I'm shopping for motor run caps for tube amp power supplies. I have a smal collection of the classic aluminium can caps like Bosch MP etc.
That style of caps is no longer made so it seems. New ones have a white plastic case. My question is: are these as good as the old style ones?
I've been looking at datasheets, they say 'metalized polypropylene' and what used to be oil is now polyurethane resin.
https://www.tme.com/html/EN/capacitor-polypropylene-450v-sr-passives/ramka_11117_EN_pelny.html
Thanks!
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That style of caps is no longer made so it seems. New ones have a white plastic case. My question is: are these as good as the old style ones?
I've been looking at datasheets, they say 'metalized polypropylene' and what used to be oil is now polyurethane resin.
https://www.tme.com/html/EN/capacitor-polypropylene-450v-sr-passives/ramka_11117_EN_pelny.html
Thanks!
(edited)
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Those plastic motor run caps sounded pretty meh to me. They're big, bulky and frankly not very good. I used to use them a lot but when I discovered DC Link caps it was a no-brainer - I sold the lot. Polypropylene doesn't mean all caps sound the same - far from it. Don't bother with these - get DC Link caps from Kemet etc.
The DC Link capacitors are stacked construction. (interleaved electrode plates). This reduces the ESR and ESL greatly, and makes the mechanical structure more consistent. It's not a great surprise that they sound much better.
Motor-run MKP types are often rolled construction, and these have none of the advantages; some of them sound MUCH worse than electrolytics.
Motor-run MKP types are often rolled construction, and these have none of the advantages; some of them sound MUCH worse than electrolytics.
There's an extreme price range in DC Link caps, and I have no idea why.. Where to start? With the cheapest ones. These from TDK;
https://product.tdk.com/system/file...r/film/ac-motor/data_sheet/b32320i_series.pdf
The Wima MKP4 DC links also have my sympathy, they are a little more expensive.
https://product.tdk.com/system/file...r/film/ac-motor/data_sheet/b32320i_series.pdf
The Wima MKP4 DC links also have my sympathy, they are a little more expensive.
https://uk.rs-online.com/web/p/film-capacitors/1744495?gb=s
These were the last ones I bought - plenty in stock and a good price. You can parallel them up.
These were the last ones I bought - plenty in stock and a good price. You can parallel them up.
I found the opposite of what some are reporting when I tried some Wima DC link caps. I swapped a pair into an amp in place of some Solen film caps used as the first cap in the power supply and the bass response instantly became very weak. Same uf, same ESR and I even measured the impedance vs frequency. I was shocked as I would never have expected that and honestly didn't expect there to be any change at all. Put some solen caps back in the amp and the bass response returned. I learned just because something looks better on paper, doesn't mean it will sound better or even as good!