[sdiy] Paia Vocoder clarifier mod toggle?

[harrybissell]

One difference is in the process used... CMOS has a voltage limit of
18V, so usually you are limited in practice to +/- 7.5V supplies.
Other FET processes allow +/- 15V supplies.

Linearity of the switch as the signal voltage varies is another issue...
careful design and some 'dirty tricks' can compensate for a great deal
of the effects of this change.

The speed of switching, and whether the channels ever overlap
can be a problem. Sometimes the switches are half on - half off.
Not usually a problem, as almost everyone wants "break before
make" in a switch.

Charge Injection is another issue... some of the switching (logic)
voltage can be coupled into the signal path, causing pops or changes
in the voltage (especially important in sample and hold apps)

On Resistance and Off Resistance (isolation) is another issue... does
the switch go close enough to zero ohms to be considered fully 'on'
in your application, and does it go high enough in resistance to be
considered all the way 'off'

Hey kids, what did I forget here ???   ;^P

H^) harry

Stephen Begin wrote:

> What (in practice) is the difference between high quality analog switch ICs
> and cheap ones?
> -Steve
>
> ----- Original Message -----
> From: "Seb Francis" <seb at is-uk.com>
> To: "Stephen Begin" <trypannon at hotmail.com>
> Cc: "synth" <synth-diy at dropmix.xs4all.nl>
> Sent: Sunday, September 22, 2002 5:46 PM
> Subject: Re: [sdiy] Paia Vocoder clarifier mod toggle?
>
> > If you're not too worried about cost, you could try some high quality
> analog switch IC(s) to switch all of the bits in and out.  Not sure if cheap
> ones would be a good idea though ...
> >
> > Seb
> >
> >
> > Stephen Begin wrote:
> >
> > > Sorry for reviving a dead thread, but I'm the type who likes closure.
> > > Given that for some strange reason, me and Phil here seem to wish to
> embrace
> > > the not-so-great-but-ever-so-rad-sounding original vocoder circuit
> design,
> > > but would also like the option of using opamps and getting a cleaner
> sound,
> > > is there any practical way to mod it so that the clarifier mod is
> > > switchable?  Nobody really said before if it could or couldn't be done.
> :)
> > > Thanks!
> > > Steve B
> > >
> > > From: "p. hendricks" <ph at attbi.com>
> > >
> > > > I agree,, and would share the same concerns. I like mine the way it
> is,
> > > and
> > > > use it just for cross modulation, I think you may lose some of that
> sound
> > > > with the mod....??? can you just do the part of the mod that improves
> the
> > > > S/N ratio? I don't mind having the bands interact, I don't want mine
> to
> > > > sound like ...well... a vocoder. I think the bands blurring together
> may
> > > > give a less synthetic sound with cross mod??? just a hunch.
> > > >
> > > > Note: I say all this not having heard one with the mod done, just
> would
> > > hate
> > > > to lose the sound it has now.
> > > > best,
> > > > phil
> > > >
> > > >
> > > >
> > > > On 9/14/02 8:14 PM, "Stephen Begin" <trypannon at hotmail.com> wrote:
> > > >
> > > > > I don't really plan to do much in the way of speaking intelligible
> > > phrases
> > > > > through the vocoder, more like adding unusual characteristics to
> short
> > > synth
> > > > > sounds.  So sometimes a little muddiness is nice.
> > > >
> >