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Modular synths / sound modules
DOEPFER/A-171-2 VC Slew Processor / Generator

DOEPFER / A-171-2 VC Slew Processor / Generator

Variations

DOEPFER Eurorack modular synthesizer thru-limiter. By adding functionality to this module, it can be used for many purposes, including portamento generator, AD envelope generator, pulse delay, and subharmonic generator.

The A-171-2 Voltage Controlled Slew Processor/Generator is a versatile slew limiter based on the Serge VCS. It is designed under license from Ken Stone VCS, which is also based on the Serge VCS.

By adding various functions to the slew limiter, it can be used in many applications, including AD envelope generators, pulse delays, subharmonic generators, VC LFOs, and VCOs.

The main functions are as follows:

Manual control of Slew Up time
CV control of Slew Up time (with polarizer)
Switchable linear/exponential response curve in the Rise section
Manual control of Slew Down time
CV control of Slew Down time (with polarizer)
Switchable linear/exponential response curve in the Fall section
Signal In for inputting the signal to be slewed
CV Up input is affected by CV Up control and the Exp./Lin. switch
CV Down input is affected by CV Down control and the Exp./Lin. switch
A constant voltage is connected when nothing is connected to the CV Up and CV Down jacks
exp. CV In: This input corresponds to ""V/Oct"" in typical modules, but since it is not exactly 1V/Oct, it is labeled ""exp.CV"". Primarily used as a VCLFO/VCO in Cycle mode, or as a common exponential control for Up and Down time in Slu-mode.
Trig In: Retrigger input when used as a VCLFO/VCO. A pulse input to Trig In triggers the envelope, or it is used as a retrigger input when used as a VCLFO/VCO.
End Out: Becomes High when the output is below approximately 20mV, and Low when it is above approximately 3.5V, generating a square wave in Cycle mode.
Cycle On/Off Switch: Switching to On internally connects End Out to Trig In, generating a periodic signal similar to a VCLFO/VCO. Maximum frequency is 2.5kHz/3.5kHz (Shape switch lin./exp.), and maximum period is 15 seconds/40 seconds (Shape switch lin./exp.).
Out: Module signal output.
LED: Displays the status of the Slu-Limiter output signal.

Typical Usage Examples
As a VC Slew Limiter / VC Portamento / VC Low-Pass Gate
Cycle Switch = Off, No Trigger Signal Connected to Trig Jack, Signal Connected to Signal In:

Functions as a CV-controlled slew limiter or portamento generator. The signal input to Signal In is ""slewed."" Slew Up and Down times are manually controlled by the Up and Down controls. The effect of CV input to CV Up and CV Down also affects the slew shape in Exp. mode. (See the symbols on the lower left and lower right of the knobs.)

When an audio signal is input and set to a short slew rate, the module functions as a simple VCF/VCA combination (low-pass gate).

As an A/D Envelope Generator / Pulse Delay / Subharmonic Generator
Cycle switch = Off, trigger signal connected to Trig jack, signal not connected to Signal In:

Functions as a simple Attack/Decay envelope generator. Rise time and Fall time, like the through Up/Down time above, control the shape of the envelope's Rise/Fall slope. exp. CV In can be used to change both Attack and Decay simultaneously.

End Out outputs a pulse when the envelope reaches its end (approximately 20mV or less), which can be used as a pulse delay.

If consecutive triggers are input and their rate is faster than the total Rise/Fall time, the module divides the input signal by an integer. In the audible range, the output signal will be subharmonic.

As a VC LFO/VCO
Cycle switch = Off, no trigger signal connected to Trig jack, no signal connected to Signal In:

Functions as a CV-controllable LFO/VCO. The waveform's Rise/Fall time, like the through Up/Down time above, controls the shape of the Rise/Fall slope.

Exp. CV In can be used like the CV input for a VCO or VC LFO. The response is exponential, but not exactly 1V/octave.

Width: 8HP
Depth: 60mm
Current Consumption:
+12V: 30mA
-12V: 30mA