Filter Caps choices

[Stevie B]

I didn't see this discussed in here.
First, are there any good choices that aren't over 15 bucks (like Sprague).

But secondly, seems that Fender typically uses two 70uf in series (with balancing bleeder resistors) for the first stage.
The highest voltage seen at that location is 450v.
Why can't these be rated for 250v? (Specified as 350v) Seems that they only see half the voltage in series.

And then thirdly, if a cap is rated at 450v, is it ok to use it with 410v applied?

[Leo_Gnardo]

Second things first today. I have seen voltages beyond 500V in some Fenders with series capacitors. No worries if the voltage across the caps doesn't come close to their max voltage rating, in fact caps seem to last longer this way. A couple days ago there was a photo posted here of a Ducati filter cap (admittedly a brand not much seen in guitar amp high voltage applications but anyway...) indicating 10,000 hours expected lifetime at full voltage, but iirc 30,000 hours at reduced voltage. Also note many Marshalls (and other UK brands) from late 1960's through the 80's ran series caps with 450V ratings. Many of those caps are still in use and functioning way beyond their expected lifetimes.

410V on a 450V rated cap is no problem at all. As I noted above, some extension of service life may be expected from caps that aren't stressed to the max.

Back to first question, sure there's some good choices. F&T make perfectly good caps and have a good reputation. Nichicon as well, but they have quit making axial style caps. It's radial only from now on from Nichi.

There's a new selection, "MOD" from Antique/tubesandmore.com/CE/Amplified Parts (3 parallel businesses under one roof, go figure) but they're so new on the market they have yet to establish a reputation. Definitely low priced! And they do offer a 70 uF 350V cap for those who insist on parts spec'd as original in their venerable Fenders.

Ruby (NOT Rubycon) had a selection of good electrolytics, sold through Magic Parts. Down part of that is they were offered only to the trade, they didn't want to be pestered by hobbyists & occasional fix-it folks and their onesie-twosie orders. I used to order 50 or even 100 at a clip. But in recent times their supplier punked out, and they've been searching for a new outfit to make their house brand. So much for that - and if they do acquire a new source it will take some time to establish their hopefully good reputation.

BMI is a USA made brand, and have a good rep also. Their legend is the company was founded by engineers that broke away from Sprague and set up their own manufacturing line presumably with the same "secret sauce" but without the absurd high prices. Some amp manufacurers, Mesa for instance, built BMI's into their amps for a good long while. What's not so good, these aren't often found on the market except occasionally in surplus shops like ApexJr, and in a very limited selection of values. When I looked at BMI website a couple years ago, the value selection there also wasn't too terrific. Assuming they're still in business, they might be a source for custom orders if you have a need for say 10,000 or more units.

Finally, if you want serious reliability in your B+ supply, forget electrolytic caps and go for film caps. Instead of needing replacement every 20-30-40 years, films can last indefinitely iow more or less forever. Carr has been using Solen film caps as filters in their amps since the company started about 25 or more years ago. They are big, and a bit expensive, but they ain't gonna break! For some repair work, often in older Ampegs with B+ in the 550 to 700V range, I've employed Panasonic and TDK film caps rated in the 800-900V range. They're rectangular, so it takes a little ingenuity and perhaps a glob of epoxy to mount them, but they also aren't gonna break down, ever. Got 'em from Newark/Element14.

I'm sure other MEFsters will ring in soon with their suggestions. I'm sure I've overlooked a few. Stay tuned...

[Enzo]

In filter caps, the voltage rating on them is "working voltage". That means a 450v cap can be run right at 450v and get the full life in the specs. Often you saw "20uf 450WV" printed on them. WV for Working VOlts. They also have a surge voltage. In tube systems, before all the tubes start conducting, the high voltage supply can spike a lot higher than the steady level. So if a 450WV cap sees 510v for a brief time it will be within the surge voltage, and thus be fine.

Why can't they use 250v instead of 350v caps? I give up, why not? They could even use 225v caps. But why? The cost savings is minimal, and you erase any safety margin you had before. And consider, what does that 450v you see goes up when you pull the tubes, or when you even put the amp in standby.

I generally stay away from the Sprague caps as they are mainly aimed at the amp-fan crowd. I am sure you can surf the web and see photos of Sprague caps cut open and a smaller cap is inside it.

