8 HP
55 mm deep
Current Draw
40 mA +12V
? mA -12V
0 mA 5V
$110 Price in €

This Module is discontinued.

Universal Vactrol Module

We call the A-101-9 an universal vactrol module. It contains two identical sub-units. Each unit has two vactrol outputs available that are controlled manually (Man control) and by an external control voltage (CV In) with attenuator (CV). A vactrol is a combination of a light depending resistor (LDR) and a light emitting diode (LED) both put into a small light-proof case. For more general details about vactrols please look at the Vactrol Basics page. Increasing the LED brightness causes a decrease of the LDR resistance. The LED at the front panel displays the brightness of the LEDs of the vactrol pair in question. The resistance of the two vactrols changes simultaneously. This allows to control two parameters at the same time or to control a parameter that requires two resistors at the same time (e.g. certain filter circuits). The LDR terminals of each vactrol are connected to the jack sockets labelled VAC1 and VAC2. In contrast to other A-100 sockets the VCA1/2 sockets are not grounded, i.e. the two terminals of the vactrol are connected to the two terminals of the socket in question.

Applications: The module introduces voltage control to any function that is controlled by a manually adjusted variable resistor (i.e. a potentiometer with only 2 terminals used). Some examples within the A-100 are: Attack, Decay, Release of all envelope generators (A-140, A-143-1, A-143-2), slew time of slew limiters (A-170), delay time and duration of trigger delay (A-162), clipping functions of the extreme filter (A-106-1), clock rate of digital noise (A-117), random rate and level (A-118), waveshaping function for A-110. A lot of application examples within the A-100 are described in the appendix of the A-101-9 user's manual. But even so far non-adjustable parameters that are determined by a fixed resistor can be made voltage controlled. But the module can be used not only within the A-100 as the vactrol outputs are completely free (no connection to A-100). The module can be used in combination with any other equipment too that uses a variable or fixed resistor to adjust a parameter (e.g. wah-wah or parameters of other effect units). Even for "circuit bending" the vactrol outputs can be used.

A more detailed description of the module can be found in the A-101-9 user's manual


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submitted Oct 6th 2012, 13:36 by MacroDX | last Change Aug 21st 2017, 16:07 by acgenerator

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