Compressors And Limiters; The Need For Gain Control - BSS Audio DPR 404 User Manual

Compressors and Limiters

10.0 Compressors and Limiters
10.1 The need for The human ear excels in its ability to detect an extremely wide range of
sound levels. These can range from the quietest whisper to the roar of a jet
Gain Control
aircraft. When we attempt to reproduce this large range (dynamic range) of
sounds with amplifiers, tape recorders or radio transmitters, we run into one of
the fundamental limitations of electronic or acoustic equipment. In some
cases, such as amplifiers, the dynamic range available is quite good.
However, equipment such as tape recorders and radio transmitters have a
restricted usable dynamic range.
Fig 10.1 Dynamic
Range
What limits the available dynamic range of this equipment is its inherent
noise floor at the bottom end, and the maximum input signal resulting in an
acceptable amount of distortion at the upper end (See figure 1.2). The usable
dynamic range sits in between these two limits, and it is common practice to
operate a piece of equipment at a level that is somewhat below the upper
distortion point, leaving a margin of safety for the unexpected transient
loudness peaks present in program material. The safety margin is known as
headroom, and is generally in the range of 10 to 20dB. Lowering the standard
operating level to increase headroom helps distortion, but moves the average
program level nearer to the noise floor, thereby compromising the signal to
noise performance.
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