Manual-4 All features & specifications subject to change without notice. MAR98
OPERATING INSTRUCTIONS
Once all of the inputs and outputs are properly connected
in accordance with the preceding section, normal operation of
the DC 24 should be achievable. If any of the following
procedures do not appear to produce the required results, take
a step backwards and check your wiring.
PRE-FLIGHT CHECKLIST
Before proceeding, it’s a good idea to turn the control
knobs to the following positions:
1. POWER...off
2. EXPAND / GATE THRESHOLD...FULL CCW
3. EXPAND / GATE RATIO...FULL CCW
4. COMPRESSION THRESHOLD...FULL CCW
5. COMPRESSION RATIO...FULL CCW
6. LIMIT THRESHOLD...FULL CW
7. OUTPUT LEVEL...CENTERED IN ITS DETENT
Set all pushbuttons on the front and rear to their out
positions. The OUTPUTS slide switch should be in the
SEPARATE position. The gain TRIM switches should be in
their +4 dBu positions.
LIMITING
With all of the preceding properly accomplished, turn the
POWER switch on (be sure your amp is turned down). The
DC 24 is now nothing but a unity gain amplifier. Cycling the
BYPASS switches with audio passing through the unit should
yield no difference in level or sound dynamics. The GAIN
REDUCTION meters should indicate 0 and nothing else.
Assuming your input signal has peaks in excess of -20 dBu,
you should be able to rotate the LIMITER THRESHOLD
controls CCW and see some gain reduction occur on the
meter simultaneously with a randomly illuminating THRESH-
OLD LED. You should begin to hear the difference. Leave
these controls at whatever Limit level is appropriate for your
application.
COMPRESSION
To use the Compressor, set the COMPRESSOR THRESH-
OLD for an appropriate level, you should see the associated
LED illuminate as signal goes above and below this level.
The COMPRESSOR RATIO control adjusts the gain reduc-
tion slope above the level you have set.
GATE / EXPANDER
The Gate / Expander function works similarly. If the
GATE/EXPANDER THRESHOLD is still fully CCW, rotate
the GATE/EXPANDER RATIO to its full CW position. Stop
your audio source and you will see the GAIN REDUCTION
LEDs drop to the -24 dB position. This indicates that the DC
24 Channel is in the fully gated mode. If you wish to have
gating occur at a higher level, rotate the GATE/EXPANDER
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THRESHOLD control CW to a higher level. If you wish to
create special effects with this gate, you may elect to use a
lower GATE/EXPANDER RATIO setting. This inhibits full
gating by the amount indicated around the control. Experi-
ment with all the controls to obtain the required results.
STERNO
When using the DC 24 as a true stereo (a.k.a. sterno; hey,
lighten up, it’s a joke!) processor, left channel in Channel 1
and right channel through Channel 2, it is a good idea to
operate the unit in the SLAVE mode to prevent large balance
and image shifts. While in the SLAVE mode, both channels
attenuate by exactly the same amount when the Gate and
Compressor work, maintaining the stereo image.
ATTENTION SHOPPERS
This seems like a good place to throw in a few words of
caution. The DC 24 allows a great deal of flexibility. As such,
it also allows one to come dangerously close to completely
destroying an otherwise respectable audio signal if some
thought and care is not put into the operation of the unit.
There are combinations of THRESHOLD and RATIO settings
on the Gate, Expander and Limiter which allow each to fight
the others and in some cases completely cancel. The same
caution applies to any signal processor, such as an equalizer
or crossover, however these are a bit more intuitive and less
likely to be used in a destructive manner. Just be gentle at
first and you should not encounter too much difficulty. If you
become overwhelmed, go back to the PRE-FLIGHT CHECK-
LIST for initial control settings and start over.
BYPASS SWITCHES IN CROSSOVER & COMBINE MODES
Crossover Mode. Do not use the BYPASS switches when
in the CROSSOVER mode. Use of BYPASS in the crossover
mode is potentially destructive since these switches route full
bandwidth audio to drivers designed only for a limited
frequency range. (CH 2 BYPASS is automatically defeated,
but Ch. 1 is still active — do not engage the CH 1 BYPASS
for any reason.)
Combine Mode. As more users (particularly bass guitar
players) discover new applications for this mode, they want to
use BYPASS as an aid in optimizing settings. Unfortunately,
the BYPASS switches do not operate in the COMBINE mode;
however, a simple trick solves the problem:
1. Permanently engage the CH 1 BYPASS switch.
2. Patch CHANNEL 1 OUTPUT to CHANNEL 2 INPUT
using either the ¼" TRS or the XLR jacks. Be sure to use
2-conductor shielded cable.
3. The CH 2 BYPASS switch now operates in the COMBINE
mode.
