You have a guitar with a given range of tones and you want to get more out of it.

You can achieve quite a bit by redesigning the circuit inside the guitar. It may sound baffling at first but it really isn't that hard.

My goal here is to provide you with some ideas and instructions on how to achieve different sounds, by changing the ways your pickups are combined. Diagrams are included, but they are local diagrams, so that you can integrate them in bigger schemes.

The basics of a pickup

In order to understand how to use a pickup, you must first understand the pickup itself. I strongly advise you to take a look at the physics book of highschool, in the chapter about electricity and magnetism. In short, changes in the electric current flowing through a wire generate a magnetc field and vice versa a changing magnetic field generates electric current in a wire. The first scenario is called an electromagnet. A guitar pickup belongs to the second scenario. Also, some materials distort the shape of a magnetic field

In it's most basic form, a pickup is a single-coil pickup, which consists of two things: a coil (wire wound around a bobbin) and a magnet. The magnet generates a steady magnetic field. When a metalic string vibrates in this field, it distorts the field's shape back and forth. This change in the magnetic field generates alternate current in the coil, which is then sent to an amp for amplification and playback. In reality though, the magnet is usually found at the bottom of the coil and the magnetic field is carried through the core of the coil and focused on the strings with the help of metal rods or blade that go(es) through the core of the coil.

Of course there is a wiki entry too: http://en.wikipedia.org/wiki/Pick_up_(music_technology) 

3 basic properties affect how a pickup behaves in the presence of other pickups:

1. The polarity of the magnet (north/south) determines the polarity of the magnetic field. If two pickups have magnets with opposing polarities, they will tighten the field between them and it will seriously affect how they respond to the string. The rule that works is that all pickups have the same magnetic polarity. This is something you probably won't ever have to worry about.
2. The electrical polarity of the coil. It can be wound mostly clockwise or mostly counter-clockwise. Polarity matters for the humbucking effect. Two coils with opposing polarities cancel out low frequencies, like the 50-60Hz hum. A humbucker pickup concists of two such coils. Single coils exist in both types of polarity, for use in the middle position of 3 single-coil guitars.
3. The electrical phase of the coil. Usually you want you pickups to have the same phase. Opposing phases cancel each other out and in result only some high frequencies escape, making your sound very low in volume and very thin.The phase of a pickup working all alone doesn't matter. It is only important when multiple pickups are active at the same time.
   

The electric phase is practically the only thing you can affect through wiring. The polarities require radical intervention to the pickup itself and will not be discussed here.

Basic pickup wiring

In it's basic form, the pickup is a single coil and has two ends. In all electric circuits one end is connected to a "ground"/"cold" spot and the other end is the "hot" and useful portion of the signal. Good pickups have a third wire, usually a bare one. This one is also grounded but is not part of the signal-making process. It is a "shield", grounding the metallic parts of a pickup (bolts, magnets, polepieces) to prevent static electricity from building up on the pickup and affecting your signal.

A humbucker is essentially two single coils joined together like the wagons of a train: The cold end of the first coil is joined to the hot end of the second coil. These two coils have opposing electrical polarities. However humbuckers on the market today usually don't have only two wires (plus shield). Sometimes there is a third wire, giving direct access between the coils, so that you can bypass one or the other. More commonly though, humbuckers are sold with 4 wires coming out (plus shield). No, it's not more complex, it's actually more simple: the coils are not joined at all, giving you full control over how to use the pickup.

Basic controls on a guitar

There are two types of controls found on guitars: pots and switches.

• Pots are essentially variable resistors. They make use of electricity's property to prefer the path of least resistance. Two types of pot controls are common: the volume control and the tone control. They both rely on the tendency of electricity to seek a path from hot to ground. If at any point other than the pickup coil itself, the hot path and the cold path meet under ANY circumstances, the result will be that there will be no hot signal at all. That's a short-circuit (except there is nowhere near enough voltage to cause a fire.

The volume control offers two alternatives to your hot signal: hot vs. cold, separated by a resistor. With the volume wide open, the resistor prevents the signal from crossing over to the cold end. When you turn the volume down, the resistance between the signal and the cold is reduced and part or all of your signal shorts out.

