Corsynth C101B OTA Lowpass Filter Module

Corsynth C101B OTA Lowpass Filter Module Overview

Corsynth C101B OTA Lowpass Filter

The C101B OTA Lowpass Filter is a low pass filter based on cascade OTA-stages with 24dB/octave and 6dB/octave outputs. The C101B is the single width version of our C101 MKII filter. This kind of 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.

As many 4-pole low pass filters the output volume drastically drops when the resonance is increased. The C101B includes an especially designed circuit to maintain a constant output level at any resonance value. This circuit can be activated or deactivated on the front panel allowing the user to select between the traditional response and the gain compensated response. The gain compensation is not implemented in the 6dB response this way this output at high resonance levels will sound almost like a bandpass filter.

The resonance can be voltage controlled and when the resonance is set at a high value the filter will start to oscillate. The C101B can be used as a sine wave VCO and it will track perfectly over 3-4 octaves and it is also temperature compensated.

The FM1 input has a 0,66 V/Octave response expanding the modulation range to 7,5 octaves using the typical 5V envelope.

C101B main characteristics :

• Two filter outputs with 6dB and 24dB response
• Voltage controlled resonance
• Three frequency modulation inputs one of them with an attenuverter
• Filter self oscillate and it can be used as VCO (1V/Octave)
• Gain compensation circuit for the 24dB output
• Temperature compensated
• One audio input