ART Pro Audio SCL2 - Dual / Stereo Compressor / Limiter Expander / Gate - Manual (Page 8)

7
FRONT PANEL CONTROLS and INDICATORS
Power
The POWER switch turns the power on and off to the unit. The SCL2™ should be turned “on” with all monitor
levels turned down to protect against any thumping caused by power up. Likewise, the SCL2™ should be
turned off only after turning all monitor levels down. Power on the SCL2™ before any monitoring outputs or
power amps are turned on.
If the SCL2™ fails to power up when the POWER switch is turned on, check to see that its power cord is
plugged into an active outlet. If the unit still fails to operate properly, turn it off and unplug it. You can inspect
the fuse as long as the unit's AC power cord is unplugged. Consult an ART dealer or the ART Customer
Service Department if the fuse continues to blow.
Bypass Switch
The SCL2™ BYPASS switch physically connects the input jack to the output jack on each respective channel
(also known as a hardwire bypass). The switch is lit when the unit is bypassed and the unit's power is on. The
analog signal still passes from input to output if the Bypass switch is depressed even when power is off.
Threshold Control
The THRESHOLD control sets the point at which the SCL2™ will act on a signal. Turning this control
counter-clockwise lowers the threshold (adding more compression to a signal). Turning this control clockwise
raises the threshold.
Proper setting of the INPUT THRESHOLD control is dependent on the input signal. The easiest way to set
this control is to start with the control fully clockwise. Slowly turn the control counter-clockwise (lowering the
threshold) until the yellow (0) LED light on the COMPRESSOR ATTENUATION meter begins to light. Next
adjust the control (either lower or higher) for the desired amount of compression. Use the attenuation meter as
a visual guide to the amount of compression applied.
Knee switch
This switch selects either Hard or Soft knee operation. A "Hard" knee is one where above the threshold the
compressor applies the ratio setting immediately. "Soft" knee operation gradually increases the slope above
the threshold setting until it reaches the ratio setting. This gradual increase of slope happens over an input
range of 10dB or so and subtly applies the gain reduction until it is really needed.
Ratio Control
The RATIO Control selects the “amount” of compression applied to the input signal once that signal reaches
or exceeds the threshold. This compression amount is expressed as a ratio of input to output. For example if a
4:1 compression ratio is chosen, for every 4dB over the threshold the input signal rises, the output level only
rises by 1dB. In this case if the input signal increased 12dB over the threshold, the output level would only rise
by 3dB. Setting the ratio to 1:1 effectively disables the compressor.
In general, compression ratios of 10:1 and greater are considered “limiting". The SCL2™ may be used as
either a compressor or a limiter with all of the following:
- Multitrack recorder, DAT machine, hard disk recorder, or analog recorder.
- In a mixer’s channel insert points.
- Between a microphone preamp and signal processors.
- Between pre-amplified electronic musical instruments (synthesizers, guitars, bass, samplers, acoustic
instruments with pickups) and other line-level equipment.