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electrolytic capacitor question 7868 amplifier

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philips fx82

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Hi to everyone, I will be ordering electrolytic caps for my Sylvania 7868 se amp this week. There are not many manufacturers making audio grade caps in my budget, for the 200 volts-350 volt range. AES has the JJ Tesla
and F &T caps on sale this month. I looked at Mouser for Panasonic caps, but there were no audio grade caps
in the voltages that I am looking for. Any other suggestions? I tend to shy away from unbranded caps from who knows where. Does anyone here have experience with the JJ Tesla caps or the F & T caps? I would appreciate any suggestions or opinions.

my thanks in advance
 
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philips fx82 said:
Hi to everyone, I will be ordering electrolytic caps for my Sylvania 7868 se amp this week. There are not many manufacturers making audio grade caps in my budget, for the 200 volts-350 volt range. AES has the JJ Tesla
and F &T caps on sale this month. I looked at Mouser for Panasonic caps, but there were no audio grade caps
in the voltages that I am looking for. Any other suggestions? I tend to shy away from unbranded caps from who knows where. Does anyone here have experience with the JJ Tesla caps or the F & T caps? I would appreciate any suggestions or opinions.

my thanks in advance
Click to expand...
The price of film caps are quite reasonable and i would pay a little bit more for a much better product. Unlike electrolytic caps, film caps like Solen, ASC, Panasonic, etc. have no built in lifespan as long as their ratings are not exceeded. Solen has voltage ratings at 250, 400, 630 vdc. Panasonic DC link are excellent caps but only available at 500vdc.
Film caps also outperform electros in terms of speed and to me sound quality. They are very compact and should be able to fit under your chassis.
 
I've had several F&T in service with no problems, and one JJ also with no problems. Its a power supply cap, no need to get crazy about it. Audio does not pass through it.
 
I use the JJ caps in just about everything I build; they are a fantastic value and perform well. I have used the F&Ts as well (their 33uF+33uF cap is pretty handy). You don't need so-called "audio grade" for the power supply.

As for the signal path caps, I always use the Illinois yellow tubular metalized polypropylene film caps. They are also solid performers and the price is right.

All of these are available from AES. They are pretty much my sole source of caps these days, unless I have a particular need that they don't stock.
 
Installed many JJ & F&t caps (guitar amps) Never a problem ! They're half the size of originals, which makes replacement easier. Just don't exceed 500v ever.....
 
If you ever look at datasheets for "audio grade" caps, even from the big names, you'll notice a suspicious lack of actual data in them compared to a datasheet for a general purpose cap from the same maker. Such things make me highly suspicious. I won't pretend to have an in-depth understanding of every single parameter in those sheets, but when they go away completely it makes me wonder what they are trying to hide.
 
I recently used the Panasonic DC Link film (35uF 500v) as a first cap in a Sherwood S-5000 and a Fisher SA-16 and would certainly recommend them if you have space to mount them. I usually use individual Panasonics or Nichicons to replace various sections of can caps. Usually that's considerably cheaper than replacing the can. I did use a JJ can on the S-5000 because it made more sense in terms of available space.

Individual caps are also easier to find in different voltage ratings. Don't worry about having the exact same voltage rating, just be sure it isn't lower. Usually the slightly higher voltage ones aren't much larger and you get a larger margin of safety. Get quality, general use, caps from major manufacturers and you'll be fine. Forget about labels like "audio grade". Look at the specs and get ones rated for 105 degrees rather than the standard 85 and buy ones with the highest hour rating, which is usually 10,000 hours. By using individual caps you have more options (voltage ratings, temp, hours) than you generally find with can types. I just leave the old cans in place for appearance's sake.
 
I ordered my caps today from AES, they were mainly F & T, and JJ Tesla with 2 small Atoms. None of these are 105 degrees, they are mainly 85
degrees with one cap at 65 degrees. Hopefully I shouldn't have any problems. If the temperature rating is critical, why don't companies like F&T and JJ
Tesla make a higher temp rating cap?
 
I'm no technical expert but my understanding is that the closer you operate a cap to its temp rating and voltage rating, the fewer hours of use you can expect. I don't know what it is about the construction that allows for higher temp ratings or higher hour ratings. I've used 85 degree caps before and still do occasionally but when I buy new caps to replenish my stock I only buy 105 degree, 10,000 hour rated caps.

I've never seen a vintage cap that was rated higher than 85 degrees. I assume modern construction techniques allows the higher, 105 degree, rating. Perhaps there are some can type caps that are rated at 105, I don't know. Or, maybe since they are mounted above chassis where there, presumably, is better air circulation they figure anything over 85 degrees is unnecessary. I've never noticed if any of the can types publish an hour rating.

I prefer to disconnect the can and replace the sections with the highest quality general purpose cap I can find, which I mount under chassis. It's not only cheaper, in most cases, but you also have a much wider selection. Individual lytics also are quite small compared to their vintage predecessors.

I assume caps rated at 85 would be OK given that the vintage ones you're replacing had the same rating. I'd try to install anything rated lower in as cool a location as possible.
 
Part of it is packaging I expect. Jam 2 into a single can and they can't radiate heat as effectively as one cap.

The further below ratings, the longer they last. Those lifespan ratings are at maximum ripple current, voltage, and temperature. Lower any of them and the life extends. The further you lower it, the further it extends, though I expect there is a point beyond which lowering the abuse the cap deals with doesn't give any more useful life.

I also tend to like individual caps, but sometimes that physically is not an option. At that point you're left with re-stuffing or replacing with cans topside. I've done both, depending what is appropriate. I hate re-stuffing caps though, so I go with new when I can.
 
My thanks to everyone for their reply. For my next project, I will probably go with Panasonic cap with 10,000 hour life and 105 degrees temp rating.
A question for everyone, could you explain ESR rating, and is lower better? And also what type of ripple current rating should I be looking for. The next project should be a Motorola 3 channel amp, push pull 6v6 with a rectifier tube. My thanks in advance
 
ESR is effective series resistance. Capacitors have internal resistance. You can picture it as a capacitor with a resistor between the connection terminal and the actual capacitor inside the can. Lower ESR allows for higher current demands on the cap since it has less resistance. For power supply filtering purposes, I'm not sure you need special low ESR caps for it to work effectively. Modern ones are usually lower than what they replaced anyway.
 
I'm not a techie whiz so someone please correct me if I'm off base.

Yes, lower ESR is better but the difference in a power supply application between ESR of quality, new, caps is probably not worth worrying about. As for the ripple rating, I believe a higher value is better. But again, I think the temp rating and hour rating are more important. If you're considering two caps that have the same temp and hour rating and are priced about the same, then sure, buy the one with the better ripple rating or ESR. I wouldn't pay considerably more for it though.

I find that measuring the ESR is handy when I am considering the possibility of leaving an old cap in place. If its ESR is considerably higher than my prospective replacement, I replace it. It's my understanding that in most cases before a cap goes bad its ESR will start to increase so a higher ESR might be an indication that a cap is near the end of its useful life.
 
If you are worried about ESR, then film caps have the lowest. There is no electrolytic chemicals that will go bad over time.
 
Higher ESR does tend to be a way caps fail. They basically don't filter as well once that happens, even though the value might still read OK.

ESR is a modern way of measuring what used to be called "power factor". The ESR name is a better description of what you're actually trying to find out though. If you have a really old cap tester, it'll have the PF control. That was actually explained in the manual how to translate PF to capacitor efficiency. The higher the power factor, or higher the ESR is, the less efficient the capacitor is at filtering. From memory, my old Solar says that a 10% PF equates to a loss of 20% efficiency in the capacitor.
 
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