Which "FM" synths really are FM?

[wagtunes]

One it is done (and it is very easy and very nice to learn, these two books are a huge pleasure to read!) it is far more easy to understand whether a synth that you have under your eyes applies one of these synthesis or not.

Do you read the source-code of all synths to see whether a FM or PM algorithm is applied?

There is no need to read the source code.

It is always possible to inject the output in your computer and to look at the signal in a software oscilloscope to immediately watch what happens when you manage your modulations. The results are totally different when modulating the frequency and when distorting the phase.

I also see that there is a huge confusion (that I do myself still sometimes) between Phase Modulation and Phase Distortion. I's not the same thing. The book I mentioned above about the Phase Distortion is excellent to make the difference.

Madness at the most insane level. As a musician, all of this is almost laughable.

Scenario: Musician in music store talking with salesman.

Musician: I'm looking for an FM synth because I want to make those bell sounds like with the DX7.

Salesman: Well, here's an FM synth.

Musician: Can we please run it through an oscilloscope so I can see how the modulation looks when I turn the knobs?

Salesman: What for?

Musician: Because I want to see if it's really FM or just PM.

Salesman: (Plays Synth) Is this the sound you're looking for?

Musician: Hell yeah, that sounds exactly what I'm looking for.

Salesman: Then what does it matter?

End of Scenario:

Sorry. It's just hard for me to comprehend how any of this matters in the grand scheme of things when making sound.

So the DX7 was NOT an FM synth?

Amazing how the "lie" was the most significant sound breakthrough in synth history.

Yeah, this whole discussion just boggles my mind.

[BlackWinny]

I also see that there is a huge confusion (that I do myself still sometimes in their terms, not in their principles) between Phase Modulation and Phase Distortion. I's not the same thing. The book I mentioned above about the Phase Distortion is excellent to make the difference.

If you want to know EXACTLY what is the PM synthesis, there are no better ways than to read the book written by Andrew Schlesinger for the CASIO PM sound designers (Casio who created this synthesis):

• Schlesinger - An Insider's Guide to Casio CZ Synthesizers

Now what? A book about phase distortion to explain exactly what phase modulation is?

You react quicker than my speed to correct my texts.

[Tricky-Loops]

It is always possible to inject the output in your computer and to look at the signal in a software oscilloscope to immediately watch what happens when you manage your modulations. The results are totally different when modulating the frequency and when distorting the phase.

Examples? I seriously doubt that you're seeing in your oscilloscope whether a synth uses FM or PM...and for hearing the differences between FM and PD, ears are all you need...

If you claim to know everything better than the other people here, you have to prove that...

[BlackWinny]

Anyway, as long as these two books have not been read, all what is said is pure imagination on what are these synthesis.

As long as one has not read these two f**king books, the real and exact principles of these two synthesis are not known! And to discuss on only assumed principles instead of on the real exact principles is totally useless.

Who can better define the FM synthesis than the one who created it? The book "FM Theory and applications" has been written by the one who created this synthesis: Chowning! All the other sources are only second sources!

[Timman]

Does it really matter? For what I read about FM/PM they are sonically the same, but I'm happy to read and listen to examples if anyone wishes to enlighten me

[BlackWinny]

It is always possible to inject the output in your computer and to look at the signal in a software oscilloscope to immediately watch what happens when you manage your modulations. The results are totally different when modulating the frequency and when distorting the phase.

Examples? I seriously doubt that you're seeing in your oscilloscope whether a synth uses FM or PM...and for hearing the differences between FM and PD, ears are all you need...

If you claim to know everything better than the other people here, you have to prove that...

I don't say that, Tricky.
What I say is that it is not by their ears that the engineers study the waveforms and their modulations, it is by oscilloscopes! The ears are important AFTER, when comes the step of the MUSIC!

And I also say that noone better than the creator of a synthesis (or the engineer who works on this synthesis) can give the EXACT definition of that synthesis.

What I say is that if you want to exactly know what are these synthesis there is no better way than to read the books made by these engineers!

Is it illogical?!?

Incredible!

[Tricky-Loops]

Anyway, as long as these two books have not been read, all what is said is pure imagination on what are these synthesis.

As long as one has not read these two f**king books, the real and exact principles of these two synthesis are not known! And to discuss on only assumed principles instead of on the real exact principles is totally useless.

Who can better define the FM synthesis than the one who created it? The book "FM Theory and applications" has been written by the one who created this synthesis: Chowning! All the other sources are only second sources!

You don't need to read books by Nicolaus August Otto to learn about the Otto engine...

And to drive a car, you need a driver's license, not the original books about the Otto engine...

I hope you did read all the original books by Darwin if you're a scientist...

[Chris-S]

It's getting funny...

[Tricky-Loops]

What I say is that it is not by their ears that the engineers study the waveforms and their modulations, it is by oscilloscopes!

I said I seriously doubt that you could detect with an oscilloscope whether a synth uses PM or FM...

[Angus_FX]

You can't have negative frequency. You can have negative phase.

Yes you can. Frequency is change in phase over time, which can be negative. What you can't have is *pitch* below 0Hz (because pitch is log of a fundamental frequency).

Try it in Poly-Ana. When FM modulated, Poly-Ana's oscillators are designed to give the same musical pitch range positive and negative
around the center frequency the oscillator is set at.

Yes, that's because you're modulating pitch (in semitones) not frequency (in Hz, or expressed as a linear multiple of the root frequency).

This is the obvious setting for balanced vibrato and trill effects. The pitch goes down just as many semitones as it goes up. But you can't ever go negative, you just keep finding lower and lower octaves -- right? So when you apply this, even a little bit (where we don't approach 0 or negative frequency at all) the oscillator seems to go out of tune, at least when modulated at an audio rate. Perhaps there's another way of scaling the frequency modulation so this doesn't happen, but then the FM would be less useful for typical LFO applications (vibratos and trills).

Indeed there is. Linear scaling as described above. It's better for "FM" sounds, but not as good for LFO applications. So in the case of Cypher, the audio rate FM input is linear frequency scaling, the control rate LFO input is pitch scaling. Does it sound different to Phase Modulation? Arguably not by much, but I can't see how you would do PM on a pure VCO-style oscillator - it's almost a contradiction in terms.

[wagtunes]

Well, it's official. This is the most pointless thread at KVR. And that's saying a lot with that CA fiasco going on for over 275 pages now.

Really, who cares?

[Syntilla]

As I remember (badly, normally) Yamaha used to call AM RingMod on some of their synths.
Can't wait till the OP reaches the Ring Modulation module of his course!

[Phorous]

Well, it's official. This is the most pointless thread at KVR. And that's saying a lot with that CA fiasco going on for over 275 pages now.

Really, who cares?

I think people do care what makes up the various types of synthesis behind the scenes. Clearly the OP did. I find it very interesting as well. You can just stop reading the thread if you think it is pointless

[Ingonator]

Listing all available FM synths is really not helpful for this discussion, also as most of them are doing phase modulation (PM) instead of real frequency modulation (FM). This is rue for all synths that are emulation of the Yamaha FM synths, including NI FM8.

As alraedy mentioned FM and PM could sound the same (e.g. with a Sine wave) but depending on the waveform used they could also sound very different.

Best way to check this is Tone2 Nemesis with the NeoFM moes (= real FM) and PM modes (= phase modulation) using a complex waveform.

In Nemeis using the NeoFM modes you could use ANY waveform properly. Nemesis already included a bunch of waveforms but you could import you own single cycles or ouse the additive like waveform editor (16 partials).

[Gone soft]

In my experience in some select cases the difference does certainly matter, one of the most prominent perhaps being self feedback. Self feedback with phase modulation gives an increasingly chaotic waveform the higher the value. This happens because phase modulation leaves the frequency intact and crazy shit happens when the waveform modulates its own phase. The result can be useful for percussive sounds and adding a "breathy" quality to sounds. Self feedback with frequency modulation simply stretches and compresses the waveform in a consistent manner for each cycle.