User's Manual

52 The Editor View
The amount of compression applied to the part of the signal exceeding the threshold value
depends on the Ratio parameter which varies between value of 1:1 and 1:16. This parameter
represents the ratio, in dB, between the portion of the output signal from the compressor above
the threshold value and the portion of its input signal also exceeding the threshold value. As one
might expect, increasing the ratio also increases the amount of compression applied to the signal.
For example, a ratio of 1:5 means that if the input signal exceeds the threshold by 5 dB, the output
signal will exceed the threshold by only 1 dB.
Two other controls affect the behavior of the Compressor. The Attack knob is used to set the
time, in milliseconds, before the Compressor fully kicks in after the level of the input has exceeded
the threshold value. A short value means that the compressor will reach the amount of compression
as set by the Ratio knob rapidly. With a longer attack, this amount will be reached more gradually.
In other words, the attack time is a measure of the attack transient time of the compression effect.
The Release parameter is similar and represents the amount of time taken by the Compressor to
stop compressing once the amplitude of the input signal falls below the threshold value.
The Makeup knob is used to adjust the overall level at the output of the Compressor module
and is used to compensate from an overall change in signal level due to the compression effect.
The attenuation or gain reduction level meter, located in the middle of the module, indicates
the amount of compression applied by the module. It is the difference between the input and output
signals of the module before makeup gain is applied.
5.4.3 Delay
The Delay module consists in a stereo feedback loop with a variable delay in the feedback. It is
used to produce an echo effect when the delay time is long (greater than 100 ms) or to color the
sound when the delay time is short (smaller than 100 ms).
The Delay knob is used to adjust the amount of delay, in seconds, introduced by the effect.
Turning this knob clockwise increases the delay. The Feedback parameter is a gain factor, varying
in the range between 0 and 1, applied to the signal at the end of the delay lines. It controls the
amount of signal that is re-injected in the feedback loop. In its leftmost position, the value of this
parameter is 0 and no signal is re-introduced in the delay line which means that the signal is only
delayed once. Turning the knob clockwise increases the amount of signal re-injected at the end of
the feedback loop and therefore allows one to control the duration of the echo for a given delay
time. In its rightmost position, the gain coefficient is equal to 1 which means that all the signal is
re-injected into the feedback loop and that the echo will not stop. In addition to this gain factor,
low pass filtering can also be applied to the signal re-injected into the feedback loop. The cutoff
frequency of this filter is controlled using the Cutoff knob.