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Operating Manual - DPX-100 Graphic 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?
EQ Controls Do Nothing
Is the master EQ switch in?
The lowest and highest frequency sliders 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. Turn down the gain. 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 some-
where else in the signal path. Adjust the rela-
tive gain of each component in your chain to
keep everything at a comfortable level.
Excessive Hum or Noise
Hum will usually be caused by a ground
loop between components. Try using the sug-
gested balanced input and output hook-ups if the
other pieces of equipment used in conjunction
with your equalizer have balanced inputs and
outputs.
Noise (excessive hiss) can be caused by
insufficient drive signal. Make sure you are send-
ing a nominal 0 dBu line level signal to the
equalizer. Most noise problems occur because
gain is applied to audio signals too late in the
chain. For best performance, apply gain to in-
dividual source signals as early as possible, like
at the mixer input preamp section. As gain in-
creases, it also boosts the noise content of that
signal. Any cumulative noise built up in a mixed
signal will only be increased by using an equal-
izer as a gain device, so make every attempt to
operate the equalizer with as little gain as pos-
sible.
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.
-
+
+
-
-
+
+
-
CHAIN
LIMITER
LIMITER
LIMITER
EQ OUTPUT
EQ
EQ In/OutHPF In/Out
6dB/15dB
15 BAND EQ
SIG
GAIN
HPF
3
3
2
2
1
1
CHANNEL
INSERT
DETECTOR
CLIP
CLIP
TH
3
3
2
2
1
1
IN/OUT
GAIN REDUCTION DISPLAY
THRESHOLD
RELEASE
ATTACK
RATIO
CIRCUIT
DETECTOR
INPUT
INPUT
GAIN
LEVEL
OUTPUT
INPUT/OUTPUT METERS
VCA