From what I hear, it seems like the tone knob adds both harmonics and noise, so you could run a square wave and noise into a filter and modulate the cutoff frequency for example.
You also have wavetable oscillators in rack, if you search wavetable in the library you’ll find them, if that’s what you want of course
If the input here is a sine (which you imply but don’t show), then this is a waveshaper / distortion. It’s outputting odd and even harmonics, so it’s not a symmetric wave shaper. “morphing to a saw” is kind of what it’s doing. or even to a pulse wave. Others here say it adds noise, too. I believe it, but can’t really see it clearly in the spectrum.
However, there is an intermediate stage where there is a rounded peak on the positive side of the wave on either end. I’m beginning to think the tone control is just another wave table morph. They have that engine at their disposal anyhow. This might be doable with a custom table in Valley Terrorform.
On second listen I think you’re right, it seems to morph from a sine to a rectangle without too many waves in between, and there isn’t necessarily noise (except for antialiasing probably).
The special thing is it morphes from a pure sine to a 60:40 square. If it would go to a 50:50 square then XFX wave PD square could do the job. Maybe adding a phase distortion modulator in XFX that increases slightly while moving through the wavetable could be a way to go.
That wave looks exactly like a sine to pulse morph. That should be trivial to do. And I do see a tiny amount of high frequency noise in the square. I might try offsetting the sine and running through a saturation simulation like Vult Debritus. You’ll also add a touch of noise as the saturation increases. Seems a bit of work.
Important lesson for all: when trying to reverse engineer a sound, present it in the simplest form you can.
That was fast! thanks. I loaded it up, and as you say the offset has a stairstep. But if you look at the output of the bogaudio LFO on another scope is has the same stairstep! I have no idea why it’s doing that. stairstep-2.vcv (5.2 KB) Don’t know if it will come through if I just paste it in here: