[music-dsp] FM Synthesis

Didier Dambrin didid at skynet.be
Wed Sep 14 06:19:25 EDT 2011


I believe FM sounds got back in fashion at the time everyone had forgotten 
that shitty GM FM bank in Windows, when FM meant cheesy MIDI files.
..but the problem with FM is that no one can program presets, it's very 
unpredictable when you deal with more than 3 operators, and I'm not sure 
today's musicians wanna deal with such complexity anymore. Actually, if the 
story that "most DX7s never got their patches tweaked" is true, maybe no 
musician ever wanted to deal with such complexity.



> On 13/09/2011 21:06, Theo Verelst wrote:
>> Hi
>>
> ..
>> Remember that Frequency Modulation of only two operators already has
>> theoretically (without counting sampling artifacts!) a Bessel-function
>> guided spectrum which is in every case infinite, although at low
>> modulation indexes the higher components are still small. Also think
>> about the phase accuracy: single precision numbers are not good at
>> counting more samples than a few seconds for instance.
>>
>
> Not too much of a problem if you use table lookup, which is what I
> assume the DX 7 did. Phase errors are a problem in single precision if
> you compute and accumulate.
>
>
> ..
>> Oh, there are Open Source FM synths maybe worth looking at: a csound
>> "script" (or what that is called there)
>
>  Csound has the "foscil" two-operator self-contained opcode, and of
> course you can roll your own operator structures ad lib. Somewhere there
> is a full DX 7 emulation complete with patches (poss in the Csound book;
> not to hand right now).
>
> Have we now reached the point where FM sounds are back in fashion?
>
> Richard Dobson
> 


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