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Operating Manual - DPX-200 Parametric Equalizer - Compressor/Limiter
10. BLOCK DIAGRAM
11. Equalizer Troubleshooting Tips
No Audio Output
Check AC power - is the pilot light on?
Check in/out connections - are they reversed?
Are you sure you have an input signal?
Is the correct input selected?
Is the gain control turned all the way off?
EQ Controls Do Nothing
Is the individual filter or master EQ switch in?
Is the bandwidth set too narrow to be heard?
The lowest and highest frequency filters may be
beyond the range of the program material or speakers and
may produce little or no audible effect.
Peak Light Flashes or Stays On All the Time
If the peak light flashes, the signal level to the
equalizer is too high, or a particular filter is boosted too
much. Turn down the gain or switch the EQ filters. If it
is on all the time, disconnect the input and output cables.
If it is still on, the unit must be returned for service.
Distorted Sound
This will only be caused by too much signal
which will show on the Clip LED. If the LED is not
flashing, there is an overload within another product
in the signal path. Adjust the relative gain of each
component in your chain to keep everything at a com-
fortable level.
Excessive Hum or Noise
Hum will usually be caused by a ground loop
between components. Try using the suggested bal-
anced input and output hook-ups if the other pieces
of equipment used in conjunction with your equal-
izer have balanced inputs and outputs.
Noise (excessive hiss) can be caused by in-
sufficient drive signal. Make sure you are sending a
nominal 0 dBu line level signal to the equalizer. Most
noise problems occur because gain is applied to au-
dio signals too late in the chain. For best performance,
apply gain to individual source signals as early as
possible, like at the mixer input preamp section. As
gain increases, it also boosts the noise content of that
signal. Any cumulative noise built up in a mixed sig-
nal will only be increased by using an equalizer as a
gain device, so make every attempt to operate the
equalizer with as little gain as possible.
Note: Unshielded cables, improperly wired con-
nectors, and cables with broken strands of wire are very
common problems. Use quality cables with quality, cor-
rectly wired connectors.
11.1 Compressor/Limiter Troubleshooting Tips
No Output
Check AC power. Is the power switch on? Check
input and output connections - are they reversed? Are
you sure you have an input signal?
Controls Have No Effect
Is the limiter in/out switch in? Perhaps the ratio
control is set too low to produce an audible effect or the
input level is below threshold. Is the threshold LED light-
ing up? If not, lower the threshold setting or increase the
gain. Do not expect to hear any effect when the input
level is below threshold, since the unit is simply a linear
amplifier at those levels.
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Individual EQ Band In/Out
EQ Master In/Out
OUTPUT
DPX-200 Block Diagram
Mic
Line
(4)(3)(2)(1)
PARAMETRIC EQ
4 BAND
LINE
MIC
CHAIN
LIMITER
LIMITER
EQ OUTPUT
GAIN
3
3
2
2
1
1
CHANNEL
INSERT
DETECTOR
CLIP
CLIP
TH
3
3
3
2
2
2
1
1
1
IN/OUT
GAIN REDUCTION DISPLAY
THRESHOLD
RELEASE
ATTACK
RATIO
CIRCUIT
DETECTOR
INPUT
INPUT
INPUT
GAIN
LEVEL
OUTPUT
INPUT/OUTPUT METERS
VCA