The tone control is an alternative route instead of the volume control. It too offers a path for your signal to short out. Except that there is a capacitor that only allows high frequencies to short out. Higher capacitor values increase the frequency range that is allowed to short out. With the tone wide open, the maximum resistance between hot and cold is ensured so that the treble is not lost.

It becomes evident that the amount of resistance the pots have, affects the strength and brightness of your signal. Higher resistance values give a brighter and more powerful signal/sound.

• Switches are, well, switches. Typically they switch between the available hot sources (pickups), allowing one or several of them to be active. Any pickup or coil that doesn't have both its cold and hot side simultaneously connected to the output jack, will not contribute to the signal. With humbucker pickups it is common for switches to deliberately short out one of the humbucker's coils in certain switch positions. This is known as coil splitting or coil tapping. When a humbucker is split, it functions like a single coil. In more complex situations, switches handle more complex hot/cold activations and occasionally they may even be used to shuffle hot and cold connections (effectively reversing the electrical phase of a pickup/coil).

This is roughly how a blender switch works:

Putting the pieces together

You can find instructions on common wiring schemes at the sites of major pickup manufacturers (ie. DiMarzio, Seymour Duncan, ...). Different manufacturers use different color codes for the wires so it is important to consult the right diagrams. Even so, requests for wiring schemes that are not available or are slightly different than the ones available at the manufacturers' sites keep showing up. This article's goal is to help you be able to add the individual details that make your case not match exactly one of the available schemes and set you on your way to making your own schemes from scratch.

NEVER FORGET THAT:

(a) Electricity will always follow the path of least resistance between hot and cold. This means it may even go "backwards" in a cable, so always treat your wires as two-directional roads. No wire is a one-way so don't fall in the trap of assuming they are, otherwise you'll likely get bleed-throughs and short-outs that will mess with your signal and with your head.

(b) It doesn't matter (much) where you branch your signal. The following are all (ideally) equivalent:

Some common setups explained

Before we increase complexity, let's make sure that you understand what the common basic schemes are about.We'll see 3 examples: the 3 single coil (S-S-S) strat-style, the humbucker - single coil - humbucker (H-S-H) superstrat-style and the humbucker - humbucker (H-H) lespaul-style. you can find diagrams for these all over the internet. Here I've made my own and highlighted the key features. Things that may be left unexplained in one of them will be better explained in one of the other two.

S-S-S

The pickups are in their simplest form, a single coil each.

Switching is performed by a 5-way blender switch. In positions 1, 3, 5 you get one pickup respectively. Position 2 = 1+3 and 4 = 3+5. In both cases the pickups are activated in parallel with each other. Since all pickups have their cold end grounded, they are all also in phase with each other (we'll discuss this later). 

A single master volume controls the signal.

The neck and middle pickups have each their own tone control. Since the tone controls must apply to specific pickups only, the controls' hot sides must come from the pickups BEFORE the signals are blended with each other at the switch. Generally anything that is pickup-specific goes before the switch. Therefore here, we draw the hot line for the tone controls right before the pickup signals are blended. The tone controls share the same capacitor.

Often the middle pickup will have a reverse polarity compared to the other two. Therefore positions 2 and 4 will be humbucking. This doesn't change anything about how the wiring looks like.

H-S-H

Here the tone control is a global one. Therefore it draws its hot line AFTER the switch, where the signals are now blended. The volume is global as previously.

The middle pickup is exactly as would be found on an S-S-S setup, minus the individual tone control.

The two humbuckers are each internally serially connected and function like a single pickup each. The "purple" wires represent the coil splitters, one per humbucker. These are used to bypass one of the two coils, so that in positions 2 and 4 you get two coils working instead of 3.

The 5-way switch has one pole wired as in a S-S-S setup. The 2nd pole activates the splitters. The coil that finds itself with both ends hot or both ends cold is turned off. Since a humbucker's two coils have opposite polarities, choosing the right coil to split to will allow you to achieve humbucking properties in positions 2 and 4 in combination with the middle pickup. However, since only one of the coils is connected to the switch, it makes sense to keep this one active instead of the other. Since that coil has its hot side taken care off, the splitters must provide the cold path. If this setup hums, there are some more changes that must be done other than switching the splitters from cold to hot.

