dbx DriveRack, User Manual

Detailed Parameters

®

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Section 4

DriveRack

™  

PA

DriveRack™ PA User Manual

Section 4

The DriveRack™ PA also offers Compression and Limiter modules.  The Compressor is a full
bandwidth Stereo Compressor located prior to the Crossover.  The Compressor is the perfect
tool for tightening uneven signal sources such as vocals and guitars.  The Limiters are located 
on each stereo output channel and have been strategically placed for speaker and amplifier pro-
tection. Note that Compressor/Limiter threshold metering can be observed on page two of the
Utility section.  The parameters for the Compressor/Limiter are as follows and are user
adjustable.

COMPRESSOR

Compressor On/Off

Turns the Compressor module on and off.

OverEasy  (O) Off to 10

There are ten levels of OverEasy® that can be used for the limiters.  The point when the com-
pressor starts to compress is the "knee." When the compressor starts to reduce the level of a
signal abruptly as it passes over the threshold, this is called "hard knee" compression.
OverEasy® (soft knee as it is sometimes called) is when the volume of the sound is compressed
gradually. OverEasy® compression starts to compress before the level of the signal reaches the 
threshold and reaches full compression after the level has gone above the threshold.
OverEasy® compression, by its very nature, sounds much smoother and more natural and will
be used for most applications. When it is gentle (natural sounding or light) compression that
you are looking for, the compressor offers VariKnee™.  VariKnee™ gives you ten levels of
OverEasy® compression to choose from (1 being almost hard knee and 10 being the most
OverEasy®). This lets you choose the exact knee that is needed for the dynamic effect you are
looking for.

Threshold (T) -40 to +20dBu

Threshold is the signal level at which the unit starts to compress the signal. If the level is set to
-10 dBu, than any signal larger than -10 dBu is compressed while any signal that has a level
that is lower than -10dBu is left at the same signal level. Light compression is where only the
loudest parts of the signal go over the threshold. Very heavy compression can be achieved by
setting the threshold low enough that almost the entire signal content is over the threshold. For
most signals the most natural compression is achieved when most of the signal content remains
just below the threshold and only the peaks cross the threshold.

Ratio (R) 1.0  to Inf:1

Ratio is the amount the unit reduces the signal level of the sound that is above the threshold.
A 2:1 ratio means that if the incoming signal is 2dB over the threshold the unit will compress
the signal, and outputs a signal that only goes 1dB over the threshold. For light compression
choose a lower ratio, while a heavy compression requires a higher ratio. A setting of Inf:1 makes
the compressor act as a limiter.

Gain (G) -20 to +20 dB

This parameter is used to compensate for the gain lost during compression. By using heavy
compression on a signal and then boosting the signal with the output gain, the user can create
a signal that sounds much louder than it actually is.

4.6 Compressor/Limiter