Modifying the wiring of a guitar may seem like rocket science, but it is no harder than tying your shoelaces and, once you get the hang of it, it can really enhance the versatility of your electric guitar. If you can’t tie your shoelaces, maybe you should stop reading and step away from any tools, because chances are you are going to hurt yourself.

DISCLAIMER: I will not be held responsible if you damage your guitar, its current or future parts or yourself in any way. By reading further and applying the ideas presented, you agree that you do so at your own risk. Solder paste is toxic and the soldering iron tip is very hot and can melt and burn stuff that comes in contact with it. If you are in doubt of your abilities, have a guitar tech do the mod for you.

The stuff that follows applies to passive pickups. Active pickups follow the same rules but the implementation is more complex. I’ve never seen an active setup up close and I won’t presume to know anything about them.

The first sections are dedicated to understanding the basics. Once you are confident about them, the next sections will elaborate into humbucker modes and additional controls. You can find several schematics for common setups on the websites of guitar and pickup manufacturers, but I always get asked about stuff, so I’m trying my best here to teach you how to figure it out on your own. Not that I don’t like to help but teaching you how to solve a problem is better than to solve it for you, don’t you agree?

Contents:

• Electricity, wires, connections
• What is a pickup (construction, connection)
• Integration into a circuit (switch, volume, tone)
• The bigger picture
• Coil splitting
• Volume and tone controls

Electricity, wires, connections

Bringing this up so early in the article is premature but anywhere else it disrupts the flow. This is a very important section to understand. It is the key to understanding why things that look different are in fact the same.

• Electricity only flows in complete continuous circuits. By this I mean that you have to be able to track a continuous path through wires and switches and pickups from the output jack and back to the output jack. More commonly though, if you connect a global volume control correctly, that control will serve as your start and end. Switches are a point where you selectively break the continuity of one circuit and establish continuity for an alternative one. When designing a circuit you must always think of the entire active paths for all the combinations of switch positions and make sure for every path that everything you want active is on the path and that nothing that you don’t want active is on that path.
• Theoretically, every spot along the active electrical path is electrically identical until a “device” is found. In a guitar with passive circuitry, the only “devices” you are likely to find is the pickup (well actually it is the power source, but that complicates things), the tone control and the volume control. The switch is NOT a device because it has theoretically no resistance/impendance and neither do the wires that connect the “devices”. Every point along the path between two devices is identical to every other point on the same path. Dead-end branches of a circuit are not to be ignored. Any branch of the active circuit is also active.

Putting this graphically is a little challenging for me but I’ll try. Here is a rudimental schematic of two pickups, a 3-way switch, a volume control and an output jack. Red and green are the wires. Blue are the movable parts of the circuit. In the first schematic, only one pickup is active, in the second one both pickups are active. 3 portions of the path can be seen and all the points on each portion are identical with all the other points of the same portion. The purple highlight is the ground portion (all points along the purple are considered ground, yes even the dead-end branch leading to the inactive pickup), orange is the final hot portion and yellow is the hot portion between the pickups and volume. Notice that points on both sides of the switch are identical, unless the switch interrupts that branch. This means that points A, B, C, D, E and F are identical. If you branched a tone control at any of these points it would act exactly the same, for THAT position of the 3-way switch ONLY. Changing the switch position may cut off some of these points.

pic 0.1

A consequence of this is that all the ways to electrically connect three points shown below are identical:

pic 0.2

What is a pickup?

http://en.wikipedia.org/wiki/Pick_up_(music_technology)

It is the device that turns mechanical energy into electrical energy, in other words it converts the motion of the strings into an electrical signal that amplifiers and effects can work with. This would be a good time to look up electromagnetism in your highschool physics books. You’re looking for induction, that is the ability of a changing magnetic field to generate electric current. The opposite phenomenon to the one used in pickups is the electromagnet, where electricity is used to generate a magnetic field. While you’re looking this up, also look up electricity (helps with understanding circuits) and waves (helps understand phase, hum cancellation etc).

