Audio Effects by Joshua D. Reiss & Andrew McPherson

Author:Joshua D. Reiss & Andrew McPherson [Joshua D. Reiss]
Language: eng
Format: epub
Tags: Digital Media
Publisher: CRC Press
Published: 2014-10-22T16:00:00+00:00

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Input Sample

Output Sample

FIGURE 7.1

The characteristic input/output curve for a quadratic distortion.

169Overdrive, Distortion, and Fuzz

Hard and Soft Clipping

Both digital and analog systems have limits to the magnitude of signal they

can process. For analog systems, these limits are typically determined by the

power supply voltages and architecture of each amplier stage. In digital sys-

tems, the limits are usually determined by the number of bits in the analog-

to-digital converter (ADC) and digital-to-analog converter (DAC). When a

signal exceeds these limits, clipping occurs, meaning that a further increase

in input does not produce any further increase in output. Clipping is an

essential feature of distortion effects, and the way that an effect approaches

its clipping point is a crucial part of its sound.

Distortion effects are often classied by whether they produce hard clipping

or soft clipping. Figure7.2 compares the two forms. Hard clipping is character-

ized by an abrupt transition between unclipped and clipped regions of the

waveform, which produces sharp corners in the waveform. Soft clipping is

characterized by a smooth approach to the clipping level, creating rounded

corners at the peaks of the waveform. In general, soft clipping produces a

smoother, warmer sound, whereas hard clipping produces a bright, harsh,

or buzzy sound. Hard versus soft clipping is not a binary decision, and any

given characteristic curve will fall on a continuum between the two.

The simplest, purest form of hard clipping simply caps the input signal

above a certain magnitude threshold:

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Soft Clipping (Exponential function, G = 5)

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