FM synthesis - How does it work?

[symplectiq]

Toucher? Like the one who touches everything?

[jee_pack]

toucher: french expression... it meant: well said

[symplectiq]

This one?

[Sotiris]

EXACTLY HOW DO YOU PREDICT OR UNDERSTAND THE OUTPUT RESULT OF FM SYNTHESIS?

FOR EXAMPLE:
IF I have a PULSE wave with variable width (the fm modulator) modulating a SQUARE WAVE (the carrier), and both oscilators are at the same pitch. How will the carrier wave be affected by the pulse width of the modulator wave...

The only way i can understand/predict what will happen is by breaking EACH waveform into its individual harmonics, do the (simple?) FM math on EACH individual harmonic combination (between carrier and modulator), and then ADD all the results together to create the final spectrum.

So, if a square wave consists of the 1st, 3rd, 5th, 7th etc. harmonics in "decaying" amplitudes, and this is modulating a sine wave with the same frequency (Freq.ratio=1), then EACH of these harmonics creates new harmonics on the output, and then all the results are summed together to create the final waveform. When you take into account the "varying" amplitudes of the modulators (over time) things get crazy, but, anyway, this is the way i understand it ...
Maybe its useful for someone out there, maybe not ....
Anyway, hope this helps...

[L-Day]

yah... this is that what makes fm character sounds... modulate the harmonics to the carrier... harmonics are fulli the same like carrier frequency but in different octaves... you can made disharmonics too... the result are realistic spectrum... so much have i understand...

[L-Day]

look... i have made a cheapy vst that creates fm sound cheap by one modulator and one carrier mixed with subtractive, a lfo(for vibrato effect) and a chorus effect. but the heart of it is FM ... the pur fm has a better effect you modulate the Phase of an Oscillator(signal)...

but if you have a pulse wav as MOD and a SINE as CARRIER you will get a SAW ! But the only realistic one is MODULATOR: SINE and CARRIER: ANY WAVE.... ?!

[DavenH]

toucher: french expression... it meant: well said

touché? From fencing.

[jee_pack]

This one?

you know what, I read that description and I realy can't say. Cuse I've never heard of fencing. But it sounds right: an acknowledgement of a hit... that's usualy what its used for...

[TotcProductions]

I hear ya Jee_Pack. It's a very confusing thing to grasp when you're trying to look at the whole picture without ignoring the details. FM Synthesis was NOT my forte for some time (lol, listen to the Pro-Sounds presets that ship with Octopus...not at all my 15 minuntes of fame ). However, I've gotten much better at it by simply ignoring the details and experimenting. Deconstructing other folks patches is helpful as well, but usually just leaves you asking "Why did they do that" instead of "How did they do that." If you're a "Why did they do that" type of person, like myself, my best suggestion is to experiment with it and teach yourself some of your own tricks. Have to start somewhere.

peace

[jee_pack]

I hear ya Jee_Pack. It's a very confusing thing to grasp when you're trying to look at the whole picture without ignoring the details. FM Synthesis was NOT my forte for some time (lol, listen to the Pro-Sounds presets that ship with Octopus...not at all my 15 minuntes of fame ). However, I've gotten much better at it by simply ignoring the details and experimenting. Deconstructing other folks patches is helpful as well, but usually just leaves you asking "Why did they do that" instead of "How did they do that." If you're a "Why did they do that" type of person, like myself, my best suggestion is to experiment with it and teach yourself some of your own tricks. Have to start somewhere.

peace

thanks, that's great advice, I'm a why did they do that person to... and I will take your advice