Grove Audio GMS-712 User manual

GMS-712 DUAL VOLTAGE CONTROLLED
AMPLIFIER
PRELIMINARY OPERATION MANUAL
06/08/2019
COPYRIGHT 2019 –GROVE AUDIO LLC
ALL RIGHTS RESERVED

Features
2 high quality voltage controlled amplifiers
Linear or logarithmic response switch selectable on each channel
Control voltage input routed through a reversible attenuator
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Basic Operation
VCA Channel
When the toggle switch for a channel is set to the LIN position, the amplifier gain response to the
control voltage signal varies in a linear fashion with respect to the control voltage signal. When
the toggle switch is set to the LOG position, the amplifier gain response will vary in a logarithmic
fashion with the control voltage signal. The gain will be approximately X1 with a 5 Volt input and
will have a value greater than X1 for control voltage inputs greater than 5 Volts.
CV LVL Reversible Attenuator
With no control signal inserted at the control input, 5 VDC is normaled through the control input
jack and fed to the input of the reversible control voltage attenuator. Varying the control position
between 0 and 5 will allow the input signal to appear on the output jack for the corresponding
channel. The signal gain will vary from –infinity to approximately X1.5 at the 5 position. At about
the 3 position the amplifier gain will be X1 which means that the amplitude of a signal going
through the amplifier will be equal on input and output. The phase of the signal going through the
amplifier is not affected and is in-phase on the output.

When a control voltage signal is applied to the control input of a channel, the reversible attenuator
will act as a variable gain control with approximately the range of –X1.5 at –5, X0 at 0, and X1.5
at +5.
INIT GAIN Control
The INIT GAIN control determines the initial output level of the amplifier with the CV input at 0
Volts or if no CV input is used, the CV LVL control at the 0 position. This is useful, as an example,
for patches that require varying the amplitude of a modulation signal from an initial value to
something higher or lower in amplitude.
Internal Gate Inputs
There is an internal gate input connector for each channel that will accept a 0 to +5 Volt signal
that is added to the output of CV reversible attenuator before the gain control signal is applied to
the VCA. This input can have various uses including gating the audio on and off for the
corresponding channel or applying an initial gain control signal.