[sdiy] monolithic VCO chips for FM??

[WeAreAs1 at aol.com]

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