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paulovski
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Wavefolding

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It's a simple concept. you give an audio signal a big, hefty DC offset, on purpose. One polarity ends up with more amplitude than the other. When you distort the signal, that polarity clips first. Job done.

The bias can be positive, or negative. It doesn't really matter. I've rigged up both here. Inputs 2 and 3 (marked with song automation) of the mixer in the second row. It's easier to balance modulation, adjusting equal amounts of both.

Input 2, of the second mixer, in the third row, is a depth control.

There's an LFO in the second machine. Input 2, first mixer, third row, controls negative level.
Input 1, second mixer, third row, controls overall depth.

You can send any audio you like through it, but simpler waveforms tend to be a bit more fruitful (the FM Pair is good).

And everything else is based on this machine.

nitro27
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Joined: 10/11/2015 - 18:27
Wait something doesn't look

Wait something doesn't look right on that scope, almost like...

There! When the waveform goes too high or low, it switches polarity, just for a bit, then goes back! That's spooky. It could be an integer overflow error, or...

I heard tell from an electronics guy not too long ago, that in olden times, if you saturated the input of an op-amp (which is used in distortion effects) too much, there's a voltage where it would suddenly jump to the opposite rail for no apparent reason. They'd call this a phase reversal error, because it made them sounds smart. Nowadays all our op-amps are better behaved, and linear, too! But they say if you apply just the right voltage to just the right circuit, a ghost will come and eat your soul.

Or something, that guy was really boring.

So, is it a bug? Or a *really* accurate simulation? Sounds nice either way

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paulovski
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So. Are you claiming that the

So. Are you claiming that the modsynth is, actually, haunted? I'll go with that.

Erm. Something, something lack of input over-voltage protection? Anyway. What's in it for us?
Let's put that EG in negativeland and juggle things around a bit. 'Summon Pan Module'.
I think this is a, pretty rich, vein.
Good catch squire :)

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paulovski
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This is a bit more refined.

This is a bit more refined. Not a lot of point slamming things positive, and back again, to trigger the SH Module. Straight out the nozzle will do fine.
That, marked, mixer input 2 is a threshold control. Bring that up, and the negative spikes kick in. At 12 o'clock, the envelope joins in. Keep going, and, eventually, the envelope hits the positive voltage.

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paulovski
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you, may, be familiar with

you, may, be familiar with the terms, East and West Coast. Two approaches to analog synthesis. This, first machine is a, basic, representation of the two.

You're familiar with the East Coast concept. If you turn the volume up, you'll hear the same, old, same old. You send a, harmonically rich, waveform out of an oscillator, filter it, and whatnot, and, generally, muck it up. Subtractive synthesis. There's a sawtooth wave, routed through a LPF. The Cutoff of that filter is modulated by an LFO. And the wave morphs between a saw and a sine.
Flip round the back, and you will see a, marked, attenuvertor control in the left column. Turn it up, and go West. Dual oscillators are a, very, West Coast thing. Though I'm only using one of them. And It's a, pretty efficient, way to achieve, much, the same result. There's a wave morphing between saw and sine. But. It's, just a sine wave. The West Coast approach. Muck the Waveform up before it gets out of the oscillator.

Wavefolding is another West Coast thing. I like wavefolding. It can be really 'Simple'. Just mix a signal with a flat voltage, and saturate it. Here's some PWM. But, it's, just a sine wave. There's a couple of, cheap and cheerful, things with that.

I'm losing count of how many ways there are to create PWM with this machine. One, good, way is to use a Pulse Generator. And saturation is, just, part of the story. And not, necessarily, necessary.

So, with 'Wavefolding 2', I'm using two oscillators, The Pulse Generator is the 'clock'. It sets the fundamental frequency. The Waveform Generator is 'synced' to the PG. If you play it, you'll hear another sine wave. Maybe, you won't.

The main thing here. If you synchronise and modulate the phase (FM) of a waveform with a pulse wave, interesting things happen. If you modulate the width of that pulse, things get, pretty, wild.

