Vocal Filter

[patchell]

Scott Bernardi wrote:

>
> Some questions about your schematics:
> On sheet 4, the bottom opamp - shouldn't that have another input of Vin
> through a 100K?
>

    Yep, left it off.  The original for sheet 4 and sheet 6 were so full of
chicken scratches I had to redraw them.  Mistakes creep in (paper and pen have
a really bad signal to noise ratio.....).  There was a mistake on another
sheet, page 8, where a diode is backwards.

>
> If I understand the circuits correctly, the output of the formant CV's
> are not going to be smooth transitions but are going to have steps in
> them due to the diodes switching in.  What are they going to look like
> responding to say a 0 to -9v triangle LFO?
>

    Actually, the transitions will be "smooth".  The plots I drew on page 3
shows how the filter frequencies will vary with voltage.  While the changes in
direction are abrubt, there should be no sudden change (step) in frequency.  I
am in the process of building the filters right now.  Today is going to be
very busy, so, I am not sure how much I will be able to get done today.  But
you can believe me when I say as soon as I am passing signals through them, I
will post MP3's (I am such a showoff).  I have a long weekend, so chances are
pretty good I might be able to do that by Monday, plus the parts I ordered for
my synth project did not show up :-(, so I won't have any distractions.

>
> 'Scuse all the questions, but this circuit has me very interested.
>
> I guess the last question is., will this sound vocal enough without also
> adjusting the Q and gains of the formant peaks, or should I just do a
> vocoder (a major undertaking). I remember building  a variable slope
> filter from Electronotes in my original synth and being very
> disappointed with the results.
>

    Well, this one I can't answer.  As I aquire more information on vocal
synthesis, the eventual design may change.  Right now I am attempting to make
it as simple as posible.  Even so, it is getting quite big.  Those diode
function thingy's really eat up a lot of realestate.

>
> patchell wrote:
>
> >     Here are some sketches of what I have done so far.
> >
> > http://www.oldcrows.net/~patchell/vocalfilter/vocalfilter.html
> >
> >     Looks like that will be it until next week.  Didn't get as much work
> > in as I liked in the last 11 days, but mental health is important
> > also...
> >
> > --
> >  -Jim
> > ------------------------------------------------
> > * Visit:http://www.silcom.com/~patchell/
> > *-----------------------------------------------
> > *I'm sure glad Merry Christmas comes just once a year
> > * -Yogi Yorgensen
> > ------------------------------------------------
> >
> >
> >
> >
>
> --
> Scott Bernardi
> sbernardi at home.net

--
 -Jim
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* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*I'm sure glad Merry Christmas comes just once a year
* -Yogi Yorgensen
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