A BRIEF DISCUSSION OF WIRING OPTIONS
PARALLEL AND SERIES
PARALLEL:
Most guitars produced today combine pups in a PARALLEL scheme. Pickups wired in
parallel usually have a constant connection to the ground ("negative") side of the circuit,
and their hot leads have a path to the output. Pickup selector switches usually interrupt
the hot lead's path to the output, allowing you to select which pickup you hear. Two (or
more) pickups played in parallel combinations typically give you a "quack" tone - a
quirky, sweet blend of the tone of the two pups. If you had a pair of identical pups wired
in parallel and looked at the circuit with a multimeter, your reading would typically be
about half of the impedance of either pup.
SERIES:
Pickups wired in SERIES cause the current to flow through first one pickup and then the
other, effectively doubling the resistance/impedance of the circuit. This usually makes the
tone of the combined pickups fatter or warmer than pickups played in parallel,
emphasizing the fundamental more that the overtones. Series is usually slightly louder.
If you had a pair of identical pups wired in series and looked at the circuit with a
multimeter, your reading would typically be about twice of the impedance of either pup.
IN AND OUT OF PHASE
Once we start talking about phasing, there is some confusion about calling the negative
lead from the pup's coil the "ground" lead. This is sloppy shorthand, and we all do it.
Every magnetic guitar pickup consists of a coil (or pair of coils) that has a "positive" and
a "negative" lead. In guitar electronics shorthand, we usually refer to the positive lead as
the HOT lead, and the negative lead as the GROUND lead. This is all well and good most
of the time, because typically, the positive lead goes to the hot side of the guitar's circuit,
and the negative lead goes to ground. But, when we talk about phase, suddenly the hot is
connected to the ground and vice-verse… what we really mean is that the positive lead is
connected to the guitar's ground, and the negative lead is connected to the hot side of the
guitar's circuit.
"In phase," which is what EVERYBODY uses, typically sounds sweet, and produces a
"quack" or "doink" tone. The drawings in the "Parallel and Series" document illustrates
in-phase connections, because both of the coils' hot leads go to the hot side of the circuit,
and the coils' ground leads go to the ground side of the circuit. The series drawing is also
in phase, as the path routes the signal from ground to hot on both coils. Teles and Strats,
Les Pauls and SG's, Fenders and Squires, Gibsons and Epiphones, Gretsch, PRS, etc…
everybody uses IN PHASE (and, almost always parallel).
BUT, when one pickup is OUT OF PHASE with another, a lot of frequencies are
"cancelled out" - the positive voltage one pickup creates is negated by the negative
voltage the other creates. Usually, lots of the fundamental is cancelled out, and the only
tones that "escape" to be heard are the tones that are harmonically different between the
two pickups - so you usually get very thin and "nasally" tones. The more alike the two
pickups sound individually, the thinner their out of phase combo will sound. This is why
you seldom see a phase-reverse option on a Strat - the middle pickup is too similar in
tone to the other two, and is too close to them to work well in parallel/out of phase - the
tone produced is just too thin for most applications. There's a way around it… but, more
on that later.
This usually brings up the question, "What does ONE pickup sound like, out of phase?"
Actually, one pickup can NOT be out of phase - phase is a relationship, and requires
TWO (or more) pickups to be on at the same time. If you are playing ONE pickup
ALONE, there is no difference in its tone if it is wired in phase or out of phase to the
other pickups - the phase relationship is only revealed when pickups are played
TOGETHER.
Phase reversal is usually implemented with a switch, rather than hard-wired. The addition
of a simple DP/DT toggle or push/pull pot can give just about any two-pickup guitar the
new, biting tone of pickups played out of phase.
Pickups wired PARALLEL/out of phase still both have their own paths to hot and
ground, but on ONE of the pickups, the leads are reversed. The tone produced is thin and
nasally, and usually has perceivably less gain than other pickup combos. Meter readings
cannot determine phase - the reading for the circuit is that same as in phase/parallel.
Pickups wired SERIES/out of phase still require the current to flow through both coils,
but (typically) the positive leads are tied together, and one coil's negative lead goes to
hot, and the other's is then routed to ground. The advantage of the SERIES/out of phase
tone over the parallel/out of phase tone is that because of the fact that the coils are wired
in SERIES, the output is stronger, and therefore a better match in volume with the
common parallel in-phase tones. In other words, you don't get as much of a drop in gain
when you switch to out of phase if you are using a SREIES connection. This would be a
good option to get some out of phase tones out of a Strat, without getting too thin. Meter
readings cannot determine phase - the reading for the circuit is that same as in
phase/series.
REAL-WORLD CONSIDERATIONS:
Now, here's the "bad news" with ANY SERIES (or out of phase) connection mod:
If the pickup's NEGATIVE LEAD has continuity with any metal parts - the cover or the
frame - you MUST break this contact to isolate the metal cover or frame from the coil's
negative lead.
WHY?
