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dirty dan / 3-channel vactrol-based analog filter and distortion  / 10 HP

Meet Dirty Dan, the eurorack rebel who doesn't play by the rules of clean and tidy. Dan's all about embracing the mess, dishing out gritty goodness, and making those pristine waveforms second-guess their existence. If your sound needs a touch of snotty charm, Dan's your man. Just remember, he's not just dirty – he's delightfully disruptive!

key features

  • Vactrol-Based Analog Filter

  • Three Channels

  • Separate Distortion Stage

  • High Pass and Low Pass

  • Cutoff controls High Pass and Low Pass 

  • Two Clipping Modes

  • Feedback Control

  • Skiff Friendly

  • Wrong Polarity Protection

specs & downloads

  • width: 10 HP

  • depth: 32 mm

  • power: 58 mA @ +12V / 54 mA @ -12V


description / manual

The module has three input jacks. The first two inputs are directly connected to the vactrol filter. The third input first goes through an additional diode-distortion circuitry and is then connected to the vactrol filter. Each input jack has a dedicated volume control potentiometer. Hence you may use Dirty Dan also as a Dirty Mixer.

The amount of distortion for channel IN 3 can be set with the DIST potentiometer. Additionally soft and hard clipping may be activated with the switches DIST SOFT and DIST HARD. It´s best to use a sine wave to hear the differences between the clipping modes.

The distorted signal can be taken from the DIST OUT jack separately and is then being disconnected from the vactrol filer and the other two inputs respectively the OUT jack. This allows you to process the distorted audio with external modules.

The filter itself is vactrol-based and has it´s own nature. The sound varies depending on the vactrols being used. It´s fine to solder retail vactrols like the VTL5C series, but the fun starts when DIY vactrols are being used. The sound from the inputs will go through a high pass filter, that can be set with the HIGH PASS potentiometer.

Also a low-pass filter will take effect. This can be controlled with the CUTOFF pot. This pot is not called low-pass as you might expect, because the HIGH PASS settings directly 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 blend between low-pass and high-pass with one knob, the CUTOFF knob.

Either low-pass or high-pass may be CV controlled. A third CV input controls both at the same time. The level of control voltage for CV H/L may be varied with the CV H/L attenuator potentiometer.

The 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.