Description

Systral is a 12HP Stereo Filter with shared frequency control (but separate resonance controls) for both channels. It also includes gain pots for adjusting the incoming signals strength per channel. The input gain controls are not to be underestimated as the signals strength strongly dictates pretty how the filter circuit behaves.

The filter circuit is based on the Korg MS-20 filter but the vision here was to break it down to make it as dirty as possible. Unstable resonance through red LEDs, and an analog noise source normalled to the CV input are part of the efforts to achieve this. The CV noise is also audible by turning up the resonance which is by design (and the noise is not (like in mörser) normaled to the audio path since this sounded so great on its own.

There is a dedicated noise output for making this part available to the rest of your system and other modules. Making Systral an awesome sound source on its own being capable or making windy sounds, lasers, and sci-fi landscapes without any input signals at all (as long as you crank the resonance).

There is a shared blend control for mixing between low and high pass filter types for exploring the places between the two. The left input is also normalled to the right input so you can create a stereo filtered
signal with just one sound source. Systral is the second release out of (more) filthy filters named after 90’s Bremen hardcore bands, the first one was Mörser (also released in 2025).

Note: this is a Panel & PCB set only – you must source the rest of the parts yourself! 

All SMD parts are already pre-soldered

Systral – Build Document & BOM