BUILT MODULE – ST Modular – Karl – Mode Expander only

£34.99 (exc VAT)

This listing is for the Mode selector expander module for Karl with mounting screws and connecting to cable to attach to your Karl filter

ST Modular website

ST Modular Build Group on FB



In stock


Multi-Mode Dual/Stereo-Filter with individual Resonance Control

Karl is an analog multi-mode filter that is loosely based on the KORG MS-10 and MS-20 filters, but has been improved to handle two mono or one stereo audio source. The Resonance can still be varied independently per channel, which is very interesting when using two different audio sources at once. If you want to merge the two audio sources there is a Mix Out next to the two independent outputs per channel.

Karl has four modes:

• Low Pass Mode: Classic Analog Low Pass Filter
• High Pass Mode: Classic Analog High Pass Filter
• Phaser Mode: A small band of frequencies is filtered next to the original signal being passed through
• Overdrive Mode: If Resonance is increased the filter will quickly jump to overdrive, which creates some nice Harmonics

The Modes may be changed using this expander module.

In any mode the Cutoff Frequency may be changed via CV. The CV signal can be attenuated with the CV potentiometer.


• Analog Dual/Stereo-Filter
• 4 Filter Modes: LP, HP, Phaser and Overdrive
• Indipendent Resonance Control
• Mix two Mono Signals
• Mono to Stereo Converter
• CV Control over Cutoff Frequency
• CV Attenuator
• Wrong Polarity Protection


  • 56 mA +12V
  • 45 mA -12V
  • 0 mA 5V
  • 25 mm deep



Additional information

Weight 90 g
Dimensions 128.5 × 50 × 30 mm

Synthesiser parts/components