# How is this sine shaped?

Hello

I am trying to figure out what the Tone parameter of the sub oscillator in Ableton’s Wavetable synth is doing.

Here is a snippet of the parameter being turned from 0% to 100%:

It is morphing (to a saw?) and waveshaping the original sine wave.

Which VCV module would do the same?

This is the spectrum analyzer when the Tone parameter is at its maximum:

Thanks a lot!

Maybe some sort of delay/comb filter? You could try running some simple waves through Vult’s Rescomb or one of the other comb filters in VCV.

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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

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a comb maybe, try the vult rescomb (and the 2)

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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.

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By using an oscilliscope you will see that the sine wave turns into a rectangular waveform.

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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.

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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).

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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.

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By 60:40 square, do you mean the pulse width?

yes

There is an intermediate waveform that is NOT like the interpolation between a pulse and a sine though. See https://imgur.com/a/cjBAsdp

Thanks for all the replies.

Here is the sub osc without envelopes while moving the Tone.

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.

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Yea, it does. This might not have been exactly the same patch as the previous one :o

My “Shaper” waveshaper has on offset control, and many others.

The offset function seems stairsteppy when I run a sine or triangle LFO into it. What’s up there?

seems odd. you got a simple patch of a screen shot that would show that happening?

http://ix.io/2Foz

Used: bogaudio, vcv, and squinky. Set audio-8 to point as you see fit.

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: