Type Switch; Compressor Bypass Switch; Compressor Output Level Control - Art Pro Channel User Manual

Use the Auto setting when the signal has varying characteristics (long decaying notes
alternating with quick notes, mix material, etc.)

Type Switch

This switch covers one of the more unique features of the Pro Channel. In the "out"
position (Optical), the Pro Channel's compressor employs the award-winning Vactrol®-
based compression element from our Pro VLA. Switching to the "in" position engages
the dual-triode variable-mu control element. This circuit is capable of considerably
faster attack and decay times than the optical circuit. However, when the Attack &
Decay times are set to very long time constants, the shared detector circuit will
dominate, and the two types will behave in a very similar manner. Experiment with the
two types to become familiar with how they react to different source material.

Compressor Bypass Switch

A Bypass switch is included on the compressor circuit to enable you to remove the
compressor from the signal chain. When set to its "in" (Bypass) position, signal is
allowed to pass from the preamp circuitry to the equalizer circuit with no compression.
The LED will glow red when Bypass is engaged. In its "out" (Norm) position, the
compressor is active. Also, when the compressor is bypassed the gain reduction LED
display (under the VU meter) will still operate, but at a much dimmer level. This is to
remind you that the compressor is out of the signal path, but still gives you an indication
how much compression will result when the compressor is engaged.
Use the Bypass switch when setting the compressor's output level to achieve unity gain.
Unity gain is achieved through the compressor when the active level is the same as the
bypassed level. Toggle the switch between Active and Bypass while adjusting the
Compressor Output level. Once the levels are the same (use your ears and the VU
Output Level meter), you've reached the unity setting for the compressor.

Compressor Output Level Control

The Compressor Output level control sets the output level from the compressor circuit.
Typically, the output level of a compressor is used to add gain to compensate for the
amount of compression applied to a signal. The output level is set to achieve unity gain
(no apparent level change when the compressor is active or bypassed). See Compressor
Bypass Switch for more details on achieving unity gain.
When the control is fully counter-clockwise, the output is off. Turning the control
clockwise increases the level to a maximum of +20dB of gain. While you can use the
compressor to add gain to a signal, it is better to add gain before the compressor for the
best signal to noise ratio. If you want to use the compressor to add more gain, use the
VU meter to monitor the Pro Channel's output level, or use the meter on your recorder
or mixer to make sure you won't clip the next piece of equipment in the chain.
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