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Thread: Sprague Atoms

  1. #1
    Forum Member NTBluesGuitar's Avatar
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    Sprague Atoms

    TFFer, JAM, pointed this out to me. But on a couple other amp boards, someone posted pics of Sprague Atom cut open. I think it started over at Hoffman's boards but it surfaced on Weber's, too. Apparently there's been talk of them being a little cap inside a big cap can.

    I do know that Sprague announced that the manufacture of the Atoms had become obsolete. Now I understand why. Also why they're so expensive.



    Someone then wondered if this was how they always made them. Someone posted one from '76 or '77.



    From el34world.com:
    The "problem" with Atoms is: they published the Sizes in the late 1940s/1950s, they must continue to make them THAT size or a few customers will whine, but the old fat paper/foil materials have been obsoleted and are no longer used. So you get a better cap, which is smaller, but they have to put it in an old-size can. The 50% excess space is for no electronic reason, it is just to give a mechanical "Exact Replacement".

    So what you got is a newer better cap in an old-size can.

    > are Sprague Atom caps being constructed/built/manufactured to the same specification that they used to be?

    No. They can't get the old materials. New materials ARE better.

    > have they taken short cuts, cuts that have affected long term reliability or even short term, cost actions that have put a reduced quality product into the hands of the consumer.

    You forget how bad electrolytics were in the 1940s. The new ones ARE better. Reliable e-cap production is a very high-purity process and such manufacturing has come a long way since Atoms were introduced. (They once used raw borax; now it is all extra-refined electrolytes.) Early e-cap production used foil and paper much thicker than really needed, because they didn't have anything thinner; increased demand spurred right-thickness materials. If you think an old one "sounds" better, it is probably aging processes or just self-deception.

    > Anybody have an OLD sprague they can dissect?

    I had a couple of the Original 1930s Spragues. They came in a wax box instead of a can. The box held a turd just like seen above, just like any asian cap (except asians tend to use a lighter color paper). A 16uFd 450V turd was about 8 times the cubic volume of TubeGeek's 16/475 Atom, filled most of the box. They were utterly dead, and had probably been dead for a half-century.
    Quite interesting.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

  2. #2
    Forum Member boobtube21's Avatar
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    Re: Sprague Atoms

    That is pretty interesting, and given the obsessive-compulsive nature of our ilk, not surprising.

  3. #3
    Forum Member Kap'n's Avatar
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    Re: Sprague Atoms

    Very interesting indeed.

    I think of all the folks who said "nothing but Atoms will do."
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  4. #4
    Forum Member Don's Avatar
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    Re: Sprague Atoms

    Quote Originally Posted by Kap'n View Post
    I think of all the folks who said "nothing but Atoms will do."
    What's a good alternative to Atoms?

  5. #5
    Forum Member Kap'n's Avatar
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    Re: Sprague Atoms

    I think IC and Rubycon are fine.
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  6. #6
    Forum Member sliding-tom's Avatar
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    Re: Sprague Atoms

    Quote Originally Posted by Don View Post
    What's a good alternative to Atoms?
    Molecules?

  7. #7
    Forum Member Don's Avatar
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    Re: Sprague Atoms

    How about TAD and F&T?

  8. #8
    Forum Member Kap'n's Avatar
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    Re: Sprague Atoms

    TAD is just a relabeler. I have no idea where they're sourced from.

    F&T is a European supplier. I don't know if you can get them here, but I'm sure they're good as well.

    Xicon is another supplier.
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  9. #9
    Forum Member NTBluesGuitar's Avatar
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    Re: Sprague Atoms

    Quote Originally Posted by Kap'n View Post
    Xicon is another supplier.
    +1.

    Mouser carries them. Xicons are half as expensive, smaller, and rated to the same specs as Atoms. I use them pretty frequently now...used them in the SFDR tune-up I recently did:





    They sound just fine! Not that e-caps do a whole lot to overall sound...

    Now, they don't have the same uF values available as the Atoms, but at +/- 20% going from a 16uF to 22uF isn't changing much. I also read that Sprague continued to make the Atoms, obsolete manufacturing and all, because they are considered 'direct replacement' and are built out to that size and specs as a result.

    I don't have a problem with the Atoms. I just don't think it's necessary to spend the extra cash on them.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

  10. #10
    Forum Member Don's Avatar
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    Re: Sprague Atoms

    F&T .16uF@475v caps are readily available but cost almost as much as Atoms (how's that? ).

    How does changing from .16uF to .22uF caps affect an amp like my 5E3 clone and is there any benefit in having caps rated 475v over 450v?

  11. #11
    Forum Member NTBluesGuitar's Avatar
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    Re: Sprague Atoms

    I would say that you won't really notice much at all with that uF hike. I've done it in a 5E5, 5F1 and now the SFDR.

    I haven't heard anything change. Whats 25 microfarads between friends, eh?

    Only advantage you have with that 25V rating, is, well, 25V more. Now that's 25 more in'n it?
    Last edited by NTBluesGuitar; 06-21-2007 at 11:43 AM.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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    Forum Member Offshore Angler's Avatar
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    Re: Sprague Atoms

    He he, I love all the conspiracy theories this will start. Why do they put the little cap in the big one? I'll tell you why. There is a mil-spec for that cap that has a drawing showing it's form factors and electrical characteristics. It's easier to put a cap in a can than to change the mil-spec, so that's whay they did.
    "No harmonic knowledge, no sense of time, a ghastly tone, unskilled vibrato, and so on. Chuck is one of the worst guitar players I know" -Gravity Jim

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    Forum Member rudutch's Avatar
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    Re: Sprague Atoms

    I like the conspracy theorys better, at least they are more fun to read
    do I look like I know what I'm doing?

  14. #14
    Forum Member Kap'n's Avatar
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    Re: Sprague Atoms

    Quote Originally Posted by Offshore Angler View Post
    He he, I love all the conspiracy theories this will start. Why do they put the little cap in the big one? I'll tell you why. There is a mil-spec for that cap that has a drawing showing it's form factors and electrical characteristics. It's easier to put a cap in a can than to change the mil-spec, so that's whay they did.

    Sure if it's supposed to occupy a certain space, there might be instances where there's a bracket keep it from rattling. Sort of like a Fender 'doghouse' cover sometimes has that foam strip on the underside.

    If you shrink it down, the bracket doesn't work anymore.
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  15. #15
    Forum Member Don's Avatar
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    Re: Sprague Atoms

    Plus, if it was smaller, it wouldn't be special and people might buy another brand of cap.

  16. #16
    Forum Member trevorus's Avatar
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    Re: Sprague Atoms

    It's not the size of the cap, it's the girth of your tubes...

  17. #17
    Forum Member Offshore Angler's Avatar
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    Re: Sprague Atoms

    Quote Originally Posted by Kap'n View Post
    Sure if it's supposed to occupy a certain space, there might be instances where there's a bracket keep it from rattling. Sort of like a Fender 'doghouse' cover sometimes has that foam strip on the underside.

    If you shrink it down, the bracket doesn't work anymore.
    Simpler than that. It has to match the drawing! BTW, I'm not basing this on having seen a mil-spec for it, but having worked for a defense contractor I'm making an assumption. I've seen all kinds of wierd stuff like this. I'll bet my theory is correct. Whenever you see a non-vlaue adding addition that doesn't save weight or cost you can usually bet the military is involved.
    "No harmonic knowledge, no sense of time, a ghastly tone, unskilled vibrato, and so on. Chuck is one of the worst guitar players I know" -Gravity Jim

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    Re: Sprague Atoms

    what about "mustard caps" ive heard so much about?

  19. #19
    Forum Member Kap'n's Avatar
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    Re: Sprague Atoms

    Quote Originally Posted by jerryjg View Post
    what about "mustard caps" ive heard so much about?
    The grayish-tan-yellow (not the yellow) caps here are mustard caps.



    They're coupling caps, and found in Marshalls, Traynors and other amps from the 60's-70's.
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