set, is
sufficient to power both instruments. Battery life is reduced to approximately 6 hours.
For long term storage, it is recommended that the batteries are removed in order to
maintain their life and also as a general safety precaution.
3.2.2. Battery replacement
Unlock the battery drawer and pull it out. Remove the depleted batteries and place four
new batteries with polarities as shown in the drawer. Push the drawer back into place
until the lock is secured.
Fig. 3.2. Battery replacement
3.2.3. Mains Power Supply and Charger ZG 0254 (option)
The battery drawer of the ZG 0254, containing 4 rechargeable cells, can be recharged
either in or outside the Filter Set via the socket on the side of its battery draw. The
Charger delivers enough current for simultaneously powering the Filter Set and Sound
8
Fig. 3.3. Mains Power Supply and Charger Type ZG 0254
Level Meter and recharging the cells to which the charger is attached. When only recharging the cells (drawer pulled out or instrument switched off), a recharging cycle
takes approximately 5 hours. When recharging cells while powering the instrument, the
recharging time is of course longer.
Note: It is not necessary for both battery sets, in the Sound Level Meter and in the Filter
Set, to be rechargeable. To avoid confusion, however, only those with rechargeable cells
have the socket receiving the charger mounted on the side. If both instruments have
rechargeable battery sets, it is necessary to use a separate power supply for each set.
3.3. FREQUENCY ANALYSIS
3.3.1. Introduction
In this Instruction Manual discussion is confined to the practical aspects of performing
frequency analyses with a Filter Set and Sound Level Meter combination. For comprehensive details on the theory of analysis, the book "Application of B & K Equipment to
frequency Analysis" by R. B. Randall should be consulted.
In the following paragraphs, the settings given for the Sound Level Meter apply to both
the Types 2230 and 2233. When the settings for the two sound level meters are different,
the setting for Type 2233 is given in brackets.
3.3.2. Frequency Analysis
The frequency selector is stepped manually to display, on the Sound Level Meter, the
SPL in the various frequency bands. The green LED is inactive unless the Filter Set is
connected to a Level Recorder.
Proceed as follows:
1.
On the Sound Level Meter set:
DETECTOR:
TIME WEIGHTING:
"RMS"
"Fast" or "Slow"
9
DETECTOR:
TIME WEIGHTING:
DISPLAY:
SOUND INCIDENCE:
EXT. FILTER:
POWER:
OPERATING MODE:
FSD:
RESET:
FREQ. WEIGHTING:
2.
"RMS"
"Fast" or "Slow"
"SPL" ("Lr" for 2233)
As required
"In"
"On"
"Operate"
As required
"All" or "Max./Min." ("Max." for 2233)
"All-Pass" (The weighting selected is applied to the
signal analysed)
Select the frequency band on the Filter Set, and read the corresponding level on the
Sound Level Meter display.
To avoid noting analysis results by hand, the Level Recorder Type 2317, 2306 or 2309
may be be used for semi-automastic recording of analyses.
3.3.3. Frequency Analysis with Level Recorder
Semi-automatic recording of octave band frequency analysis is possible using Level
Recorder Type 2317, 2306 or 2309. Recording of the frequency analysis provides a hardcopy result which is very convenient for documentation in reports.
Fig. 3.4. Level Recorder Type 2317
The synchronization of filter stepping and paper advance is achieved using control cable
AQ 0034 (or AQ 0182 for earlier 2306 Level Recorders, see section 3.3.4), while the level
for each octave band is transmitted by cable AO 0173 connected to the Sound Level
Meter (see Fig.3.5).
10
Level Recorder
2317 (or 2306)
Two Channel Level
Recorder 2309
83004811
Fig. 3.5. Set-ups for semi-automatic octave analysis and recording
with Type 2317, 2306 or 2309
The Type 1624 is equipped with a green LED which is lit when analysis in one octave
band is completed and the centre frequency has to be stepped to the next centre frequency. Recordings may be made on a frequency preprinted paper (see Fig.3.6).
00000000000000000000000000000000000000000000000000
BrUei&Kjar
Recording Mode: OCLin Q!!l DClog . 0
ACLog. O AC Av•.. ing _ _ Range : ~(dB) PaperSpeed: _
3_
mm/s
Wr Speed : ~mm~~
~~-~~~~~~~11111~1~11~1~1~11111
Oate: _ _
10
Time : _ _
Sign.: _ _
Zom Le•e1 oJ!Q_ 0
M:~hi~eobj.:_ lo
~
analysis
20
with 1624
and 2317_ 30
QP 0151
~:::: ~:: ~~~~~~ 25 ' ~~ SO
31 5
125
63
80 100
1
250
160 200
315 400 S00630 800
k~2~ 1.6
2
4
2.5 3,15
1
16
S
6.3 B
10 12.5
20
ri;,!2~'-"';
· n.3,.,--15--::40:--:-;-:-LI"------;;16;-;-o13/;;o,16j
83031912
Fig. 3.6. Octave analysis on Type 2317 or 2306
For octave band analysis recording proceed as follows:
Recording with Type 2317
Carry out preliminary checks on all three instruments (Sound Level Meter calibration,
battery level, etc.) and load the Level Recorder with recording paper QP 0124. Connect
the Sound Level Meter to the Level Recorder using cable AO 0173, and calibrate the
Level Recorder for AC Log or DC Lin (see Instruction Manuals for 2317 and 2230).
Set the controls on the Sound Level Meter as follows:
DETECTOR:
TIME WEIGHTING:
DISPLAY:
SOUND INCIDENCE:
EXT. FILTER:
POWER:
OPERATING MODE:
FSD:
RESET:
FREQ. WEIGHTING:
"RMS"
"Fast" or "Slow"
"SPL" ("Lr" for 2233)
As required
"In"
"On"
"Operate"
As required
"All" or "Max./Min." ("Max." for 2233)
"All-Pass" (The weighting selected is applied to the
signal analysed)
11
Without readjusting its calibration for AC or DC recording, set the controls on the
Level Recorder as follows:
WRITING SPEED:
PAPER SPEED:
POWER:
PAPER DRIVE:
PEN LIFT:
"Normal"
"1 mm/s" or as required
In
In
Off
Proceed with recording of the analysis, as outlined later in this section.
Recording with Type 2306 (or Type 2309)
1.
Carry out preliminary checks on all 3 instruments (battery level, etc.) and calibrate
the Sound Level Meter.
2.
Load the Level Recorder with recording paper QP 0124 (QP 2100 for Type 2309). If
the Sound Level Meter is equipped with a DC output, connect this output to the
Level Recorder using cable AO 0173 and calibrate the Level Recorder for DC Lin
(see 2230 and 2306 Instruction Manuals).
If the Sound Level Meter used is the Type 2231, then its AC Output must be used.
The Level Recorder must then be calibrated for AC Log recordings, and its WRITING SPEED set to "1 00 mm/s" (see point 5).
3.
Fasten the Filter Set to the Sound Level Meter and interconnect the REMOTE CONTROL sockets of the Filter and Level Recorder as shown in Fig.3.5. With earlier
Type 2306 Level Recorders use cable AQ 0182 (see section 3.3.4.).
4.
Set the controls on the Sound Level Meter as follows:
DETECTOR:
TIME WEIGHTING:
DISPLAY:
SOUND INCIDENCE:
EXT. FILTER:
POWER:
OPERATING MODE:
FSD:
RESET:
FREQ. WEIGHTING:
5.
"RMS"
"Fast" or "Slow"
"SPL" ("Lr" for 2233)
As required
"In"
"On"
"Operate"
As required
"All" or "Max./Min." ("Max." for 2233)
"All-Pass" (The weighting selected is applied to the
signal analysed)
Without readjusting its calibration for AC or DC recording, set the .controls on the
Level Recorder as follows
WRITING SPEED:
PAPER SPEED:
POWER:
PAPER DRIVE:
PEN DRIVE:
"250 mm/s" ("1 00 mm/s" when using Type 2231)
"Ext."
