Re: [AH] FM synthesis - SY22vector

From Nicholas D. Kent
Sent Mon, Jan 18th 1999, 18:19

> << Ps. As far as i know FM is not analogue synthesis, right? (it is digital 
>  then?) >>
> Not in any of the traditional "FM synths". FM is possible and common in
> analogue synths, but not to the degree of any of the Yamaha synths. 

(pretty much a FAQ)

an FM synth from Yamaha will be digital. 

In analog it must be remembered there are 2 kinds of FM. It just means
Frequency Modulation, so every unit that lets you modulate frequency
will have FM, but thats not really the feature people mean. If you FM
fast enough (an audio frequency) the sound color changes quite a bit.
The problem is in most analog units the timbre changes on every note, so
you will get a great sound on one frequency and something different and
probably unpleasant on everything else besides octaves. Unusable for a
melody, but okay for abstract sounds.

What unlocks analog FM is Linear FM capability (the above is exponential
FM, but nothing I know of calls it that as a label). This was built onto
some Curtis OSC chips so units using them will have that capability. The
Oberheim Xpander is one, Doepfer's apparently discontinued A-111 High
End Osc module is another. With Linear FM the tone color remains the
same at different frequencies and melodies are playable. A few units
also have Linear FM and no chips. The Fenix would be a recent one with
linear FM ability