[Leo_Gnardo]

surf the web and see photos of Sprague caps cut open and a smaller cap is inside it.

Save the surfing, here ya go...



It's no sin imho to take up less than all the volume inside the cylinder. But what Sprague Atoms buyers are led to think, is they are exactly the same caps as Sprague made in the legendary days of yore when Atoms were the bees knees and all others were second best, at best.

Speaking of legends, the Holy Grail caps supplied in Ceria amps (made in Malaysia) are supposed to be house-branded Sprague Atom made in the far east (Malaysia? Indonesia?) specially for Ceria, and packaged without the oversize cans that are marketed in the USA. AFAIK Ceria does not offer these caps sold separately from their amps. Ceria could likely add to their profit margin by selling them. Might be some marketing agreement, who knows? In any case, some amp goo-roos and their acolytes consider Holy Grails to be super desirable caps. Maybe more so because they're more or less unobtainable. I'm sure that factor lends to their reputation.

At the - supposedly - other end of the legend scale, lots of techs plus followers of gear website trends hold IC - Illinois Capacitor - in low regard. No, they're not made in Illinois USA. I believe they are made in China. (And that's not to say everything made in China is junk.) Presumably Illinois fail early on and maybe have other undesirable characteristics. Stinky feet? Fleas? Covid? MSG? I dunno. What I've found, is they work 'til they fail. Maybe a little more often than we'd like, but I don't automatically replace them every time I see 'em. I replace 'em only when they've actually failed, good enough for rock 'n roll. (These days usually with F&T.) If you're on a budget, and don't stress Illinois at or beyond their specs, also don't subject them to high temperature, they'll probably be OK.

[eschertron]

IIRC some 30 years ago a large number of IC caps mounted on computer mobos failed on a spectacular scale. That was then, this is now. Even after having learned that bit of history: to me, they still have stinky feet. Go figure.

[g1]

IIRC some 30 years ago a large number of IC caps mounted on computer mobos failed on a spectacular scale. That was then, this is now. Even after having learned that bit of history: to me, they still have stinky feet. Go figure.

Are you possibly thinking of the 'capacitor plague'? https://en.wikipedia.org/wiki/Capacitor_plague
If so, it was not IC brand in particular.
The bad rep of the IC brand that I'm aware of is due to their being problematic in Fender amps, particularly the 'Hot Rod' style series. And they do go back some 30yrs.

[Chuck H]

My own experience with IC caps has nothing to do with Fender HR series amps or any "capacitor plague". I've just seen the charcoal and gray colored ones fail within ten years in a number of different amps. That doesn't mean that Illinois Capacitor doesn't make good capacitors. It just means that they were offering these particular caps that looked to the manufacturers like a deal and they were purchased and used in a number of amps for a number of years. And yes, as a result I won't even patronize their product. Because something about their marketing got them into a bunch of amps where they under performed. (<period) Let them reap the fallout of their actions. I avoid them, you should too. If they sold a bunch of companies sub par capacitors because specs were falsified or omitted and that was a problem later then that company should fail now that we know better. (<period) Why should we trust that circumstances will be better now? It takes short time to sully a reputation. Once you've done that it takes a lot longer just to get back on par. As it should be. We reap what we sew. (<period)

JM2C

[mikeydee77]

I wonder if there is an environmental factor with IC caps falling more in the US. I am in the UK where the weather is bit middle of the road and whilst I do occasionally need to replace them and have seen the odd ruptured one but I don't feel like it is all that commonplace.

If I am replacing caps I will go for F&T 9 times out of 10. There is also JJ available as well which do some of the handy multi section value.

[Randall]

I don't know much about much, except to say that when I worked at a Fender Authorized shop a while back, it was not uncommon for factory support to right off the bat ask if we had "changed those IC caps" in many models of a certain era. They didn't even want to proceed too much further than that until we could tell them they had been replaced. If that tells us anything.

That, and if given the choice I will install F&T filter caps every time. I like them, and have never once seen a failure. I just wish they made the 25/25v cathode caps so I didn't have to pay for Sprague.

[Leo_Gnardo]

I don't know much about much, except to say that when I worked at a Fender Authorized shop a while back, it was not uncommon for factory support to right off the bat ask if we had "changed those IC caps" in many models of a certain era. They didn't even want to proceed too much further than that until we could tell them they had been replaced. If that tells us anything.

