Allen&Heath PA28 - Manual (Page 26)

26 PA User Guide
The AB Output Channels
Overview
Two output channels labelled A and
B are provided. These include 4 band semi-
parametric equalisers, TRS jack slave outputs, level
trimmers and balanced XLR main outputs. The
source to these channels is selected using recessed
assignment switches.
The philosophy The output channels provide
a similar function to those found on standard format
powered mixers. They can be used in the same way
to provide speaker equalisation when working with
external amplifiers or powered speakers. They can
also be used as ‘problem solvers’ by providing
feedback and resonance reducing equalisation, level
trim and the ability to drive very long distances to
remote equipment using balanced cables. The
parametric type of equaliser provided allows more
accurate control than the typical graphic (slider) type
EQ found on similar consoles.
LEVEL
Trims the level feeding the XLR outputs.
Does not affect the AB slave outputs. Turn the
control fully off when plugging up the equipment.
When working with amplifiers, turn it up to the
position where it produces the loudest volume
required with the console meters reading around ‘0’.
SIGNAL METERS
Each channel provides
two LED meter indicators. These detect the signal
fed to the XLR outputs after the LEVEL control. The
green SIG indicator turns on when audio signal
presence is detected. The red PK indicator turns on
to warn when the signal is within 5dB of clipping. If
PK lights then back off the LEV control until it stops
flashing.
SIG
SIG
PK
PK
parametric output equaliser
200
120Hz
1k
500
2k
30
20Hz
70
200
100
-10 -10 +10 +10
7k
20k
2k5
1k
500Hz
2k5 5k
10k 1k5
-10 -10 +10 +10
200
120Hz
500
1k
2k
70
30
20Hz 200
100
-10 +10 -10 +10
7k
10k
20k
2k5
1k
500Hz
2k5 5k
10k 1k5
+10 -10 +10 -10
L R + R FB2
MAX MIN
FB1 L FB1
MAX MIN
LM HM HF
4 BAND EQUALISER
LF
A
B
LEV
LEV
SIGNAL
PEAK
A
SLAVE OUT
LEV PEAK
SIGNAL
B
A OUT B OUT
FB2 R + L R
FB1 L FB1
SOURCE SELECT
LM HM HF LF