Would anyone have some sample Lowpass Filter code for me to copy? I saw that rack has built-in filters (see here), but I’m looking for an example that I can follow to get me started.
I don’t know if I need a TRCFilter or TBiquadFilter? I don’t really know the difference.
To put this into context, I hope to add a lowpass filter to the Groovebox module.
I would go with a biquad. You can’t get any resonance with a one pole filter. I’ve used the rack biquads. Not in any library plugins, but they work fine. I think the are SSE friendly, also.
Sounds good to me. However, I can’t seem to find any examples of what the implementation would look like. Specifically what I’m looking for is a concrete code example of a lowpass filter in VCV Rack.
Biquads work fine. I’ve only ever experienced a problem with them in super collider when no control smoothing was applied to the knobs. “hand” twisting caused some discontinuous “squeally/pop?”
I’ve found the opposite - so much junk comes out of most biquads if you try to modulate them. I usually use a cruddy “Chamerblain” filter when I need to modulate the parameters.
I thought the same when I read the post. They are derived assuming constant coefficient and resonance so modulating them is kinda cheating unless you do it “slowly.” Unit circle, complex plane, path between the poles, etc etc hand wave hand wave fake some math and blammo
One of the several problems with biquads in situstiins beyond more basic settings
That simper svf is quite nice though. Snappy and fun. And of course there’s that new module set with buckets of new filter models which just dropped too…
yeah, the chamberlain filter is a two pole SVF. It has some well known limitations, but it works pretty well. I used it in a lot of modules. I only use biquads for fixed filters.
I guess the takeaway for the original poster is: there’s a lot of filter algos with distinct characteristics. Not just a single low pass filter. And they can really impact the sound of your instrument. A simple high cut at a near static cutoff is probably fine with a biquad but a modulated filter sweep in a synth will benefit from more.
But I haven’t used groovebox so am not sure which case applies!
Are there any state variable (or Chamerblain) filters built into VCV Rack that people would recommend? Imagine that people are modulating the lowpass filter for different steps in a drum machine. Would there be a responsive lowpass filter that would be a good choice for this situation?