In
In
In
Recordings with the Level Recorder Type 2309 are similar to those with the Type 2306.
Proceed with recording of the analysis, as outlined overleaf.
12
Recording of the analysis:
On the Filter Set slide the CENTRE FREQUENCY selector to "Start Recording T" or
to another centre frequency. When the paper stops, switch PAPER DRIVE "Off" and
move the paper so the pen lies 7,5 mm before the starting centre frequency printed
on the recording paper. Depress PAPER DRIVE.
To start recording slide the CENTRE FREQUENCY selector to "Start Recording T"
for a frequency analysis from 31,5 Hz, or to the centre frequency chosen to start the
analysis.
The recording of an octave has a length of 15 mm. During the first millimeter, which
corresponds to the settling time, the Sound Level Meter is disconnected from the
Filter and a low level is recorded. During this same time, the green LED - READY
FOR NEXT FILTER is Lit. The level in the octave band is then recorded over the last
14 millimeters and the green LED - READY FOR NEXT FILTER is lit again. Slide the
CENTRE FREQUENCY selector to record the next octave until the analysis is completed. After the highest octave is recorded, slide the CENTRE FREQUENCY selector to "Lin." to obtain the "All-Pass" recording.
To record the "A" or "C" frequency response when the frequency analysis recording
is completed, set FREQ. WEIGHTING to "A" or "C" and EXT. FILTER to "Out" on the
Sound Level Meter. Slide the CENTER FREQUENCY selector to the next filter or to
"Lin" or to "Start recording", and the "A" or "C" frequency response will be recorded.
3.3.4. Frequency Analysis with earlier Level Recorder Type 2306
Level Recorders
with serial number
718058 or higher
Level Recorders
before serial
1---------i number 718058
1/ 3 oct
5 mm
1 / 1 oct
15 mm
Fig. 3. 7. 5 mm 113 octave and 15 mm octave paper drive adjustment with Level Recorder 2306
13
Complete details of synchronization and use are given in the 2306 Instruction Manual. It
should be noted, however, that when using a Level Recorder Type 2306 before serial
number 576 700, it will have to be modified by connecting a 1 kQ resistor between the
two solder points indicated in Fig.4.4, or the filter cannot control the recording (the
"Ready for next filter" LED will not light).
14
4.
APPENDIX
Lin
I
Buffer
and
Low Pass
Filter
I
Input
Low Pass
Filter
~ II o
Octave
Band Pass
Filter
I
I
I
I
I
~
Oct.
I
I
I
I
I
Output
I
Ready for next Filter
I
I
I
.,..
'
I
I/
I
I
I
~-L __ L __ L ________ L __
I
I
Filter Switch
Block Diagram of Type 1624 Octave Filter Set
830073
Fig. 4. 1. Simplified block diagram of the Filter Set 1624
Equiv. SPL.
dB
+20
0~ ---~~-----------------------------------------------------
31,5
125
63
250
5 0
1k
2k
4k
Sk
16k
Frequency Hz
84035011
Fig. 4.2. Inherent noise level of 2230 Sound Level Meter with the Filter Set 1624
Phase
deg.
841057
Fig. 4.3. Phase relationship
15
5.
SERVICE AND REPAIR
The Type 1624 is designed and constructed to provide the user with many years of
reliable operation. However, should a fault occur which impairs its correct function, then
its internal batteries should be removed to prevent risk of further damage. For repair
consult the separate Service Instruction Manual available for the Type 1624 or contact
your local 8 & K service representative. Under no circumstances should repair be attempted by persons not qualified in the service of electronic instrumentation.
16
1624
+
Printed in Denmark by Ncerum Offset
Bri.iel & Kjcer DK-2850 N.LERUM, DENMARK Telephone: + 45 2 800500 Telex: 37316 bruka dk
0
°
English OK BE0563-12
1624
+
Printed in Denmark by Ncerum Offset
Bri.iel & Kjcer DK-2850 N.LERUM, DENMARK· Telephone: + 45 2 800500 · Telex: 37316 bruka dk
English DK BE 0563-12