Hi Floris,

> the sounds that go in are less loud than normal doepfer vco's or noise sources, would it be possible to have those sounds as loud as the vco's etc by modding the filter module

There is a 27k resistor immediately after the audio in 'level' pot (between the pot and capacitor C1, but easy to find by following the trace from the pot wiper). If you lower this that should increase the gain, but (and I'm guessing here) I don't suppose you'll get much more than 2x or 3x improvement out of it before it goes 'haywire' (I could be wrong!). I suggest trying an 18k first, see what effect that has, and if that's OK, perhaps try a 10k - lower than that and it's anybody's guess! (Because the filter uses digital inverters as amplifiers, these are 'biased' by a variety of resistors, and lowering this one may have an effect on this biasing which stops the whole thing working properly, but without trying it, I can't be sure!)

Tim