Hi Florian,

Maybe I don't understand the issue, but seems to me this should FM correctly. The sine
converter *always* maintains an exact phase lock with the tri core. So however the core is
modulated the correct sine phase is produced. Do you have a specific example where this
wouldn't work for FM

Looking at a the Synclavier FM oscillator design, looks like they too used a triangle-to-
sine converter but in the digital domain. The phase index is a ramp generator (triangle)
that feeds a triangle-to-sine wave lookup table to generate the final sine shape. They
called it "phase modulation" so Yamaha won't sue them, but sounds like pretty good FM to
me.

--- In Doepfer_a100@yahoogroups.com , Florian Anwander <fanwander@...> wrote:
>
> Hi Laryn
>
>
> > Actually the high-quality sine circuit is *quite* common. According to my schematic
> > library, most vintage oscillators used this standard design. For example, my Aries
VCOs
> > produce a pretty good purity sine using this:
> >
> > http://www.leinermedia.net/aries/AriesSchematics/AR-317s.gif
> Sorry, these are converters, but no sine oscillators. it is a sine-like
> waveform, but not a sine. Every frequency modulation affects the core
> oscillator, not the sine. So the result will be what the waveform
> converter makes out of the fm'ed core waveform, but will not be a fm'ed
> sine.
>
> Florian
>