Triangular Simmetry

Hi guys, I have already proposed this topic a short time ago but formulated it badly. I received a lot of advice but, however good it was, they solved problems and created others for me. Now I give some more precise data to show you my goal more clearly:

  • I need to implement wave symmetry adjustment (not just pulse)
  • I need to do this using my VCV VCO at the base of this patch (no one else)
  • if you propose other oscillators it is important that they have all the functions of the VCV VCO

Do you have any requirements around aliasing? I.e. is it ok if a “solution” adds aliasing distortion? (Fundamental VCO is very clean, and free of aliasing).

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could you explain a bit more what you need all this for?
and what you want to do with the VCV VCO?
or maybe share the patch to get a better idea of your needs?

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No man I need a solution that doesn’t include alias addings. Infact FN-3 would be perfect if only there wasn’t the aliasing problem

Simply there isn’t a patch. I like how fundamental VCO works, but unfortunatly it doesn’t allow me to change sine and tri simmetry and I would like to be able to do this too, without changing the oscillator.

I potentially could use this function in every patch I made, actually I’m not trying to reallize a specific one

so, conclusion is:
you want a feature in VCO that is not implemented yet.
that means no way to have it now.

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I mean that I need a way to create a patch with other module to implement this function. An example is using FN-3. The problem is that FN-3 produces aliasing

It’s likely that any way that uses other modules will produce aliasing - there’s not that many modules that have anti-aliasing in VCV and the ones that do are mostly VCOs.

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Do you know a VCO that has all of the following functions?

  • v / oct
  • hard and soft sync selector
  • sin, tri, square
  • analog and digital waveshape selector
  • tri and sin symmetry
  • symmetry modulation
  • FM
  • PWM

Closest I can think of is dBiz TROSC - it has everything on your list except symmetry modulation between triangle and square (it has the symmetry but no CV control for it) but you can use Stoermelder uMap to do that.

Instruo Ts-L/Cs-L also worth a look (although they don’t have the A/D selector)

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Some waveshapers do, but afaik most general logic kind of modules won’t.

You can also get a sine out of Tidal Modulator with the integrated smoother and shape it. I haven’t measured it but I expect it to be antialiased very well, since it’s the original mutable instruments hardware code.

For other types of symmetry and much more there’s XFX Wave, which is completely free of aliasing.

I also wish there would be one oscillator that does everything, phase control and linear FM would be on my wishlist for VCV VCO… but in the end you usually also get a better sound if you use different VCO’s for different tasks, since they complement each other better with their subtle differences and you end up with a fuller mix of flavours.

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Hi guys I have a new task. I state that I have finally managed to get my x3 crossfade to work by putting two two-input crossfades in series. In this way I am finally able to achieve the smooth transition between ramp, triangular and saw, even if not literally changing the symmetry. I wanted to share the patch but unfortunately as a new user I can’t do it.

That said I’m still trying to get rid of the aliasing generated by the FN-3 so that I can really do something about the symmetry adjustment as such. Furthermore, that module is also convenient for the presence of the bipolar phase regulation.

I ask you a very simple thing at this point: do you know a way to flip the wave, in order to move the alias from the inside to the outside corner of each peak of the wave itself? I don’t need a simple reversal.

I wish I could delete the alias with a limiter, but to do this I need the alias to be outside the waveform

Pretty sure that’s not how aliasing works… that’s not what you are seeing on the scope and aliasing is not something you can ‘delete with a limiter’ (even if that little distortion at the top of the triangle was on the outside).

Aliasing is essentially the generation of inharmonic frequencies and therefore to see aliasing you need to be using a frequency analyser, not a scope.

Here’s probably everything and more you will ever need to know about aliasing:

Although if you do want a bit more, this video of Dan’s talks about the best way to visualise aliasing:

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Hi @marco.male.music , You have probably tried these approaches already, but this is how I would go about it. (Given that I’m limited to one oscilator).

If you just want to crossfade between SAW/TRI/RAMP, there are a few ways to do it, heres one:

But you can clearly hear the difference between SAW/RAMP and Triangle.

If you are not concerned with the waveshape, but want it to sound like a PWM triangle I will do this:

M2

That is clearly not a triangle at 50 percent pulse width, but sounds ok, and you end up with something which can be modulated.

I don’t know if this helps your dilemma at all, just thought I will throw in my 2 cents.

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Not quite. Can always show how to see it inside VCV with free VCV modules :wink: Demo/aliasing2.md at main · squinkylabs/Demo · GitHub

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Thank you so much for the attemp to help me, the first patch has been really useful to make easier the one I thought and the sound resulting is really smooth. The second patch unfortunately sound too much different from tri wave shapes so I won’t can use it for my goal.

But, referring to the first one, do you think that sound is really similar to the try pw modulation? If you say yes to me I will convince myself too continue using the x3crossfade and I will stop searching for a way to realize it working on the Simmetry.

Another question: do you know a polyphonic module that could change the phase of a wave in a bipolar way? I ask because it is another function I would like to have on my synth and doing it with delay doesn’t make me able to work with precision on a single wave cycle. (for this reason FN-3 was so freaking good if only there wasn’t the aliasing: it made me change tri pw and wave phase. I’m crying so f*cking much I swear)

To be honest, crossfading is not the same as PWM, but if you like the sound, use it. I think anything you do to try to modify a wave (at audio rates) will introduce artifacts, fading between them is cleaner, but has not got the same effect as PWM. The FN3, as with all function generators, works well at LFO rates but not at audio rates, so if you plan on using it to modify an envelope or LFO it will work perfectly. I consider @steve and @Squinky brilliant developers with a much deeper knowledge of DSP and audio than I could ever dream of, so you should really use their advice. But at the end of the day, if the aliasing is getting you down, just use a low pass filter to try to hide it. Good luck on your journey and please upload your synth once you are done with it, it sounds like it could be very interesting.

Man you just gave me a damn nice idea! Maybe I’m seriously freakin’ up but… I just tried using FN-3 with VCO brang to sub-audio rate and finally saw a wave shape absolutely alias-less. Please say to me that you know a method to bring back the wave frequency to higher values once it’s out from the FN-3. I know they’re very good. Unfortunately their solutions would make my patch too complex for what I need, but I learnt a lot thanks to them in these days. Once I will solve this problem I will upload the patch o’ my Synth setup, I Swear

Thanks, I appreciate the sentiment, but just for the record I have absolutely zero knoewledge about DSP :slight_smile: I’m more on the concept and design side. Squinky Labs on the other hand most certainly does.

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