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!
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Cheap modern and reliable. There's also high temp, electrolytics up to 550V too, some will fit into your old can if you wish.
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 have same KEMET C4AQ caps in my amplifiers. Good caps.👍
Thanks everyone, I ordered a bunch of those Kemets. Some for cathode bypass, and a lot for power supply duty. I'm curious.
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!
I've been using the Kemets mentioned above for a couple of weeks now.
Replacement of cathode bypass caps made the biggest difference. I used a combination of the ugly white motor run caps and trusty aluminum can Bosch MP oil caps there earlier.
In the power supply the difference was less obvious (old caps there were only the ugly whites) but it has tidied up the sound. (It's a pushpull amp)
Thanks for the solid advice guys!
Replacement of cathode bypass caps made the biggest difference. I used a combination of the ugly white motor run caps and trusty aluminum can Bosch MP oil caps there earlier.
In the power supply the difference was less obvious (old caps there were only the ugly whites) but it has tidied up the sound. (It's a pushpull amp)
Thanks for the solid advice guys!
I started using Vishay MKP 1848's some years ago as I got a nice lot of them for a really decent price from a friend Germany.
Since then I found that most any of the MKP's (polypropylene dielectric) these days are worth trying if the price is right. I use them in power supplies. These C4AQ ones from Kemet were very good as well.
Since then I found that most any of the MKP's (polypropylene dielectric) these days are worth trying if the price is right. I use them in power supplies. These C4AQ ones from Kemet were very good as well.
Does anybody know where to buy ASC X386S in Europe? Buying outside is now impossible due to the crazy custom taxes.
Here I may easily source Cornell Dubilier. Any experience with them? A friend of mine working with large UPS old me that CORNELL DUBILIER "Motor Run & General Purpose AC Capacitors" (Z series) are very good. These are also much cheaper than the ASC.
Here I may easily source Cornell Dubilier. Any experience with them? A friend of mine working with large UPS old me that CORNELL DUBILIER "Motor Run & General Purpose AC Capacitors" (Z series) are very good. These are also much cheaper than the ASC.