User Manual
Allen & Heath     23   ZED-12FX, 16FX & 22FX User Guide 
MASTER SECTION 
Aux output jack sockets 
Standard 1/4” jack sockets for Aux 1 to 3 outputs (FX or Aux 4 is 
the internal Effects bus and does not have an output socket. Imped-
ance balanced, nominal level = 0dBu. 
Mix L R Insert jack sockets 
Standard 1/4” (6.25mm) Jack sockets for unbalanced insert send and 
return signals. Wired Tip = send, Ring = return, Sleeve = Chassis. 
Nominal level is 0dBu. 
Main L R output xlr sockets 
Main left & right outputs. Impedance balanced signals, pin1 = chassis, 
pin2 = hot (+), pin3 = cold (-). Nominal level = 0dBu. 
Mono output jack socket 
A mono sum of the main left & right post-fade signals. 
Headphones jack sockets 
One 1/4” and one 3.5mm jack socket for stereo headphones. Wired 
Tip = left, Ring = right, Sleeve = Chassis. 
It is recommended that headphones with an impedance higher than 
30ohms are used. 
48v Phantom Power switch 
Press this in to switch 48v Phantom Power to all the Mic input xlr 
connectors, if any of the microphones attached require power. Dy-
namic microphones won’t mind being connected to a phantom 
powered input, but care is needed to ensure that 48v is not 
switched on if an xlr is used to input a signal from an electronic 
circuit (ie. Another mixer or keyboard). 
When switching 48v on or off, or plugging in connectors to 
channels with 48v present, it is important (and normal 
practise) to mute the channels. This will avoid loud clicks 
and bangs potentially getting through to the amps & speak-
ers with the possible effect of damaging the speakers, or 
the audience’s hearing! 
Left Right meters 
12 segment LED meters, peak type response, the “0” position re-
flects 0dBu at the outputs. These display the signals from the moni-
tor selector switches below, or the PFL (pre-fade listen) signals 
from any selected channels, which overrides. 
! 
Footswitch connection 
Standard 1/4” (6.25mm) Jack socket for use with a footswitch. 
Wired so that a switch closure between Tip and Sleeve will activate 
the effects mute circuitry to cut the effects return (and ST4) from 
the main LR mix and the Aux 1 & 2 sends. 
30
L
+16
-6
-9
-20
-30
-16
-12
-3
0
+3
+6
+9
R
PFL ACTIVE
MIN MAX
PHONES
AUX1
AUX2
2TRK RTN
USB RTN
STEREO
OO +6
ALT
OUT
MONITOR
LR
OO +6
AUX1
MASTER
OO +6
AUX2
MASTER
5
20
10
5
0
10
POST
PRE
LR
L
R
POWER
48V
INSERT R
AUX1 OUT
PHONES
MAIN OUT
0
0
0
PHANTOM POWER
ALLEN HEATH
AUX2 OUT
AUX3 OUT
INSERT L
MONO OUT
+16
-6
-9
-20
-30
-16
-12
-3
0
+3
+6
+9
16
15
14
13
12
11
10
9
Plate (decay)
Plate (predly)
Plate (colour)
Hall1 (size)
Hall2 (size)
Arena (size)
Flanger (dpth)
Chorus (dpth)
F/SWITCH
FX MUTE
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