[sdiy] monolithic VCO chips for FM??

[Scott Stites]

Well, don't toss out those chips yet (and certainly don't build any weird
keyboards to accomodate strange VCO's!).  I don't know about the XR2207, but
the XR2206 is performing *amazingly* well on my breadboard.  This is, by the
way, something I would have come up with in, oh, say, a trillion years.
Well, maybe a trillion.  But, it comes from the manuscript of the
forthcoming Thomas Henry book that I'm lucky enough to have in my hot little
hands.

According to Thomas  the XR2206 is performing *better* than the 8038 - he's
gotten nine flat octaves out of it, but has gotten only seven out of the
8038.  I'm sorry I don't have the 'gnat's ass' measurement tools so I can
give you the nitty gritty on what I'm getting, but I'm getting pretty much
the same results with the XR2206 - it is absolutely, positively musically
useful!  Mebbe I can whip some samples out here when I get some time.

For the XR2206, Thomas says the key is to hearken back to the first
principles - in other words, wad up the data sheet, throw it away, and start
from scratch, with no preconceptions.    Well...save the pinout =-D).

For you engineers that love a challenge, try that route.  For non-engineer
type guys (like me) who have a steeep learning curve, his VCO Chip book will
be out pretty quick.   And it *is* a learning book - not just 'here's the
circuit, build it'.   He not only gives you the circuits, but also the
theory and calculations on how and why they work.

Cheers,
Scott



----- Original Message -----
From: "James Patchell" <patchell at cox.net>
To: <synthplayer88 at spymac.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, August 19, 2004 4:43 PM
Subject: Re: [sdiy] monolithic VCO chips for FM??


> It depends on what exactly you want to do with them.  Monolithic
oscilators
> that are availiable are the 8038, XR2206, XR2207...plus a few others.  If
> you want to use these as pitch sources for a synth, well, in my opinion,
> forget it.  Those parts have problems that cause them to me non-linear,
> some a quite bad.  If you are not concerned with pitch, any of those will
> work.  Otherwise, I would stick with a tried and true VCO like the TM
> (ASM-1) type....
>
> -Jim
>
> At 10:44 AM 8/19/2004 -0600, synthplayer88 at spymac.com wrote:
> >Hi guys,
> >Just wondering if there is an offshelf monolithic VCO chips available out
> >there?
> >It would really make the circuit much smaller and easier to make, am
thinking
> >about building a multi VCO circuit with patching points for some FM, may
> >be there
> >is a kit out there? :)
> >
> >Thanks again!
> >
> >You guys are an AWSOME bunch!!!!! :)
> >
> >Can't wait to do some patching and knob tweakin!!!! Well, I'll need to do
some
> >soldering first......
> >
> >
> >
> >---- Introducing Spymac MailPro: http://www.spymac.com/mailpro/
>
>          -Jim
> ***************************************************************
> http://www.oldcrows.net/~patchell
>
> ***************************************************************
>
>