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Posted by mjk (P) on June 20, 2008 at 11:28:14

In Reply to: RE: Polypropylene vs. polystyrene for a Dynaco posted by Paully on June 20, 2008 at 07:17:01

I'm evaluating caps in that value range for a line level crossover. I'm looking at the following types:
------------------------------
Silver Mica
example = CDE CD15
tolerance = 5%
DF = <0.1%
WV = 200-500VDC
tc = 50ppm/C

Polystyrene
example = Xicon 23P
tolerance = 5%
DF = <0.1%
WV = 50-500VDC
tc = -150ppm/C

Ceramic NPO/C0G
example = kemet C410
tolerance = 5%
DF = <0.15%
WV = 100VDC-500VDC+
tc = +30ppm/C

Polypropylene
example = Wima FKP
tolerance = 1%-5%
DF = <0.1%
WV = 100-400+VDC
tc = -200ppm/C

------------------------
All of the above types are popular in filter and EQ circuits.

First, what is the negative with silver mica? It looks like a good option but maybe I'm missing some important characteristics?

It looks like Polystyrene would be a really good substitute for the Wima
(I assume you refer to the type FKP2) in terms of temperature characteristic, low dissipation factor, stability, etc.

For filters and crossovers I buy 100 caps and select so tolerance isn't much of an issue. Most 5% components are within 1% anyway.

I'm leaning toward Silver Mica or Polystyrene for the crossover FWIW.

Cheers,

Michael

Edits: 06/20/08

• RE: Polypropylene vs. polystyrene for a Dynaco - Paully 11:42:13 06/20/08 (0)

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