Overdriving a bass signal significantly changes the timbre, adds higher overtones (harmonics), increases the sustain, and, if the gain is turned up high enough, creates a "breaking up" sound characterized by a growling, buzzy tone.
In the 1960s and early 1970s fuzz bass was associated with the psychedelic music (e.g., Edgar Broughton Band), progressive rock (e.g., Genesis), and psychedelic soul/funk (e.g., Sly and the Family Stone) styles, and it tended to be a "warmer", "smoother", and "softer" overdrive-type sound caused by soft, symmetrical clipping of the audio signal that "round[ed] off the signal peaks rather than razor-slicing"[3] them and filtered out the harsher high harmonics.
This is achieved by hard clipping of the bass signal, which leaves in "harsher high harmonics that can result in sounds that are heard as jagged and spiky.
In the context of electric guitars, the terms "distortion", "overdrive" and "fuzz" are often used interchangeably, but they have subtle differences in meaning.
In practice, when a bass amp is "cranked" to its maximum volume, the fuzz tone will also include some power amplifier clipping.
The downside of using a pedal designed for the electric guitar is that the lower-end bass tone is mostly lost when the signal is heavily clipped.
Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability.
"Hard clipping" flattens peaks abruptly, resulting in harsh-sounding, high amplitude odd harmonics.
More complex pedals have different distortion effects (e.g., overdrive and fuzz), gates to trigger the volume at which sounds will get overdriven, mixers to mix the natural and fuzzed sound in the player's desired proportions, and multiple band equalizers (typically for low and high frequencies).
Boutique fuzz bass pedals even have unusual effects such as a "starve" effect, which mimics the distortion sound a pedal gives with a dying battery, a diode selector (either silicon or germanium) for selecting the transistor overdrive tone, and an octave selector (above or below the pitch being played).