by Antti Pussinen and Wolfgang Spahn

The Dynamics of synthesized sounds are controlled with a Voltage Controlled Amplifier, or VCA. In a classical subtractive synthesizer arrangement the VCA is controlled through an envelope generator, allowing more interesting dynamic possibilities than just the on/off of a note gate.

Vactrol based Opto-VCA add an Attack and Release time automatically due to the relatively slow turn on, and off times of the led-ldr pair inside a vactrol. The ”opto” part of our VCA is a fast and accurate AC-Optocoupler, which adds a tiny bit of Attack time and Release tail to the signal, but not so much as a Vactrol would. We Decided to go with the optocoupler since factory made Vactrols are getting more rare and expensive, and also rolling your own is a good choice, the response varies due to LED and LDR types and manufacture tolerances.

The Paper Synthesizer PS411 adds more control to the Opto-VCA with Attack and Release control potentiometers. If both turned to zero, the module acts like a normal VCA, controlled by external CV. If Attack or Release are adjusted, it affects the input CV before it controls the VCA. If CV input is a Gate signal, the envelope generator works like a normal Attack Release generator. Created envelope can be used to also control other modules view envelope output connector. A LED is used to visualize the envelope. A jumper in the board selects between long and short attack and release ranges.

The module comes also with an bipolar offset potentiometer for manually controlling the amplitude. It‘s powered with Eurorack standard +-12 volts or +-15 volts and uses Eurorack power sockets and 3.5mm jacks.

In the workshop we will build the PS411-EnvAmp. We learn the basics principles how the attack/release envelope generator works and how the optocoupler controlled VCA. And certainly we learn how to use the PS411 - EnvAmp.

All the tool and materials will be provided. The workshop will be held in English and German.

13. Mai 2017 11am to 6pm
Werkstaatt Berlin
Mülhauserstr. 6. Hofgebäude 1. OG, 10405 Berlin\\
Studio A.Pusssin & W.Spahn
Gerichtstr12-13
Aufgang 5
Berlin Wedding (S-Bahn Humboldhain)
Costs: 70€ incl. undrilled Faceplate

Registration: post<at>wolfgang-spahn.de

Link:
http://paperpcb.dernulleffekt.de/doku.php?id=paper_synth:ps411_envamp

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