Allen&Heath ML3000 VCA User Manual
VCA GROUPS
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ASSIGN
Assign MUTE and VCA groups:
Select using GRP MUTE
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Assign using CH MUTES
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Press and Hold with GRP MUTE
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View on channels
VIEW
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VCA Groups Explained
VCA groups provide an important alternative to
audio subgroups for simultaneously controlling the
level of more than one channel using a single fader.
Unlike an audio subgroup the signal is not routed
through the group fader itself. Instead, you route
the signal directly to the main output. The VCA
group fader sends a DC voltage to remotely control
the assigned channel levels, so providing the group
control. This is possible because each channel has
a pre-pan VCA (voltage controlled amplifier) which
can be controlled by both the channel fader and
group faders. This means that all post-fade outputs
from assigned channels will be affected by the VCA
master faders. Note that the channel pre-fade
(monitor) sends are not affected by VCA groups.
Note that the channel fader always controls the
signal level. If the channel is assigned to one or
more VCA groups then both the channel and the
group faders control the level as if they were in
series. Refer to the diagrams on the next page.
The ML3000 has 8 VCA groups. Mono and stereo
input channels can be assigned to one or more
groups. The VCA group assignments are stored as
part of the console snapshot memory system
(externally controlled).
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The benefits of VCA grouping
Effects balance is maintained. Because the
channel post-fade sends are affected, the reverb
level returned elsewhere in the console also follows
the group fader movements.
Stereo groups on one fader. Because the level is
controlled before the channel pan circuit, a single
VCA group fader is all that is required to control a
stereo or LCR group. This would take 2 or 3 faders
using audio groups if the channel pan image is to
be maintained.
Multiple output control. The relative balance
between all outputs is maintained when moving
VCA group faders.
Multi-level grouping. A channel can be assigned
to more than one VCA group. This lets you assign
multi-level groups, or even a ‘grand master’,
impossible with audio groups.
Conventional audio groups are still useful when you
need to insert a signal processor such as a
compressor to affect a group of signals, or you need
to feed different groups of signals into the matrix.
However, fewer such groups are usually required
on a VCA equipped console. For this reason the
ML3000 provides the mode switching to reconfigure
unused audio groups as full featured aux sends.
34 ML3000 User Guide
Using VCA Groups
Use audio groups where you want to insert group
signal processing or send groups of signals to the
matrix. Use VCA groups if you want grouped level
control only.
Route the channels to the mix by pressing the MAIN
MIX switch. Adjust the PAN and BLEND controls
for the image required. Assign the channel to the
required VCA group using method described on the
next page. The channel GROUP ASSIGNED LEDs
next to the faders light channels are assigned to
one or more VCA groups. Once assigned, the
group fader affects the channel level. Start with the
group fader set to its nominal ‘0’ position.
You can assign the channel to more than one
group. Take for example a theatre musical
production. Here, you may have stage
microphones assigned to Group 1, radio mics to
Group 2, and all microphones to Group 3. You may
also have all channels assigned to Group 8 as a
‘grand master’ to control the overall volume. In this
case, a radio microphone would be assigned to
Groups 2, 3 and 8. Note that the VCA groups affect
all channel post-fade sends such as effects and
direct outputs but not the pre-fade monitors.
ASSIGN
CHANNEL
PAN
ASSIGN
CHANNEL
FADER
CHANNEL
PAN
VCA
+
DC
CHANNEL
FADER
PRE-FADE SENDS
POST-FADE SENDS
SUBGROUP
AUDIO BUSS
PRE-FADE SENDS
POST-FADE SENDS
DC VOLTAGE
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PAN
INSERT
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MATRIX SEND
AUDIO GROUP
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VCA GROUP
MASTER
FADER
MAIN MIX
MASTER
FADER
MAIN MIX
MUTE. This momentary action switch turns all
assigned input channels on or off. It acts as a
remote control for the mute switches on those
channels. The channel pre-fade, post-mute sends
are also affected. The mute switches on assigned
channels light when the group is muted.
The switch also functions as the group select key
when in ASSIGN mode.
The VCA group mute cannot be assigned to a mute
group or snapshot memory. However, channels
which have been muted by the group can be stored
in the memories.
VCA GROUP FADER. The fader adjusts the level
of all channels assigned to the group. The ‘0’
position is referred to as the ‘nominal’ operating
setting. At this position the channel levels are as
marked on the channel faders. Any adjustment
made to the group fader offsets the channel level by
that amount. It is best to start with the group faders
set to their ‘0’ position.
At minimum position the fader shuts off all assigned
channels. At maximum position it provides a further
+10dB boost. Note that the maximum boost that
may be applied to the channel VCA is +10dB
regardless of how many group faders are assigned
and set above ‘0’. It is best to work with the faders
around ‘0’ and avoid excessive boost.
The following diagrams illustrate the combined
channel gain when assigning more than one VCA
group. In this case the final gain is affected by the
channel fader and three VCA groups.
Example 1
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IN
0dB
Example 2
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IN
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Example 3
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IN
0dB
CHANNEL GROUP 1 GROUP 2 GROUP 3
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CHANNEL GROUP 1 GROUP 2 GROUP 3
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off
OUT
+10dB
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ML3000 User Guide 35
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