[sdiy] monolithic VCO chips for FM??

[harrybissell]

synthplayer88 at spymac.com wrote:  <snip>

> I think all modular control keyboard should have a pot for each key to fine tune
> the control output voltage in order to nail the note frequency for precision, may
> be this is already available and I am just unaware of this? or may be in midi?
> ---- Introducing Spymac MailPro: http://www.spymac.com/mailpro/

I had such a system (PAiA 2720) which is admittedly a crude approach.... but you
would have
a more stable system with precision fixed resistors... or if you want to be really
sure... an
accurate DAC with a table of tuning offsets.

Temperature stability and no long term changes with age and vibration would make the
trimpots a tough choice. Calibration of such a system could be a nightmare.

When I switched to 1% resistors... all my troubles disappeared.  Today with 1%
resistors
at $4/200... you could match yourself and get .1% easily.  Good enough !

H^) harry