Why the (continued) love for Sprague Atom "Big Blue&

[Paultergeist]

I think the thread title kind of says it all.....I continue to be curious about this.....

Regularly, I observe gut shots of some exceptional amp builds -- often from builders much more skilled than myself -- and I often notice the use of those large blue Sprague Atom filter capacitors. Frequently, significant efforts must be employed to fit those large capacitors inside of an amp chassis. I continue to ask myself why the popularity of these capacitors persists?

My understanding is that the reason these capacitors are so large is that they are designed as replacement capacitors for devices which originally used physically-large capacitors -- thus the over-sized Atoms make a good physical fit in such applications. Inside of that big blue Atom capacitor tube, however, is a much smaller capacitor, and I cannot find any listed parameter which shows optimized performance of these caps.

If bigger truly is *better,* or at least if physical capacitor size was some sort of indication of quality, then it would seem that -- for example -- F&T caps or Illinois caps might be a preferred choice, as the size of those caps is larger than the actual size of the inner cap inside of the Spragues I have seen opened up.

So.....aside from being a pretty shade of blue, is there some other parameter (tone, etc?) which consistently makes the Sprague Atoms a premium brand of filter cap?

[pops]

Seems to me they used to be a better cap and now are being sold on an old reputation.

[Firestorm]

Size is a consideration in restorations, especially for those of us who do the anal thing of putting new caps inside the old sleeves. But the "bigger is better" thing is based on the size difference between plain foil and etched foil caps. It is argued that plain foil is better for smoothing applications (I don't know why) so that's why the ATOMs were preferred.

If you've cut one open and found a smaller cap inside, I guess that changes things. Might be amusing to cut up a new one and a 30-year old one to compare.

[Paultergeist]

But the "bigger is better" thing is based on the size difference between plain foil and etched foil caps. It is argued that plain foil is better for smoothing applications.......

Well, that is interesting, and at least it is a data point. So......how does one know if the construction of an electrolytic capacitor is of plain foil vs. etched foil construction?

If you've cut one open and found a smaller cap inside, I guess that changes things. Might be amusing to cut up a new one and a 30-year old one to compare.

I do not have an old vintage cap to open up, but I did open up a Sprague Atom (I believe it was a 40 uF) a few years back. I would estimate that about 2/3 of the interior space was air, with the other 1/3 being occupied by the inner capacitor. The inner capacitor was unmarked; appeared to be wrapped in wax paper. I might have a picture somewhere, but I know that there are photos of others doing similar dissections on the web.

I am not saying that these are bad caps. Given the challenges of size, however, I am asking if there is a performance or tonal-based benefit to using these large caps, coupled with the awareness that the large size is an artifact of being packaged into a (partially-hollow tube)?

[LPC78wino]

Real Sprague Bumblebee

[img:499:700]http://img.photobucket.com/albums/v671/ ... blebee.jpg[/img]


N.O.S. "Gibson" Sprague Bumblebee - WESCO

[img:418:700]http://img.photobucket.com/albums/v671/ ... eissue.jpg[/img]
[img:640:480]http://i72.photobucket.com/albums/i168/ ... C03253.jpg[/img]

[beasleybodyshop]

Yep - i cut open a few of those newer blue sprage filter caps that went bad, all of them were actually smaller ones inside bigger ones. This is, to me, actually very bad because if it fails or starts to blow out electrolytic you would never be able to tell from looking at it.

[eniam rognab]

i got screwed on a pair of 18650 lithium batteries, removed the label to find a completely different label with different mAh, then i noticed they would run out WAY quicker than my older ones, watched a video on utooob where a guy took one of these Faker 18650s apart and exposed the real battery inside. only lost a couple bucks on the deal, not losing any sleep over it, but still principles.....

moral of the story: be careful

[guitarmike2107]

"So.....aside from being a pretty shade of blue"

Well the blue and orange drop caps do look nice, that's about it really

If I am trying to build a high quality amp then I use 10000hour caps, like these:

http://capacitoredge.kemet.com/capedge2 ... 4UD2100QT1

otherwise 2000 hours caps are good enough for guitar amps and will last for ages.

[Leo_Gnardo]

Matryoshka capacitors (stacked inside each other like Russian dolls) were covered by TAG a couple years ago. This thread has photo teardowns of Sprague Atoms then others, plus many tales of woe and intrigue. Read up:

http://ampgarage.com/forum/viewtopic.ph ... sc&start=0

[Cliff Schecht]

Or you can go with Nichicon and never get lied to again (assuming you buy from a legit supplier). Heck even Xicon's have never failed me when used within their limits. Learn to use the ripple current charts manufacturers provide in the datasheets and your caps will never be sad again .

[vibratoking]

Well, maybe...there are PCs and monitors filling dumps due to bad Nichicon caps. Don't know the exact failure mechanism...overvoltage, ripple current, whatever. I don't think you can say that Nichicons are a panacea.

[LPC78wino]

I have only built 2 Plexi builds and always learning things from you guys here, like in this thread. Thanks for that...
I have used the yellow 1st & 2nd gen in one of my builds and sound comparable to the (Philips) Mustard's.
I've known of these for a while, but haven't heard these yet.
[img:400:227]http://www.sozocapacitors.com/images/ro ... acitor.jpg[/img]
As alternatives to N.O.S., I suspect they are a good choice in their respective positions. (as well as the F&T's)
I think they're great for builds if the Tone is there, and doesn't require the cosmetic's. It is my understanding that being a newer production, in most cases not have to worry about properly forming, or if they were done right. They are ready to go from the manufacturer out of the box. Otherwise, I do prefer N.O.S. for the eye candy & coolness factor.

[gktamps]

-10%+75% seems a little unimpressive at the high end.
Heat range is lower than many as well, no?

[jelle]

Temp tolerance that is listed on those is not impressive. Especially when they are placed close to the powertubes on a plexi.

But the numbers on a cap are just numbers, unless we know the testing method.

The real question is how they hold up in an amp over time.

On the topic of NOS filtercaps, why risk it? I prefer reliable amps that do not ghost, and do not have exploding filter caps, or even burn out that hard to find vintage output or power transformer. It is like keeping the original tires on a vintage car from the 60s. And then taking it out on the highway.

[Turret]

Sozo doesn't sell those since ages