Electrolytics - other than the "usual suspects"

[Gregg]

Hi,

What brands of high voltage electrolytic caps other than the usual /Illinois, Sprague, LCR and stuff/ do you use in your builds? What's the reason to favour those brands and types instead of less bulky and equally priced radial electrolytic caps from Panasonic, Samhwa or Cornell-Dubilier for example?
I would appreciate if you share your experience and your pros and cons.

[Rob Mercure]

Gregg, I can't speak for others but for those of us who make part or all of our living doing repairs we tend to buy the best capacitors that our usual suppliers have for a reasonable price -which may be a sale price. The brands you first mentioned, plus JJs and a few others, are the common repair stock caps. I don't believe I've seen a new CD electrolytic in years and something like Nichicon is more common than Panasonic.

For my own builds I use anything in the parts box that forms up good - many of these caps are far too old to put in a paying customer's amp but I'm fine with 'em in mine. I particularly like the three section electrolytics that have an octal plug - while most of these are 40 years old I've not had one that was bad and the octal socket makes a great set of tie points. In fact I replaced the four section heater/bias filter can on my Scott 340B with an octal socket and four individual caps that I bundled around a chop stick glued in the octal plug locating key - there just wasn't room under the chassis to add four discreet replacements.

So perhaps it just depends on how long one has been doing this stuff, how good a "junk" box you've got and what building techniques you prefer.

Rob

[Gregg]

Nichicon and Rubycon are definitely worth to mention. All those companies have nice selections of 450v and 500V electrolytic caps but you can't see them very often around. I was just wondering if there was any specific reason /except that you need a PCB/ not to use those but the "usual" ones.

[Tom Phillips]

Nichicon and Rubycon are definitely worth to mention. All those companies have nice selections of 450v and 500V electrolytic caps but you can't see them very often around. ...

Gregg,
I have never been able to find them above 450V. If you can point out some sources it would be much appreciated.
Thanks,
Tom

[Gregg]

Me neither but I noticed that Digikey carries a nice selection of Panasonic 500V caps:

http://dkc3.digikey.com/PDF/T072/P1359.pdf

Also Allied have some 500V Cornell-Dubilier.

http://www.alliedelec.com/catalog/pf.asp?FN=1445.pdf

[Satamax]

Well, F&T are rather common. I like them for british amps. I like RIFA caps too, availlable through RS components.

[R.G.]

What brands of high voltage electrolytic caps other than the usual /Illinois, Sprague, LCR and stuff/ do you use in your builds? What's the reason to favour those brands and types instead of less bulky and equally priced radial electrolytic caps from Panasonic, Samhwa or Cornell-Dubilier for example?
I would appreciate if you share your experience and your pros and cons.

Some general observations on aluminum electros.
- 400 to 500V is about the limit you can do with aluminum. More than that simply has to be done by stacking. There is some question about whether you're better stacking them even at 400-500V. Putting two caps under somewhat less stress rather than running one cap right at its limit is going to be more reliable. I run the Workhorse amps with two 350V caps stacked rather than single 450V's which is possible.

- in electronic components, just like restaurant food, you need to look for turnover and volume. You want to buy from the place that has a respected specialty, not from a place that says "yeah, we make those too." Panasonic, Nichicon, and some other Asian sources make a large part of the caps which go into switching power supplies in the world. They simply have to be good. Otherwise warranty and failures would take them out of the business.

- Guitar amps is a parasitic industry. There is simply not enough volume in it to command parts unique to the practice. Tubes are the exception, and that is because the guitar amp and hifi tube equipment industry is keeping alive some factories that would otherwise be out of business. But for the jellybean stuff, resistors and caps and so on, we have to exist on whatever is still out there. Volume is a key to consistent manufacturing. When you can tweak a part in to be ...perfect... on an ongoing basis, you can get them to come out very closely matched, and afford to throw away the misfits because your volume supports it. In the case of guitar amps, it makes good sense to put radial switching power supply caps in instead of axials. It used to be that axial caps was what a cap maker was trying to make, and radials were a concession to those crazy PCB guys. In high voltage caps today, radial caps for switching power supplies is what the manufacturer is trying to make, and the axials are "oh, yeah, we can make those too." You get a better, more consistent cap in a radial.

If the physical setup is such that you can use radials and there's not an existing owner hounding you for an exact replacement, use radials.

Remember, you can always dumb down a tight, sharp, high performance low ESR, low ESL cap. You can't smarten up a sloppy, high ESR, high ESL cap into a good one.

[Gregg]

Thanks for the info. Thorough and informative as usual. I'll take it as a PRO for radial caps.
When stacking caps is it a good idea to bypass them with film caps or it's too "hi-fi".
When a cap is rated at certain voltage does it actually mean that the cap is conservatively rated and can take a little more so that the manufacturer can rate it safely at that voltage?

[bob p]

- in electronic components, just like restaurant food, you need to look for turnover and volume. You want to buy from the place that has a respected specialty, not from a place that says "yeah, we make those too." Panasonic, Nichicon, and some other Asian sources make a large part of the caps which go into switching power supplies in the world. They simply have to be good. Otherwise warranty and failures would take them out of the business.

i like the ubiquitous little Nichicon caps too, but as RG said, where you buy them makes a difference. I bought a cathode bypass cap at the local RatShack because I didn't want to place an order with Mouser. I paid about 4x what it would have cost me otherwise, and the cap failed after only a few hours of service. It had probably been in the drawer a LONG time.

In the case of guitar amps, it makes good sense to put radial switching power supply caps in instead of axials. It used to be that axial caps was what a cap maker was trying to make, and radials were a concession to those crazy PCB guys. In high voltage caps today, radial caps for switching power supplies is what the manufacturer is trying to make, and the axials are "oh, yeah, we can make those too." You get a better, more consistent cap in a radial.

the writing has been on the wall for a long time -- high power axial caps are on the way out, radial caps are here, and the high-voltage high-capacitance caps of the future are probably going to be screw terminal or snap-in. while it makes sense to use axial caps to replace dead axial caps in existing amps, it realy makes sense to look to the future if you're building a new amp. right now i'm building a KT88-based stereo amp that will use double-stacked 400-450V or triple-stacked 250V CDE 381LX/LQ series snap-in caps. when the caps eventually fail a few years down the road, i'm thinking that the CDE snap-ins should still be readily available.

[Chuck]

How about...

The Mouser catalog has had film caps off and on for the last few issues. I've thought of experimenting with them instead of electros. They are smaller than the Solens and I like the idea of not having to replace them every 10-15 years. I did the math and figured it would cost an extra $15.00 to $20.00 over Atom caps for most amps. Considering the cost of replacing aluminums and the labor it seems like a bargain.

Not to hijack the thread...But any pros and cons the films vs. aluminum electros would be great.

Heres a link: http://www.mouser.com/catalog/630/667.pdf

There are more of even higher values on the following page too.

TIA

Chuck

[R.G.]

Those particular caps are not good for filter caps. Their current rating is too low. I did the math on the 8.2uf/630Vdc cap and the max current is less than 1ma. You'll burn them out.

What does work and very well is AC motor run caps. These caps are intended to pass current, lots of it, and to live in the same high voltage world as tubes do. Mouser does stock them, but they're not in the catalog. You can see them by putting "motor capacitor" in the mouser search box. You need run caps, not start caps. The run caps are polypropylene film in a metal can. Some of them are two section caps, which is handy.

Using motor run caps is part of my "Immortal Amplifier" concept, where one replaces things which wear out with things that don't. CDE targets their motor run caps for a 94% survival rate at 60,000 power on hours within the specified voltage and temperature specs. 60K hours is 6.8 years of being on 24/7. That's the same as 10,000 six hours shows or 27 years of 6 hours a day, every day. And at the end of that you have only a 6% chance that one needs replaced.

A good place to get AC motor run caps is the local heating ventilation and air conditioning (HVAC) supplies store. There is almost certainly one in your town. Find it. You can get prices as low as $0.25/uF at 370Vac, which is the voltage rating you want for up to 523Vdc, or 440Vac for up to 620Vdc.

[Amp Kat]

Some of the caps that Nichcon makes we never even reallize they are out there. Nichcon has several different lines and in guitar amps like RG was saying we rarely only see the LQ series radial that almost every Audio Co. out there uses mainly because of cost and size. Their line is actually quite large and can get very good and very pricy. You'll see their gold line Audio caps used in some PA amps like the Carvin DCM series and several others but they do have some other series that do get up in the 450 volt range and yes usually a radial. The main problem is no-one carries or distributes these series. I had a Nichcon product catalog from FAI on all the series Nichcon carries and have to say it was pretty damn impressive but as stated the demand for these applications keep distributors from marketing the product for lack of high volume sales which is the way they really make their money. Volume to didtributors goes a very long way.

[gdgross]

Anyone have an opinion on Xicons?

I've been using them since I started building amps a few years ago, and I've never had any problems with them. I did swap them out for sprauge atoms in one amp, and I couldn't tell the difference in tone.

[dai h.]

this "3uF film" (two 1.5uF 630V in parallel) sounds pretty good for the filter in the normal ch. of my Marshall 50W guinea pig (basically a 1987 circuit) after I tweaked my Power Brake (which I'm using as the load--listening through my Palmer PDI-03). I "Y"'ed the power supply so the normal ch. has its own filter. It was a bit of a surprise since when I last tried it months ago, I didn't particularly like it. The caps were bought cheap as surplus, so looking for surplus might be a possibility (though Solens seem to be pretty reasonably as far as films in the size/voltage you'd want for filters).