Ever wonder about the Sprague Atom controversy?

[Randall]

I had the occasion to replace a blue Atom cap, and have always wanted to cut one open to see what they are made of. I guess we've all seen or heard the claims that some are fakes with little chinese caps stuffed inside. Well, here is what this one looks like.

[nosaj]

I had the occasion to replace a blue Atom cap, and have always wanted to cut one open to see what they are made of. I guess we've all seen or heard the claims that some are fakes with little chinese caps stuffed inside. Well, here is what this one looks like.

[ATTACH=CONFIG]53646[/ATTACH][ATTACH=CONFIG]53647[/ATTACH][ATTACH=CONFIG]53648[/ATTACH][ATTACH=CONFIG]53649[/ATTACH]

Is the Date code 7/92? Did I read that right? If so probably well before the fakery.

nosaj

[nevetslab]

Is the Date code 7/92? Did I read that right? If so probably well before the fakery.

nosaj

7th week of 1992.

[J M Fahey]

It´s probably a semi-fakery ...made by the original maker: a regular modern smaller electrolytic (of reasonably good quality if it worked for 15 years) but packed in a way too large MOJO-full blue case and sold at 2X or 3X the regular price.
Was it floating inside or there was some kind of structure to avoid it vibrating to death?

[nosaj]

It´s probably a semi-fakery ...made by the original maker: a regular modern smaller electrolytic (of reasonably good quality if it worked for 15 years) but packed in a way too large MOJO-full blue case and sold at 2X or 3X the regular price.
Was it floating inside or there was some kind of structure to avoid it vibrating to death?

I think what your seeing is the plastic wrap was cut an then expanded out some.. Looks legit to me.

nosaj

[Chuck H]

Pretty sure Juan was talking about the size of the actual capacitor as it relates to the can. I've cut open a number of them over the course of the last decade (some old, some newer) and they always look like Randall's photos.

[The Dude]

I don't think it matters what's inside. Everybody knows the tone and mojo comes from the pretty blue plastic shrink wrap on the outside.

[Justin Thomas]

I like F&T. Same quality, great price, GREAT presentstion, half the frickin' size. So if I wanna upgrade my Fenders, they'll fit in the blasted doghouse... Unlike Sprague!

Jusrin

[nsubulysses]

Here's one from United Chemicon. Not as much extra space inside the cap. So as you can see it has FAR less mojo than the sprague.

At least on the plus side it's only about $5-6 for a long life cap rated at 15,000 hours lifetime at +85°C with the rated ripple current applied.

I cut this one open because once in the past I tightened the capacitor clamp too much and I made a dent in the casing. I worried it might have damaged the cap. Guess they add a little safety margin in if you do a klunky move like that ??

[Chuck H]

FWIW I stopped using Atom caps, or any axial cap, several years ago. I've selected a brand and model of radial cap that is more forthcoming in it's specs and a lot less expensive (Atom's are up to about $15+ for 100uf @ 450V!!!). And I did this because I had a couple of builds that I used "fresh" Atom caps on that exhibited symptoms of failing filter caps. I bought the new Atom's from Mouser and I don't expect they grabbed some old, dusty crap they found under the shelf, but I can't know. But that was the last straw. Atom's have very vague spec sheets and a very high price. Having two amps requiring service to those parts as new was the deciding factor and I switched. So... Why go to radial instead of just a different axial product? Simple. All modern products have changed to radial lead board layouts so the greatest selection, options and price break was in that category. Axial caps are the odd man out now with fewer options and, very often, less defined spec sheets. The most you can often hope for with axial options is what gets said about them on "tube amp" forums. Bah! There are ways around the axial lead implementation even on older amps and the options and savings in radial offerings was just too great to ignore.

JM2C

[Justin Thomas]

I still use axial caps cuz I build so few amps, but that design you posted a few years ago about how to work with radials was flat-out badass. I doenloadedit. Then between 3 gadgets lost it. But friggin' brilliant.

Justin

[Chuck H]

I still use axial caps cuz I build so few amps, but that design you posted a few years ago about how to work with radials was flat-out badass. I doenloadedit. Then between 3 gadgets lost it. But friggin' brilliant.

Justin

Why, thank you! I don't think it should go unmentioned though that I probably wasn't the first to come up with the lay down and zip tie method. I know for sure I'm not the only one anyway because at about the same time there were other members here already doing it just about the same way. An added benefit I've found is that it lends itself to locating filters with their respective gain stages and it can also be a space saver in the linear direction because you can usually have two capacitors on the same board width that would typically just have one cap in the middle. Maybe it takes the thread a little off topic, but I'll see if I can locate the thread and link it in an edit.

EDIT: Well I'm not sure I found the thread in question, but here's some good info on using radial caps in place of axials and there IS a diagram of the method I've used for new builds.
https://music-electronics-forum.com/...t=28261&page=2

[SoulFetish]

you guys and your electrolytic caps..

This large housing used in atoms is annoying. I can only assume they do it is for the perception of ruggedness/quality of the brand; if you consider how consumers place value on components in audio electronics, I guess I can understand it.
What I can't understand at all, is how any self respecting modern manufacturer sells an electrolytic with a temp rating of 65˚!!!
I would never spec a capacitor in an amplifier build with a capacitor temperature rating like that, particularly in a tube amp.
having said that, I really never see them fail. My observation working on amps that use atom filter caps is that they may actually be a pretty reliable cap.
Personally, I use MKP caps unless there are constraints that make it prohibitive. But I think they are worth designing around. In our service shop however, we've been regularly using F&Ts in the HT power supply, and Vishay's for bypass caps for replacement parts with great success.

[Enzo]

They do it because there is a market for old school parts. Atoms were used on older gear. They had long bodies and longer leads. Just what you need in point to point stuff. When I rebuild old jukeboxes, the paper caps had long bodies and long leads. I use nice radial 0.047/630v caps in them, one inch leads, and I have to clip the old wires off at the old cap body, then splice the new cap to the old wires. Looks crappy.

[Chuck H]

I really never see them fail. My observation working on amps that use atom filter caps is that they may actually be a pretty reliable cap.

Same here. And that's why I used them for years. They were a recognized staple and people generally liked seeing them in the amps. As long as I wasn't having a problem I just ponied up the extra cash. But then I started having problems with new Atoms. Not "unused sitting in the drawer for a few years", but ordered new specifically for the project. I deal with enough of that trying to get good tubes that'll hold up. I sure don't need to start doing the same with components. I've been using Nichicon PW's for the last three amps and also as replacements for re-caps. No problems yet and they take a smaller bite out of the budget.