H-H

Here we have two humbuckers that typically don't split. Each pickup has its own volume and tone. As such, both the volume and tone controls come BEFORE the (single-pole) 3-way blender switch.

The tone controls here are set to use each its own capacitor. This way you can choose different capacitance values for the two pickups (remember, the capacitance affects the frequency range that is cut).

Hopefully this gave you enough of an understanding of basic connections of the components for you to also understand the next sections, concerning mods. Many common mods are basically the insertion of extra controls between the existing ones. This allows achieving more types of connections, but each individual connection will have to be in the spirit of what has been described in the sections above.

Let's look at few simple mods to get your brain and your imagination working.

"Blow" switch

The blow switch is the simplest mod. It is used on guitars with 3 pickups and its goal is to activate all 3 pickups, an option not available through a conventionally wired 5-way blender switch.
In order to activate all 3 pickups, we must provide a path for the hot side of each of them to reach the global hot point. This can be achieved in several ways, but the most efficient one is also the best one. Instead of thinking about how to activate all 3 pickups, you can think about it differently: at least one pickup will be already active anyway. All you have to so then is find a way to re-route the hot path of the other 2 pickups onto the path of the active pickup.

For this we use a double-pole double-throw (DPDT) switch, like the ones found in push/pull pots (yes, you are required to replace one of your pots with a push/pull pot. These pots are the most common way of adding a switch without altering the guitar).

When the switch is down, the re-routes are all cut. When the switch is pulled up, the signal from each pickup is re-routed to all of the switch's positions at once, effectively bypassing the switch and activating all 3 pickups.

The result is a more wide-spread sound.

Neck-Bridge with a 5-way

One of the things that has bugged me on an H-S-H guitar is that by using positions 2, 3 and 4 to achieve more strat-like sounds by using the middle pickup, I can't get the sound of the two humbuckers together like on an H-H setup.

With a DPDT (or SPST, single-pole double throw) switch this can be achieved in the same way the blow switch works. Except that the middle pickup is not included this time. A cool side-effect is that at positions 2 and 4 you will have all 3 pickups and at position 4 you will still only have the middle single coil.

Ditching the middle pickup

If you ever feel you don't want the middle pickup and want to keep only the neck and bridge pickups, simply removing the pickup will suddenly make position 1 = 2 and 4 = 5 and position 3 will be silent. Now that is not very useful. This is how I turned my 5-way into a 3-way: 1=neck, 5=bridge, 2,3,4=1+5.

Alternatively, you can move either 5 or 1 and connect it on 3. This will free up 1 or 5 respectively which will then be silent. You can use it to "turn off" the guitar instead of turning the volume down or maybe to simulate a kill-switch ala Buckethead. I find it a bit awkward when the neck is not at 1 and the bridge is not at 5 with intermediate sounds between them.

Series/coil splitting switch

H-S-H guitars have this integrated in positions 2 and 4 in order to maintain the humbucking quality. If the humbuckers weren't split, you'd have 3 coils in operation and odd numbers of coils are generally not humbucking.

Installing a switch for coil tapping allows you to use your humbuckers as single coils, without depending on the presence of a middle pickup and a 5-way switch. It allows you to use the humbuckers as single coils even on their own. This gives a brighter, less powerful and more focused sound. It won't be humbucking though.

The concept is essentially the same as coil splitting with the 5-way. There's a splitter that gets activated when you pull up the knob. With a DPDT switch you can coil tap both humbucker at once.

Alternatively you can leave the two coils disconnected, and connect them only through the switch. This, however requires both sides of the DPDT. It may prove useful to know both ways.

Series/parallel switch

Alternatively to splitting a humbucker to get a brighter quieter sound, you can also get a brighter and quieter sound (not as quiet and focused as the single coil mode) by wiring the humbucker's coils in parallel. This (unlike coil tap) is still humbucking. You need a DPDT for each humbucker for this one.

