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Old 31st March 2004, 06:48 AM   #1
Zombie is offline Zombie  Sweden
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Default Silver micas as coupling caps?

Hello!
What about 0,1uF silver micas as coupling caps in tube amps - instead of copper foil, beeswax, teflon and PIO?
Cheers,
Tom
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Old 31st March 2004, 08:15 AM   #2
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Yikes, those things must be enormous!

That's the only reason, besides cost. Which doesn't seem to deter the idi...erm, fanatics.

Tim
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Old 31st March 2004, 08:47 AM   #3
Zombie is offline Zombie  Sweden
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Hello!

I asked about the suitability for audio, especially in valve amps...

They aren't that big, 2" x 1 174" x 1/4", 0,3% tolerance, 350V and price is $16 for 10
cheers,
t
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Old 31st March 2004, 09:10 AM   #4
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Hi,

I expect the high frequency response will be better or even say "TOO much" with the silver mica capacitor as the coupling path.
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Old 31st March 2004, 09:16 AM   #5
dhaen is offline dhaen  Europe
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Default I'll take mine without the snake oil....

Since they come pretty close to being the "ideal capacitor", they should be fine
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Old 31st March 2004, 12:24 PM   #6
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Hi,

Quote:
Since they come pretty close to being the "ideal capacitor", they should be fine
Amen to that...
350VDC is likely to be a little low for some applications so be careful where you put them.

I'm curious to know what you think about the sound, never found them in .100F values.
Mostly use them in RIAA correction where they do an excellent job.

Cheers,
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Old 31st March 2004, 03:21 PM   #7
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Hi Frank,

Did you read this?
http://www.diyaudio.com/forums/showt...664#post262664
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Old 31st March 2004, 05:00 PM   #8
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Hi Peter,

Thanks.
Interesting thread...
To be perfectly honest, I had no idea whatsoever those small values even existed in Teflon.

Currently I use polysterenes or metalized polypropylenes for the simple reason that I don't easily find the silvered micas in the values and tolerances I need.

Metallic powder,he? Never noticed any of it, I swear.
Then again it's not that obvious when you use only a pair per channel burried in a correction network, I presume.

Next time I'll give the Teflons I fair shot.

Cheers,

P.S. I had no idea one could catch a handful of philosophers just by posting an excerpt of a book...

SLIPPERY SLOPES....
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Old 31st March 2004, 05:40 PM   #9
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Hi there,

Honestly speaking, I had got an all FET preamp using silver mica capacitor on the feedback channel. This silver mica capacitor is from RS components and have a tolerance of 0.5%

What I should say the sound will be a little bit metallic on the high frequency range. After that I changed the cap into a pp one. The outcome is more musical and natural.

I recommend the application for silver mica cap should be in precision instrument NOT audio.

Rgds,
Red
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Old 31st March 2004, 05:59 PM   #10
dhaen is offline dhaen  Europe
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Hi Red,

I think the circuit you describe was probably working well with the mica cap. By changing to a "non-ideal" (pp) cap, you were masking a problem that exists elsewhere.

That's my opinion....

Kanpei
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