EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: ELS122 on August 28, 2023, 06:45:02 am
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In a fender amplifier this capacitor usually was red in color, but few of them are cream colored.
It's 250pF; +-20% EIA spec Mica in an M4 shell, these are from 1959, maybe someone recognizes what company made it? :D
The last picture shows the usual red colored one, maybe it's the same brand just that a few of them were cream colored?
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In Oz, 1950s micas were usually brown.
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I remember "postage-stamp" micas from Arco Elmenco, usually red.
Catalog pages (black/white) from a 1960 Master catalog: https://hallmanlabs.com/wp-content/uploads/2020/01/ARCO_Electronics_Elemenco_capacitors_1960_REM_24-1.pdf
I have some "dip" micas labeled "EM" (which I assume are Elmenco) that are a cream color, as well as "CD" dip micas in the usual dark red that I assume are Cornell-Dubilier.
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My understanding is that conventional mica capacitors (not silver-mica) in the "postage-stamp" package were brown or cream colored, but silver-mica capacitors were pink or red. Silver-mica capacitors are more stable and more reliable than regular mica capacitors, but the difference at audio should be negligable. I've found both types sound good in audio applications. The brown epoxy "dipped" mica capacitors are always silver-mica, as far as I know.
- John
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"Postage-stamp" moulded micas were either "stacked mica" (alternate layers of metal foil and mica) or layers of metallized mica.
"Dipped" micas were always silver-mica, and were considered to be more stable than moulded micas.
It's not clear from the article below if there is a difference between "silver mica" and the metallized micas available in moulded.
https://worldradiohistory.com/hd2/IDX-Consumer/Archive-Consumer-Miscellaneous-ISX/IDX/Electronics-Digest-1983-Spring-OCR-Page-0020.pdf