User Guide Owner's manual

Table Of Contents

Maximum voltage range limit

Some ampliers use a maximum voltage that is lower than 10 VDC. Using a voltage that

exceeds the requirements of the amplier can damage the equipment. Using a voltage

that is lower than the requirements of the ampliﬁer will limit the maximum audio volume

reached. Determine what the maximum signal requirements are for the ampliﬁer you are

using and use SIS commands to set the maximum control voltage that can be provided by

the MLA VC10 Plus.

ATTENTION: If you are controlling the volume using voltage, be sure that you know

the control voltage range for the ampliﬁer that you are using. Consult

the user guide for the ampliﬁer you are using or measure it, following

the instructions starting on page 8. Setting the control voltage too

high for the ampliﬁer may damage that equipment.

The MLA VC10 Plus can control ampliers that use a maximum control voltage that is

greater than 10 VDC but the maximum volume for the amplier may not be reached.

Maximum resistance range limit

Some ampliﬁers use a maximum resistance that is lower than 10 kilohms. Determine the

requirements for the ampliﬁer and, if necessary, set the values using SIS commands

(see page 35).

NOTE: All Extron amplifiers use the default 10 kilohms resistance control.

The resistance between the reference (V) and ground (G) pins of the MLA VC10 Plus is

always 10 kilohms. When a maximum range limit is applied to the resistance control, it

only limits the maximum resistance across the wiper (C) and ground (G) pins. This usually

limits the maximum volume output from the ampliﬁer.

If using 3-pin potentiometer control to connect to an ampliﬁer that requires a total

resistance of anything other than 10 kilohms, Extron still recommends that the 10 kilohms

setting be used to ensure full volume range.

Inverse Mode

By default, when the voltage is 0 VDC or the resistance is 0 ohm, the volume is considered

muted. At 10 VDC or the resistance is 10 kilohm, the volume is considered maximum.

Some ampliﬁers reverse their voltage or resistance requirements. Maximum volume is at

0 VDC or 0 ohm and the minimum volume (mute) at 10 VDC or 10 kilohm. For these

ampliﬁers, the volume control knob on the RS-232 control processor works counter-

intuitively: turning it clockwise decreases the volume and turning it counterclockwise

increases the volume.

Inverse mode reverses the resistance or voltage control signal sent to these ampliﬁers

so that the volume control knob on the RS-232 control processor works the way the

user expects: clockwise decreases the voltage or resistance, but increases the volume,

counterclockwise increases the voltage or resistance, but decreases the volume.

NOTE: Inverse mode should be disabled (the default setting) for all Extron amplifiers.

The inverse mode can be turned on or off (default), using SIS commands (see page 35).

MLA VC10 Plus • Operation 21