Quad Operator Schematics and Code!

Hi! I wondered if it might be possible to get schematics and code for quad op? I’d like to mod mine, potentially porting the code to another processor & DAC.
I love the hardware unit but it could sound less harsh for me. It’s either the oscillator model or sample rate I want to mess about with.
Cheers for any advice!!

Yes, we actually open-sourced the code some time ago. Here are the code and schematics:

There are definitely some limitations here since we just about max out the capabilities of the MCU (as far as we can tell). We can’t, for example, oversample and or do things like cubic/hermite interpolation which might give better results around sharp edges of waveforms. I can’t be certain I’m doing the best job possible for comparable CPU cost. There are the BLIT & BLEP-based implementations of oscillators and some possibility of subtle issues with my implementation. There might be some SIMD optimization possible as well.

I’m currently moving over to a Rust implementation for my next project based on a higher performance CPU, so at some point I expect to explore oversampling and other potential performance enhancements. But I don’t expect those to affect the Quad Operator, which I’ve stopped work on at this point.

Since I released the QO, this interesting talk on wavetables was given at ADC22. I’ve been wanting to revisit some of the topics touched on here:

Digital Sound Generation Parts 1&2 were helpful in the development of the QO. There are some different approaches that could be used hinted here as well.

Appreciate if you share any learnings :smiley:

:pray: Amazing! And, thank you for the links. Tbh I only intend to reduce the frequency bandwidth and see where I go from there.