Self oscilating filters

Hello, It is clear to me that this happens, but as a newcomer it happened to me that sometimes something stumbles to me, especially if it is controlled by CV (especially resonance :)). Is it possible that this is also due to the computer hardware or just the module? I did a few tests because it happened to me, especially with the Vult Tangents. I measured 3 versions and this worked out for me. the Red Tangents begin to oscillate at 0.6 the Yellow Tangent does not oscillate at all even at 1.0 and eventually Blue Tangents begins to oscillate around 0.85 Is it just a SW implementation?

also you can see different modules make different calculations using the same circuit, which may mean a better simulation, it can be answered better by @modlfo

On the core, the three versions of Tangents are the same. The one that does not self oscillates could be that I forgot to add internal noise when nothing is connected. The filters in order to self oscillate they require a bit of initial energy to become unstable. Since the software lives in a noiseless world, I have to add a bit of noise.

Regarding the point where they star self oscillating, the three could be different because depending on the version, I have adapted the resonance curves. It is more or less like this:

  • Original Tangents: no adjustments, the filter self oscillates wherever the circuit wants to.
  • Freak (slim): Exactly the same as the original Tangents, except for the internal noise bug.
  • Freak-HW(hardware clone): resonance knob is logarithmic, that way we get more fine tuning before the filter starts self oscillating.

The CPU consumption is not to trust in this case. If the inputs/outputs are disconnected I take advantage and turn off some of the processing. The hardware Freak is always on.


Thanks for the clarification. Described clearly so that I will understand it too :slight_smile: