Extron Electronics MLA VC10 Plus User Guide - Manual (Page 26)

Operation
This section of the guide describes
z
Operation
z Troubleshooting
Operation
The Extron MLA VC10 Plus Volume Control Module converts RS-232 commands from a
control system into voltage or impedance changes to control audio amplifiers with volume
and mute control ports. The MLA VC10 Plus is used to mute or make level changes on
an Extron MPA Series or half-rack XTRA
™ Series amplifier from a TouchLink ™ Touchpanel
system, an RS-232-capable MediaLink ® Control Processor, or other third-party control
system. The control module also supports third-party amplifiers that use either voltage or
potentiometer control.
SIS commands from the RS-232 port can also be used to control the relay switch for audio
mute or some other purpose.
Voltage or Resistance Control
The MLA VC10 Plus controls the volume of an audio amplifier by regulating either:
z Variable DC voltage (up to a maximum of 10 VDC in 100 increments).
z Resistance (up to a maximum 10 kilohm in 100 increments).
The MLA VC10 Plus uses 8-bit resolution to set the volume range, providing 256 available
steps, although only 100 will always be used. If the maximum resistance (or voltage range)
is set to 4 kilohm (or 4 VDC), only 40% of the total possible steps (102) are available.
Below 4 kilohm or 4 VDC, you will no longer have true 100-step resolution as some of
the 100 steps will be repeated. Below 2 kilohms or 2 VDC, you may start to hear audible
jumps in the audio volume. The 100 steps here refer to the 100 SIS volume control
commands
Determine whether the amplifier you are using is controlled by voltage or resistance and
use SIS commands to set the control mode to voltage or resistance (default). Connect the
amplifier to the appropriate port (see “
Connections for volume control by voltage ” on
page 9).
NOTES: • Only one port (voltage or resistance) is active at any one time. By default,
this is the resistance control port. In addition to physically wiring the
amplifier to the correct control port, you must use SIS commands to set the
correct control mode.
• All Extron amplifiers and the majority of third-party amplifiers researched and
tested by Extron work with the MLA VC10 Plus straight from the box, using
10 kilohm resistance control, without further configuration.
MLA VC10 Plus • Operation 20