15 Distortion

Clipping

Occurs when the input signal is too high for the system it is passing through
When an amplifier is pushed beyond its maximum limit, it goes into overdrive; this causes the amplifier to try and produce an output voltage beyond its capability, which is when clipping / distortion occurs
This means that the peaks and troughs of the waveform are flattened, and the resulting signal has more power, giving a harsher / brighter / crunchy / gritty tone; for some purposes e.g. for electric guitar, this is desirable
If the gain is too loud when you are recording, you will end up capturing a distorted signal; this can’t be removed
Distortion make the harmonics above the fundamental more audible; this gives a fuller sound – analogue clipping can add desirable harmonic content and sometimes you might drive a preamp a little to get this
Digital clipping is normally undesirable; a digital system can be overloaded at the input to the point of clipping.
At 0dBFS, it has run out of headroom and dynamic range because we don’t have any more 1s and 0s (11111111).

Valve amplifiers were used almost exclusively until the rise of solid state amps in the late 60s / early 70s
Solid state amplifiers used transistors which were cheaper, smaller and more reliable than valves
This made amplifiers more efficient, which had an impact on their affordability and size
There has been resurgence in the use of valve amplifiers as they soft clip the signal, giving a warmer overdrive
Solid state amplifiers exhibit hard clipping that gives a harsher overdrive
Soft clipping starts saturating and adding harmonics at a lower level; these harmonics are quiet and we hear them as as warmth and richness; we hear hard clipping as harsh and brittle.

Overdrive occurs when the signal exceeds the maximum input level the amplifier can handle causing clipping; it is described as rich / warm and gives sustain
Fuzz gives a more distorted / higher driven sound than overdrive which can create IMD (intermodulation distortion) and when pushed, makes the waveform look more like a square wave
Saturation occurs when an input going into analogue gear e.g. tape / preamp is around the point of distortion
It responds at this point in a non-linear way; the loud parts just start to clip, adding harmonics and colour
An exciter adds harmonics by distorting a specific frequency range; they are often used for adding high frequency content and making parts cut through the mix more effectively, or in remastering / tape recordings
Bit distortion occurs when the bit depth of a signal is reduced; this can be used as a lo-fi creative effect in electronic music production to add character or grit to a sound (e.g. in electropop), or as unwanted alias tones

Amp simulators are convenient DAW plugins that allow us to emulate the sound of a physical amp, entirely in the box (on a DAW), or to create our own completely original amp setting
Many different amplifier types can be achieved without having to buy many amplifiers and if software plugins are being used, the amp settings can easily be altered during the mix stage
You can have multiple instances of an amp simulator running with different settings on different tracks
Enthusiasts say that real guitar amplifiers sound much better than amp simulators because of their analogue electronics; whether that be the soft clipping valves or harsher hard clipping transistors.

Distortion offers a range of textural and lo-fi effects, helping a part cut through the mix by adding more harmonics and giving a harder-edged / grittier production; it can also create lo-fi effects
In addition to adding harmonics, distortion limits the dynamic range and helps guitar parts blend
Saturation can make a vocal part more expressive by bringing out breath noise / add warmth
When applied to drums / percussive parts it will be most audible on the transients / peaks
Bitcrusher can emulate the alias tones of early samplers / game music that used a lower bit depth (e.g. 12 bits)
Tape delay units, pushed into distortion with high levels of feedback can create distortion and saturation
Plugins can emulate soft clipping associated with analogue gear – e.g. tape, mixers and valve pre-amps.

Distortion

Types of distortion: overdrive and fuzz

Parameters: gain/drive, output, tone

Valves

Soft clipping

Tape saturation

Solid state

Hard clipping

Amp modelling

Amps and speaker types

Virtual mic types / placements

Harmonic distortion

The effect of distortion on harmonics

Exciters

Electric instruments

Electric guitar

Bass guitar

Development of music technology

The wider impact of distortion on the music industry