[PD] help with oscillator modulation

[Carl]

hi Oliver,

i followed a hunch and patched up a version that has a full wave rectifier before the osc1 mod input. this sounds closer to the example. it sounds even nicer with soft clipping of the mod signal before scaling. oh, and this signal gets added to the pitch input of the osc like in your FM example. it doesn't sound perfect and i could be wrong about this method. it feels okay. 

i remember buzz around analog through-zero oscillators from when i eaves dropped in modular hardware forums. the thing that made them special was negative pitch modulation capability. because a more conventional oscillator would respond to all voltage input positively instead of reversing the phase when the mod signal went 'through zero.'

it might be fun to try clipping the mod signal at zero instead of doing full wave rectification. 

i think you should be able to just send a signal and its inverse [*~ -1] into both sides of the [max~ ] object to get the full wave rectification. 

and it could be interesting to add the mod signal to the note number before going into mtof~

the tricky part is getting it to sound pretty at low mod amounts. synths i've played that have osc mod do this well usually. maybe scale it to allow subtle mod depths at the beginning of the control. 



> On Sep 21, 2018, at 9:12 AM, oliver <oliver at klingt.org> wrote:
> 
> hi, dear list !
> 
> here's one for all synth wizards ...
> 
> in trying to understand sound synthesis a little better than i do,
> i'm attempting to clone a nice VST synth that i like a lot (POLYVOKS).
> 
> it's a fairly simple synth and i understand and can recreate most of
> it's features and functions, safe for the following:
> 
> POLYVOKS has 2 Oscillators. Osc 1 can be modulated by 2 different sources:
> 1.) a global LFO
> 2.) Oscillator 2
> 
> while point 1 is easy, i didn'zt succeed in finding out what's going on
> when OSC 1 is "modulated" by OSC 2. it doesn't sound like any of the classical
> modulation techniques (RM, FM, PM) but more like a combination/modification
> of the above that i'm not able to figure out. my guess is that the OSC2 get's
> itself "modulated" while it modulates OSC 1 (depending on the mod amount)
> 
> please, if anybody might want to have a look at the following example patch.
> it includes the things i tried so far and a 4 second sample of the original
> (= the modulation effect recorded from the VST synth).
> 
> http://klingt.org/fileservice/downloads/00693153753552230-mod_osc_210918.zip
> 
> my testing setup was this: the synth got a note (C1) and both Oscillators
> had the same waveform (sine) and octave offset. then i raised the modulation
> (OSC2 -> OSC1) from min to max, over a course of 4 seconds.
> 
> if anybody has an idea what's going on here, that would be a big help !
> 
> thanks a lot in advance
> 
> oliver
> 
> 
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