Panning Electric Bass: Pot Options

Electric bass guitars use potentiometers, or pots, to control their volume and tone. Pots are variable resistors that change the volume or tone by increasing or decreasing resistance. The most common resistance values for guitar pots are 250K and 500K, but there are several others such as 100K, 300K, and 1000K (1 Meg). The higher the resistance value, the more treble you will hear. Pots also have a taper, which refers to the resistance-position relationship. The two types of taper used in guitars are logarithmic (known as an audio taper) and linear.

Electric bass guitar potentiometers

Electric bass guitars use potentiometers, or "pots", to control their tone and volume. Pots are variable resistors that change the tone or volume by increasing or decreasing resistance. The resistance value of a pot determines how much of the signal is bled to the ground. The higher the value, the more treble you will hear. Pots with a resistance value of 250K are generally considered the most useful for bass players, as they offer plenty of treble response that's suitable for all playing styles.

There are two main types of taper used in guitar pots: logarithmic (known as audio taper) and linear. The taper refers to the "resistance-position relationship". With a linear taper, treble cuts off quickly early in the turn of the knob. With an audio taper, the treble decreases much later in the turn, allowing for more use out of almost the whole turn of the knob. For this reason, audio taper pots are preferred by bass players.

When upgrading or replacing pots, it is important to consider the shaft length, diameter, and type of splines, as these factors affect the fitment of control knobs. There are also mini-pots and full-size pots. Mini-pots are usually associated with low-end guitars, while full-size pots are found on higher-end brands. It is generally recommended to upgrade to full-size pots when replacing guitar pots.

In addition to pots, capacitors (or "caps") also play an important role in the electrical system of electric bass guitars. Caps are used to manipulate specific frequencies to shape the tone. By lowering the pot, the treble is throttled, and the tone gets darker. Larger value caps allow more signal to pass to the ground, knocking down high frequencies and better exposing the midrange tones at lower volumes.

Audio vs linear taper pots

Audio taper and linear taper potentiometers (pots) are two types of rotary potentiometers that control the volume and tone of an electric guitar. The difference between the two lies in how the potentiometer's resistance changes as it is turned.

Audio Taper Pots

Audio taper pots, also known as logarithmic taper pots, are designed to compensate for the fact that human hearing doesn't work in a linear fashion. In other words, our perception of volume changes is not directly proportional to the electrical signal strength. An audio taper pot will increase or decrease most of its resistance in the final 50% of its rotation, resulting in a more natural progression when used for volume control. This means that turning the knob from "1" to "2" or "3" will have little to no effect on the volume, but once you pass "3", the volume will increase significantly. Past "8", there will be very little volume increase, and the signal will start to clip.

Linear Taper Pots

On the other hand, linear taper pots provide a uniform taper. When the pot is turned to its halfway point (50%), it will reach 50% of its total resistance, following a straight line. For example, if it is turned to 25% of its cycle, it will have a resistance reading of 25%, and so on. Linear taper pots are often used in tone control settings.

Choosing the Right Pot

The choice between an audio taper and a linear taper pot ultimately depends on personal preference and the desired effect. Audio taper pots offer a more instant increase or decrease in volume or tone, making them a good choice for quick volume boosts on stage. Linear taper pots, on the other hand, provide a smoother and more predictable transition, giving players more control over the signal increase or decrease.

It is worth noting that some guitarists prefer to use a combination of both types of pots, with audio taper for volume control and linear taper for tone control. Additionally, different guitar models and brands may use different types of pots, and some pots fall between the two categories, offering a more uniform taper sweep.

Potentiometer resistance values

A potentiometer is a manually adjustable variable resistor with three terminals. Two terminals are connected to the ends of a resistive element, and the third terminal is connected to a sliding contact, called a wiper, that moves over the resistive element. The potentiometer functions as a variable resistance divider, with the resistive element acting as two resistors in series. The wiper position determines the resistance ratio of the first resistor to the second.

The resistance value of a potentiometer is determined by the position of the wiper. The higher the potentiometer resistance value, the more high-end frequencies will pass through. The most common values for guitar pots are 250k and 500k, but there are several others such as 100k, 300k, and 1000k (1 meg). The resistance value determines how much of the signal is bled to the ground. The higher the value, the more treble you will hear.

The taper of a potentiometer, or the "resistance-position relationship," is also an important factor. In guitars, the two most common types of taper are logarithmic (also known as audio taper) and linear. With a linear taper, treble cuts off quickly early in the turn of the knob. On the other hand, with an audio taper, the treble decreases much later in the turn, making it the preferred choice for bass players as it provides more use out of the knob's rotation.

It is worth noting that there is no official rule requiring the use of a specific potentiometer resistance value or taper type in electric bass guitars. Ultimately, the choice depends on personal preference and the desired sound.

Capacitor values

The capacitor values determine the performance of the guitar. The capacitor diverts the flow of specified guitar frequencies through the electronics. The higher the capacitor's rating, the darker the tone knob will be.

The three most common capacitor ratings are:

• .015 µF capacitors: These offer fine control of treble throughout the tone knob's range, removing harsh frequencies without transitioning to a dark, muddy tone.
• .022 µF capacitors: These are the perfect middle ground, working well with both single-coil and humbucker pickups, offering a balance of clarity and warmth.
• .047 µF capacitors: These are darker and can be great for brighter guitars like Teles and Strats, but they are also used by jazz players with humbucker-equipped guitars as they deliver warmth and a fat tone.

The capacitor values are not set in stone, and experimentation is encouraged to find the best sound for your instrument.

Shaft length

The shaft length of a potentiometer is an important consideration when upgrading the pots in your electric bass guitar. The shaft is the part of the pot that has threading and sticks through the guitar top or pickguard, where it is held down by a threaded nut.

The shaft length you need will depend on the thickness of the guitar top or pickguard where the pot will be mounted. If you are mounting the potentiometer to a thicker-topped guitar, such as a Gibson Les Paul, you will likely need a long shaft pot to ensure it can be securely mounted. Guitars with thinner tops or pickguards will require short shaft pots.

Long shaft pots are typically around 3/8" long, which is suitable for passing through a 1/4" thick guitar top and applying a 1/8" thick nut to hold the pot in place. There are also shorter shafts available that are 1/4" long, which are designed for mounting to 1/8" thick pickguards. However, you can use a 3/8" long shaft on a pickguard-mounted pot by adding a second nut to the bottom of the shaft to shim the pot lower in the pickguard.

It's important to note that different guitar manufacturers may have different ways of making their control cavities or contouring their tops, so it's recommended to measure the shaft lengths of the existing pots before purchasing new ones.

Frequently asked questions