As an extension to this line of thought, you can wire any two(or more) pickups in series with each other, whether they are single coils or humbuckers.

Phase switching

Reverse phase produces a tiny, very thin and low in volume sound. The closer the pickups that are out of phase are with each other, the tinier the sound will be. I find that this type of sound goes well in indie styles or for some really retro blues sounds. You can reverse the phase of an entire pickup so that the effect kicks in when you use it in combination with another pickup, or if you have a humbucker you can treat it as two individual pickups and wire it out of phase internally (for ultra puny sound).

Just like any situation in which more than one coil are involved, you can wire the pickups/coils in series (stronger) or in parallel (weaker).

To reverse the phase of a pickup/coil, the hot side most become cold, and the cold side must become hot, hence the "X" shaped cross-connection on the DPDT switch.

Pickups in series

Owners mainly of 3-single coil guitars occasionally want to beef up their sound. One way is to replace the pickups with half-sized humbuckers but that's an expensive mod and the pickup market is vast and confusing. A cheap alternative is to use an extended 5-way switch in order to be able to configure each position independently of the others and connect the existing pickups serially in positions 2 and 4 instead of parallel.

There is some serious change in perception needed for this to work. Instead of using the 5-way to turn on different pickups like in normal parallel configuration, we will use it as a mega split-controller. The 3 coils are connected serially with each other, forming a "train" that is always on. Two splitters are inserted between the 3 pickups. By setting the splitters to hot or cold, we can isolate different portions of the pickup "train", namely one or two pickups at a time.

Ultra mode-switching (requires altering the guitar or the pickguard)

For the sake of demonstrating some megalo-mania, here is some wicked mode switching. The modes are all discussed in the sections above. Instead of using a vast and confusing array of push/pull pots and mini switches, I have installed a 4-pole 5-way on my guitar. It is an intrusive mod and it will lower the value of your guitar so don't do it if you have a nice guitar. The 4-pole 5-way provides an ideal tool for performing multiple tasks with a single move, which allows gathering all the modes of operation mentioned above to a single control.

Each humbucker has the hot side of one coil sent to a normal 5-way blender switch and the cold side of the other coil sent to the global ground point. Instead of joining the remaining two wires to form the serial connection, the wires are sent to the 4-pole switch where their fate can be controled.

• In position 5: both humbuckers are internally in serial mode via jumper connections across poles. Like in the final option of coil splitting discussed earlier.
• In position 4: both humbuckers are split. Since their intermediate wires are not joined, all I have to do is leave one completely disconnected and send the other to ground to keep active the coil that is on the blender switch.
• In position 3: the other coil is kept active instead, by sending the intermediate wire to hot. Since this coil is not connected to the blender switch and the coil that is connected to the blender switch is inactive, we still need a way to control if we want the bridge or neck. So instead of connecting directly to hot, we're connecting to the blender switch instead.
• In position 2:  both humbuckers are now internally set in parallel, by simply combining the previous two configurations.
• In position 1: Well... nothing is happening here really. It is an "off" position, since the humbuckers are internally disconnected. Well, not entirely true... The middle pickup will still be accessible since it is unaffected by what I'm doing on the humbuckers.

In past implementations of the ultra mode controller I've used position 1 for various things. For example, phase switching of a humbucker. This is not possible in the layout discussed here because I need two poles of the switch exclusively for phase control. If I didn't want the parallel connection of position 2, I could instead implement coil splitting through splitter wires, which requires half the number of poles, thus freeing up two for phase control. It's basically a choice between phase control or parallel operation. Only one or the other can be implemented on the switch with the other options uncompromised.

More insanity

• The middle pickup get's it's own individual volume control and is removed from the blender switch. I can thus turn it on anytime regardless of what the humbuckers are doing.
• Similarly, the two humbuckers share a volume control independently of the middle pickup.
  
• The 5-way blender is modded to work like a 3-way blender like described earlier.
• Phase of the bridge humbucker is controlled by a push/pull DPDT. No matter if the humbucker is serially or parallelly connected or split to either side, whatever is active gets phase-reversed.