14
PA-CP
User Guide
GAIN
Adjusts the sensitivity of the channel preamp to
match the connected source to the 0dBu operating level of the
console. The control has a very wide range matching mic
levels from a low -63dBu (0.5mV) to a high +5dBu (1.5V), and
line levels from -25dBu (45mV) to +10dBu (2.5V).
The mic preamp
is probably the most important stage
in the console signal path. Its performance is often the
measure of how good the console is. The
PA Series
uses a
high grade dual stage design developed from our top end
consoles. The mic input passes through both stages for
increased gain range and correct matching to low impedance
microphones. The line input passes through the second stage
only, so ensuring very low noise and high impedance for
matching to a wide range of instruments and equipment.
Plugging into the line input TRS jack breaks the signal path
from the first stage. This overrides the mic input.
☺
Setting the gain
Use the channel PFL function to view
the signal level on the console meters. Adjust the gain control
for average signal level around meter ‘0’ with loudest peaks no
more that ‘+6’. If you see the channel PEAK indicator flash
back the gain off a little.
100Hz HPF
Switches in the high pass filter which
attenuates very low frequencies. Use this to reduce mic
handling noise and ‘popping’, stage rumble and bleed through
from other low frequency sources.
The HPF
is a second order design with 100Hz cut off
frequency and 12dB/octave slope. This means that it is 3dB
down at its 100Hz cut off point and reduces the frequencies
below that by 12dB every octave (halving of frequency).
☺
Using the filter
The high pass filter is an invaluable tool
for cleaning up the mix. The majority of live sound sources
have very little content below 100Hz. Modern microphones
have wide frequency response and can pick up bleed from
nearby low frequency sources such as bass and kick drum
even though they are placed on other instruments or voices.
For example, switch the filter in on vocal channels to reduce
mic handling noise and close proximity ‘popping’, on drum
overhead mics to reduce kick and bass pick up, on higher
frequency instruments such as flute and acoustic guitar, on
stage mics to reduce foot noise, and so on.
INSERT
Lets you patch external processing equipment
such as a compressor or noise gate into the channel signal
path. Plugging in interrupts the signal path after the 100Hz
filter and before the EQ. With nothing plugged in, the signal is
routed through the normal contact within the socket. The
connection is unbalanced with both the insert send and return
signals presented on the same jack. Connect the equipment
input from the send (TRS jack tip), and its output to the return
(jack ring). Wire the cable shield to the jack sleeve. The insert
operates at 0dBu line level. Ensure that the external equipment
is set to operate at similar level and unity gain. The diagram
below shows a typical insert cable with plug links to unbalance
the external equipment connections.
PK !
=
O
PAN
O
+6
R
L
O
FB2
O
-15
FB1
+6
+15
O
O
AUX
O
O
+6
+6
10
30
-5
50
40
20
10
-5
0
LINE
MIC
0
25
-5
12kHz
-15
-10
+15
100Hz
63
7k
3k
350Hz
600
-15
60Hz
250Hz
+15
-15
+15
1k5
