Rane DC 22 (2003 version) - Manual (Page 7)

Manual-5
LIMITING
A limiter is a special form of compressor set up especially to
reduce peaks for overload protection. In other words, it’s a com-
pressor with a maximum ratio. A compressor is used to change
the dynamics for purposes of aesthetics, intelligibility, record-
ing or broadcast limitations. Once the threshold of a limiter is
reached, no more signal increase is allowed. The DC 22 acts as a
limiter when set at a very high ratio of 10:1.
LINKING IN STEREO
When using the DC 22 as a true stereo processor, with left
signal in Channel 1 and right signal in Channel 2, it is recom-
mended to turn the LINK switch on to prevent large balance
and image shifts. While LINKed, both Channels attenuate by
exactly the same amount when either Compressor works, main-
taining correct stereo imaging. Only Channel 1's controls are
active, Channel 2 becomes the slave.
RATIO relatively high, just enough to limit the peaks. Set the
GATE THRESHOLD very low, though you might want to raise
it just above the noise floor to get rid of tape hiss or processor
noise.
Of special interest are instruments which have large level
differences in their tonal ranges. String pops on a bass are one
example, shrill peaks on a flute are yet another. The higher tones
require more breath and can seem much louder than lower
pitches. Another good application would be a drum mix or vocal
submix.
LONG DISTANCE LINE DRIVER
The DC 22 is excellent as a line level amp for driving long
lines (from the mixer to the stage for instance). With the COM-
PRESSOR switch in the BYPASS position, the INPUT LEVEL
control and the output amplifiers remain in the circuit. This pro-
vides a very low distortion, low noise line driver. Balanced XLR
connections are recommended for the long run from the DC 22's
outputs (anything over 10 feet [3 meters]). A balanced piece of
equipment (equalizer or amplifier) must be used at the receiving
end of this long line.
For unbalanced systems, use the ¼" inputs on the DC 22
and use the balanced XLR outputs to run the long distance. See
the RaneNote “Sound System Interconnection” included with
this manual for proper cable wiring.
SOUND SYSTEM WITH COMPRESSION
Let’s run a stereo system with compression. For this example,
we use a Rane SAC 22 2-Way Crossover and a SEQ 30S Stereo
Equalizer along with the DC 22 Stereo Compressor. See the wir-
ing diagram on page Manual-3.
Patch the DC 22 Compressor Inputs from the program
source or mixer outputs, and send the DC 22 Outputs to the
system equalizer (if you have one), and then on to the crossover
inputs (if you have one). Set the equalizer and crossover Inputs to
unity gain. Set the LINK switch to ON, and adjust the CHAN-
NEL 1 COMPRESSOR THRESHOLD and RATIO controls
to keep the entire system dynamic range under control. Locating
the compressor before the equalizer results in correct spectral
balance during compression.
DRIVER PROTECTION
To individually limit Low and High drivers in a biamped
system, connect the Crossover Low Output into one DC 22 In-
put, and the High Output into the other DC 22 Input. The DC
22 Outputs go right to the respective low and high frequency
power amplifier inputs. For a stereo configuration use two DC
22 Stereo Compressors. Be sure the LINK switch is OFF. Set the
RATIO controls to 10:1.
Assuming your input signal has peaks in excess of -20 dBu,
you should be able to rotate the COMPRESSOR THRESH-
OLD controls and see some GAIN REDUCTION meter action.
You should begin to hear the difference. Leave these controls at
whatever level is appropriate for your application. For the most
precise settings, see the section on the next page.
DC 22 APPLICATIONS
TWO CHANNEL COMPRESSOR/LIMITER
In this case, the audio path on Channel 1 is completely
separate from Channel 2, allowing you to use it as a stereo unit
or for doing two completely different processes to two completely
different signals. For stereo use, the front panel LINK switch
allows you to link Channels. When either Channel’s Threshold
is reached, both channels compress equally, preserving the stereo
image. Channel 1’s Threshold and Ratio settings will affect both
Channels.
GUITAR & BASS
Where does the unit go in the signal chain? Well, that
depends on how you want it to function. If it’s a comp/limiter
for the input signal, it would go after the guitar (if the guitar has
a line-level output) and before the preamp. If it’s to function as
a limiter to protect the speakers in the rig, it would go after the
preamp and before the power amp. Another method is to insert
the unit in the effect loop of the preamp. This allows the bass
signal to be affected by the pre-amp first, then the comp/limiter,
and then sent to the power amp. This can be desirable with tube
pre-amps.
RECORDING
Use it on bass guitar, piano, drums, or vocals—as an effect or
to tailor dynamic range for a particular recording medium. Patch
it between line-level devices or in your mixer inserts or “loops”.
The DC 22 gives you more control and a less tortured sound,
and keeps instruments sounding “up-front.” In digital recording,
compress an extremely wide dynamic range into a signal that
won’t go into digital overload, i.e. severe clipping. This is really
valuable during a live digital recording when you just don’t know
how loud it may get, and digital distortion can ruin an otherwise
good take. Set both the COMPRESSOR THRESHOLD and