Valve input channel, Channel 1 valve, Drive – Allen&Heath GS-R24M User Manual
Page 21: Gain control, Drive control, Level control, Bus routing switches, After fade listen switch, Allen & heath 21 gs_r24 user guide, Afl m l-r 1-2
Allen & Heath 21 GS_R24 User Guide
Gain Control
This adjusts the gain of the input amplifier to match the signal level
of the input. The gain is varied from +6dB to +60dB for signals
plugged in to the xlr socket (Mic Input) and –14dB to +40dB for
signals plugged into the Line/Inst input jack (without Boost being
pressed).
The Gain control does not affect the signal if the input is sourced
from the DAW interface.
Drive control
The Drive control determines the amount of signal that passes
through the valve stage and therefore the amount of signal with
thermionic valve pre-amp characteristic. In addition to increasing the
amount of even harmonic content, the volume level may also be in-
creased when swept towards the MAX setting.
A 3 colour LED indicator illuminates green, orange then red to show
the signal level after the valve stage.
VALVE INPUT CHANNEL
60 40
-14 6
30
40
50
0
20
GAIN
MIN
MAX
Drive
Channel 1
Valve
10
-30
-20
-5
0
5
-10
LEV
L
R
PAN
AFL
M
L-R
1-2
BUS
3-4
0.00 ms
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
1.99
-8.70
-6.53
-4.35
-2.18
0.00
2.18
4.35
6.53
8.70
V
0.00 ms
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
1.99
-8.70
-6.53
-4.35
-2.18
0.00
2.18
4.35
6.53
8.70
V
Drive control characteristics at around +10dBu. Two graphs show MIN then MAX
0.00 ms
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
1.99
-17.40
-13.05
-8.70
-4.35
0.00
4.35
8.70
13.05
17.40
V
The third graph shows extreme
overload characteristics of the
combined instrument input and
valve stage with maximum drive.
Note the asymmetric soft clipping
on each half-cycle.
Level control
Effectively the fader for the valve channel (or master volume). Ad-
justs the level from fully attenuated to +10dB of gain.
PAN
The pan control adjusts how the signal from the mono input channel
is shared between the left and right buses and between odd and
even group buses.
Bus Routing Switches
The routing switches connect the channel signal to the mix
buses in a similar way to the mono input channel.
After Fade Listen switch
Connects the post level control signal in mono to the AFL
monitoring system.
A full description of the console monitoring system is given on
page 29.