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Aura8ip / Jan 2012
A u r a 8 i p P r o G U I
of the AGC Attack controls could achieve a 50ms Attack and 1000ms Release, we do
not suggest using AGC Attack times faster than about 150ms and Release times faster
than about 2000ms IF all parts of the processor are enabled (AGC, Compressor, Lim-
iter, etc.).
Compressor Attack/Release
These next two adjustments control the timing of the Compressor. Unlike
the AGC however, the Compressor is designed to work primarily on short
term dynamics and therefore helps to not only build density, but it allows
the limiters upstream to not work so hard on the audio coming out of the
AGC/Compressor stage.
The Compressor Attack (Comp. Attack) control range is adjustable be-
tween 3ms and 100ms. Compressor Release (Comp. Release) is adjustable
between 50 and 1000ms (1 second). The ranges of the Compressor controls
have been limited to what we feel are the most useful settings and they cannot
be set to sound bad. That said, we recommend Compressor Attack settings
of between 3ms and 20ms and Compressor Release settings around 300ms.
These settings may need to be modified to work better in concert with other
controls later downstream.
Compressor Ratio
The Compression Ratio (Comp. Ratio) control adjusts how much the audio
output level is allowed to increase as the input level increases. A Compres-
sion Ratio of 1:1 would make output level changes be a mirror image of the
input, i.e., there would be no processing. Likewise a Compression Ratio of
20:1 would allow the output level to only increase by 1dB even though the input level
increased by 20dB (a 10:1 change).
The ‘correct’ setting of the Compression Ratio control is highly subjective, just
like many other controls in any audio processor. However, our experience is that a
Compression Ratio setting of between 2:1 and 6:1 is the most useful, with a setting
halfway between (at 4:1) a good all around tradeoff.
Higher Compression Ratios will sound tighter and more squashed while lower
Compression Ratios will sound more free and dynamic. The user is completely free to
use whatever Compression Ratio he feels sounds best in his application.
It would not be uncommon to see different Compression Ratio settings for each
processing band, although that is never a requirement. Our recommendation is to pick
a number, say 4:1, and set all bands to that Compression Ratio. Then after adjusting
the other controls for the desired density and impact, make small adjustments to the
ratios as needed to tame a particular issue. Let us provide an example of when the
Compression Ratio is the right knob to grab:
Suppose the Aura8ip is running in its 3 Band mode and everything is sounding really
good but you notice that sometimes the high end isn’t quite controlled enough on some
material. The best way to even things out would be to slightly increase the Compression
Ratio for Band 3, and only band 3. Suppose you look at the Compression Ratio setting
for that band and see that it is set to 4:1. Try setting it a bit higher, to perhaps 4.4:1 and
then listen for a while. If there is too much control, reduce the ratio a little and listen
again. If it’s not controlled enough, nudge it up a little and listen again.