Guitar Wiring and Pickup Modifications
Continuing from the previous page, here are a selection of modifications that can be done to your guitar's internal wiring and pickups to change or increase the range of tones available.
1 - Phase reverse switch
Suitable for: Most guitars with two or more pickups.
1 - DPDT mini-toggle switch or Push-pull Volume or Tone pot
A very simple modification that can give a very useful additional tone for your guitar is a phase reverse switch. The concept is very simple - fit a double pole, double throw (DPDT) switch to reverse the connections to one of your pickups when it is activated. This will only be noticeable when the pickup is used in conjunction with another pickup.
As the two pickups are located in different positions along the length of the vibrating string, they will pick up different wave shapes, with a differing balance of harmonics. By mixing these two signals together out of phase, certain frequencies will be cancelled out, whilst other frequencies will be reinforced. The resulting tone is "comb filtered", reminiscent of the effect given by a phaser or flanger pedal with the sweep turned off. Sonically, this gives the guitar a bright, "hollow" tone.
Please note that it is not recommended to try this mod on a pickup with a metal cover that is connected by a single core screened cable - this would result in the metal cover being connected to the "hot" audio connection, which would inevitably cause hum and noise pickup.
On a guitar with two pickups, you can modify the connections to either pickup - check to see which is the easiest to apply it to. On instruments with three pickups, it is best to fit the switch to the connections from the middle pickup - this will give two different "out-of-phase" sounds.
You can use either a separate DPDT mini-toggle switch (Easier, but you will need to drill an extra hole in your guitar) or replace one of your guitar's volume or tone pots with a push-pull pot - this is a standard pot with a switch "piggy-backed" that can be actuated by pulling out or pushing in the shaft of the pot.
Wiring a phase reverse switch
2 - Coil tap switch
Suitable for: Guitars fitted with one or more humbucking pickups with three or four conductor wiring.
1 - DPDT mini-toggle switch or Push-pull Volume or Tone pot
This is probably one of the easiest and most effective mods that can be done. The concept is very simple - just bypass one of the coils of a humbucking pickup to turn it into a single coil pickup. Many modern production guitars do use this technique, however there are a huge number of instruments in use that could incorporate a coil tap, but do not.
This mod can be performed on pickups that have a single core plus screen connection, but this does involve dismantling the pickup - if you have any doubts about your ability to do this successfully (or have a vintage instrument), please do not attempt it! A competent repairer will be able do this for you for a reasonable fee. If you feel up to doing this yourself, please see the section on Coil Splitting below.
If you are coil-tapping two pickups, you can use one switch to switch both pickups together as shown below, or use separate switches for independent control of both pickups - this is great for live performance, allowing you to (say) switch from a single coil in the neck position to a fat bridge humbucker tone for a solo.
The illustration shows a single wire leading to the coil tap on the pickup, however, with 4-conductor pickups, this would be replaced by two wires joined together. Please note that no wiring colours are shown for the connections to the pickup, if you do not have access to the pickup manufacturer's data sheet, please check my Pickup Manufacturer's Colour Codes page for more information.
Wiring a coil tap switch
3 - Series / Parallel switch
Suitable for: Guitars fitted with one or more humbucking pickups with four conductor wiring.
1 - DPDT mini-toggle switch or Push-pull Volume or Tone pot (per pickup)
Whilst the tonal difference between series and parallel configuration is not as great as that given by coil tapping a humbucker, it does have the advantage of being fully humbucking in both positions - I find that it is very effective on the "hot rails" strat style pickups, and the parallel configuration gives a very convincing "tele" sound in the bridge position with this style of pickup.
Again, if you wish to use this mod on pickups that have a single core plus screen connection, you will need to dismantle the pickup - if you have any doubts about your ability to do this successfully (or have a vintage instrument), please do not attempt it! A competent repairer will be able do this for you for a reasonable fee. If you feel up to doing this yourself, please see the section on Coil Splitting below.
If you are coil-tapping two pickups, you will need to use separate switches for independent control of both pickups as all six tags of a DPDT switch will be used to switch one pickup.
As in the example above, no wiring colours are shown for the connections to the pickup, The drawing below shows how the switch should be connected to a 4 conductor wired pickup, in its standard configuration. Please check my Pickup Manufacturer's Colour Codes page for more information.
Wiring a Series / Parallel switch
4 - Independent pickup switches
Suitable for: Instruments fitted with three pickups.
3 - DPDT mini-toggle switches (3 position - centre off)
1 - Additional Tone Capacitor (optional).
This is a very nice mod, as it gives an enormous range of sounds - 13 (usefully) different configurations, by replacing the normal 5 way switch with three separate in-phase/off/out-of-phase switches. Yes, I know that 3, 3-position switches can give 27 different combinations, but half of them sound identical - ie bridge in-phase/mid out-of-phase sounds exactly the same as bridge out-of-phase/mid in-phase.
This does involve drilling some holes in your instrument's scratchplate, and some quite fiddly wiring, but it really does open up a great range on tonality from your instrument.
Wiring independent pickup switches
- Remove the original 5-way switch, unsoldering all connections from it (HINT - make a quick sketch showing which wire goes to each switch terminal).
- Carefully drill 3 holes (diameter to suit your switches, usually 6mm), one at each end of the slot, and one in the middle of the slot - hold the drill steady to make sure it does not "wander" down the slot.
- Fit the 3 mini-toggle switches in the holes and tighten the mounting nuts with a box spanner.
- Solder the two wire links on each switch in position first, then the four links connecting together pins "a" and "b" on each switch.
- At this stage, you need to consider how to wire in your tone controls - if your instrument just has one single tone control, this will usually be hard-wired in to the volume pot, and you will not have to change anything, if, however, your instrument has two tone controls, these should be connected as shown in the drawing below - you should unsolder the ground connection from one tag of each tone pot so that none of the tags are grounded (it is ok to leave the metal body of the pot grounded). If your instrument has only one capacitor "shared" between both pots, you will need to purchase another (your local TV repair shop should come in handy here!), make sure it is the same value. Use a short length of heatshrink sleeving or pvc insulating tape to insulate the connection to the capacitor, as shown in the drawing.
The standard arrangement on stock Strat type guitars is to connect the top tone control to the neck pickup, and the bottom tone control to the mid pickup - this is the arrangement shown in the drawing above. Personally, I prefer to connect tone pots to the mid and bridge pickups, but this is down to taste - experiment!
- Finally, connect the pickups to the switches, and the two wires from the "a" and "b" tags to the volume pot on the guitar.
Wiring tone controls to independent pickup switches
If you are reasonably adept with a hacksaw and file, a small metal or plastic escutcheon plate can be made to cover the slot in the scratchplate and restore the appearance of your guitar.