source file: m1419.txt
Date: Sun, 17 May 1998 17:01:04 -0500

Subject: Re: Microtuning Yamaha FM synths

From: "jloffink" <jloffink@pdq.net>

> From: Drew Skyfyre <steele@bom2.vsnl.net.in>
> I've been racking my brains and searching the net for a solution to my 
> quest for an accurate  real-time microtuning synth.I use software 
> synthesis to finally realise a composition,but for the initial  process 
> of  composing,I need a real-time  system. 
> 
> One possibility I thought of follows.I don't know if it will work as I 
> have never used a Yamaha FM synth,so I'm hoping someone can shed some 
> light.
> 
> -Since the carrier frequency can be specified in hertz (I hope it can, 
> along with floating point no.s,anyone here know ?)
> , it should be possible to tune one accurate note per MIDI 
> channel,thereby giving 16 notes on a 16-part synth like the SY/TG-77 & 
> SY-99.then depending on how fast these synths respond to program change 
> messages ( anyone here know how fast in ms ?) ,it could be possible to 
> obtain all neccessary pitches/notes.
> 

Carriers on Yamaha FM synths are specified in decimal ratios relative to
the tonic, 0.50 to 61.69 on a Yamaha DX7IIFD, for instance.  Since the
ratios only have 2 decimal points of resolution and the resolution worsens
as you go higher, you'll actually get worse frequency resolution using this
method instead of the built-in tuning tables (1024 steps per octave).

If you need better than 0.2 cent resolution your only current option is a
Kyma system or CSOUND.

John Loffink
jloffink@pdq.net