Comb Room

The comb room effect combines a dual delay (room circuit) and a comb filter to make echo/reverb-type sounds and resonant feedback. The comb filter is in the feedback path of the delays. An envelope follower gives movement to either the comb filter or the room circuit. The comb resonance control in conjunction with the comb return control can create self oscillation. The preamp for the 1/4” input has selectable gain of 10x or 40x and a soft clipping characteristic. The comb and room circuits are both built around 1 bit delta-sigma converters. In the case of the delays, the analog to digital conversion is done in the PT2399 echo IC. The comb filter uses a simple and gritty A/D converter built of logic chips and op-amps. Which gives the filter a characteristic sound. Clock noise can be heard at lower frequency settings. Patching the room output to the return will bypass feedback through the filter, allowing all frequencies to echo.


Banana Patch Points

  • Banana CV inputs max voltage +/- 8v.
  • Banana Signal Inputs and Outputs are AC Coupled.

Audio Inputs

  • 1/4" TS instrument input, gain of 10x or 40x
  • 1/8" TRS line input summed to mono

Power Input

  • standard 12v 5.5mm x 2.1mm supplying at least 500mA of current

Audio Outputs

  • 1/4" TS line or intstrument output (selected with push-pin switch)
  • 1/8" TRS line output dual mono

Sound Samples

SK1 Drums

SK1 organ

Double Knot

Double Knot with modulation


Infosheet PDF (300kB)


What's Included:

Comb Room + Printed Infosheet + Power Supply (US plug)