Allen&Heath 21 Series - Manual (Page 6)

3
Channel Inputs:
XLR sockets. Electronically balanced suitable for safe connection
of external phantom power supply of up to 48VDC.
XLR pin 3 = hot
pin 2 = cold
pin
1
= screen
Input Impedance - mic = 1000 to 1500 ohms
line = 10kohms
Gain - mic = continuously variable from +20dB to +60dB
line = continuously variable from -5dB to +35dB
Pad - mic = -20dB
line = -12dB
Insertion Points - unbalanced 1/4" stereo jack sockets
tip = return
ring = send
outer = earth
normal operating level = +4dBv
Peak Overload Indicator - turns on at 3dB before clipping.
Echo Return Inputs:
mono 1/4" jack sockets
Maximum Gain to Stereo Outputs = +16dB
Input Impedance = greater than 4kohms
Stereo Tape Input:
stereo 1/4" jack socket tip = left
ring = right
outer = earth
Input Impedance = 40kohms
Gain to Monitors - 0dB or +12dB selectable by an internal connector
for either +4dBv or -8dBv normal operating level.
Stereo and Mono Outputs:
unbalanced XLR sockets pin 3 = signal
pin 2 = pin 1 = earth
Normal Operating Level = +4dBv or -8dBv selectable by an internal
connector.
Cue and Echo Outputs:
unbalanced 1/4" jack sockets mono
Normal Operating Level = +4dBv
Maximum Gain from Input = +10dB