Bastl Instruments - Dynamo


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Really odd and unconventional module combining and intertwining an envelope follower, a rectifier, a comparator and a voltage controllable switch.
You may ask: What for? Well, for extracting gates from an audio signal. For generating a compressor curve CV which turns any better VCA into a flexible compressor. Or for creating a "fake" Thru-Zero modulation!
The individual sections can be used separately of course.



Envelope Follower (EF):
Its input is passively connected to a socket which passes the signal unprocessed, like a thru. The release speed of the envelope follower is set in three ranges using the EF Release switch. The envelope voltage is available at the EF OUT socket and inverted at -(EF OUT).
The socket |EF IN| carries a variant of the inupt which has been processed by a rectifier. The negative signal parts are inverted i.e. mirrored into the positive range which resembles the sound of an octaver's frequency multiplication.

The envelope follower's output is normalized to the comparator's input which allows for extracting gate signals from the audio signal. When the audio amplitude is higher than the Threshold the gate output goes high.
The threshold is set with a potentiometer or a CV at the THR socket. The comparator is also equipped with a direct input for using it with other signals for usual comparator applications.

Compressor CV generator:
This unique function of the Dynamo uses the same threshold value like the comparator. As soon as EF OUT exceeds the threshold value, a negative CV is generated which is proportional to the audio signal's amplitude. To achieve a compressor effect you have to connect this CV to a modulation input of an opened linear VCA which its attenuator being a ratio control.

This output subtracts the threshold voltage from the EF-OUT voltage and provides you with an alternative dynamics voltage which can be flipped around the threshold value to turn the compressor into a limiter or a negative compressor.

classic switch with bi-directional sockets. Either you route one input alternately to outputs A or B, or you connect inputs A or B to the output.
Input A inverts the signal and normalizes it to B, i.e. we have a gate controllable inverter. The comparator's output is normalized to the gate input of the switch.


- envelope follower: signal inputs, output, inverted output, rectified output

- comparator: input, output, threshold input, "Threshold minus EF" CV output

- switch: bidirectional inputs/outputs A and B, bidirectional output/input A or B, gate switch input

compressor CV output


3U Eurorack module, 5HP wide, 35mm deep
current draw: <30mA at +12V and <53mA at -12V

0.1 kg
Article Number

This item is discontinued or sold out and no longer available, please feel free to look for comparable new stuff in the following categories.