Because, when you put the pup in SERIES - or out of phase - everything on the negative
side of the pickup's coil is now on the positive side of the guitar's circuit. That means that
a metal cover or frame - and so, its mounting screws and springs, pole pieces etc - will
have continuity with the "hot" side of things. No arcs and sparks, smoke and flame, BUT,
this may make the pickup more susceptible to hum, and it will certainly have the potential
for unexpected and unwanted noises if you touch the pup or its screws while playing the
guitar. If you actually touch it with a STRING, which is grounded, it will actually
SHUNT that pickup out of the tone (series) or mute the guitar (parallel).
Because of this, I am in the habit of always recommending that if you just do the out of
phase mod, it is the NECK pup whose phase is reversed - most players are less likely to
touch the neck pup than the bridge pup while playing. Also, if you are doing a series or
out of phase mod to a Tele, it is FAR easier to mod the neck pup. Many Tele bridge pups
have an integral baseplate with continuity to their negative lead, and also require you to
remove the bridge to get at them - too much work involved!
SPECIFICALLY TELE:
On your typical Tele neck pup, there is a metal cover. One of its mounting tabs, folded
under the coil, usually has a small, short jumper to the eyelet on the pup's chassis that
connects the coil to the negative lead. To "unground/reground" the cover, all you need to
do is carefully clip that little jumper, breaking the connection, and then add a new
INSULATED wire from the cover's tab back into the control cavity, where you will
attach it to any ground. Now regardless of where you rout the coil's negative lead, the
cover will stay on the shield/ground side of the circuit, offering you what protection from
hum as it might. The coil has two independent leads which you can connect any way
without fear of shorts or contact with something "grounded" - like, your fingers - outside
of the circuit.
SPECIFICALLY STRAT:
On a stock-style Strat pup, luckily, this is never an issue. They are build on non-ferrous
frames, and have plastic covers - no worries about continuity with coil's the hot or
negative there. That's why I was able to so readily exploit all the series and series/out of
phase combos with my rotary switches.
There IS a problem with some aftermarket custom Strat pups that are built with metal
frames/chassis, and are wired up with only two conductors (leads). I simply do NOT
recommend the use of my switches - or that any series or phase mods - be attempted with
pups built like that. Especially as it has become popular to shield the entire underside of
the pickguard. If the pup's metal frame has continuity to the negative lead, it will also
have continuity to ground through the mounting springs and screws touching the
shielding foil on the back of the pickguard. Reverse the phase or go series on one of these
pups, and you have an instant short circuit.
MOST pup manufactures have wised-up to the mod market, and now, if using a metal
frame, wire their pups THREE-CONDUCTOR - the hot lead, the negative lead, AND a
separate ground/shield wire (to ground the frame and/or cover) which has NO continuity
with the coil's negative lead.
SPECFICALLY HUMBUCKERS (and P90s):
As for HUMBUCKERS, most modern/aftermarket FOUR-CONDUCTOR wired pickups
also have a FIFTH conductor, which is typically a bare wire included inside the jacketed
lead that will be the ground/shield connection to the chassis of the pup, and is completely
independent and insulated from any leads from the coils. No worries, if this is the case.
Where you run into the problem on humbuckers (and P90s) is if they are constructed
using a coaxial two-conductor lead with a braided/external shield, like the traditional
Gibsons are made. The external braided conductor is typically soldered to the pup's metal
chassis, and used as the ground/shield AND the coil's negative lead - yikes! Now you
have a pickup where not only the metal chassis, cover, and screws, but also the entire
length of the lead has uninsulated continuity with the ground of the guitar! These require
some special treatment to do series and phase mods with. If you have an open-coil
humbucker (no cover) or a P90, a simple trick is running a length of heat-shrink tubing
over the entire length of the lead. This quick and dirty compromise - the mounting
screws and pole pieces are still "hot" - works, but is less than ideal, particularly if your
pickup has a metal cover. Now, you COULD, if you were an adventurous sort, go in and
unsolder the coil's negative lead at the point where it is soldered to the pup's chassis and
the braided shield, and solder up a new negative lead for the coil (leaving the braided
shield soldered to the chassis as the ground conductor). That would certainly address all
the issues, but it's a long way to go and can be hazardous to the pickup and your wallet. It
is my strong recommendation that you should instead just shelf that old pickup intact,
spend the bucks and get yerself a four-conductor pup to replace it.
COIL SHUNTS
WHAT IS A COIL-SHUNT?
A coil-shunt is a scheme (usually accomplished by a switch) that basically allows the
current to bypass one coil of a two-coil pickup. A jumper is put in place that routs the hot
output of one coil to ground, "shunting" its effect on the tone and volume of the pickup
out of the circuit. Hence, the name… Since most of today's humbucking pickups utilize
two similar coils in series, they are candidates for the coil-shunt mod.
A pickup played with one coil shunted will have a brighter tone and (typically) less
output (there are exceptions to this, as with the DiMarzio stacked humbuckers for Strats,
but, with most Gibson-style, side-by-side two-coil humbuckers, this will be the norm).
Coil-shunts are an easy option to give another voice to your instrument, for example, to
get a "Fender-ish" tone from a "Gibson-ish" guitar.
A LOOK AT HUMBUCKING PICKUPS:
The original Gibson humbucker, which is the prototype for most of today's "side-by-side"
humbuckers, only has two leads, and many of today's "vintage-style" pups are built this
way. If you have one of these, you will have to modify it by adding a lead between the
coils to be able to coil-shunt it. A slightly tricky task, but not beyond most intermediatelevel hot-rodders. I have seen a few import designs that are three-conductor (some
Ibanez, Squire, others), having the traditional hot, ground AND a coil-shunt, but these are
less common. Fortunately, the custom/aftermarket pickup industry has paid attention to
what's going on out here, and most modern humbuckers come with four-conductor wiring
(standard or as an option), which makes them ready to be wired with the coil-shunt mod.
On your typical, aftermarket custom four-conductor humbucker, there are two leads from
each coil (and typically a fifth conductor, a bare ground/shield drain wire). To hook up
this humbucker for "regular" humbucking tone, on the FIRST COIL, one lead ("-") goes
to ground and the other lead ("+") goes to the other coil. On the SECOND COIL, one
lead ("-") is tied to the first coil's "+", and one lead ("+") goes to the output, typically a
switch or volume pot.
To coil-shunt this pickup, a "jumper" is added to the junction of the two leads (first coil
"+" and second coil "-") which ties the coils together. This jumper then goes to a switch,
which allows it to either be OPEN or closed (connected). Open, and the pup stays
humbucker; closed, and the pup is coil-shunt - one coil is "bypassed." The closed
connection can be to ground, or to the output of the pickup. If the connection goes to
ground, the first coil is shunted, and the second coil stays active. If the connection goes to
the hot, the second coil is shunted, and the first coil stays active.
Does it make a difference which coil is shunted? Yes, but it can be a very small
difference, IMHO. I like to keep the screw coil active, as I have the illusion that I can
adjust and balance the pickup with the pole pieces. There's also something to be said for
the small variation in tones concerning which coil is closer to (or farther from) the bridge,
or another pickup/coil…You will have to decide if it's worth the trouble to switch which
coil is shunted and which coil stays active, if you do not get the desired coil right off the
bat.
ABOUT SPECIFIC PICKUPS:
On DiMarzio pickups (which I have NOT used much, personally), it's quite easy because if you follow the factory specs, the slug coil is the FIRST coil, connected to
ground. If you switch the jumper to ground, it shunts the slug coil, leaving the screw
(second) coil active, which is typically what you want.
On Seymour Duncans, they do the opposite - if you follow the factory specs, the
SCREW coil is first, closest to ground. This means that you must shunt S-D pups to hot
to keep the screw coil active. Why did they build them that way? My BEST GUESS is
because this is also the way Gibson builds their humbuckers - whenever I mod a Gibson
humbucker by adding a coil-shunt lead, I must switch that lead to the output of the pup NOT ground - to shunt the slug coil and keep the screw coil working. Remember, the
original Gibson humbucker was developed LONG ago, before hot-rodding yer axe was
the rage it is today, and eventual mods to the pup were probably never a design
consideration...
FWIW: AN ALTERNATIVE FOR S-D PUPS:
The alternative to shunting-to-hot (which can be a pain) is to install the S-D pups in
reverse-phase. By their color code, this would make the black wire ground, and the green
wire hot. On double-humbucker axes with a pair of S-D pups, this has all the benefits of
the DiMarzio-style wiring, and no ill effects. On Fender AmStd Fat Strats, this is exactly
what Fender does. If you are installing a humbucker on a Strat, and you find that this
"phase reverse" installation makes the humbuckers sound out of phase with the
brand/model single coil pups you are using, it is simply a matter of wiring the single coils
out of phase, to get them all back IN phase. As the typical Strat-style pup has no metal
base plate or conductive parts, this usually has no repercussions. There are exceptions some aftermarket Strat pups DO have metal baseplates, and are two-conductor
wired…sheesh!
In conclusion:
If you have a guitar with a pair of pickups, armed with the information form my website,
logic tells us that there are SIX possible combinations of pickups (tones) to chose from:
bridge or neck alone; both parallel, both series; both parallel/out of phase or both
series/out of phase. Any Les Paul, SG, or other two-pickup guitar can be modified with a
few switches to give you these six tones, as opposed to the "stock" three offered by the
unmodded guitar.
If you have a pair of humbuckers, you can add a coil-shunt or two and really fine-tune
your tone. Over twenty possible combos! It's Jimmy Page, déjà vu! Although, since some
of the combos will sound similar, and some will just sound horrible, I usually recommend
that you select from your favorites and try to accomplish just those combinations, rather
than everything possible. Ergonomics comes into play here - too many switches make for
a confusing instrument! Consider the success of the Telecaster and its three simple
tones…
Speaking of Teles, Teles can easily take advantage of some of this info with the use the
Fender 4-way or the four-pole/five-throw SuperSwitch, allowing you to select from four
or five of the six possible combinations from two pickups, yet retaining a "stock" look.
Three-pup Strats offer even more possible combinations, and some of the series and
series/out of phase tones can be really amazing. Using my rotary switches, you'll still
look stock… NO NEW HOLES! Yup, here it is - the plug for the FAT-O-Caster! Hey,
it's MY website, after all…
EB