Saw Wave Folder

Ricko · Posted: Sat Aug 18, 2018 4:38 am Post subject: Saw Wave Folder

Here is a circuit idea. Wavefolders are now pretty well-known kind of waveshaper. They are often made from a chain of circuits that fold the wave back on itself, after it has reached a certain level. The effect can be like a sweep up harmonics or hard sync. It tends to work best for sine/triangle waves, not so good with sawtooth (too much variation in strength of harmonics) and pulse (not much effect).

So I wanted to make one for sawtooths. I am not sure whether the idea is really mine: probably not. It can be built with a quad comparator, & 3 dual op-amps, all vanilla components.

This version here does not use a folder, it uses a chain of fairly standard sawtooth doublers: once the sawtooth is over a threshold, each subtracts the PP amount. So increasing the level causes more folds: first the first doubler, then the second and so on.

So this circuit has four doublers that act to allow sweeping up to 5 x the frequency. You can see example waveshapes in the image below. The green is the input, the purple is the output.

As a bonus, there is a kind of pulse-width option too. It is an offset, so it could be a CV quite readily.

SAWWAVEFOLDER.JPG

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vladosh · Posted: Sun Aug 19, 2018 10:20 am Post subject:

this looks interesting i built similar but fixed version from electronotes ,second thought this idea with stages can be useful musically ,thanks for sharing

Ricko · Posted: Wed Aug 22, 2018 3:25 am Post subject:

Ricko · Posted: Fri Jun 14, 2019 10:34 pm Post subject:

VIDEO + AUDIO: I put up an example of the prototype PCB version of these.

https://www.youtube.com/watch?v=mbRE_3tlnFI

I am taking another iteration of the PCB: the plan is to bring it out as a module called fricko Rasp maybe next month, if it is OK.

Ricko · Posted: Sat Jun 15, 2019 10:18 pm Post subject:

AUDIO: And here is a sample audio file showing one of the kinds of sound, in this case right on the edge of a transition so that sometimes you get a little second thin pulse that shows up as sizzle sound. Unfortunately is is only 16kHz sample, so you don't get the top octave of sizzle, but I thought people might be interested.

sizzle.wav

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"sizzle" sound of saw wave folder (fricko Rasp prototype) with slight modulation by LFO.

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