[sdiy] VCF caps in modern synths

[Roman Sowa]

I dare to disagree.

Ferroelectric materials of Class II like X7R are indeed being improved 
every day, but even the best kind of X7R is nowhere near the C0G. 
C0G/NP0 is Class I, which is completely different kind of material. Does 
not drift from aging, temperature, bias voltage, do not show microphonic 
effect and dielectric absorption, and all those things end up as 
distortion in audio path.

But for the same reason of being non-ferroelectric, Class I ceramics 
have thousands times smaller permittivity, so making big capacitance 
means huge dimensions. 1uF could be maximum available value in C0G with 
a price that might knock you out.

In short, with a bit of oversimplifying exageration one might say that 
C0G are THE capacitors, and X7R are merely piezoelectric transducers.

Roman

W dniu 2021-01-07 o 20:47, Mike Bryant pisze:
> Manufacture of polycarb capacitors stopped in the late 1990s so I really 
> doubt if anyone is using them now.  I assume it was an old document in 
> dire need of updating to modern capacitor technology.
> 
> In most applications you won’t see much difference between C0G and X7R 
> nowadays.  Obviously smaller values for things like filters are C0G/NP0 
> because of better tolerance but you’ll find large numbers of X7R in 
> commercial products as well.
> 
> *From:*Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of 
> *ColinMuirDorward
> *Sent:* 07 January 2021 20:20
> *To:* Vladimir Pantelic
> *Cc:* *SYNTH DIY
> *Subject:* Re: [sdiy] VCF caps in modern synths
> 
> Thanks for the chats on this.
> 
> Curious to hear that sh101/202 used ceramics. Sounds like this is quite 
> normal in the industry. I would hope that today we at minimum have a 
> predominance of C0G types since they don't cost much more than a cent each.
> 
> I was noticed in the ssi2140 docs that "Ceramic C0G/NP0, polystyrene, 
> some polyester and polycarbonate types are recommended".I was surprised 
> to not see polypropylene in the list and also have never heard of 
> polycarbonate types.
> 
> Colin
> 
> On Wed, Jan 6, 2021 at 2:06 AM Vladimir Pantelic <vladoman at gmail.com 
> <mailto:vladoman at gmail.com>> wrote:
> 
>     On 2021-01-06 08:56, ColinMuirDorward wrote:
> 
>      > In the world of hifi/mastering gear, attractive looking WIMA
>     packages,
>      > non-polar electrolytics, and the like, seem to add credibility to
>     a product.
>      > I don't see this trend perpetuate in the commercial-synth market,
>     despite
>      > VCF-fetishes. At
> 
>     Well, I have seen some suspiciously red and bulky capacitor packages in
>     Synthesis Technologies latest products, given they generate the
>     sound digitally
>     they are not VCF or S&H related... but then I don't think Synthech
>     needs to add
>     extra cred, no?
> 
> 
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