[sdiy] analogue phase modulation

[JH.]

>
>When I was doing the Modcan VCDO research I found that 314% mod index
>was enough (funny - that number looks familiar).

314% as in 3.14 periods, or as in 3.14 (= half of one period) ?

Ok, must be the latter, or there would be no significance in the Pi*100% 
number.

And indeed. I made some simulations with phase modulation of only +/- Pi, 
and
it gives a very rich spectrum already.

So ...
If we _only_ need sin / cos function fitting for [-Pi .. Pi], two 
multipliers and a well-tracking
QVCO (or an ordinary VCO plus a dome filter instead of QVCO), then building 
DX7-style
operators completely in the analogue domain will be very easy, and I wonder 
why we've
had so much trouble about it in the past.

Too good to be true? At the moment, I don't see any catch ...

JH.










Any more than that
didn't sound sufficiently different to be worth the reduced resolution
at the low end of the range. The number may seem a bit low compared to
the Chowning values quoted above but we get some pretty nice bells out
of that module.

Eric