# what's so special about $35 Capacitors?



## Lincoln (Jun 2, 2008)

I was filter cap shopping this morning,

20uf, 600 volt, electrolytic, aluminum, axial leads

There’s a Vishay/Sprague TVA Atom series that’s selling for $35 each.
What makes it so much better than all the other caps selling for $0.79 to $5 each??? Reliability? 
The only thing I can see is they have no value printed under tolerance. Does that mean +/- 0??
Is there something I’m missing? I don’t understand why one would be so much more money than
the rest.

Avoid Illinois Capacitor, right?
How about Multicomp?


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## nonreverb (Sep 19, 2006)

600 Volt rating would be the reason...


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## gtrguy (Jul 6, 2006)

You're probably also looking at the -E3 version which is ROHS compliant (lead free). Stick to the non-ROHS (without the -E3 at the end of the part#) and you'll save $10 in the same value and voltage rating.


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## Steve_F (Feb 15, 2008)

ROHS compliant, High Voltage tolerance and tighter tolerance (i.e. +/- 1% instead of +/- 5% or 10%) to listed values will increase price. So will snake oil. High price can be any combination of reasons. Sometimes snake oil is one of them. I can't speak to the quality of the caps above but sometimes it really pays to use a higher quality component. Sometimes it doesn't.


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## nonreverb (Sep 19, 2006)

There aren't many making a 600V cap these days. I have a couple of those 20uF/600V caps from Sprague. They're twice as big as a 22uF/450V. I'm guessing here but probably due to much higher manufacturing costs to create a cap with that high a voltage rating.


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## Steadfastly (Nov 14, 2008)

nonreverb said:


> There aren't many making a 600V cap these days. I have a couple of those 20uF/600V caps from Sprague. _*They're twice as big*_ as a 22uF/450V. I'm guessing here but probably due to much higher manufacturing costs to create a cap with that high a voltage rating.



Yes, they need to size for higher voltage rating. But if you don't need that rating it is mostly money wasted. The biggest reason for the difference in price is the volume produced. They make far, far less of these than capacitors with a lower voltage rating. The uF rating has to be what is specified but you can increase the voltage rating from the original but you can't go lower on the voltage rating than what is specified.


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## Lincoln (Jun 2, 2008)

nonreverb said:


> There aren't many making a 600V cap these days. I have a couple of those 20uF/600V caps from Sprague. They're twice as big as a 22uF/450V. I'm guessing here but probably due to much higher manufacturing costs to create a cap with that high a voltage rating.


I found 20uF/450V for as little as $0.77 each. Just Radios in Toronto sells 20uF/600V for just under $6 each. The baby blue ones, I forget the brand name on them (if there is one even). They are +/- 20% and rated for 1000 hours. It's going to be filter caps for a 5F6A. Good enough?

what I don't need is to spend $35 a cap and then discover they are too large to fit under the cap can


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## nonreverb (Sep 19, 2006)

With a tube rectifier? Nah....you don't have to go that high. The schematic has the plate voltage @ 432V. Even with the elevated 120VAC from the spec 117VAC you should be ok....500V rating should be sufficient. If you're worried, do the series configuration with a couple of 40uf/300V's and a couple of 220K resistors for the first filter section.



Lincoln said:


> I found 20uF/450V for as little as $0.77 each. Just Radios in Toronto sells 20uF/600V for just under $6 each. The baby blue ones, I forget the brand name on them (if there is one even). They are +/- 20% and rated for 1000 hours. It's going to be filter caps for a 5F6A. Good enough?


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## jb welder (Sep 14, 2010)

nonreverb said:


> They're twice as big as a 22uF/450V.


That's so they can fit the 2 real caps in series inside the can. Or maybe that's not Sprague


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## WCGill (Mar 27, 2009)

A picture is worth 1,000 words. The F&T 20/500 is smaller still, perhaps the same size as the Sprague is internally. I should cut one open and see if all the dissing is true.


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## dtsaudio (Apr 15, 2009)

Granted Spragues have always been expensive, even overpriced, but in a lot of cases you get what you pay for. I've seen numerous pieces of gear, new and old with failing caps that according to their ratings shouldn't have failed. What a lot of manufacturers stress is voltage and tolerance. It's the specs you don't see that tell the story. ESR, Ripple Current, temperature coefficient will tell you whether a cap is any good and worth the money. I've seen 30 year old Spragues that still meet spec. I've also seen cheap caps less than a year old fail. Just ask anybody that's worked on Blues Deluxe and Deville amps.


> Avoid Illinois Capacitor, right?
> How about Multicomp?


IC makes good and bad caps. Multicomp could be anything - re-labelled from a few manufacturers. They generally are ok in lightly stressed situations.

I do agree though that $35.00 is a bit over the top.


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## Lincoln (Jun 2, 2008)

Any point in making the first filter cap 600 volt, and then leaving the rest of them as 450V or 500V? Would that be unnecessary with a GZ34 in play?


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## WCGill (Mar 27, 2009)

Fender ran two 70uf/350v (or thereabouts) in series right after the rectifier. This gives you 35uf/700v as capacitance in series halves and voltage rating doubles. I use 100uf/350 F&T's, the modern variant. Make sure you bypass the caps with 220k resistors. Whether you should do it or not depends on your power transformer but with the slow starting GZ34 probably not necessary unless you're running very high B+.
And, and this is really important, the first reservoir cap(s) should be before the standby switch if there is one.


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## nonreverb (Sep 19, 2006)

The 5F6A does not really need a 600V cap. As stated the slow turn on time with the rectifier and the fact that it's sitting at around 430V - 440V doesn't justify the 600V IMO. I would not however, install a 450V cap in there. B+ would be much too close to it's max rating....add the ripple on top and you might have a problem.


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## dcole (Oct 8, 2008)

Fender used the double stacked capacitor as the first capacitor because they put the standby switch after it. What that does generally is raise the voltage out of the PT as its voltage tends to decrease with the current draw. No load applied causes the voltage to rise, thus the need for the high voltage cap. The guy at London Power thinks this is a very stupid arrangement and that a standby if used should switch the ac side before the rectifier.

http://www.londonpower.com/standby-switch


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## WCGill (Mar 27, 2009)

If you're using a GZ34, there's really no need for the standby but putting it on the AC side would negate the slow turn-on advantage if you're using this bottle. Switching screen supplies works well also.


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## YellowBrick (Mar 7, 2015)

I'm guessing that's the price to pay for extra mojo ;-)

What's wrong with Illinois?

You could also have a look at F&T.


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## Lincoln (Jun 2, 2008)

WCGill said:


> If you're using a GZ34, there's really no need for the standby but putting it on the AC side would negate the slow turn-on advantage if you're using this bottle. Switching screen supplies works well also.


I was thinking of moving the standby to the HV CT, rather than where the schematic shows it. 

Other than that with my limited knowledge I'm hesitant to start making changes to the circuit for fear of doing something that would alter the magic. I rely very heavily on the "panel of experts" here to steer the ship. "Thank you" to all of you


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## WCGill (Mar 27, 2009)

I think that will be fine Lincoln.


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