How Do Distortion Pedals Work?

Tube Distortion Pedals

Tube distortion pedals contain an amplifier and a distortion circuit. The amplifier increase the strength of an input signal and sends it to a tube based distortion circuit to distort the audio waveform. This is usually done by adding a pre-amplifier just in front of the tube. The pre-amplifier increases the tube's supply voltage past its design limits. In mild distortion, the tops and bottoms of the audio sine wave are clipped. In moderate distortion, the curves of the sine wave start to become more square, with more of the tops being clipped. In extreme distortion, the wave form changes from sine to a square wave. Tubes tend to compress when they distort. The output signal levels are flattened. Quieter notes are amplified more and louder notes are amplified less. Tube distortion is smoother and more dynamic than other forms of distortion. Tubes that are overdriven for distortion wear out and eventually need to be replaced.

Solid-State Distortion Pedals

Solid-state distortion differs from tube distortion in its tone, timbre, and other audio qualities. The basic principle is the same as in a tube distortion pedal. A signal overdrives a transistor based distortion circuit causing the tops and bottoms of the sine wave to clip and flatten. Solid-state distortion is harsher than tube distortion. Solid-state distortion tends to compress less, allowing for more of a difference between quiet and loud note. Other than a difference in sound, an advantage of solid-state distortion is longevity. A transistor lasts a very long time when overdriven.

Fuzz Boxes

Fuzz boxes are a specialized type of solid-state distortion. A fuzz box often uses a specialized germanium transistor, although scarcity of germanium transistors has resulted in some outstanding silicon transistor designs. The germanium transistor reacts uniquely to being overdriven. Its wave is more square than solid state or tube giving a germanium distortion pedal, or fuzz box, a rougher more organic sound. Fuzz boxes are rich in harmonics and harmonic distortion, with the harmonics being unrelated to the tone of the input signal creating dissonance. Fuzz boxes tend to compress the signal more than other solid-state distortion pedals. They tend to create more feedback when used with high volume amplification.