Extron Electronics MLA VC10 Plus User Guide - Manual (Page 28)

Linear or Logarithmic Taper Mode
The MLA VC10 Plus is set to linear taper by default. Each increment or decrement will
change the voltage or resistance by a constant amount. In logarithmic taper mode, the
volume control module modifies the steps to increase or decrease the voltage or resistance
logarithmically.
When the amplifier increases the power provided to the speakers in logarithmic
increments, the human ear hears a linear change in sound volume. Some amplifiers
provide this compensation internally and work best if the MLA VC10 Plus uses the linear
taper mode. Amplifiers that do not provide their own compensation will sound better if
the MLA VC10 Plus uses logarithmic taper mode.
NOTE: This feature should be set to linear taper mode (the default setting) for all
Extron amplifiers.
The volume taper can be set to linear (default) or logarithmic mode using SIS commands
(see page 35).
Auto Mute
By default, the relay is used for the Auto Mute function. The relay automatically triggers
on whenever the volume level on the MLA is zero. For a third-party amplifier that has
contact closure terminals, the relay can be used to mute the audio.
To use a RS-232 control device to switch the relay on or off for other purposes, the auto
mute function must be disabled (see the
SIS commands on page 35).
Soft Start
After a power cycle or unmuting the MLA, the audio level returns to its previous value.
When soft start is enabled (the default setting), the audio level rises slowly after a power
cycle or a mute, to avoid abrupt changes in power to the speakers. This can prevent
damage to equipment and loud bursts of audio. The rate of volume increase can be set by
SIS commands (see page 35).
For example, if the volume is currently at 50%, when the audio is muted or the unit goes
through a power cycle, the volume will decrease to 0% immediately. When the audio is
un-muted, the volume increases slowly from 0 to 50% over a few seconds.
NOTE: If the Auto Mute feature is on (default setting), the relay will also be triggered
when the volume is muted.
The soft start mode can be turned on (default) or off, using SIS commands (see page 35).
Troubleshooting
If you have problems with the MLA VC10 Plus, try some of these suggestions.
The MLA VC10 Plus is not receiving power
z Check the Power and Activity LED ( a in figure 2 ) — it is lit when the unit is
receiving power.
z Check the wiring at the power port of the MLA VC10 Plus for the correct polarity
(see page 11).
z Verify that the power supply has been connected to a functional power outlet.
MLA VC10 Plus • Operation 22