GMS-712MU Dual VCA

Selectable LOG/LIN control response

The GMS-712MU Dual Log/Lin Voltage Controlled Amplifier contains two high quality VCA devices in a 1MU panel. Each amplifier can be used with an external control input to produce a change in amplifer gain from infinite attenuation to a gain factor of 1 or more. The control curve can be set for a linear or logarithmic response to the input control voltage.     


The module contains two separate high quality voltage controlled amplifier channels. Each channel has an associated control voltage input that passes through a reversible attenuator. The attenuator allows the control voltage to be prescaled from zero up to twice the applied level. When the attenuator control is positioned to the left of 0, a greater negative voltage on the control input will produce higher gain values approaching a gain of 1 in the associated amplifier channel.

The control voltage response curve is determined by a panel toggle switch. When the switch is down, the response curve has a linear action. When the switch is up, the response curve has a logarithmic action. This response is similar to the logarithmic taper on a normal volume control.  


Technical Specifications

Input Range
+-5 Volts AC or DC

Output Range
+-10 Volts AC or DC

Control Range
+-10 Volts

Linear Mode Gain Constant
0.5 Volts per Volt

Module Power
+15 Volts 20 mA.,
-15 Volts 20 mA.,
+5 Volts 10 mA
(internal jumper allows deriving
+5V from the +15V power bus)

Module Size
Panel height - 8.75 inches (222 mm);
Panel width - 2.125 inches (54 mm);
Depth (behind panel) 1.5 inches (38 mm)



We produce electronic synthesizer modules in the two most popular formats, MU (Moog compatible 5U) and EU (Eurorack compatible 3U). A wide range of voltage controlled modules including oscillators, amplifiers, mixers, envelope generators, special effects units, wave generators, filters, power systems and cases allow users complete freedom to configure any desired electronic music instrument.


Grove Audio builds microphones, preamplifiers, equalizers, compressors and other professional audio equipment for performance and studio use. We build units in popular formats such as 19 inch rack mount and 500 series 3U modules. We can also produce custom designs on request. Contact us for a consultation.


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Grove Audio has been manufacturing professional recording and modularized electronics for musicians and performers since 1995.