Uncoated PET Caps

[tv]

This is a question to resident forum gurus:

Namely, I have some of those "silver" stacked (afaik Epcos) PET's and I seek opinion from people who actually have a hands-on (ears-on) experience with those (see pic attached, that's what they look like).

- How do you rate "sound" of those caps? F.e. against Wimas or Panasonic pets.
- Did you actually use these in real devices (Eq. or preamps)
- How do they hold-up to mechanical vibrations once they are soldered into the circuit (I know leads break off easily)

IOW are they good enough for production or are they better used in prototyping or general fooling around?

 

[ChrisRoberts]

In my experience these caps are very unreliable. Due to their design they are not properly sealed and fail very easily. They were upgraded buy painting the ends but this did not help massively. 1982ish SSL's were full of them and they are often the cause of trouble.

IMHO i think that there are better sounding caps out there but there is nothing wrong with them per-say.

Chris

 

[abbey road d enfer]

I've used hundreds of thousands of them, when they were Siemens-branded. The only problem was if the PCB holes were not properly done (that was before Excellon CNC drilling machines), the wires may snap. To my knowledge, this would happen at manufacturing time; once QC'd, I don't think the problem would appear later.
In terms of quality, there is nothing wrong with them, excellent stability, very low loss.

 

[tv]

Thanks to both for responses.

I see two diametrally opposite opinions. May I assume that:

a) ChrisRoberts is speaking of silvery-greyish (i.e. transparent) types (Epcos calls them "SilverCaps") which "supposedly" kill the high frequencies and
b) AbbeyRoad is speaking of "blue-ish" Siemens-es which are supposedly held in high regard even among audiophile crowd?

I have the transparent, grey-ish, Epcos "SilverCaps".

 

[abbey road d enfer]

I'm referring to the silver type (MKH in Siemens parlance); the blue-end types are MKT. Their audio performance is utterly the same. When MKT became available, I used them because they didn't have the manufacturing problem of MKH's, but there was absolutely no difference in operation.

 

[tv]

These Epcos are MKT (radial, uncoated, "silvercaps"):

http://www.epcos.com/web/generator/Web/Sections/ProductCatalog/Capacitors/FilmCapacitors/MetallizedPolyester/Page,locale=en.html

 

[abbey road d enfer]

So the references have changed between siemens and Epcos, apparently. In fact I just saw that some distributors use indifferently one or the other. They are all the same in terms of electrical performance.

 

[tv]

A-ha. So it looks like these are the same caps that you used.

One minor concern: I have some of 2u2/250V (R15mm) that seem a little big and heavy for their small leads (being uncoated). Any experience with these bigger, heavier variants (regarding mechanical stability).

Perhaps they would fit better in equipment that "sits" on the shelf instead of being portable (thrown around).

 

[abbey road d enfer]

Regarding the bigger ones, we used to put a drop of hot-melt glue, just in case. The larger ones I used were 10mm, 1uF, no experience with 15mm type.

 

[tv]

Hot-glue, what else..
Perhaps I should have written in the OP that I have the "heavier" ones. 1uF, 2u2, R15mm.

But if you glued the "little" 10mm ones...