PreenFM > preenfm2 and preenfm3

Which parameters on DX7?

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frompuggle:
I'm reading Howard Massey's great book "The Complete DX7" to better learn FM. It's really great! But I'm confused on what some of the parameters are called on a DX7 versus a PreenFM2.

On the DX, he keeps talking about coarse freq (op freq on Preen, but it goes to 31 rather than 16?), but then he talks about operator amplitude which goes to 100 on the DX. There's IM, which seems to be modulator amp, which goes to 16 on the Preen. But then there's the envelope, which I think modulates this same parameter between 0 and 1, and I'm not really sure how these interact.

Massey says when you have a 1:1 freq ratio between carrier and modulator and 100 modulator amp (full IM?), you should get a saw wave, and 2:1 and 70 amp (about 10 IM?), you get a square wave. I've been able to get the square wave and something saw-like, and the pulse mod exercises he explains, but more when IM is closer to 6 and envelopes are static. He then describes detuning particular operators in particular algorithm configs as creating beating, phasing, wah-ing, and (if you use audio level fixed freq carrier) as phasing. I'm not sure I hear all the differences between these. I'm curious how much these differences are due to those between FM on the Preen and PM on the DX, or that I'm doing something wrong. 

Any help on translating between these two interfaces?

Btw, the Preen sounds AMAZING, such a cool synth, which is why I want to understand all this better. Thanks so much for a great synth!

Xavier:

Hi,

You cannot map the DX7 parameters to preenfm2 with precision.
Freq on the DX7 from 0 to 31 are internal integer values of the DX7.

With the preenfm2 i tried to make the values more relevant.
The freq is the ratio of the op freq / the note you play. Ex : freq is 2.0 : you play a A 440hz, the freq of the op will be 880 Hz.

The IM is only relevent to FM, the DX7 is phase modulation not real FM.
And the IM is what you'll read about if you read generic FM manual.

The DX7 preset import was hard to do and is limited because of that.

Reading DX7 manual is very interesting but it's not easy to map that to the preenfM2.

Xavier

frompuggle:
So the IM on the Preen roughly corresponds to something like modulator amp on the DX?

More importantly, how do IM and the operator envelopes for modulators interact on the Preen?

(and I must admit, I don't really know what he's talking about with the differences between phasing, chorusing/flanging, wahing, beating techniques).

Xavier:


--- Quote from: frompuggle on January 07, 2016, 11:54:48 AM ---So the IM on the Preen roughly corresponds to something like modulator amp on the DX?

--- End quote ---

Yes.
Except for the lower level of operator (the ones that produces the sound / carrier operators). Then you have volume and Pan on the preenFM.


--- Quote from: frompuggle on January 07, 2016, 11:54:48 AM ---More importantly, how do IM and the operator envelopes for modulators interact on the Preen?

--- End quote ---

Enveloppes are inside an operator.
IM is a multiplier between operators depending on the frequency of the operators. The spectral impact is so the same for all note you play.

Xavier

frompuggle:
I am still confused. On the DX, frequency ratio is timbre, modulator op amp level is brightness, and envelope simply modulates modulator op amp (brightness).   

The Preen seems to work really differently. If you set IM to 0 and mod envelope sustain to 1, you hear nothing from the modulator, so the envelope is not merely modulator amplitude with 0=nothing and 1=full modulator amplitude. But when you raise the IM it seems to change not only brightness (like on the DX) but also timbre, yet differently from that done by the freq ratio. 

So when you say that "the IM is a multiplier between operators depending on the frequency of the operators," what does it exactly multiply, and how does it do this in relation to the envelope?

Also it takes MANY turns of the encoder to go between 0-16 on the Preen, which makes me think it unusual that you'd use the higher values, and looking through the presets seems to confirm this. How to best think of what these values are doing?

Thanks!

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