Microcompressor Eurorack ttt




MICROCOMPRESSOR EURORACK - compact VC compressor for modular synths.


This is compact but hi-quality compressor. I used THAT4301 dynamics processor.

THAT 4301 Dynamics Processor, dubbed "THAT Analog Engine®", combines in a single IC all the active circuitry needed to construct a wide range of dynamics processors. The 4301 includes a high-performance, exponentially-controlled Blackmer® VCA, a log-responding RMS-level sensor and three general-purpose opamps.

Design is based on THAT Corp. design notes - Fully Adjustable Compressor / Limiter. This is a feedforward VCA compressor.


Adjustable by potentiometers Treshold, Ratio, Attack, Release, Makeup gain.

Reduction LED which lights when signal level exceeds treshold.

Treshold, Makeup, Attack and Release can be controlled by CV. -+5V covers all pots range.

Hard/soft knee switch.

Two timing modes are available -- auto and manual. In auto mode attack and release rates are linked, and depend on the non-linear capacitor circuit. In manual mode, variable, independent adjustment of the attack and release dynamics are possible.

RMS, Peak or Automatic timing detector options.

Two CV outs. CV1 after RMS-level sensor and Treshold control works something like envelope follower. CV2 after all controls beforeVCA, using this out any VCA can be patched as compressor or modulating a filter gives interesting effect.

Sidechain send and receive to external sidechain processing.

Two Microcompressors can be linked in stereo pair by Stereo 1 and Stereo 2 jacks. Master/slave switch off controls on slave unit. Stereo 1 to link the two RMS detectors. Such coupling results in true power summing and a more euphonic behavior. Note that, when linking detectors in this manner, means to adjust for the +/-3 dB tolerance on each detectors' 0 dB reference level must be provided. Stereo 2 to send CV from master unit to slaves VCA.


PCB - 2mm thickness, gold platted, black mask. $30


Two panels - 16HP front & back. Anodized alu, black print. $35


SMD parts + soldering. $15


Shipping per set: $5 - only board, $8 - board+panels.


TOTAL for complete set witch shipping: $88


Paypal info(at)greenexpo.by


Assembled module $330 + $15 shipping.


MUFFWIGGLER forum thread http://www.muffwiggler.com/forum/viewtopic.php?t=82527




Soundsample. Tube VCA works as compressor modulated from CV2 out of Microcompressor. Filter - Mutant vactrol VCF. No effects.









PCB top.


PCB bottom.


Front panel.


Back panel.






PCB with soldered SMDs:






Microcompressor at work:

Not compressed Compressed


OLD VERSION PCB (still in stock)





(c) 2012 L-1 Synhesizer. E-mail: info@greenexpo.by