Usually, I'd mark the parameters that are worth playing with. That would be, near as damn it, everything, here. Front and back. Just, leave the negative feeds, into the attenuvertors, alone. Everything has a knock on effect with everything else, and there are, too, many variables for me to list them all. So I won't. Just, a few things.

Drop the tuning of the WG by an octave. Ooh. It's folded in on itself. That is full wave rectification. Flip round the back. There's a mixer in row 2. It mixes the output with a DC bias. Input 1 is straight negative. Input 2 is either positive, or negative, depending on the bottom, left 2>1 mixer, modulated by the LFO (the sub oscillator). Bring up Input 1 a bit. That will centralise things, and the scope will become clearer. It's a bit sparky. If you turn down FM depth, the sparks will go away. Turn it up, full, and take that negative bias out. Sparky triangle. This FM depth control is, very, important. As is pulse width. Modulated, or not. Time for PWM. Get some of that in there.

The two mixers in row 3. Attenuvertors. A1 and A2. A1, input 1 is a, manual, saturation depth control. input 2, same thing, modulated by the LFO. Bring up input 2.
A2 controls LFO frequency. Input 1, manual control. Give that a go. Input 2, LFO modulates it's own frequency. Yes they can.
Output B of the pan module provides a DC output from the LFO. Output A provides an inverted version. I can't wire up every option, here. Swap those outputs around. Or use the outputs of the other oscillators as modulation sources instead. Or velocity. Change things round a bit.

So. Pulse width, FM, bias, ratio. Modulate the lot. This thing could do with another LFO.

Happy folding.

Though, what this has to do with Blackpool and Hull is anybody's guess.

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Rej - Dev
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Joined: 12/18/2011 - 15:52
Paulovski (and others). It

Paulovski (and others). It seems from quite a few threads that you're getting deep into the modular, which is really cool. Can you keep a list of components you'd like to have that would allow you to do things you can't right now. They may be really simple things like DC offset or more complicated things like KS units or West Coast sequencers and other random generators.

But if you could keep a list in say a Google docs page with a clear definition of inputs, outputs and what it does, that would help me. I'd like to push the modular a lot further in the future and I think there will need to be a lot more components (and slots) to allow this.

SToons Music
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Joined: 03/01/2018 - 02:48
I'm split between being

I'm split between being impressed with your output and concern over why, lol. #9, 10 and 12 of More Folding are so cool (again my bias is exposed)

Edit: removed my non-thread related comments. Sorry, wasn't being considerate.

carl-alex
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Joined: 11/08/2012 - 05:30
I would find the following

I would find the following things helpful for the modular synth:

1. Something "like a parametric eq" to change voltages. At least it should offer a front knob for cut/boost and two inputs/outputs for different (or stereo)signal processing. Other things as voltage shifts or inversions may follow.

2. The VCO of the subsynth / bassline 3.2 could be offered as a modular component.

3. The "Send notes" function of the sound input module could get a note filter. The notes sent to the other machine should be restrictable to a key range and a velocity range. Some other functions (maybe usable for automation) for transpose or velocity offset could follow. This is no real request for modular sound design but for live play and orchestration of different instruments.

 

paulovski
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Joined: 09/19/2012 - 06:13
@Rej. Yeah, for sure. Once

@Rej. Yeah, for sure. Once the dust has settled :)

It would be a pleasure. It might help if I had, just, a little bit more of an idea about your plans. What you do might make something, I'd suggest, irrelevant. If you see what I mean. Can I email you about it?

@Causticians. Brainstorming is good, of course. But, let's keep this machine elegant.

And my thread. This is'nt going turn into a frenzy, is it?  :)

On it.

Rej - Dev
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yeah sorry, I didn't mean to

yeah sorry, I didn't mean to derail your thread. And I certainly don't want this to turn into a general feature request thread. I'll email you about specifics. This is long term.

paulovski
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Tuesday's good with me.

Tuesday's good with me.

SToons Music
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https://nerdaudio.com/blogs
paulovski
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Ooh. That is fierce. And for

Ooh. That is fierce. And for the most part, just a sine wave.

