[sdiy] monolithic VCO chips for FM??

[Scott Stites]

Oh, dang, just sent my last email and saw this.  This is quite true, and
something I hadn't thought of.  I'll have to give that a try (with two
XR2206's), for sure.

Cheers,
Scott


----- Original Message -----
From: <WeAreAs1 at aol.com>
To: <patchell at cox.net>; <synth-diy at dropmix.xs4all.nl>;
<scottnoanh at peoplepc.com>
Sent: Sunday, August 22, 2004 3:23 PM
Subject: Re: [sdiy] monolithic VCO chips for FM??


>
> In a message dated 8/22/04 8:44:41 AM, patchell at cox.net writes:
>
> << This I find very amazing...(i.e. BS)....If you look at the data sheet
for
> the XR2206, sweep linearity is only 8%....this is no where close to
> flat....the ASM-1 oscillator is somewhere around 0.01%.... >>
>
> The real-world test for VCO accuracy is:  Build two of them and see how
well
> they track when tuned exactly in unison.  One VCO that has poor linearity
will
> sound pretty much OK if you play it by itself - kind of like the way a
guitar
> string sounds OK even if the intonation up the neck is slightly off (or
the
> way a solo violinist usually sounds pretty much in tune, even when they
are
> not).  But two of those same VCO's tuned toegther... that will immediately
show
> your ears if and where any tuning/linearity problems exist.  Let's get two
of
> those XR2206 VCO's up on the bench and see how they perform, then we'll
really
> know how "amazing" they are (using Jim's definition of "amazing").  Or
better
> yet, let's get one of them and one well-calibrated ASM-1 VCO playing
together,
> and see how close they stay in tune over  multiple octaves.
>
> Michael Bacich