Distortion

Truthfully, there's no hard line that separates overdrive from distortion from fuzz. They all kind of hang out in this nebulous world of spillover from an auditory standpoint. If looking at the manner in which an audio signal is manipulated (changed) to get to a "clipped signal", it might be easier for us to understand where the distinction between the terms distortion, overdrive, and fuzz make a difference.

Similar to overdrive and fuzz, distortion is the modification of a sound wave such that the tips of the peaks and tips of the troughs of the sound wave are "chopped off" or "squared". This act of squaring the sound wave also creates higher-order harmonics in the sound you hear. This differs from overdrive and fuzz: first by the degree, or amount of squaring of the sound wave, second, by the number of frequencies that are "squared off", and finally, the nature of how the squaring occurs.

Distortion is most generally described as a clipped electric instrument signal, typically with both halves of the sine wave of the music signal being clipped. This differs from overdrive in that an overdriven signal tends to have only the "bottom" of the sine wave squared off while the top remains unchanged. However, like overdrive, Distortion also tends to have an asymmetry in the shape of the squaring of each: the top of, and the bottom of, the sound wave. This asymmetry means that the while the peaks of both the top and the bottom of the waveform are clipped, they are clipped to different degrees and in different ways, resulting in different shapes, and different amounts. This clipping (or cutting-off of) on both halves of the waveform results in both even-order and odd-order harmonics being generated.

LET US BE CLEAR: Distortion, for all intents and purposes, IS THE RESULT OF A FAILURE, whether intentional or accidental, of the electronics or of the physical components of the signal chain. This failure doesn't usually mean that the equipment will blow up, but the failure is manifested as changes to the sound. In particular, we define "distortion" as the phenomenon of when a signal is amplified beyond the ability of the amplification device (either tube, transistor, or integrated circuit) to handle the desired level of amplification, *AND* when that out-of-bounds amplification is cascaded across multiple amplification stages. So like others, overdrive and fuzz, the signal is clipped. Distortion differs, especially from fuzz, because the clipping occurs as a result of an attempt to amplify beyond the capacity of the amplification device.

This is also where we get the term "Gain". Gain isn't necessarily the same thing as distortion, however the two are often used interchangeably. Gain is simply the act of boosting an audio signal. The waveform clipping occurs when the device receiving the inputted sound signal cannot handle the amount of signal being jammed through the device.

Diodes can also be used to clip a waveform, but because this clipping isn't the result of a failure to meet the functional specification of the electronic amplification component, it's not associated with "Gain". Sound wave clipping is addressed in greater detail under fuzz.

It's certainly possible for an amplification device to amplify a signal and then for that signal to be fed into diodes which clip them. In fact, this is really the only way you can get diodes to clip. It's a subtle distinction, and in terms of the electronics, it may not be meaningful (there exist "distortion pedals", like the MXR Distortion+, that use diodes to clip), but we consider this difference to be the essential difference between "fuzz" and "distortion".

Contrast Guide

Overdrive

Minor waveform squaring-and-rounding from over-amplification, Effects usually only applied to one half of a sound's sine wave. Usually only through one or two gain stages.

Distortion

Major waveform squaring-and-rounding from over-amplification. Effects usually applied to both halves of a sound's sine wave. Usually cascaded through multiple gain stages.

Fuzz

Major waveform squaring without rounding due to diode clipping of waveform. Effect applied to both halves of a sound's sine wave. Usually only occurs through a single gain stage.

Distortion Pedals

• Boss DS-1
• Electro Harmonix Big Muff
• The Rat
• The Womanizer
• The Demonizer
• Solid Metal
• SS11B Modern

Revered Amps

There is no way we are going to get the list of "Revered Amps" correct for everyone's liking. There will always be a case to be made for some obscure amp (for example, a 1964 Supro Coronado 1690T a la Jimmy Page), but we're not discussing obscure, rare amps. We're talking the workhorses - the ones that people say, to themselves and others, "I want THAT sound". Here are some examples (alphabetical):

• Laney AOR 100
• Marshall JCM-800
• Mesa Boogie Mark III
• Mesa Boogie Dual Rectifier
• Soldano SLO-100
• Sunn Model T

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Jim Dunlop Guide to Overdrive, Fuzz, and Distortion