100% phase-driven oscillator?

I’m looking for an oscillator not with a phase offset, not a phase reset, but one whose frequency I can set to zero and drive with CV. Is there such a module in Rack?

I have: A lot of sawtooth waves

I want: A lot of other, different waves

Or (alternate question) if such a thing does not exist, what would be a good way to fake it using something else?

I would recommend the PhO module from docB.

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Oh nice! Looks like the docB manual also has a list of…

Other modules which can be phase driven

There are several modules which can be phase driven:

SPL (new, see below): generates spline waveforms from up to 16 points
GeneticTerrain (updated, now with phase input)
Geneticsuperterrain (updated, now with phase input)
SuperLFO (updated, if the frequency is set to the lowest value)
Valley's Terrorform: connect the phase to the FM input, set the attenuator to 0.5 and set "zero mode" on.

Mindmeld ShapeMaster runs at audio rate, you can drive the playhead with CV (unipolar or bipolar) and you can have absolutely any waveform you want (by drawing it in). Jakub Ciupinski has made some Oscillator presets for it which you will find in the Shape Presets > Community Shapes menu.

It will probably have aliasing though - more or less depending on the waveform. This may or may not bother you too much.

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Aliasing shouldn’t be much of an issue - I suppose I should mention I want this mostly for CV / low frequency oscillations. Thank you!

In that case ShapeMaster should be ideal - just put it in CV playhead mode, select uni or bipolar, select/draw your shape and send your phase signal into the channel’s T/G input.

Screenshot 2022-08-23 at 16.35.33

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Another perfect option is the Bogaudio VCO - it can give you 0Hz phase control over all 4 basic waveforms

Activate the LINEAR button and keep the frequency knob at 0V, which is 0Hz when in linear mode.

Set the FM toggle to LIN (linear) mode, which in reality is phase modulation, and put your phase CV into the FM input. Leave the V/OCT input unpatched.

You can send a trigger to the SYNC input with 0V FM input to establish a good phase starting point.

With the FM depth at 100%, it takes about 3.142 Volts to go from 0 to 360 degrees

If you set the FM toggle to EXP (exponential), then you actually get 1V/Oct linear true frequency modulation - kind of weird, but I guess it makes sense that the FM would be linear if the “V/Oct” input is also linear.

Either way, the Bogaudio VCO is a great module for exploring 0 Hz carrier wave FM

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Nice thank you!

I stared at this for a while before realizing 1V = 1 radian. That doesn’t make it more intuitive but at least I know what it is

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if you need an LFO you can use the LFOMultiphase too
0 → 10V => 0º → 360º

(output number 9)

(as a bonus you can sync to external clock by trig of by TAP)

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OMG - How did I miss pi ?!

I was puzzled as well by the “odd” scaling. Now it makes sense - thank you.

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So now that we understand the Bogaudio linear scaling, it is trivial to get perfect waveforms at the correct frequency, especially if you use the docB PHSR as the phase input.

Rack parameter entry understands pi. So simply bring up the Bogaudio VCO FM knob context menu and enter pi*10. Patch in the PHSR Phsr (saw) output, and the Bogaudio VCO will output any of its waveforms at the same frequency as PHSR.

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Valley Terrorform can also be used in this way; click the toggle labeled “Zero”. It also has a Phasor output.

https://valleyaudio.github.io/rack/terrorform/

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Here’s what I wound up doing with this - streaming now:

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Sounds great so far!

Can’t determine much at that zoom level, especially with the lights low.

Which VCO(s) did you use? Are all phase driven? or only some voices?

Is this fully auto-generative? or do you have a midi device adding some user control?

Will the patch be posted?

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The answers are…

  1. I’m using the docB PhO, driven by a saw LFO, and in turn driving another docB PhO. These produce triggers for the four voices in this patch.

  2. There’s no MIDI or performance input of any kind; this patch is 100% autonomous

  3. I could post this patch later today! You’d also need the .csv to load into 02NAGOL, which contains a scannable array of inputs to the Probably Not(e) Math Nerd, which create the just-intoned scales you hear in the chord progression of this patch, but I could probably find a way to share that too

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To be honest, I couldn’t quite wrap my head around what you were talking about here. Until I sat down and actually tried it out and, wow, a bunch of new possibilities. Thanks @DaveVenom , I’ve always had to use delay for phase relationships , bit this bogaudio VCO trick is great.

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I got excited about 0 Hz carrier wave FM after watching Jacub Ciupinski’s video about Through 0 Linear FM Reese Bass, and I went looking for other VCOs that could easily implement the technique. The Bogaudio VCO was the best alternative that I found.

The 0 Hz capability is buried in the documentation, and the power of the feature is barely hinted at.

I did a bunch of experimentation, and have a cool test bed comparing 4 different 0 Hz carrier wave VCOs with various waveforms and other settings. I’ve been meaning to post a video about it, but it is buried in the long backlog of interesting stuff I’ve been wanting to share.

I need to make 1 correction - when the VCO is in linear mode, the “EXP” FM is actually linear FM. The “LIN” FM is phase modulation.

The VCO is a bit odd in that you cannot do audio rate modulation through the V/Oct input (doesn’t matter if in normal mode, or linear mode). I’m not sure what the issue is.

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