C101 OTA Lowpass Filter

This product has been discontinued , the new version can be found here

The C101 OTA Lowpass filter is a four pole low pass filter ( 24db/octave ) based on four cascade OTA-stages. The design is similar to the one found in classic synthesizers like Roland System 700, Roland System 100m, Roland SH-1, SH-7, SH-101, Roland Jupiter 8, Jen SX1000 and many more.

When the Resonance control is set at a high value the filter will start to oscillate and the C101 can be used as a sine wave VCO. The filter will track perfectly over at least 5-6 octaves and is also temperature compensated.

In many 4-pole low pass filters the output volume drastically drops when the resonance is increased. The C101 OTA Lowpass filter is specially designed to maintain a constant output level at any resonance value ( with the exception of when the filter is set to auto-oscillation ).

Another important feature is that the C101 has voltage controlled resonance.

C101 main characteristics

  • Filter response 24db/octave
  • Filter self-oscillate
  • Can be used as VCO ( 1V/Octave )
  • Voltage controlled Resonance
  • Temperature compensated
  • Two Frequency Modulation inputs
  • Two audio inputs
  • 1V / Octave input

The C101 OTA Lowpass filter is built using high quality electronic components, Switchcraft jacks, Cosmo knobs (the same used by Moog Modular) ,  silk screened front-panel….



  • Module Format : 5U, MU format ( Synthesizers.com, Moog )
  • Module Width : 2 MU ( Moog Unit )
  • Power : +15V@23,2mA , -15V@22,1mA
  • Power connectors : Synthesizers.com , MOTM ( 4 pin )
  • Frequency Range :15Hz – 21 KHz
  • Signal Levels : Typical 10Vpp ( -5V to +5V )


High Resolution Photos

User Manual


The C101 OTA Lowpass filter is a four pole low pass filter in MU format based on four cascade OTA-stages.The same kind of filter found in many Roland synths