Audio Filter based on open303 (TB - 303 emulator) - need some help

Cinezaster

New member
Hi,

I like to present an audio filter I ported from the open303 project.
You can find it on my github page: https://github.com/Cinezaster/Teensy-open303-TeeBeeFilter (Code + example)

I'm currently working on a digital synth that is based on the signal path of a Roland TB-303. But the current available filters where not completely up to my taste.
That's why I went looking for an open source filter. I found an online emulator based on the open303 project (https://olawistedt.github.io/BassMatrix/) that sounded more like a 303.

I copied all the code and incorporated the highpass feedback filter within the code.

I still have one problem.
When the signal amplitude exeeds 50% the output signal goes completely distored. On my oscilloscope it looks like the signal is warped like a wavefolder.
The open303 project uses an -1 to 1 float input signal, and I convert my input signal like this
Code:
float input = block->data[i] * (1.0f / 32768);
Do I miss something?

I want to implement an pre-filter overdrive, which can create nice distorted effect, this worked nicely with the State Variable Filter of the Audio library. But this seems to be impossible with the filter I copied .

I still need to build the external cutoff and resonance control, like the AudioFilterLadder.
 
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