SToons Music
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Have to admit I'm getting

Have to admit I'm getting really intrigued. Check out 2:55. Hmm. Looks familiar lol. Nice job. Maybe 'long term' we'll see a Foldback component.

15:22 - 16:00 .....oohhhhhh.

https://youtu.be/mvE18alrN5E

SToons Music
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Reviving a thread.

Reviving a thread.

At the time when paulovski originally posted this thread I was not very knowledgeable about modular synthesis - I'm still not but have learned quite a bit, relatively, the past few weeks.

So I was watching a video on wavefolding earlier tonight and remembered this thread. I dig it up and looked at it again. Looking at the circuit I noticed several things that didn't add up so I'll address the first few that caught my eye.

In theory, because of the shape of a square wave, if it were truly folded on itself at would eventually cancel itself out, or at least in my mind it should. Then when looking at the mixer with the marked attenuator I realized that on one side of the crossfader was a sine and on the other a square (due to the saturation).

Plus I couldn't understand how this circuit would actually fold anything, it was simply mixing waveforms.

The main thing though was the timbre and the fact that the folding didn't really look (or sound) like the examples I was seeing on YouTube.

So I experimented. I realized that sending a waveform thru the mixer and modulating it with negative polarity, or vice versa, inverts the waveform. At first this is not obvious because a scope with trigger on does not accurately seem to reflect an inverted sine, triangle or square wave, probably because of their symmetry. It does however become obvious with a saw wave.

If you look at Inversion you can see the top 2 scopes look identical, you cannot visually see that the second is actually inverted. However the true test is what happens when they are mixed- as you can see in the third scope, when the two waveforms are combined they cancel each other out. You can adjust the marked mixer knob and see what happens when the negative polarity is removed.

Inverse 2 clearly shows that the two saw waves are indeed inverse.

Wavemix shows what happens when you mix an inverted sine with a square - it sort of looks like a folded wave but in my mind isn't. The peak of the inverted sine is just pushing the middle of the square down. Or so it would seem.

Then it dawned on me that the Distortion effect has a "Foldback" mode and I wondered if it might have some sort wavefolding type of results. Turns out it sure does - it is literally a textbook wavefolder, or seems that way to me.

If you play the song while watching the Folded scope you can clearly hear and see wavefolding. For measures 16 - 24 I jacked up the output of the Folder 2 wave and Distortion input (it's automated in the sequencer) to get maximum wavefolding, more as an illustration than anything else.

In the final example I wavefolder a Pulse wave; it's a little extreme for the sake of demonstration purposes, not really intended to be musical.

Anyways as a relative novice to modular synthesis I appreciate any and all feedback. Especially if I'm making a fool of myself and making too many assumptions.

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SToons Music
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Part 1/2

Part 1/2

I'm really hoping paulovski shows up, I can't thank him enough (and UncleAfx, Nitro etc. apologies to others I'm forgetting) for his/their contributions here and know they could offer some great ideas to help mine this (as paulovski would say) pretty rich vein.

I saw a vid on wavefolding LFOs. The details weren't particulary relevant for several reasons but the concept seemed cool so off I went to start playing around.

There are so many details I just don't have time to get in to but I'll try to address the most relevant. Sure enough, the wavefolding mangled the LFO... in a beautiful way.

LFO Fold is simply an LFO thru a mixer. Long story short but, like most distortion, how strong the input is affects the amount of distortion available.

In the FX section the LFO signal goes thru some saturation (Batman - but that's also a story for another day) and is then the folded.

Wavegens: there are three wavegens, one tuned to 5th. Throughout the song there are no note changes, in fact the Note CVs aren't even connected. However if you flip the modular you can see how many of the folded LFOs imprints are there - the folded LFO signal is affecting filter cutoffs (I incorporated a sample and hold to tighten things up a bit), pulse widths and modulation.

lndycat is some Indian percussion that comes with Caustic. So I mangled it with some folding then shoved it into FiltrdPerc where the cutoff is modulated by the folded LFO.

