Preferred Filter Cap Brands?

[Roe]

doesn't the application matter? Some caps are designed for tube amps, some are not

[Leo_Gnardo]

If you can get an account with Magic Parts (distributor of Ruby Tubes) they have a selection of house brand hi voltage filter caps that I've found to be reliable at very affordable prices. Magic doesn't accept dinky orders though, you better need a couple hundred $$ worth of items. They aim their business at manufacturers & repair shops, not hobbyists & tinkerers. One other tiny drawback, in 2 cases, out of some thousand-plus caps I've bought from them over a couple decades, I found two mislabeled with the sleeve on backwards. I don't know who makes them for Magic but they've worked well for me in spite of those 2 rare instances. I try to keep in stock at all times 22/500, 47/500, 50+50/500, 100/350 and 220/350, that way I can deal immediately with 90% of the amps that arrive here for repair & maintenance.

I've also used plenty of Nichicon, Panasonic, Lelon & Xicon branded caps in recent years, occasionnaly F&T and JJ. Had no problems with any of them. Sourced mostly from Mouser. Newark (Element 14) and DigiKey are good sources for the far east brands, Antique/CE stock F&T & JJ at fair prices. And let's not forget ApexJr, a collection of surplus caps can always be found there at rock bottom prices.


[Roe: doesn't the application matter? Some caps are designed for tube amps, some are not ]

Despite any claims by dealers/manufacturers I truly doubt ANY power filter caps are designed for tube amps, it's a niche market that is way too small. Quality electrolytic caps will work fine in guitar amps as well as any other purpose. Some builders & dealers may have runs of capacitors specially labeled for them, like Holy Grail, but I seriously doubt they're made in any special way that would make them extra-suitable for use in tube amp gear. Any such claim, in my humble opinion is hucksterism. If the sales department writes some blurb that says what you want to hear, you may be more inclined to pay them for their product whether it's really better or not, and practically every case it's not. Some signal film caps like Sozo, Dijon, Jupiter & others of that sort may be aimed at the tube amp build/mod market, and if you want to pay their prices you may wish to believe their claims whilst you twang a tune on your tube operated prize. Naturally none of the hucksters allow any real A/B blind testing. There are some tests on YouTube that reveal little to no difference between ordinary and boo-teek parts, no surprise there, but admittedly it's hard to tell anything on a pair of cheap 2 inch computer speakers most people use for computer sound.

And we can all amuse ourselves with the old classic YouTube video: Bozo vs Knucklefux . Just punch on the link for 2 minutes of fun.

https://www.youtube.com/watch?v=_agbTOn1fnQ

[R.G.]

doesn't the application matter? Some caps are designed for tube amps, some are not

As Leo says, the market is too small. I would add as a caveat that there are a few places supplying twist lock can caps that may be intended for tube equipment specific replacement, but I believe that this is simply a way of packaging existing capacitor insides in a different can. It's much the way that canned vegetables are made by very few suppliers, and have a unique paper label put on the can, or a different or odd shape can used.

To answer your question a little more directly and at a lower level, yes, application matters, but use in a tube amp is not that special. Electrons don't know they're headed for a tube a little later in the circuit, and caps don't know that the electricity they store and release is headed for a tube.

Then there is the question of knowing what to do. If one decided to make the perfect tube amp capacitor, how would that be different from caps that are already produced for, say, switching power supplies?

[Roe]

there are quite a few filter caps made for tube amps. see for instance these german made caps https://www.die-wuestens.de/dindex.htm?/k1.htm Cf. https://www.die-wuestens.de/kd/KONEL100.pdf

[R.G.]

A couple of things come to mind.

One is the really big one - if one had the power to change any particulars about a capacitor to make it perfect for tube amps, what exactly would need to change? What details would be different from the stuff that's available over the counter in great quantity?

Let's leave specific terminals and packages out of it for the moment. The big question is what makes a cap good for tube amps.

And here's a spoiler: back in the tube Golden Age, the designers cursed at the poor qualities of the parts they had to use then, too.

[xtian]

The big question is what makes a cap good for tube amps.

Marketing.

Also black labels with gold foil graphics.

Anything with gold foil monkeys on would be best, absolute, period.

[Roe]

A couple of things come to mind.

One is the really big one - if one had the power to change any particulars about a capacitor to make it perfect for tube amps, what exactly would need to change?

apart from voltage (550v etc) this seems complicated. Yet those who change filter caps in amps often experience a difference in sound and response. and not always for the better.

[norburybrook]

A couple of things come to mind.

One is the really big one - if one had the power to change any particulars about a capacitor to make it perfect for tube amps, what exactly would need to change?

apart from voltage (550v etc) this seems complicated. Yet those who change filter caps in amps often experience a difference in sound and response. and not always for the better.

I would say that's because they'd got used to the sound of the amp with failing caps. Replacing them would I imagine restore the bottom end transient response of the amp, and perhaps make it quieter ,something which the player may not like. When I re capped my 1970 bandmaster after 40 years service I did notice a change......for the better


M

[norburybrook]

duplicate...

[Roe]

I would say that's because they'd got used to the sound of the amp with failing caps. Replacing them would I imagine restore the bottom end transient response of the amp, and perhaps make it quieter ,something which the player may not like. ...

If it only was that easy. No need for different caps with many different parameters

[R.G.]

if one had the power to change any particulars about a capacitor to make it perfect for tube amps, what exactly would need to change?

apart from voltage (550v etc) this seems complicated.

It is complicated - and that is exactly the point. "Designed for tube amps" is one of those things that are easy to say, but really, really complicated to actually do. I have worked in the electronics industry for decades, and maintained an active interest in and research about tube amps for nearly the entire time. The research has led to lots of buried nuggets, things like what metals are most useful for cathodes and plates, what materials make resistors with what qualities, and so on. In that time, I've never seen a hint of what qualities make capacitors good for tube amps. I've found numerous instances of the designers figuring out how to work within the limitations of the parts that were actually available. The general direction of the comments is that the designers wanted just more theoretically perfect parts, not parts with some specific mix of imperfections. That is - they would love to have had available the caps we have today.

Yet those who change filter caps in amps often experience a difference in sound and response. and not always for the better.

With respect: yes, those who change filter caps in amp often do report a difference in sound, and not always for the better. However, many players that change filter caps report a vastly improved sound. Are there more that like it than don't like it? Who knows? I have never seen anything like a proper study of whether guitarists like the sound of new filter caps versus the sound of old ones, let alone what would need changed to make them sound even better. I >>have<< sat and watched as a quite-famous guitar player watched his amp tech swap resistors end for end and make listening tests on the fly about which direction the resistors sounded better. Guitar players are generally people with strong opinions about what constitutes good sound, but not much technical background for digging into what makes it that way. Given that, they easily fall prey to the general human tendency to see subtle variations for any - or no - reason, even where there are no significant variations, and all the other psychological foibles that humans are subject to.

In the words of Sir William Thomson, Lord Kelvin, in 1883:
"To measure is to know."

"If you can not measure it, you can not improve it."

"In physical science the first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be."

Literally - if you can't measure it, how can you improve it?

I would say that's because they'd got used to the sound of the amp with failing caps. Replacing them would I imagine restore the bottom end transient response of the amp, and perhaps make it quieter ,something which the player may not like. ...

If it only was that easy. No need for different caps with many different parameters

Paraphrasing Albert Einstein,
Everything should be made as simple as possible, but not simpler.

[tonequest]

Has any one tried the Miec e-cap offered by just radios ? Lots of different values and they claim NASA uses em--