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OPERATION ORBAN Model 8400
The range is 25 dB at ∞:1 and 12 dB at 2:1. However, the range of input lev-
els that the AGC can handle is unaffected, remaining at 25 dB.
Bass Thresh determines the compression threshold of the bass band in the AGC. It can
be used to set the target spectral balance of the AGC.
As the
AGC Bass Coupling control is moved towards “100%,” the AGC Bass Thresh
control affects the sound less and less.
The interaction between the AGC Bass Thresh control and the AGC Bass
Coupling
control is a bit complex, so we recommend leaving the AGC Bass
Thresh
control at its factory setting unless you have a good reason for read-
justing it.
Idle Gain. The “idle gain” is the target gain of the AGC when the silence gate is active.
Whenever the silence gate turns on, the gain of the AGC slowly moves towards the idle
gain.
The idle gain is primarily determined by the
AGC Drive setting—a setting of 10 dB will
ordinarily produce an idle gain of –10 dB (i.e., 10 dB of gain reduction). However, some-
times you may not want the idle gain to be the same as the
AGC Drive setting. The Idle
Gain
control allows you to add or subtract gain from the idle gain setting determined by
the
AGC Drive setting.
You might want to do this if you make a custom preset that otherwise causes
the gain to increase or decrease unnaturally when the AGC is gated.
AGC Bass Attack sets the attack time of the AGC bass compressor (below 200 Hz).
AGC Master Attack
sets the attack time of the AGC master compressor (above 200 Hz).
AGC Bass Release
sets the release time of the AGC bass compressor.
For example, to make the idle gain track the setting of the AGC Drive con-
trol, set the
Idle Gain control to zero. To make the idle gain 2 dB lower than
the setting of the
AGC Drive control, set the Idle Gain control to –2.
Master Delta Threshold allows you to set the difference between the compression
thresholds of the sum and difference channels. (This control is only useful when you set
the
AGC Matrix to sum/dif.) By setting the threshold of the difference channel lower than
the sum channel, you can have the AGC automatically produce more gain reduction in
the difference channel. This will reduce the separation of material with an excessively
wide stereo image (like old Beatles records). To make this work, you must set the
Max
Delta GR
control away from zero. For example, to limit an excessively wide image while
preventing more than 3 dB difference in gain between the sum and difference channels,
set the
Max Delta GR control to 3.0 and the Master Delta Threshold control to some posi-
tive number, depending on how much automatic width control you want the 8400 to per-
form.
Bass Delta Threshold
works the same as Master Delta Threshold, but applies to the bass
band. You will usually set it the same as
Master Delta Threshold.
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