Construction

A pickup consists of two major elements: the coil (wire wound around a plastic bobbin) and the magnet. The magnet creates a steady magnetic field and the coil picks up the changes in this field caused by the motion of the strings. Sort of like setting up a bait and a trap and waiting for the mouse to show up.

3 properties affect how you connect a pickup:

1. Magnet polarity (north/south). On a guitar with multiple pickups, the magnetic fields should all be facing in the same direction. This is something you probably never have to worry about, unless you actually make pickups yourself.
2. Coil polarity (+/-). Clockwise and counterclockwise wound coils produce opposite currents. Pairing two coils with opposing polarities is commonly used to cancel out the 50-60Hz hum of the electrical powerlines and it is called a humbucker. The reason the signal is not entirely cancelled is because the coils are offset, producing lightly different signals except for the ambient 50Hz noise which will be close to identical for the two coils.
3. Coil phase. Each coil has two wires coming out. Which you use as hot and which you use as cold greatly affects the sound produced when the pickup is blended with other pickups. Opposite phases cancel out frequencies and it can create interesting twangy sounds for blues, funk or indie or it can sound hideously thin and weak. The same concept can be applied to humbuckers too.
4. Some pickups are not symmetrical. On most guitars you can’t choose how to orient a single coil pickup because their casing (the pickups’) is not symmetrical and neither is the guitar cavity that houses them. But humbuckers are symmetrical in shape and you can install them with either coil facing the bridge. With some humbuckers this will affect the sound but there’s often no right or wrong, only what your ears like most.

Connection

pic 1

First of all let me say that the (+) and (-) have no electrical meaning in this pic because we’re talking about alternate current. They are just there to identify sides.

A pickup in its basic form is a single coil. For it to work, the two ends of the coil must form a circuit. For this, one side is connected to ground and the other is the active portion of the signal sent to the amplifier. If either side is disconnected, the pickup is inactive. Commonly the ground side is permanently connected and by connecting/disconnected the other (the hot) side we can turn the pickup on/off. A humbucker follows the same principle, one side is grounded, the other side is hot. In its basic form a humbucker is connected to the rest of the circuit exactly as if it were a single coil. Notice in the pic that a humbucker has two coils daisy-chained together. This is known as the “in series” mode. There are other ways to use a humbucker, which we’ll explore later.

CAUTION: Different brands use different color codes for the wires coming out of their pickups. Consult the manufacturer for their color code before starting a swap of pickups.

CAUTION: Always make an accurate and detailed chart of the current wiring of your guitar (all connections and wire colors and origin and anything additional that will help you tell one wire from the other). That way you have something to go back to if you mess up.

CONVENTION: In this article I use red for hot, green for ground. Later in the article if things get complex and I need more colors for clarity, I’ll use red (hot) with black (ground) for one coil and blue (hot) and green (ground) for the other coil of a humbucker.

Integration into a guitar circuit

There’s more to a guitar’s electronics than a pickup and an output jack (well, there are exceptions). Typically there is a selector switch, one or more volume controls, one or more tone controls and in some cases other controls as well.

There are serial controls and parallel controls in a circuit. You can combine such in various ways but typically the pickups, main switch, volume controls and output jack are serially connected. Tone controls and coil-split switches are parallel to elements of the main circuit.

