VCO Control Voltages...

[List, Christopher]

	-----Original Message-----
	From:	Tadej Bozicko [SMTP:tadej.bozicko at uni-mb.si]
	Sent:	Saturday, June 27, 1998 2:26 AM
	To:	Synth DIY
	Subject:	VCO Control Voltages...

	Hi!
	 
	Initial work on my home built modular has just started. I've
tryed the VCO (well... only exp converter) on protoboard and it work
(finally as I almost threw all away). 

	Congrats!

	Anyway, my question is about the control voltage
standards/recommendations. I've decided, my VCO would track from 0 to 10
V over a ful range (10 octaves). As I saw in ASM VCO design and notes,
it states that ASM's control voltage ranges fro -15V to 15V. I am
wondering if ASM is scaled strictly musical or rather freelance... My
explanation is that only 0 to 10V on ASM are really musical (octaves:)
and other voltages just extend frequency range. Correct me as I am
probably wrong. I'd appreciate comments/hints from other users. 

	Hmmm, I'm a little confused with what you are seeking here. If
you say that the lowest usable tone should come with an input CV of 0v
and not -15v, then it's simply a question of an offset voltage. There's
no need to limit the range of input voltages that the circuit can accept
(at least not in the case of an ASM-1). My ASM-1 has a course tuning pot
that outputs a voltage from -15 to +15, though I never use it at the end
of it's range, it's nice to know that I could (the ASM-1 tracks well at
these extremes, but not perfectly). I usually have this course tune pot
set to about -2v or so,a dn my CV inputs go from 0 to +5v, because
that's what my midi->CV converter outputs...  

	My current idea is 0 to 10V CV range and -10V to 10V VCO output.
Comments?

	I think +10/-10v output is a little big - especially with a
+/-15v powersupply, not enough headroom for filters and stuff = more
clipping. Standard output is +5/-5v.

	- CList