Most electric guitars offer at least a basic tone and volume control. These controls are audio-taper potentiometers that work as rotary dials, and allow you to change the volume and the tone of your guitar. The potentiometers are exactly the same. Therefore, a manufacturer must install capacitors and resistors onto the tone potentiometer to change it from a standard volume knob to a tone knob. Capacitors and resistors do have an affect on your guitar’s tonal output.
Capacitors Versus Resistors
You will find capacitors soldered into the electronic circuits of almost every electric guitar that has built in controls. However, you will not find resistors when inspecting the circuits of most electric guitars. Resistors restrict the flow of electricity whereas capacitors bleed electricity to ground. This makes resistors less valuable and capacitors extremely valuable when wiring a guitar circuit.
How Capacitors Change Tone
A capacitor, when wired to a potentiometer, creates a tone control rotary knob. When you turn the knob, the capacitor increases the amount of high frequency tones that bleed to the ground circuit. This removes the treble signals that travel from the guitar to the amp and makes your guitar sound like it has more bass tone.
Different Capacitor Values
There are countless capacitors on the market and most have different values. Capacitor values are referred to as “MDF”, “uF” or Microfarad. The higher the uF valve, the more treble the capacitor bleeds to ground. As an example, in standard electric guitars it is common to see capacitors ranging between 0.020uF and 0.047uF and when inspecting bass guitar circuits, it is common to see capacitors ranging between 0.047uF and .100uF.
Locating the Capacitors
The capacitor always connects to the tone control potentiometer. To locate the capacitor, inspect the center soldering lug on the tone control. The center lug holds one half of the capacitor. On most circuits the second half of the capacitor solders to the casing on the back of the potentiometer so it can bleed the treble circuit to ground.
Are Resistors Ever Used?
Resistors are used as permanent, non-adjustable high-pass filters on some guitars. You will locate the resistor soldered to the lugs that connect the volume control potentiometer and the tone potentiometer together. The resistor replaces the wire that connects the two lugs together on a standard circuit. Manufactures use resistors when a guitar’s tone is too shrill, even with the standard tone control.