Re: [AH] Modular VCO spec questions/comments

From Drew Neumann
Sent Wed, Sep 10th 2008, 17:37

100 ma for the digital VCO isn't too much--though it would be too much 
for an analog VCO.  As for FM range--going to the extreme of the full 
audio spectrum would be nice but require the addition of a fine tune 
knob--FM patches sometimes need to be very finely tweaked.

On Sep 9, 2008, at 9:00 PM, Paul Schreiber wrote:

> I am designing 2 new Frac VCO modules (1 analog, 1 digital) and I 
> started looking at other folk's specs. Noticed that no one publishes 
> (that I can find) what the scaling of the Linear FM input is. 
> 500Hz/volt? 1000Hz/volt?
> Anyone have any ideas what would be a good spec?
> Second question: what would be an upper limit of +15V (-15V is pretty 
> small) DC current spec? Is 100ma "a whole lot" or no big deal? The 
> digital VCO uses 3.3V internally for the DSP (I have a little switcher 
> for it). I am also looking at "high end" TI/Burr-Brown op amps that 
> are supposed to be great sonically but suck current like no tomorrow. 
> I'm going to have several people listen to different op amps to see if 
> in this VCO instance, there is enough audible difference to justify 
> adding 20ma current drain to the +15V line.
> For example, the Blacet Hex Zone is a 150ma module, and their 2100 VCO 
> page lists nothing, "spec-wise" for power or the linear FM scaling. 
> Maybe someone can measure it?
> Paul S.