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Guitar Pickups - Combinations
Two pickups can be combined in parallel or series, either in or out of phase (see diagram below).
With the two pickups each on their own, that's a total of 6 different sounds for the price of just 2 pickups. If you make coil taps available, or add another pickup, the combinations can very quickly become unmanageable, particularly if you play live.
The usual way to combine pickups is in parallel and in phase. In fact, this may be the only option you have for those pickups which are sealed and wired internally, providing only a shield and "hot" wire for connection.
As it happens, I actually prefer these types of combinations - a properly matched pair of humbuckers gives a great country-rock or jazz-rock sound. The strat pickup combinations give a funky sound which oozes character (after all, if it's good enough for Mark Knopfler and Robert Cray, it's good enough for me!) This sound is often mistakenly called an out of phase sound, because its slightly nasal character is typical of out of phase sounds.
To provide a sensible number of alternatives requires a little time and experimentation. I can offer some recommendations, but the ideal way to find the good pickup combinations is to first install the pickups where you like their individual sounds, then bring all of the pickup wires outside the guitar and try different wiring arrangements.
If you're not sure how to go about this, ask a friend with some electronics knowledge for help. After you have found a realistic number of good sounds, try to come up with a practical switching arrangement. My rule of thumb is that you should never need to move more than 2 switches to get to any sound, and your main solo sound(s) should be accessible from just one master switch.
If you play live, you may find it useful to experiment by playing along to music, with the music and guitar set to similar volume levels. This is because sounds that impress you in the peace and quiet of your own practice room (or recorded) may not have enough highs or middle "punch" to cut clearly through a band. The music will help mask these "great but useless" sounds.
An easier path is to stick to a few traditional set-ups, which are guaranteed to give good results as long as you follow a few simple rules.
The different ways to wire 2 pickups:
Probably the most common trap is to go for a super hot bridge pickup with a clean neck pickup. A great idea in theory, and fine if they are the only two sounds you want, but when you combine these pickups (in the usual way - in parallel and in phase), it doesn't sound very different from the neck pickup on its own. This happens when there is an impedance mismatch between the pickups, and the lower impedance single coil shunts (or drains) much of the sound of the higher impedance humbucking pickup. The lower impedance neck pickup, however, is hardly affected by the higher impedance bridge pickup.
You can avoid this trap by measuring the DC resistance of a pickup with a multimeter. Even though this does not measure the impedance, it is a reasonable guide - you can expect to measure values of about 5 Kohms for lower impedance single coil models, 7-8K for vintage humbuckers, up to around 15 Kohms or more for the higher impedance super-hot humbuckers. If one pickup is over double the resistance of the other, you can be fairly sure they won't mix well. Less than double will at least provide a noticeable difference, but of course identical pickups are guaranteed to combine best.
If your guitar provides a separate volume control for each pickup, you can compensate for mismatched pickups, but I find this fiddly, and not as clear as a properly matched pickup combination. For this reason I prefer to have the pickups and switching come before a master volume control, and use the master volume control for level changes.
Combining pickups in parallel and in phase provides a special tone due largely to the inductive (coil) load each pickup places on the other. This sound is not the same as combining pickups electronically, such as using a separate pre-amp channel for each pickup, or combinations found in some active pre-amp guitars.
Not all pickups have the same "polarity", even similar models from the same manufacturer are not guaranteed to be the same. Polarity refers to the phase of the signal in relation to the string vibration. Most custom pickups provide (as indeed ALL pickups should) a pair of wires for each coil, and a separate shield connection which must be earthed. At the other end of the scale you will find some pickups with their connections encapsulated in epoxy resin, providing only a single wire and shield.
Reversing the coil connections reverses the polarity, and may be necessary on one pickup to allow the standard "in-phase" connections. Your ears are a good guide - if you expect an in-phase sound you should hear a full, slightly nasal sound. If you get a hollow, middley sound with a volume drop, you probably have pickups with opposite polarity, and need to reverse the connections on one pickup to restore normality.
