Stepped waveform from frequency multiplier + Feedback

I was playing with my VU002 and using the feedback to generate more complex shapes, something I use a lot, but last night came across something that surprised me and was wondering if anyone could help me characterise the behaviour.

Feeding a triangle wave into a 2Q VCA, then taking the output to the x16 on the VU002 and then back into the CV on the VCA results in a reasonably clean edged stepped waveform at certain knob positions (in other positions it does the normal feedback noise thing I’d expect).

Can anyone help provide some technical explanation for this?


I have no idea what is going on here but I wanted to reply because this topic is a healthy development for our forum. @DesertMuseum can you help us figure out what’s going on here? :100:

I don’t have any Syntonie in my rack so would not feel comfortable diagnosing this but I do know that @Bastien is a regular contributor here and could likely lend a hand.

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Thank you for your kind reply! I know @syntonie is preparing for a big HD IO release, maybe in the meantime @rempesm knows what’s up?

Thanks both! To expand on the question, I wonder if it’s reproducible on a staircase or other frequency multiplier paired with a VCA? Also to clarify this isn’t a complaint of any sort, just trying to understand whats going on!

Thinking about it today I was wondering if there’s a phase shift at some point, with some complex superposition of the feedback etc but I think it might be simpler than that. I think it might just be clipping due to the offset control on the gainbrain. When it clips any of the noise which you’d expect from feeding back a multiplier gets removed, giving the clean edges.

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Yeah, this is curious you’re getting those results from a full wave rectifier as that function typically goes in the opposite direction of stepped waveforms on its output.

I’ll patch this up and scope it so we can see what’s going on with the waveform here.