[sdiy] cem-3396 questions

[Jim Patchell]

Jim Patchell wrote:

> Atom 'Smasher' wrote:
>
> > does anyone know where i can find out more about the filter design of the
> > CEM-3396?
> >
> >         http://www.synthtech.com/cem/c3396pdf.pdf
> > the block-diagram on the data sheet just shows at as 4 amps in series,
> > controlled by a mystery module, and somehow decoupled by capacitors.
>
>     Not decoupling capacitors....these set the resonant frequency in
> combination with the tuning current.
>
> >
> >
> > how do the capacitors affect the sound?
>
>     By selecting the capacitor you will affect the overall tuning range.  If
> you make the capacitors larger, you will tune over lower frequencies.  Make
> it larger, it will tune over higher frequencies.
>

    Correction...that last line should read Make it smaller, it will tune over
higher frequencies....guess I was just thinking larger today :-)


>
>     As far as the sound quality, the capacitor type will have some affect,
> but probably very small, to the point where if you use ceramic vs
> polystyrene, you will probably not notice the difference.
>
> >
> >
> > what is the box [e^x] below it?
>
>     This is a voltage to exponential current converter.  This is what tunes
> the filter.
>
>     Hope this helps, a bit...
>
>     -Jim
>
>     Visit: http://www.silcom.com/~patchell