That, and if given the choice I will install F&T filter caps every time. I like them, and have never once seen a failure. I just wish they made the 25/25v cathode caps so I didn't have to pay for Sprague.

Some insight there, right from Fender.

As for cathode bypass caps, they're under so little stress - typically 0.8 to 2V or so - any brand will do. Save your money on those 25/25 Spraygoos. Also no point in paying gold dust money for dual caps from F&T or anyone else. I use the generic caps available from Antique/CE, cheap as dirt, and never seen a failure. Come back in 30 - 40 years and we'll see if they are still working. Bet they are!

Dual caps: "Fender used 'em in their classic amps! Must be some magic pixie dust there." Nah, they were cheap and available back in the day. If they cost a premium price like they do now Leo & his mates would have nixed them for sure. Also, the leads on F&T duallies are very fragile and easily break, one of the few down sides to that brand.

[Chuck H]

Also, FWIW, I had some trouble with the Sprague Atom caps over the course of a couple of builds some ten years ago or so. All the Atom caps I'd used in the past were, and as far as I know still are, working fine. But I got two shipments from Mouser many months apart and both batches were "stale" (I guess). They were purchased at the time of the projects and installed as new and the amps started to exhibit symptoms of bad PS filters within months. I never actually tested the caps but replacement fixed the amps so I have to assume they were the cause. This could have been the Mouser's fault. Perhaps they were warehousing old caps. Perhaps whomever is supposed to handle inventory wasn't aware that electrolytic caps actually have a shelf life and that inventory should be managed with "stock rotation" like food at the grocery store. So this may have had nothing to do Sprague or the Atom line of caps, but... As a result of this happening and the ever increasing cost of the Atom product I gave up on them and never looked back.

I've been using Nichicon PW series caps ever since. I don't mind designing around the radial leads or retrofitting radial caps into axial applications. It's just a big deal to me because I don't believe that geometry = mojo.

[Chuck H]

I can't be sure why and I absolutely don't have politically correct or even good explanation for my aversion to Xicon caps. That said, here's my less than good explanation Somehow I feel like I'm sending my money more directly to the east Asian manufacturing machine. There's probably no significant difference in the 'manufacturer to consumer' chain of events, but for some reason it sort of felt that way when I made some decisions years ago. That said...

I know I'm not alone in this position and Xicon caps don't enjoy a lot of respect in our little genre, and...

I've never had any problems whenever I've used them and some of those repairs and mods are fifteen years old now.

[Leo_Gnardo]

I can't be sure why and I absolutely don't have politically correct or even good explanation for my aversion to Xicon caps. That said, here's my less than good explanation Somehow I feel like I'm sending my money more directly to the east Asian manufacturing machine. There's probably no significant difference in the 'manufacturer to consumer' chain of events, but for some reason it sort of felt that way when I made some decisions years ago. That said...

I know I'm not alone in this position and Xicon caps don't enjoy a lot of respect in our little genre, and...

I've never had any problems whenever I've used them and some of those repairs and mods are fifteen years old now.

Xicon was Mouser's house brand. AFAIK the Xicon brand is now defunct. Of course I could be disinformed - there's a lot of it going 'round. I used to get Xicon film caps which look and as far as I can tell, act like the "brown chiclet" Panasonic film caps. Never had one fail, and they all sounded good in amp applications, also installed as tone caps in guitars.

About your funky Atoms, did they have a date code? All (except the low value, low voltage) ones I've ever seen are date coded, all the way back to the days when they had yellow plastic jackets before the "modern" blue ones.

[tdlunsfo]

Like the rest of you, a good bit of my business is changing out IC caps for certain Fender amps but I did have a first gen early 90's Deluxe reissue come in with original IC caps with no leakage, good ESR and no hum about 6 months ago. Surprised me. Some of my other tech friends question if Fender just got a bad batch, maybe counterfeit? Maybe IC saw the money in cutting corners before Fender ordered 500,000 more CAPs? Who knows, but I've made a little dough off of the Fender/IC relationship.

[xtian]

If other cap manufacturers printed in gold foil on black, I'd consider using them, too.

Srsly, tho, I use a lot of Nichi and Panasonic radials because they're small, inexpensive, and reliable. But for Fender doghouses, those F&Ts are the best...looking.