C101 OTA Lowpass Filter MKII

OTA Lowpass filter with 24db and 6db outpus.

The C101 OTA Lowpass filter is a four pole low pass filter ( 24db/octave ) based on four cascade OTA-stages. In this MKII version a new 6db output has been added expanding the sonic possibilities of this filter. The OTA filter can be one found in classic synthesizers like Roland Jupiter 8, Roland System 100m, Roland SH-1, SH-7, SH-101, Roland System 700, Jen SX1000 and many more.
The C101 has been redesigned adding new features and improving other presents on the original design.

The main changes / improvements are:

A new first order output with a 6db / octave response. With high resonance this output will sound almost like a bandpass filter.
A dedicated modulation input for envelopes. This input has a 0,66 V/Octave response expanding the modulation range to 7,5 octaves using the typical 5V envelope. In case you use10V envelopes the input response can be changed to 1V/Octave with a jumper located on the back of the module. An inverter switch has been added to easily invert the input signal.
A better gain compensation circuit for the 24db output. Not more volume drop when you turn up the resonance.
An attenuverter has been added to the resonance modulation input.
Better temperature compensation.

At high resonance settings the filter will start to oscillate and it can be used as a sine wave oscillator. The tracking is perfect over 5 octaves.

C101 MKII main characteristics

Two filter outputs with 6db and 24db response
Temperature compensated
Dedicated envelope input with 0.66V / Octave response with inverter
Filter self oscillate and can be used as VCO ( 1V/Octave )
Voltage controlled resonance
Two audio inputs one with attenuator


  • 35 mA +15V
  • 33 mA -15V
  • ? mA 5V
  • 52 mm deep
  • Ø 4.75 (4 Votes) Average Rating

This Module is currently available.

$263 Price in €
2 HP Filter
submitted Oct 2nd 2015, 09:45 by thalassa | last Change Aug 1st, 07:18 by thalassa
Specs are approved by the manufacturer