Aurora Audio GTC2 - Manual (Page 5)

Auto Release Off/On (Green Switch) :- If the switch is deselected the attack and
release times are set by the two blue potentiometers. The user should always experiment
with the settings of these controls to see how they affect the sound.
When the Auto button is pressed the release time is dependent on the nature of the
program material passing through the compressor. Generally the release times are longer
but, if the material is short bursts of sound, the auto timing capacitor will have less
stored energy and will produce shorter release times. If the material is long, flowing,
rifts then the capacitor will charge up more and produce longer release times. The actual
timing value changing constantly with the nature of the material passing through the
compressor.
Combined Off/On (Blue Switch) :- When deselected the control element is either the
opto or FET path depending on whether the red FET switch is selected.
If the Combined switch is pressed, relays reconfigure the internal circuit paths so that
both control elements are in circuit. The signal passes first through the opto path and is
then applied to the FET path for additional control. As both paths are unity gain before
compression, there will be little difference in compression until both sections start
working hard and then it will be seen to compress as much as another 6dB. In Combined
mode the meter will read gain reduction automatically with no option for O/P level.
The Combined mode's main function is not just to squash the living daylights out of a
signal but rather to provide the user with a third option of sound signature. When the
Combined switch is used, try having the Threshold and Ratio controls at minimum and
then gently rotating the Threshold until the gain reduction meter indicates that the side
chain is beginning to work. Listen to the color of the sound at this point and the effect
on that sound by adjusting the other controls. It's a very useful feature!
Stereo Link Off/On (Green Switch) :- If not selected the two compressor channels
work completely independently and can be assigned to different circuit paths with
different degrees of compression.
If the Stereo button is pressed the compressors will work together as a stereo unit (i.e. as
a stereo bus compressor) with whichever channel has the most side chain voltage (i.e the
most compression at that instant in time) taking control over both channels and
providing identical amounts of compression.
The control will pass seamlessly from one channel to the next depending on which of
the two is working hardest and, as a consequence, the stereo image should not drift from
center.
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