FS-2 (was: Re: [sdiy] analogue DX-7-style Phase Modulation using quadraturesignals ?)

[jhaible]

Hi Magnus,

> This is where I chime in and start to question your statement. In essense
I
> think your saying "it's not reasnoble" here, and that is what I think is
wrong,

You're probably right. It wasn't my intention to disqualify any method
of making analogue PM - I just remembered a recent discussion on synthdiy
where my concluding impression was than no one had a really good solution.
Now I know Don, and you too, are working on it - so much the better!
I'm looking forward to see what comes out of it.

> So, when will we have an analog DX-7 clone? ;O)

This, and the entire PM matter is not in my own focus right now.
The whole idea came from my work on a new Frequency Shifter, and
unlike my fist one, where all is hard-wired, I want to make an open system
where you can patch everything to everything, and I want to find out
if that PM application would be worth to implement in form of a sin / cos
network for arbitrary CVs rather than quadrature VCO only.

BTW, I've finally found a reason to really have 2 Dome filters, with the
possibility
to have an external (non-quadrature) VCO replacing the internal QVCO!
The downside, which I often said, is that the second dome filter does not
allow
near-zero shifts. BUT an external (or internal, but non-quadrature), well
tracking
VCO + 2nd dome filter allows precise V/Oct control of the shift frequency,
und thus perfectly harmonic playing with altered spectra!

So instead of building a "super thru-zero-quadrature" VCO that also tracks
precisely, I rather use *two* VCOs, one for thru-zero and ultra-slow
modulation, and another one, with precise tracking, and a tracking VCF
for sine purity, for the harmonic stuff.
I might just use a MOTM VCO + 440VCF, the two dome filters and two
multipliers
to get precise, "harmonic" frequency shifting - and use a simple QVCO for
the
slow phaser-like stuff.

Sorry that the thread is going into a different direction for me - but this
is the
background why I was asking - to find another application of the thing
I'm just building, and keeping it "open" for such applications.

The other, actual PM thread, is very interesting as well. Yes, Sines run
thru
Wavefolders certainly have that "Bessel spectrum" sound of FM synthesizers.
I noticed this before, but I never thought that it could be actual PM that's
going on there. So that postprocessing - PM stuff that you, and Roman,
mentioned
is very interesting as well!

JH.