About Wima film capacitors

You can see the trend looking at Morgan Jones books, 3rd & 4th edition - for phono/RIAA preamp he used polystyrene for dc series coupling and now he shows MKP1840 in the same position.

I could not find polystyrene in any meaningful value above 2n2 in 250-630Vdc range.

The same with polycarbonate - what can be found are old Philips stocks ( locally , 1uF/100Vdc ).
 
According to various docs I've seen...

MKP is metalized polypropylene, while FKP is polypropylene film-and-foil.
MKT is metalized PET film, while MKC is metalized polycarbonate film.
Is MKS metalized polystyrene? I forget...

https://www.wima.de/wp-content/uploads/media/WIMA-Audio.pdf

They have different MKP series that are single-sided metalized polypro (e.g., MKP4) vs double-sided (stacked?) metalized polypro (MKP10).
Hello There,

I recently left Vishay after 5 years as their product marketing manager for film capacitors in the Americas region. We offered similar products to Wima. I know people get heated if I were to comment on which may be better for audio and I don't have expertise to comment, so I'll just mention the construction styles below....

The double metallized is not stacked film but refers to the fact that the film itself has double metallization (both sides) as opposed to one side.

Vishay followed similar nomenclature for their products

MKP = Polypropylene
MKT - Polyester
KP = Film/Foil

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