User`s manual

AEQ FORUM - DIGITAL AUDIO MIXER FOR BROADCAST APPLICATIONS

Configuration screen Compressor / Limiter

Dynamics processors are used to modify the dynamic ranges of an audio signal to adapt it to

specific needs or to produce certain sound effects. A compressor enables you to reduce the

dynamic range of the signal. Your purpose may be to adapt a signal with a very broad dynamic

range to a circuit that will not support such wide variations in level, or to generate a certain

sound in a signal.

The graph represents the variation produced in the different levels of the signal applied to this

function. On the horizontal axis are the input levels, while the vertical axis shows output levels.

The “Compressor / Limiter” function acts as a “constant gain” compressor; that is, below the

threshold, all input signals are amplified (or not amplified) equally, while above the threshold,

the input levels are reduced to a greater or lesser degree according to the compression ratio.

If the compression range selected is the maximum, the function will act as a limiter in such a

way that the signals that exceed the selected threshold at input will not exceed a certain level at

output. For example, with a threshold = 0 dB, a gain of 10 dB and a compression ratio of 1:50,

you will ensure that all the signals that exceed 10 dB at input will also be output at 10 dB, while

the signals that are below the threshold will have an overall gain of 10 dB.

The controls available are:

• Threshold: This is the threshold above which the compressor will act. Signal levels that

exceed this threshold will be affected by the compressor settings. The threshold range

varies from -42 dB to +22 dB.

• Attack Time: This is the time it takes the compressor to react to an increase in the input

signal. The shorter this time, the more sensitive the compressor will be to pulse signals,

and the more it will act on this type of signals. With a long attack time, the compressor

will not respond so well to pulse changes in the input signal.

• Release Time: This is the maintenance time during which the compressor keeps acting,

even when the level of the input signal has fallen below the threshold. A long release

time will maintain uniform compression, even when there are quick level fluctuations in