[sdiy] vco-vcf CV tracking

[harry bissell]

What filter are you using ?

Some filters are not designed to be accurate over
a wide range of CV... some work very well !

Temperature compensation of the filter expo converter
is almost always used / needed in designs that track
over a wide range.  If it is not compensated, its
probably not expected to track very well.

Trimming for 1V/oct is needed to get accuracy. If the
design does not include this, again... its probably
not expected to track well.

Our hearing is not super accurate for changes in tone
color (timbre) as it is for pitch. You can tolerate
a sloppy filter cutoff WAY more than an oscillator
that
is even a tiny bit out of tune !

H^) harry




--- Gavin Russom <elmystico at earthlink.net> wrote:
> Okay, 
> If I am using a patch where the same CV is
> controlling a VCO and the VCF
> that is filtering it, then I should get this result:
>  as the CV changes I
> would hear the pitch change but each pitch would be
> filtered in the same
> way, if filter cuttoff was selected to produce a
> hollow reedy sound then
> each pitch would have a hollow reedy sound, right?
> What shouldn't happen is that the changing pitch
> goes in and out of
> audibility because it is being filtered in different
> ways, right?
> Standard modular procedure is to use 100k input
> impedence, which was
> followed in this case, but when I use a sequencer to
> control my homebuilt
> VCO and VCF in this manner, they do not track
> properly.  What would need to
> be adjusted in this case?  Perhaps a trim pot for
> the 1V/oct inputs? 
> Temperature compensation?
> Glad to hear all ideas
> Thanks again
> Gavin
> 
> 


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