[sdiy] ASM-1 cap types

[harrybissell]

See the EDN design ideas (this week) for a circuit that may make you doubt
the multilayer cap (in low performance dielectrics like X7R or worse).  They are

using one for a varistor... and getting a 4:1 frequency change in a VCO....

hmmmm......

(they do make excellent decoupling caps)

H^) harry  (who does NOT use multilayer caps in audio coupling apps unless they
need to
be really, really tiny... or I don't care.  I 'might' even care in a fuzzbox
;^P  )

Theo wrote:

> I would probably use:
> 1) Normal  Elkos, tantalum only when specified.
> 2) IMO for (100n) decoupling caps multi-layer is the pick
> 3) Also ceramic multi-layer for everything from 470n to 1n
> 4) Ceramic disk/plate below 1n
> 5) Polyester/Mylar/MKT for critical stuff, like SH, timing cap in a VCO, VCF
> filtercaps(maybe).
> Think the ASM is not too critical, except for the VCO timing cap,
> multi-layer should work ok.
>
> Some pp vote against ceramics in the audio path.
> While there are applications (like high end mic pre-amps) where they do have
> a point,
> multi-layer works ok for many applications as is shown by almost all
> commercial available audio equipment.
> OTOH some pp won't be satisfied with the sound of a fuzz box unless all caps
> in the audio path are silver-mica.
>
> Theo
>
> From: <synth at charlielamm.com>
> To: Stephen Begin <trypannon at hotmail.com>
> Cc: synth <synth-diy at dropmix.xs4all.nl>
> Sent: Tuesday, March 25, 2003 3:38 AM
> Subject: Re: [sdiy] ASM-1 cap types
>
> > I used ceramics for the 18pF and 100pF on my ASM-1 VCO and it worked fine.
> >
> > I used mylar for the 2n2 on the VCO and it worked fine.
> >
> > Can't speak for the other caps (VCF, VCA etc) as I have not built these
> > circuits.
> >
> > On Mon, 24 Mar 2003, Stephen Begin wrote:
> >
> > > I did check the archive for this, but didn't find any answers
> > >
> > > I'm hoping to build an ASM-1 as my next project, and I'm having trouble
> > > figuring out what kind of caps to use.  I guess I don't have the
> experience
> > > to tell me what would be good choices, it mentions that polystyrene and
> > > polycarbonate caps are "good caps" and on the elby designs page where
> they
> > > sell the kit, they say
> > > "All capacitors less than 1nF are generally polystyrene*
> > > All capacitors between 1nF and 1uF are generally polyester*
> > > All capacitors greater than 1uF are generally tantalum* "
> > >
> > > I can't seem to find polystyrene caps smaller than 100pF on mouser,
> would
> > > ceramic be okay for the 18pF and 30pF caps?
> > >
> >