Bandpass Filter Patch

Here’s the beginning of a 4x pinged bandpass filter patch on the ER-301

I made a custom unit, inside of which was 4 mixers, each mixer has a lowpass and a highpass in series (which effectively gives you a bandpass filter).

A1, B1, C1, and D1 go to linear custom controls that are linked to each respective LP and HP pair’s f0
A2, B2, C2, D2 go to linear custom controls that are linked to each respective LP and HP pairs Q
A3 is linked to Voct for all the filters (like a global transpose)

f0 gain for all 4 sets of filters is set to 5000, f0 bias is 440Hz, q is set to 0 bias, 1.0 gain for all 4 filters. Gain for all the custom controllers is set to 1.0

The freq and resonance are very touchy, it may be that I need to dial them in a bit more by varying the above mentioned gains in order to widen sweet spots

Here’s what it sounds like pinging 2 of the 4 BP filters while also sequencing the global Voct


One thing I considered is that since a narrow bandpass filter is pretty much a sine wave, and since the mutable instruments Streams can ouput a CV that mimics the response of a plucked vactrol, that I could record various-lengthed Streams plucked vactrol CVs into a sampler, slice them up and have them selectable via CV input, and use that to modulate VCAs in front of the sine waves…


Just moved these here as I thought it exploring this idea deserved it’s own thread!!

Great idea and I totally agree about MI Streams, one of my favourite modules, I prefer it to the actual vactrols I have in my system and I’ve never met anyone who could correctly identify which was real or not!

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So far, Streams is definitely my preferred plucked vactrol sound compared to what I have heard so far

Yeah, vactrols are strange and I have very mixed feelings about them, sometimes they seem to behave wonderfully but other times no matter what I do they just seem to have a bit of a teenage tantrum and just won’t do what I want; Streams is like the grown up version, very flexible, totally controllable, always sounds great and when you don’t want a vactrol emulation it does half a dozen other things. The envelope follower also considers the spectral centroid of the sound - it’s magical!!

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