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Thoughts about operator tuning

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SirPrimalform:
I noticed that some FM synths allow detuning in cents and Hz. I originally assumed that it was just to allow finer degrees of detuning, but now I understand more about synthesis and sound in general I realise the purpose

 Hz is of course a linear measurement whereas cents are a (very small) musical interval. So a detune in Hz is actually a different interval depending on what note you're playing. "How could that be useful!?" I hear you think. Well anyone who is familiar with detune by cents on a digital (therefore stable) synth may have noticed that the beat frequency is proportional to the note you're playing. A note an octave higher will beat twice as fast.

The beat frequency is the difference in Hz between the two oscillators, so the beating is changing frequency because when you play an octave higher you've doubled the frequency of both oscillators, so the difference between their frequencies has also doubled - doubling the rate of beating.

If you detune by a fixed number in Hz then you get the same beating rate on every note. This is particularly useful in FM where detune between modulators and carriers causes timbral changes and note just a 'chorusing' sound.

This isn't a feature request, just some thoughts.

I would propose it as a third "FTyp" parameter, maybe called KeHz or something. Freq would still be a ratio setting on this mode, but Ftun would be in Hz instead of cents. This would allow for sounds that have a cycling quality that is at a consistent rate across the keyboard. I think 2 decimal places (allowing for 0.01) is good as it allows incredibly slow phasing.

Đorđe Golubović:
That would be fun!

Or Hz based detune per timbre, for flanger-like effect when using same patch on different instrument slots.

I might actually try this, when I make me some more free time...

Computation-wise I suppose it wouldn't be to hard on cpu, just adding simple increment value (related to detune value) to phase increment :)
I haven't yet touched anything in preenfm2's UI code, so that might get a bit tricky there, I don't know...

SirPrimalform:

--- Quote from: jarilo on March 25, 2016, 04:09:28 PM ---That would be fun!

Or Hz based detune per timbre, for flanger-like effect when using same patch on different instrument slots.

I might actually try this, when I make me some more free time...

Computation-wise I suppose it wouldn't be to hard on cpu, just adding simple increment value (related to detune value) to phase increment :)
I haven't yet touched anything in preenfm2's UI code, so that might get a bit tricky there, I don't know...

--- End quote ---

Yeah, I can't imagine it's difficult computationally - it's just adding an offset to the phase increment at a later stage (cent detune is obviously before the 12th root conversion).

Prints:
Can someone PLEASE make this happen. This would be so incredibly useful.

SirPrimalform:
It probably wouldn't be too hard, but I wouldn't know where to begin in terms of setting up the build environment because I'm not really a programmer. But you can get a linear tuning offset by adding directly to the phase increment.

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