Guitar Potentiometers Explained

Guitar Potentiometers Explained

What is a Guitar Potentiometer?

A guitar can be intimidating to modify, especially if you don’t understand what’s happening under the hood. This article is all about potentiometers (“pots”) and what they do. A potentiometer is a variable resistor often used as an adjustable voltage divider.

Audio pots are a device’s tone and volume controls, such as with an electric guitar, but they have many other uses. It’s time to  have guitar potentiometers explained, see why they’re so crucial on electric guitars, and understand what to look for when shopping for replacements.

Volume and tone pots are the same component. The difference comes in the guitar wiring. The volume control pot affects the electrical output of the signal, and tone modifies frequencies. Guitar potentiometers work by passing an electrical signal from one side to the other when turning a knob. The higher the intensity, or resistance, the more power will pass from one side to the other.

Each pot contains a resistive strip and a sweeper (or wiper). The resistance strip is connected between lug one and lug three. When turning the knob, the sweeper attached to lug two moves over the resistance strip.

The third lug is grounded. As you turn the knob toward lug 3, more of the signal goes to ground. After it’s fully turned, volume is at zero. If this lug isn’t grounded, volume will not reach zero, rendering the volume pot useless.

Guitar Potentiometers Explained

Pots are split shaft or solid shaft. Be careful about finding the right size for holes and knobs. Push-on knobs go with split knobs. Knobs with set screws go with solid shaft pots.  Do not use a screwdriver to pry apart a split shaft if it feels loose. The need to do this means you bought the wrong kind of knob.

Pot quality is essential. Just ask Cheech & Chong! You will generally find full-size pots and mini-pots inside guitars.  Mini-pots (Alpha pots) are cheaper and less desirable. You see these in budget guitars. Upgrading existing pots is something to think about if you’re going to mod your instrument.

Which Pot Value Should I Choose? 

The best type of pot depends on the guitar pickups you have, as well as your personal preference. 

Higher resistance pots allow fewer treble frequencies to pass to ground, and the guitar will present a brighter tone. To increase treble, choose a higher value. For warmer sounds, go with a lower value.

A 250K pot is, therefore, the usual selection for a single-coil pickup (to smooth it out), and a 500K pot is the standard choice for a humbucker (to provide brightness and clarity). The correct choice is the resistance value that sounds best to you. 

Active pickups usually use 25K pots, although any resistance between 25K and 100K should work. Output impedance is much lower in active pickups than in passive pickups. Using 500K and 250K pots with active electronics creates horrifically shrill tones. Actives, therefore, necessitate lower resistance pots.

Guitar Potentiometers Explained

P-90 single-coil pickups traditionally use 500k pots, which create denser sound than you find with Strats or Teles.

1 Meg pots affect guitar tone by providing a brighter sound with bass roll-off and boosted highs. These crank-out intense treble that dissipates as you reduce volume. You sometimes see these on the Fender offset guitars and Les Pauls. 

Linear vs. Audio Taper

Taper is the measure of how a pot’s resistance changes with shaft rotation.  The issue with taper is that the human ear works differently than you might logically expect.

Audio ( logarithmic) taper creates a gradual volume increase up to the radial mid-point. A significant increase occurs at the mid-point and a more gradual increase through the remainder of the turn. The ear perceives this as a smooth transition, however. Linear taper creates an even increase or decrease in volume throughout the turn.

Our dumb ears perceive a significant volume change when you start turning, which almost sounds like an on/off switch. Audio taper pots are more popular than linear pots due to their perceived smoothness. I imagine my cat is better at accurately hearing these volume changes.

What About Capacitors?

A pot becomes a tone pot when a capacitor is attached. Capacitors alter specific frequencies to manipulate tone control. Adding a capacitor to a pot creates a tone pot acting as a low-pass filter, meaning you will lose treble as you turn up the knob.

A higher value capacitor will allow more high-end to pass to ground more quickly. .022 and .047 are the usual capacitor choices. .047 will lose more high-end.

Tone pots, therefore, control the flow of high frequencies to ground. High resistance guitar pots mitigate the loss of high frequencies.

What Are Push-Pull Pots?

A push-pull is a potentiometer containing a built-in switch, which adds a toggle switch to the guitar pot, meaning you don’t need to add another component to control added modifications. The most common use is probably to coil-split humbucker pickups.

There are so many possible wiring configurations for push-pull guitar pots. Check out my guitar wiring diagrams page.  

Tone Pot

Conclusion

Pots are a crucial component of any electric guitar setup, and understanding how they work can help you get the most out of your instrument. 

These little devices may seem inconsequential at first glance, but trust me when I say that there wouldn’t be much music happening in your gross basement without them.

I’ve covered everything from what pots are to resistance options–all to help you understand what kind of pots might suit your needs best. If you still want to learn more, check out this video for additional information