Feedback in FM synthesis

[Martin Czech]

1.AFAIK the feedback loops are completely user defined.
I have to look into the manual.

2. Please note that analog tri-oscs can do linear through zero FM.
An extra circuit has to be added for that.
But: Yamaha operators do PM, this sounds different.
We had this dicussion some time ago, it was concluded that using a 
differentiator before the FM input would theoretically give
PM, but it is of course not feasible.
I remember that I posted a proposal to use an unmodifyed
osc as index into a table (really a function network)
in order to produce tri waves, another control voltage (the PM input)
is added to that. This way the index will move arround in PM fashion.
The table has of course to contain a couple of tri cycles in 
order to get a reasonable output.

But: frequency accuracy is really important doing this kind
of modulation (be it FM or PM). It is very hard to have this
kind of accuracy with analog osc.


m.c.