Switch

The switch is your means to quickly turn pickups on and off. At the same time, in a typical setup, the switch is also your blend point; the point where individual signals from the pickups are blended. This is important in deciding where to put certain controls. Pickup-specific controls (pickup volume, pickup tone and others) must go before the switch (it makes sense, right? Put the pickup-specific controls before the signals are blended together into one signal). Global controls (global volume, global tone…) must come after the switch (makes sense too, huh?). Except for the pickups and output jack, everything else in the schematic below is optional, at the cost of the respective functionalities.

pic 2

There are various types of switches used for various things in a guitar. The two most common switches are the 3-way (for two pickups) and the 5-way blender for 3 pickups. It is called blender because in positions 2 and 4 it automatically blends the signal from 1 and 3 or 3 and 5 respectively. The 3-way has one blend position, the middle one.

  pic 3

Volume

Without going into much detail, the volume control is a split of paths for the signal. One path remains hot, the other path is a shortcut to the ground. The two paths are separated by a variable resistor. In the pic, signal input is the rightmost connection to the control. Hot output is the middle connection and the alternative ground output is the leftmost connection. By adjusting the volume control, you balance how much of your electrical signal goes to each output. The more that goes to ground the less volume you have. The back of a volume pot is often used as the gathering point for all ground connections. You can find more details on the volume control at the bottom of the page.

pic 4

Tone

The tone control works in a similar way. It offers an alternative path to the signal and that path leads to the ground too. The difference from the volume is that the path is gated by a capacitor. The type and value of the capacitor affect which frequencies are allowed through (a high-pass filter). High capacitor values allow a wider range of treble to pass through. But since the path leads to the ground, the frequencies allowed through the capacitor are effectively removed from your signal (hence you lose treble when you roll down the tone). By controlling the resistance of this path, you determine how much signal is lost this way. The tone control is a parallel element to the circuit. You can find more details on the tone control at the bottom of the page.

  pic 5

The bigger picture

Ok now you’ve seen, how each individual control comes into the game. Even though you should be able to roll on your own now, chances are you are still confused. So let’s put together a model circuit, piece by piece. I’m intentionally copy-pasting elements and sub-sections of the schematics to show you that it is all modular. You don’t need a complete exact schematic of the wiring you want to implement because often you can’t find the exact match. But if you can identify the modules in the circuit, you can find and take elements from other schematics to make your own setup work.

• First, let’s add the volume and tone. It is more convenient to connect everything on the volume control than directly to the output jack. The back of the volume control is the gathering point for all ground connections.

  pic 6

• That’s not very interesting, although it was popular in the ‘80s. We need at least one more pickup to make it electrically interesting and we have to decide if we want global or local controls. I say we let them be global. So let’s add a second single coil and a humbucker to spice things up. For the tone and volume to be global, the switch will come before them.

  pic 7

Notice nothing changes for the volume and tone. Instead of being fed a signal from a single pickup, they are fed the blended signal from the switch but as far as they are concerned nothing has changed. Also notice that the 3 pickups are all connected in exactly the same way to the switch and volume control. There is still something missing from pic 7: the splitting function for the humbucker, but I leave that for later (pic 10).

• Now let’s also make a schematic with pickup-specific controls. Let’s take 2 humbuckers and give each its own volume and tone (LP style).

  pic 8

Again nothing changes for the volume and tone, except now there’s a second pair of them. Each pair handles signal sent directly from one pickup. Basically it is pic 6 twice (if you can’t see that, you’re not ready to read further). The two copies of pic 6 have to share the same output jack so a 3-way switch takes up the job of blending the two signals just before the output.

• Now let’s make a mixed setup. 3 pickups, global volume, 2 tone controls for 2 out of the 3 pickups (can you say Strat?).

pic 9

Now compare this with pics 7 and 8. Something is off, right? The tone controls are feeding off of the switch. Indeed, the connection points of the pickups to the switch are the only accessible point of each pickup’s individual signal before the switch blends the signals. Since the tone controls are parallel controls, nothing changes as far as the switch and volume are concerned compared to pic 7.

