Guitarists are notorious for their "do-it-yourself" attitude towards instrument maintenance and customization. Most of us won't hesitate to take our guitar apart at the first opportunity if it means avoiding prohibitive bench fees at the local repair shop. There are definitely conditions that call for professional intervention but with a little bit of knowledge and the right guitar parts, there's no reason that many of us can't handle some of the simpler tasks involved in maintaining, repairing, and customising our guitars.
Replacing guitar electronics is a fairly straightforward task that can be successfully handled with minimal effort. All you really need are some basic soldering skills and you're ready to go. Most conventional guitar circuits consist of pickups, switches, guitar pots, capacitors and a guitar jack socket. The hardest part is determining what value of potentiometer you need for your instrument. With that in mind, let's take a look at some of the determining factors that will help you make an informed decision when it comes time to replace a volume or tone pot.
Understanding Potentiometer Values
Basic rule of thumb goes like this: single coil pickups get a 250k pot, humbuckers get a 500k pot. Why is this? The higher the value of the pot, the brighter the sound, so higher value pots are used with humbuckers to allow a bit more high end to get through with what is, by design, a warmer sounding pickup. Lower value pots are used with brighter sounding pickups to tame some of the extended high end that is associated with single coils.
The Effect Of Potentiometer Values In Relation To Output And Tone
As a potentiometer is turned fully down, all of the signal from the pickup(s) is diverted to ground, resulting in no output from the instrument. When the potentiometer is turned up to full volume, the resistance of the potentiometer theoretically prevents any of the output signal leaking to ground, and weakening the output signal. Lower value pots, however, do not completely block the signal from leaking to ground even when turned up all the way, so using a 250k potentiometer will result in a slight loss of high frequency, as well as volume. This may please some musicians who want a mellower tone, but for those seeking ultimate purity of signal, a higher value potentiometer may be just what is needed. The higher the value, the more leakage is blocked from ground, which allows more of the signal to be sent to the output. A 500k pot may be just right, but a 1meg ohm pot will provide an all out sonic assault. Higher highs; lower lows; more volume - a rocker's dream! The only drawback of going to this higher value is the perceived range and sweep of the control. It's like going from 0 to 10 without the fine increments of control in between.
The Telecaster® is a good example of potentiometers determining the overall sound of an electric instrument. The earliest Telecasters® utilized 1meg ohm potentiometers. They were deemed too bright to be practical for a wide range of musical styles. As a result, the potentiometers were changed to 250k to "bleed off" some of the extreme treble "twang" that the early versions were known and loved for (Stratocasters® also use 250k pots for the same reason). Some Gibson® lap steel guitars had 5 meg ohm pots. Talk about bright!
Exploring Your Options
To find out if switching to a higher value pot might benefit you, try this simple test: Disconnect your pickup(s) from the circuit, and use some "jumper" wires to connect them directly to the output jack. If the pickups sound louder and fuller, then you will benefit from a higher value potentiometer. If, however, your pickups still aren't sounding the way you'd like them to, maybe take a look at our Kent Armstrong replacement pickups.
Log? Audio Taper? Linear....?
A question that we are always being asked is what is the difference between Linear and Log pots? Linear pots increase the impedance evenly as you turn them up. So, if you were to turn a Linear pot from 0 up to 5 (in other words from off position up to mid way) then the impedance is increased by half. However, the human ear doesn't actually hear this as a gradual volume increase, instead it sounds like nothing much happens for most of the sweep and then all of a sudden there is a huge jump in volume. This is where Log pots come in. Log is short for Logarithmic and is quite often referred to as Audio Taper or A Taper. Log pots are used specifically for audio applications and are adapted to the human ear so that the entire sweep of the pot sounds like a gradual increase, offering a greater degree of control and accuracy when used on a guitar or bass. Most guitar manufacturers use Log pots for both volume and tone controls on their instruments and they are by far the most popular choice amongst musicians when purchasing replacements. This is the reason why most of the pots you see on our site are Logarithmic.
The Role of Capacitors in Tone Controls
While we’re discussing pots, it’s also worth noting the role of capacitors in tone control circuits. Capacitors are used in conjunction with tone pots to filter out high frequencies, allowing you to control the amount of treble that is present in your guitar’s signal. The value of the capacitor can significantly impact the tonal range and behavior of the tone control. Common values for tone capacitors are 0.022µF for humbuckers and 0.047µF for single coils. Higher value capacitors will roll off more high frequencies, making the tone warmer as the tone pot is turned down. While these two values are traditionally the most common for most passive electric guitar circuits, there is a third option that are preferred by some players. If a 0.047µF capacitor is making your guitar sound too dark or muddy and the 0.022µF is too bright when the tone control is rolled all of the way down then a 0.033µF will get you a good in-between tonal roll-off and strikes a good compromise between both values.
Another useful modification involving capacitors is the treble bleed circuit, which is often added to the volume control. As you roll down the volume, a 0.001µF capacitor acts as a "treble bleed", that ensures that the high frequencies are retained, preventing the sound from becoming muddy. This can be implemented by simply soldering a 0.001µF capacitor between the input and output lugs of the volume pot.
For more fine-tuned control, a treble bleed circuit can also include a resistor in parallel or series with the capacitor. This combination helps maintain a more consistent tone as you adjust the volume, preserving clarity and brightness without getting too "tinny" or "thin" sounding as you turn the volume down. Whether you prefer just the capacitor or the capacitor-resistor combo, incorporating a treble bleed circuit can be a game-changer for achieving that perfect, articulate sound at any volume level. There is always an element of experimentation when trying these options and as always, it is down to personal preference depending upon the sound that you want.
Conclusion
Hopefully, this guide explains why certain value pots and capacitors are used with certain pickups and arms you with the knowledge necessary to experiment with some non-traditional alternatives. For replacement pots, check out our Electronics section. You will find top quality replacement pots from Alpha and CTS (as used by Fender since the early 60s') as well as our exclusive Kent Armstrong range. Whether you’re looking for standard values or want to experiment with something new, we’ve got the right components to help you perfect your tone.