Film Caps in Tube Amps

Structo

Member
2010-12-16 12:45 am
Oregon
A guy I know referred me to Sonic Craft for high end caps and resistors.

In particular the Sonicap Gen 1 & Gen 2 caps.

They also make one called the Platinum, which I think are Teflon because they cost $25 on up to $400 each....

Some of the brands at Sonic Craft don't seem to have an actual manufacturer, so I wonder if they are made for SC?
And they don't mention what type of dielectric in the caps, like polyester, polypropylene, Teflon, etc.

But for roughly $4 each the Gen 1 & Gen 2 are reasonably priced.

Anyway, just curious if anybody here have used the Gen 1 or Gen 2 caps?

Thanks, Tom
 
can't comment on the brand name, but I have seen a lot of my gear with film caps and even electrolytic caps bypassed with film caps. Point of interest, is that some P-P tube designs use the polarity of electrolytic caps as part of the phase inverting circuts, I have such an amp. I was curitous why this cap was the only remaining electrolytic, all the rest were metal film and the power supply caps by passed with metal film. Well it turns out you can't use a film cap in a circut that uses the polarity of an electrolytic cap for phase inversion.....film caps have no polarity. You can't even by pass this cap with a film cap.
 
Tom, I've been playing with caps since the introduction of Wondercaps in about 1980 (?). Sonic Craft's caps are designed by Sonic Craft's 'public' partner Jeffrey Glowacki, and they're made by various cap manufacturers in the US.

The Gen-1 and -2 caps are metalized 'propylenes; read the headers on each's pages to learn something of their different characters. The Platinums use an alloy of Teflon for film and are among the few VERY BEST caps money can buy.

All 3 are GREAT buys for their quality levels, and Glowacki can be trusted to give good advice.

I have lots of SoniCaps in my equipment.
 
Point of interest, is that some P-P tube designs use the polarity of electrolytic caps as part of the phase inverting circuts, I have such an amp. I was curitous why this cap was the only remaining electrolytic, all the rest were metal film and the power supply caps by passed with metal film. Well it turns out you can't use a film cap in a circut that uses the polarity of an electrolytic cap for phase inversion.....film caps have no polarity. You can't even by pass this cap with a film cap.

Could you explain this further and give an example? It makes no sense to me.
 

kevinkr

Administrator
Paid Member
Could you explain this further and give an example? It makes no sense to me.

I'm equally puzzled... A schematic of the circuit in question would be most useful, there almost has to be a misunderstanding of how the circuit works. Caps of any type generally have no significant phase shift within the intended passband. First order networks are typically 45 degrees at -3dB and second order 90 degrees at -6dB.. (IIRC of course..)
 
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quikie22

Member
2009-09-24 1:53 pm
can't comment on the brand name, but I have seen a lot of my gear with film caps and even electrolytic caps bypassed with film caps. Point of interest, is that some P-P tube designs use the polarity of electrolytic caps as part of the phase inverting circuts, I have such an amp. I was curitous why this cap was the only remaining electrolytic, all the rest were metal film and the power supply caps by passed with metal film. Well it turns out you can't use a film cap in a circut that uses the polarity of an electrolytic cap for phase inversion.....film caps have no polarity. You can't even by pass this cap with a film cap.

huh???