ST-Modular Dirty Dan, Vactrol-Based DIY Analog Filter & Distortion With A Raw Character

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ST-Modular shows with Dirty Dan, a very characterful vactrol-based analog filter & diode-based distortion combo in one 10HP Eurorack module.  

For Superbooth 20 Home Edition, ST-Modular announced Dirty Dan, a very dirty/raw-sounding 10HP vactrol-based analog filter & distortion module for Eurorack. The module has individual inputs for both features so you can use the module separately as a filter and distortion. Three inputs jacks with volume knobs are located on the front panel where the two first inputs are directly routed to the vactrol filter. The third goes through the adjustable diode-based distortion with soft/hard clipping and then to the filter. Thanks to these potentiometers, you can also use the module as a dirty mixer.

The filter is vactrol-based and has its own character. The module has lowpass and highpass without saying this on the front panel. Mainly because the highpass settings influence the cutoff pot. If the high pass knob is fully counter-clockwise, cutoff acts as a classic low pass filter knob. If you turn high pass clockwise the cutoff knob will also act as a high-pass filter in some knob settings turning it further than 12 o’clock. This way you can morph between lowpass and highpass with one knob, the cutoff knob.

ST-Modular Dirty Pan

Either lowpass or highpass can be controlled via CV or both together via the third CV input. The level of control voltage or CV H/L may be varied with the CV H/L attenuator potentiometer

Distortion Without Filtering

Nice is here that you can disconnect the distortion from the filter via the dist out and process it further with external modules. The distortion is diode-based and comes with two clipping modes. The feedback (FDBK) potentiometer sets the amount of audio being fed back into the filter circuitry providing a nice resonance to the signal. The range of feedback amount can be set with a trimmer on the back of the PCB.


  • vactrol-based analog filter
  • three channels
  • separate distortion stage
  • highpass & lowpass
  • cutoff controls highpass & lowpass
  • two clipping modes
  • feedback control
  • skiff friendly
  • wrong polarity protection
  • 3U Eurorack module, 10HP wide
  • The module consists of two boards: front PCB panel, Main PCB

It is a pity that the module does not come as a finished module but only as a DIY kit.

ST-Modular Dirty Dan price & availability TBA.

More information here: ST-Modular 

Eurorack News

Superbooth 20 Home Edition

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