Filter caps

So, what are you guys using for filter caps? Which brands are to be avoided? Any good ones that dont cost the earth or do I have to suck it up?

Most caps are made overseas now in the orient. Since power caps have tolerances, temp and voltage ratings I dont pay a whole lot of attention to brands. Even companies like Mallory, Siemens, or Sprague and others are all subcontracted to third world countries so Recomending a specific brand is pointless. Electrolytic Caps have a lifespan like batteries do, they need to be replaced every 10 years or so, but even that has a ton of "if's" attatched. If a cap isnt powered up regulary it has a much reduced life over something that gets powered daily.

Caps in my 66 Fender Bassman lasted 35 years before they needed replacement so the quality is continuing to get better, and the size is getting smaller for doing the same job.

The replacements for Tube amps are usually a fairly hefty sized caps. The temp rating is usually high, the voltage ratings you would use are higher, and tolerences are usually 5~10%. This is much better than the 20% many older amps were built with which goes to show you the job of filter caps is to filter AC out. So long as thay can do that it then comes down to lifespan.

When I'm building from scratch I have been using the CDE 381LX series which are small, have a low esr and a ripple lifetime of 12,000h (~32y at 1h/day) but they are snapin and you have to double them up for V>450v. I have also been using metalized polypropylene film motor RUN capacitors like these:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120440880547&ssPageName=STRK:MEWAX:IT

(they are PP film, mislabeled motor start)

For JJ multisection "can" caps, Eurotubes has freaky low prices (32/50/100uf x2 @ 500v for $8-10)

for straight replacement axial caps, people love the Weber caps : https://taweber.powweb.com/store/capord.htm

check their multisection prices though!

Have you found a VDC rating on those polyprops or are you just assuming 1.4x VAC? Around what voltages have you been running them?

the short hand assumption of VDC = 1.4x VAC rating is on the low side.

Companies that rate both AC and DC (ASC/CDE) have ratios up to x2.8!!

ie 270VAC = 750VDC

Motor run caps are bullet proof cause they have to be, Ducati even makes some!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120462401087&rvr_id=&crlp=1_263602_263622&UA=M*F%3F&GUID=6ad392a01250a0b583813bd1ffd39835&itemid=120462401087&ff4=263602_263622

can't beat the price if you have the room IMO

Yeah, I have some of the Ducati's in 10uF for some of my upcoming projects. They spec the DC rating at 1.4x VAC, but since they're rated for 400-500 VAC, it's almost a moot point. I was more interested in the VDC rating for the CBB60's on eBay. I realize the Ducati's may be conservative, but the CBB60's are only 240VAC. They would almost HAVE to be rated for 2.8x for me to feel comfortable using them. Without the documentation to verify that, I'm a bit leery.

the key to capacitor longevity is temp much more so than voltage, and since most motor run capacitors have a ripple lifespan measured in 10s of thousands of hours you have a very good safety factor when using them at higher voltages as long as you keep them cool. See this lifespan calculator: http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp

the temp factor is an exponential one, while the voltage is geometric. Wonder why many "generic" tube amp EL caps are available at +600VDC ratings while big name cap makers charge an arm and leg for these voltages in an EL cap? Its because the "Ruby" etc brands make due with a high ESR/low lifespan. Motor run caps can't make this trade off, although they are BIG

Tuck the Ducati into the chassis with no fan and it will tolerate higher voltages badly, mount it topside and its a beast. Also motor run caps are metallized PP film and thus self heal. The start up is where voltages spike in amps, the use of soft start circuits or even (much) cheaper nTC inrush current limiters can also add a safety factor. Motor run caps handle high surges with ease.

IGBT PP caps are also pretty beastly, and check these arcotronics

http://www.surplussales.com/Capacitors/Polypropylene/Miscellaneous-Polypropylene.html

these ebay finds will go in my "EL less" tube amp project:

5 x60uf/330VAC PP ASC caps, 10 x 22uF/630VDC Solen Fastcaps all

I never did find anyone who could give me a datasheet for the CBB60's. I'm just not comfortable building with that sort of an unknown. However, I did find some ASC's like the ones in your pic in 40u instead of 60u. I emailed ASC. The datasheet they sent says that they're tested up to 660V. I ordered some and don't feel the least bit insecure about using them at 450V in a 2204 build I'm planning. Six of those things are going to eat up a chunk of real estate!

For my other build, I just found the US distributor for Ducati and am ordering a few straight from them. They're not as economical, but they're in line with normal pricing for other motor caps.

likely related:

http://www.topmay-capacitor.com/Admin/Product10/ProductFile/200912092939781.pdf

http://www.jiukang.com/images/upfile/20091103141212234.pdf

http://www.yy-electronic.com/motorruncapacitor.pdf

Hailida's server has been dead for a while, maybe that's why the price is so low?

Saw the link above as well. But I use these a lot:

http://www.tedweber.com/

Very nicely priced, especially the multi-cans.

If they aren't available there, then I just go with whatever I can find that is the same voltage and value. Oh and it has to fit!

I wouldn't spend too much time fussing over it.

oh no! Its all very complex! See here:

http://www.humblehomemadehifi.com/Cap.html

(kidding)