PMS-20 Filter Overdrive


After doing a lot of background work on my ‘beagleboard compatible’ synth infrastructure, I decided this week-end to work a bit on something that would for once be audible.

My plan was to finally test how overloading the two filters way past their usual resonance setting would sound. I didn’t want to map it directly to the resonance setting since it would make the ‘traditional’ setting for resonance from 0 to 3 -on a scale of 10 – which would make it hard to tweak, so I decided instead to use a separate filter overdrive control for boosting the resonance setting.

Then, I wanted to give the feel that cranking the volume up would make the whole synth go in full distortion zone and therefore have the volume knob to act both as a volume control but also use the end of the range to send the filter overdrive up to 11.

As it is mapped now, the volume goes from 0 to maximum gain in the first 7 ticks and past that, it increases the resonance of both hi pass and low pass filters from the usual 2.0 maximum gain to a hefty 6.0. That way it felt really physical in the sense that yeah, it becomes louder and overdrives more and more as you turn it up.

Here’s a sound demo. 2 notes played at unison most of the time. First holding the notes and pushing the overdrive factor. Then a simple progression.


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