Choice of potentiometer and capacitor values and types for electric guitar

Potentiometers

The two most common potentiometer (pot) values used in guitar construction are 250kOhm and 500kOhm. 250kOhm pots are generally used with single coil pickups while 500kOhm pots are used with humbuckers. This is a general rule and there are exceptions.

Potentiometers are available in two types often labelled type A and type B. The type refers to the taper, ie. the relationship between the angle turned and the change in resistance.
- type A - logarithmic ( 250k would be marked A254) This type is used for tone controls.
- type B - linear (250k would be marked B254) This type is used for volume controls.

There is much debate of the use of type A and B pots. Some people would use type A for volume as well as tone controls.

Regarding the choice of value 250k or 500k - actually it will make little difference to the volume control, and will have only a small effect on the tone control, so I wouldn't worry too much if you have the wrong value for the guitar type you are building.

Capacitors

A capacitor and a potentiometer together form a simple (passive) tone control circuit. Capacitor values are usually given in microFarad (uF), nanoFarad (nF) or picoFarad (pf). 1000nF is the same as 1uF, and 1000pF is the same as 1nF

Capacitors are labeled with three digits. The first 2 being the value and the third being the number of zeros, for exapmple 473 actually means 47000 picoFarad which is 47 nF or 0.047uF.

Various values of capacitor are used depending on the impedance of the pickups. A single coil pickup ( stratocaster) typically uses a 47nF ( 0.047uF) capacitor.

The table below shows typical potentiometer and capacitor values used in common guitar types. Note that different manufacturers use different values so your guitar may not be the same.

-
Guitar Volume1 Volume2 Tone1 Tone2 Capacitor1 Capacitor2
Stratocaster 250K type B - 250K type A 250K type A 47nF 47nF
Telecaster 250K type B - 250K type A - 22nF -
Les Paul 500K type B 500K type B 500K type A 500K type A 22nF 22nF

Experimenting

If you're not happy with the effect of the tone control on your guitar it is well worth trying a different value tone capacitor. If you are building a new guitar and because of the variation of pickup types and resistances, it is not a bad idea to experiment with various capacitor values and find the value that sounds the best to you! This will also allow you to put your mark on the guitar! For example if the tone appears to go from a very bright to a very dull sound in a fraction of a turn of the tone pot, then try a smaller value capacitor - say half the value.
Similarly you can accentuate the effect that the tone control has by increasing the capacitor value - try doubling the value.

It is worth knowing that if you connect two capacitors together in parallel then that is the same as adding together their values.

Similarly connecting two capacitors in series will reduce the overall capacitor value and if they are both the same value then the effective capacitor value will be halved.

Please check out our choice of capacitors at www.janika.co.uk. We stock the most common values and we can provide a kit of different value capacitors if you wish to experiment.

Janika