User Manual
GL2400 User Guide                   15 
GROUP, L, R, M OUT The main console mix outputs are on 
electronically balanced XLR. These produce the professional standard 
+4dBu when the meters read ‘0’, and provide up to a maximum +25dBu. 
The L and R outputs typically feed the house PA system in live sound 
mixing, or a 2-track recorder in studio mixing. In monitor mode, these 
outputs reverse with the Aux TRS jack connections. 
AUX OUT 1-6 Each aux send is available on an impedance balanced 
TRS jack operating at -2dBu line level. An internal option is available to fit 
a balanced line driver IC to provide an electronically balanced output 
operating at +4dBu. Note that it is not usual to require this option as the 
impedance balanced standard drive provides sufficient interference 
rejection when feeding balanced equipment inputs. The aux sends are 
typically used to feed monitors, effects devices such as reverb and delay, 
and for special mix requirements. In monitor mode
, these outputs reverse 
with the group and LR XLR connections. 
MATRIX OUT 1-4 Each matrix output is available on an impedance 
balanced TRS jack operating at -2dBu line level. An internal option is 
available to fit a balanced line driver IC to provide an electronically 
balanced output operating at +4dBu. The matrix outputs are typically 
used for stereo or mono recording or broadcast feeds, delay and fill 
speakers, zone feeds, additional monitors such as IEM, hearing assist 
loops and so on. 
MATRIX EXT IN 1-4 Each matrix has an unbalanced 0dBu line level 
TRS jack input. An external signal such as ambience mix, additional or 
sub mixer, remote source, reference tone and so on may be mixed in to 
each matrix. The inputs are normalled as shown in the diagram here.  
This means that you can plug in just one jack (EXT1) as a common 
source to all matrix, two jacks (EXT1,2) as a common stereo source to 
matrix pairs, or four independent sources. This is ideal for adding mono 
or stereo ambience to recordings or in-ear monitors fed from the matrix. 
2-TRACK IN and OUT Unbalanced TRS jack outputs and TRS 
inputs connect to popular recording and playback devices such as CD, 
MiniDisc, computers and tape machines. Nominal line level is -2dBu.  
The 2-track SEND always follows the post-fade LR mix regardless of 
mode switch configuration. The 2-track RETURN can be used for 
monitoring a mono or stereo recording, or as a simple input for playback 
of walk-in and background music. The L input normals through the R 
socket for plugging in a mono source on a single jack. 
MONITOR OUT These impedance balanced line level TRS jack 
outputs follow the post-level monitor signal. Separate sockets are 
provided for the L and R signals. Use these to feed local speaker or other 
monitor systems. 
SYS-LINK V2 OPTION A blank plate is fitted here as standard.  
The GL2400 Sys-Link V2 (version 2) input/output option kit is available 
from Allen & Heath. Refer to OPTIONS later in this guide. 
SYS-LINK V2 CONSOLE EXPANDER ( option )
OUTPUT INPUT
OUT M OUT R OUT L GRP 4 GRP 3 GRP 2 GRP 1
6
AUX
5
AUX
4
AUX
3
AUX
2
AUX
1
AUX
LISTEN WEDGEAUX 6AUX 5 AUX 4AUX 3AUX 2AUX 1
R L GRP 4GRP 3GRP 2GRP 1
GRP/AUX REVERSE
Operating Modes 
In FOH mode, LR feeds the 
main PA. M sums the L and R 
post-fade signals to provide an 
additional feed for a mono fill 
speaker or zone, or a main feed 
into a mono PA. Groups 1-4 
may be used for multitrack 
recording, zone feeds and so 
on, or simply left unconnected 
where they are used as 
‘subgroups’ to LR for level 
masters and/or inserted 
processing. 
In monitor mode
 Groups 1-4 
and LR XLRs and inserts 
become the aux mix masters.   
M becomes the engineer’s 
listen wedge AFL/PFL feed.  
This configures the console 
with 6 main stage monitor and 
an engineer’s output. The 
groups and LR are still available 
via the matrix to provide yet 
more monitor feeds. 
3
MTX
EXT
4
MTX
EXT
2
MTX
EXT
1
MTX
EXT
IN IN IN IN
3421
IN1
IN2
IN3
IN4
MATRIX EXT IN
L/MR
LR
2TRK OUT
2TRK IN
MONITOR
LR
OUT










