User Guide

FXAlg #952: Expander
Algorithm Reference-143
The signal being expanded may be delayed relative to the side chain processing. The delay allows the signal to stop
being expanded just before an attack transient arrives. Since the side chain processing ÒknowsÓ what the input
signal is going to be before the main signal path does, it can tame down an attack transient by releasing the expander
before the attack actually happens. A meter is provided to display the amount of gain reduction that is applied to
the signal as a result of expansion.
Parameters:
PAGE 1
PAGE 2
In/Out When set to ÒInÓ the expander is active; when set to ÒOutÓ the expander is bypassed.
Out Gain The output gain parameter may be used to increase the gain by as much as 24 dB, or
reduce the gain to nothing. Note that the Out Gain parameter does not control the signal
level when the algorithm is set to ÒOutÓ.
Atk Time The time for the expander to increase the gain of the signal (turns off the expander) after
the signal rises above threshold.
Rel Time The time for the expander to reduce the signal level when the signal drops below the
threshold (turning on expansion).
SmoothTime A lowpass Þlter in the control signal path. It is intended to smooth the output of the
expanderÕs envelope detector. Smoothing will affect the attack or release times when the
smoothing time is longer than one of the other times.
Signal Dly The time in ms by which the input signal should be delayed with respect to expander
side chain processing (i.e. side chain pre-delay). This allows the expansion to appear to
turn off just before the signal actually rises.
Ratio The expansion ratio. High values (£1:17) are highly expanded, low values (>1:1.0) are
moderately expanded.
Threshold The expansion threshold level in dBFS (decibels relative to full scale) below which the
signal begins to be expanded.
MakeUpGain Provides an additional control of the output gain. The Out Gain and MakeUpGain
controls are additive (in decibels) and together may provide a maximum of 24 dB boost
to offset gain reduction due to expansion.
In/Out In or Out Out Gain Off, -79.0 to 24.0 dB
Atk Time 0.0 to 228.0 ms Ratio 1:1.0 to 1:17.0
Rel Time 0 to 3000 ms Threshold -79.0 to 0.0 dB
SmoothTime 0.0 to 228.0 ms MakeUpGain Off, -79.0 to 24.0 dB
Signal Dly 0.0 to 25.0 ms
Reduction
-dB 40 20 12 8 6 4 2 0