There is an alternative, less economic way to achieve the same result:

  pic 9.1

If the explanation that follows confuses you, leave it for now. In electrical terms this is identical to pic 9. The tone controls come alive only when the switch turns on their connection to the hot point. To understand why these are identical refer to the section at the top of the article. In terms of human-centric concept however there is a difference. In this setup you could consider each tone control to be a global tone control that is however only active when the switch is in the respective position. Why global? Because if you track down the red wire (top left of the switch) which is the switch output for the tone controls, you’ll see it connects to the hot point after the pickup signals are blended. The truth is that the same is true for pic 9 too (being global controls), but the layout there is such that it is conveniently masked to look like the tone controls work on an individual pickup’s signal. In reality, all the points between the pickups and the volume control are electrically identical once they are activated by the switch.

Coil splitting

There is one more thing left to mention before we conclude the first round of sections in this tutorial. Like I said earlier in pic 7, something was missing. If you have guitars with humbuckers and single coils, this is something you have to be aware of. Splitting as it is achieved with a 5-way switch, is a little hard to grasp because it doesn’t use the output connection of the switch, but instead it joggles with the input connections, using the middle input as output.

Like I mentioned early up, humbuckers consist of two coils in order to cancel 50Hz hum. In a 3 pickup guitar with a single coil in the middle and one or two humbuckers, there are positions of the 5-way switch where you end up with 3 coils active (2 from the humbucker and 1 that is the middle pickup). 3 doesn’t cancel hum. To remedy this, you turn off one of the coils of the humbucker, the coil that has the same polarity with the middle pickup. This way you then have only two coils again and you are humbucking and happy.

To do this, you have to get in between the two coils and short one of them out. No, put that screwdriver down and slowly back away from the pickup! :P We’ll use the switch for this. Some humbuckers only offer two wires. You can’t split these humbuckers. Some others offer 3 wires (the two coils are connected together but the pickup gives you remote access to that connection). That will do fine. Most commonly they offer 4 wires, which means the coils are not connected at all, giving you full control (see humbucker modes later in the tutorial). To short one of the coils out, you connect the middle point between the coils to either the ground or the hot. Which you choose, determines which coil stays active and whether you stay humbucking in positions 2 and 4 of the switch or not. Using a hot connection to split a humbucker is dangerous in the sense that if you don’t do it exactly like I’ll show you, you are almost guaranteed to bypass the switch and have a pickup being active when you don’t want it to.

Instead of revising pic 7, I’ll use a guitar with 2 humbuckers and a single coil. You can make the extension as necessary to fit pic 7. Think modularity. If you can’t figure this out after everything I’ve said so far, you either rushed down here and need to go back up and read carefully or this tutorial has failed and you can stop reading it.

  pic 10

What is important to understand here is that the split wire sitting on input 1 is activated only in position 2 when the output wire from input 3 is also activated, and the split wire sitting on input 5 is only active when the switch is at position 4 for the same reason. The top example is with 3-conductor humbuckers, the bottom one shows 4-conductor humbuckers. Independently of this, the top example feeds a ground connection to the split connection, shutting down the bottom coils that now have ground on both ends at switch positions 2 and 4. The bottom example feeds a hot source to the splitters, shutting down the top coils that now have hot on both their sides at switch positions 2 and 4.

Think of it as a cascading fountain. You supply water to the top one and it flows from the top basin and fills the lower one. If you supply the water directly to the lower one, the top one will empty but the lower one will stay full.

Volume and Tone Controls

This is not really necessary for you to make mods. As long as you connect the two types of controls in ways equivalent to the ones shown in the pictures of the article above you should be fine. If you do want to understand them better though, read on.

In picture 0.1 while referring to active paths in relevance to the switch, I drew the volume control’s internals. Then later I mentioned it offers an alternative path to the signal, but i didn’t go into more detail. In similar fashion to pic 0.1 now I will display the active paths in relevance to the volume and tone controls. Yellow highlights the active path.

pic 11

When you roll back the volume, you bring the hot output (red arrow) closer to the ground point (green wire), thus allowing more signal to take the green path instead of the red one. However only the red path is used by FX and amplifiers.

Rolling back the tone reduces the resistance of that path allowing more signal to pass through and specifically more treble.

You may now proceed to Part II: Advanced Guitar Wiring.