Combining pickups in parallel, but out of phase is less sensitive to impedance differences, and this may the best way of getting some useful variety if you're stuck with a guitar with mismatched pickups.
Combining pickups in series is a matter of personal taste and experimentation, but I recommend NOT using similar sounding pickups. In phase it's just louder and mushier, while out of phase you will find a dramatic loss of volume. On the other hand, wiring very different sounding pickups in series will add their sounds, and exaggerate their differences when wired out of phase.
Here are some practical wiring suggestions for typical guitar pickup combinations. 2 x humbuckers
The standard Gibson-style neck/both/bridge switch is by far the simplest and easiest to use. In my own dual humbucker guitar, I have included switching to give additional humbucking sounds as well as single-coil sounds; click here to see my current circuit. Here are a couple of variations you might like to consider. The first is an implementation of the usual modification for single coil sounds. There are a couple of special features in this circuit: Firstly, changing to "out of phase" while in the single coil mode changes the coil used in the bridge pickup, offering a third bridge pickup sound.
Another possibility with dual humbuckers is to get some additional in-between sounds. You can get 5 different sounds, all at normal humbucking level. I've never seen this done commercially, so I'll call this the "GM Arts modification"! This would be best provided on a 5-position strat-style switch for 5 sounds from full neck to full bridge, but unfortunately you need a special switch (Yamaha make one), but even worse, most people will not want to attempt this type of woodwork on a good guitar. Instead, I've shown how to get the additional 2 sounds using just a simple switch, which could be placed on a push-pull pot. This circuit is completely standard, with the only addition being a switch to connect the pickup centre taps together. When connected this way, the neck pickup has a hint of bridge tone, and vice-versa. The neck+bridge sound is unchanged.
Single coil + humbucker
Because these two pickups will sound quite different, you will be able to use an out of phase series sound. This is very easy to use - there is a separate toggle switch for each pickup. You can turn either or both "on" for the standard sounds, but with both in the "off" position, the pickups are actually connected in series and out of phase. With pickups of similar impedance but different timbres, you will have 4 very different and usable sounds.
3 x single coil
The standard 5 position strat switch is hard to beat, but here are ideas for modifications. You can use 3 switches to get the extra sounds you can't get on the 5-way switch:
- neck and bridge together
- all pickups on together
I have not drawn this; if you have some basic electronics knowledge (or have a friend to help), I'm sure you can work this out for yourself. If you want to be able to get these sounds without drilling into your guitar and scratchplate, replace a tone pot with a 3-position switch, and replace the 5-position switch with an original 3-position blade switch (you can get these from guitar repairers). Here's how it works: The new mini-toggle selects middle, both or bridge pickups. The main blade switch is a master, giving you:
- neck pickup in the usual position
- middle position: neck with whatever you have selected on the other switch
- down position: whatever is selected on the other switch (middle/both/bridge)
Here's the circuit:
I found that I only ever use the strat tone controls in the 'in-between' settings. It just sounds smoother to my ears. So, here is a way of changing the wiring of the tone controls so they only come on these positions. That way, you can leave one or both turned down, and use the selector switch to choose between normal (bright) single pickup sounds and the jazzy treble cut combination sounds.
This uses the standard strat controls, including the 5-position switch. Note that this switch is technically a 3-position switch, but has 2 indents in the "in-between" positions that take advantage of the switch's "make-before-break" design to allow you to use both sounds together. This tone control mod also takes advantage of this feature so the tone controls are only available in these in-between positions. 2 x single coil + humbucker
The most common wiring for this combination of pickups is to use a 5-position strat switch so that the bridge+middle pickup uses only half of the humbucker for a more authentic 'strat quack' sound. Here's how it's done:
Humbucker, single coil, humbucker
Similar to the above, this circuit gives the same humbucker tapping in both in-between positions:
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