Polystyrene or polypropylene, given the choice? - Page 2 - diyAudio
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Old 28th December 2006, 03:10 PM   #11
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Quote:
Originally posted by MRupp
new “boxed” radial Styroflex caps?
New ?
Try Siemens KS series, 1% accurate, Dieter B's favorite.
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Old 29th December 2006, 04:33 AM   #12
adhoc is offline adhoc  Australia
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AFAIK, as a rule of thumb, for caps:

PTFE (teflon) > polystyrene > polypropylene > polycarbonate > polyester

And always:

foil > metal film

Polystyrene is not used often nowadays because of the low melting point of polystyrene. This restricts it to hand soldering only by excluding it completely from chip type mounting (no way of controlling heat during soldering).
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Old 29th December 2006, 06:05 AM   #13
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Oh, I'm so glad I wandered into this thread.

Years ago I built a tube RIAA preamp out of the "Revue de l"Audiophile" magazone that used those little clear "rolled up" axial caps. Copper foil. Sounded wonderful, the caps were inexpensive, too.
Never could remember what type the caps were. Seen them from time to time on circuit boards, but didn't know.

Thanks guys!!
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Old 29th December 2006, 06:55 AM   #14
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I first saw these copper foil caps in a Sony amp in the mid seventies. Quite nice sounding. Are they indeed polystyrene?
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Old 29th December 2006, 07:06 AM   #15
Pano is offline Pano  United States
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Quote:
Originally posted by analog_sa
I first saw these copper foil caps in a Sony amp in the mid seventies.
Right! That's where I saw them too, in Sony gear. Who made them?
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Old 29th December 2006, 07:45 AM   #16
rdf is offline rdf  Canada
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The ones I have that look similar are TRW.
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Old 29th December 2006, 12:03 PM   #17
MRupp is offline MRupp  Germany
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Quote:
Try Siemens KS series, 1% accurate, Dieter B's favorite.
Thanks Jacco,

I saw them on Ebay years ago but didn't buy any - seems that I'm a bit late now. I have lots of ERO KP 1832 which I was going to use, with smaller styroflex in parallel to get the correct capacitance. The EROs are supposed to be pretty good sounding but they are also quite big. But then again I might want to try

P.S. You mean Dieter Bohlen
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Old 29th December 2006, 05:25 PM   #18
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Lots of places still sell polystyrene caps, I just always wondered how they sounded. I had heard a lot of good things, I know Audio Research and Conrad Johnson both like using them as an upgrade, but I wasn't sure if they used better ones than those little cheap ones. Parts Connextion has them available in lots of values. I believe Mouser and Digikey has them available in a range of values. Also Handmade electronics is specialing some NOS Phillips polystyrene caps in the closeout section. I just bought a few to give them a try. I'm glad I brought this up as a question, I like all the replies.

I know the Relcap Polystyrene's are nice, I use those a lot, I really like them, but they are quite expensive for everyday use. Actually I just contacted a small capacitor company that makes custom caps, they make Polystyrene's, and I asked for some samples, they said they could give me some over runs for the cost of shipping. They are made more like the Relcaps than the cheap ones, so it might be a nice stash of good caps, if not, I'm out ten bucks.
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Old 30th December 2006, 01:48 AM   #19
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Rel is one of the best. My preference. ( RS polystyrene)
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Old 30th December 2006, 05:23 AM   #20
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The problem with the molded polystyrene caps shown so far in this thread is that they are "laid in lead" types (leads are laid in place and held in contact with the foils by the molding process) and are most likely inductive due to the way they are manufactured (one lead in the center of the cap winding spiral, one on the outside). The parasitic inductance may not be a problem with smaller values (< 1 nF), but it might start to be noticable for larger values. The wire contacts are also not very sturdy. As has been pointed out, these caps are very delicate, and a nick with a soldering iron or excessive dwell time during soldering can kill them. Don't wash your circuit board with acetone, either - it dissolves polystyrene.
I generally use whatever polystyrene/ polypropylene caps I can get my hands on for a reasonable price, mostly from surplus sources. Siemens made some molded polystyrene and polypropylene caps with epoxy coating that are more rugged. Rifa had a nice series of polystyrene box caps that are also better protected than the molded types - grab these if you find them surplus, as they are nice and compact. ITW had an interesting series of polypropylene molded film/foil caps similar to the polystyrene types but more rugged. Unfortunately, they used steel leads.
Roederstein has a series of boxed polypropylene caps (MKP1830 series?) that are available in precision tolerances.
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