SToons Music
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Part 2/2

Part 2/2

There are two scope setups to watch as you play the "song". The first allows you to visually see how the ebb and flow of the LFO is affecting all the elements you can hear. If you watch it as it loops a few times everything you hear and see starts to gel.

The second scope setup is really the key here - the top scope shows you exactly what the LFO is really doing, the bottom shows you how wonderfully mangled it becomes after waveshaping.

Incidentally there are no note changes at all. What sound like notes are filter cutoff points naturally chosen by the folded LFO and liberal use of resonance to punch out different harmonics from the fundamental.

Anyways, here is the file.

Hope some of you are enjoying this, as always it would be nice to get some feedback in this sadly diminished forum.

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SToons Music
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The Batman

The Batman

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SToons Music
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The Batcave

Timelapse footage of Batman working while the bats fly around. Enjoy!

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paulovski
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Joined: 09/19/2012 - 06:13
Cool sounds.

Cool sounds.

Your classic wavefolders, which fold multiple times, use a comparator for each fold. Full credit to Nitro 27, for an observation made, right at the top of this, very, thread, that lead to him smashing it, with one of them, here

https://singlecellsoftware.com/node/19364

One, of a myriad, applications. And, maybe, a, better place to figure out what they do. Comparators are a topic in their, own, right, and I'm not going into any detail, here. Think thermostat. And, they take up a lot of real estate. The one, here, is cut down, a bit, and it's taking up four units of rack space.
And, one of the comparator control inputs needs to be a full wave rectified version of the input waveform. So, it's not the, most, straight, forward procedure, but, there's, just about, room to generate one fold from one machine, with some, meaningful, modulation.

I'm aware of a couple of ways to get the rectification bit dealt with. A and B. Same unit count for both. The, marked, attenuvertor control, next to the scope, is the folder. The other, marked, mixer input is a low level bias you can muck about with.

A. requires the input to be synchronised to a square wave. For this one to work, properly, the duty cycle should be 50%, and the two oscillators should be in tune and phase with each other. So, plenty of options to break it.

B. No sync required, which brings phase modulation, and input modules to the party. Though, IMHO, these things tend to work, better, with, simpler, waveforms.

There's a scope there. Feel free to back engineer.

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lord_bondslave
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Joined: 08/30/2013 - 13:35
I totally missed this thread

I totally missed this thread before.  ... glad it has been revived.  I just wish I had time to wrap my head around it.  rl can suck.

80NS
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美しい。 これは便利です。

美しい。 これは便利です。

RHOMBUS ARE AWESOME!

SToons Music
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Back again for more

Back again for more punishment. Think I'm starting to get it (still a long way to go...). I know very little about electricity but I'm finally coming to terms with bipolar/unipolar, gates, triggers etc.

I did some experimenting tonight to try and wrap my brain around the folding before I get back into looking at your examples. For fun I included a file, nothing new to you, but you'll get where I'm at and others might benefit... if anyone cares to.

I'll write a more detailed explanation for others soon to explain the purpose of the first 2 mods.

So it's pretty basic - SubOsc into mixer, Mod Wheel in the other 2 inputs to give it extra juice. This is fed into the Saturator. I automated the two mixer knobs which give the SubOsc a positive bias then (on the Flip side) started adding the saturation. Some interesting things happen when the current passes a certain point, again I'll edit this later to explain better, but eventually everything is fully up and an audible buzz can be heard. The mixer output is then scaled back and despite the volumes all being very high the signal appears to sort of flatline. So now if I'm correct the wave is fully folded onto itself and cancellation occurs. There are several ways to replicate that as can be seen when the mixer output level is then raised again and on the Flipside the saturation level is reduced and the Waveform flatlines again.

Hopefully I'm on the right path here.

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on07
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Joined: 02/19/2021 - 16:57
It's nice to see some people

It's nice to see some people back.

I can really use this as a  a random Vis.

SMT

0. 北
1. 假发
2. 头盔
3. 吉祥物
4. 身份不明
5. 毛茸茸的
6. 鲨鱼
7. 南
8. 西方
9. 东方