Crown Audio P.I.P.-AMCb - Manual (Page 10)

P.I.P.–AMCb
Page 10
FREQUENCY (Hz)
10 K 20 K 200 1 K
HORN EQ = 10 kHz
–6
0
+6
+12
+18
–12
–18
dB
FREQUENCY (Hz)
10 K 20 K 200 1 K
HORN EQ = FLAT
–6
0
+6
+12
+18
–12
–18
dB
over 16 dB over will be passed lin-
early. At that point, clipping the am-
plifier is the only way the compressor
would limit the signal further.
The threshold is selectable from ap-
proximately 8 to 164.5 VRMS in 2.5 V
increments using the CH1 and CH2
threshold DIP switches (see Figure
2.1).
Figure 3.8 shows power levels ex-
pressed in watts at 2, 4 and 8 ohms
along with a column showing corre-
sponding RMS voltage levels. Use
this chart to find the desired RMS
voltage threshold. Figures 3.9a and
3.9b show the voltage outputs and
corresponding switch settings for
both Dual (stereo) and Parallel-Mono
modes of operation. In Bridge-Mono
mode the threshold voltages shown
must be doubled.
Regardless of the threshold, if an
amplifier output clips, the compres-
sor will be activated. This is because
the compressor’s drive is derived
from the amplifier’s
IOC ® error signal.
Fig. 3.7b High-Frequency EQ Response Curves (800 Hz Crossover)
Compressor Threshold
Tracing the signal path, the compres-
sors follow the crossover and equal-
izers. Variable-threshold signal-
driven compressors are provided for
both the high and low frequencies,
but by default, the compressors are
error-driven.
The purpose of the compressors is
to limit the signal level for applica-
tions where driver and/or system pro-
tection is desired.
The low-frequency compressor is set
at the factory with a 10 msec attack
time and a 360 msec release time.
The high-frequency compressor is
set with a 5 msec attack time and a
180 msec release time.
Both compressors have an infinite
compression ratio. This means that
when the threshold is reached, an in-
crease in input level will not result in
a change in output level. The range
of compression is 16 dB. If the input
is driven more than 16 dB over the
threshold, the portion of the signal