Filter Cap Temperature Rating?

[reddinis]

I needed new filter caps. This amp is a little "different". The electrolytics are radial type, with both leads on the same end, they stand up vertically from the PC board.

I found some decent caps (not too expensive but not the cheapest) that will fit, but the temp rating is 2000 hours at 85 degrees Celsius. Is that okay?

I'm really hoping they are, because I already ordered them and they were not easy to find. I saw Nichicons I could have used but wanted something a little better.

Thoughts? Thanks.

[Chuck H]

the temp rating is 2000 hours at 85 degrees Celsius. Is that okay?

I'm really hoping they are, because I already ordered them...

I saw Nichicons I could have used but wanted something a little better.

Nichicon has several lines. Many exceed 10,000 hours at max temp and voltage. Check out the selection at Mouser.

The caps you ordeered will "work" but at the spec you site they won't avoid ripple for long. Great caps are available if you know where to look. I've been using Sprague Atoms for all of my builds up until... I've been getting a lot of audible ripple on amps over 20 watts. This is unexceptable. So, after much research, I have decided to try the Nichicon PW series caps. Look up the specs for yourself.

[Steve Conner]

PCB mount radial caps are actually the standard type nowadays. It's the old axial ones which are "different", a throwback from tube days as far as the electronics industry is concerned.

There's a huge selection of radial caps, you just have to look in ordinary electronics distributors like Mouser and Digikey, not tube amp component suppliers.

Get 105 deg.C rated capacitors if you can, they should last much longer at lower temperatures. The brand doesn't really matter, but Nichicon, Panasonic, etc. are all quite respectable. (The last load I bought were some dodgy Chinese make, like "HL" or "Suntan" )

[reddinis]

PCB mount radial caps are actually the standard type nowadays

I didn't know that.

Looks like I might have to send those back and re-order.

I didn't know Nichicion had a good reputation. Maybe from people comparing them to Atoms? I got Panasonics, but they are only 85 degrees C. I had to get the right diameter and length, too, to make sure they would fit.

Next time I'll ask before I order. Thanks for your help.

[Steve Conner]

It all depends on your outlook. If you want capacitors that look like the old-fashioned ones, and would look nice in an old Fender, Atoms are probably the best. They also make a 600V one, I think, and nobody else does.

But the modern radial style are extensively used in switchmode power supplies and the like, where their performance really does matter.

[Alex R]

My view is that brand names aren't likely to help you much in choosing electronic components; you can still rely on published ratings to make your design choices. Hooray, let's be grateful for that. Are Pepsi caps better than Nike caps? Yikes.

[reddinis]

I'm more concerned about the rating.

The ones I ordered are rated for 2000 hours at 85 degrees Celsius.

Will those last a reaonable amount of time in a tube guitar amp?

[Enzo]

I don't mean to sound snooty, but I think you are worried about it too much.

We don't know what you are working on, so the question is, are these caps in a hot environment? Remember that 100 degrees is the boiling point of water. SO while it is warm inside most amps, are these caps right near anything HOT? I usually get 105 degree caps myself, but I am not going to worry about 85 degree caps unless they are crammed together near a working heat sink or some dropping resistors.

Nichicons are just fine. I have not had any service or reliability problems using cheap old Illinois Capacitor caps even.

[reddinis]

Sounds good, Enzo. I'm not re-ordering.

When I ordered, I figured 85 degrees was fine, then started worrying because I see that usually 105 degrees are used.

I'm going with the ones I ordered, they should be fine.

Thank you!

[redelephant]

Even tho 105 caps last longer at high temps, they do have higher ESR due to a different kind of electrolytic. (capacitance being equal).
If long life is important get the largest can u can afford. They also dissipate heat better, so a beer-can type 'lytic of same capacitance will last longer than a compact type, even if the latter has higher temp rating. If u can touch the component for a few seconds, it's temp is 'only' around 60degrees C, and caps are rarely even close to that hot. Granted, if building a compact amp where caps are next to hot tubes, u must use high temp caps...

[guitarmike2107]

Assuming you have the voltage rating in a safe region the life of the cap will be fine, and will be allot more than 2000 hours.

From Wiki "As a rule of thumb, the life doubles for each 10°C lower operating temperature" so lets say you stretch it to 8000 hours because your operating it at a lower temperature.

So if you play your amp for 1 hour everyday it should last ~21 years, that’s pretty good value for money for a part that costs a couple dollars/pounds.

[Gregg]

PCB mount radial caps are actually the standard type nowadays. It's the old axial ones which are "different", a throwback from tube days as far as the electronics industry is concerned.

There's a huge selection of radial caps, you just have to look in ordinary electronics distributors like Mouser and Digikey, not tube amp component suppliers.

Get 105 deg.C rated capacitors if you can, they should last much longer at lower temperatures. The brand doesn't really matter, but Nichicon, Panasonic, etc. are all quite respectable.

+1

Most big manufacturers are using 85 deg electrolytic caps in their amps. I don't see any reason to use axial caps (by the way 99% of them 85 deg) except for the mojo or for repair/replacement. In new builds I use only radial 105 deg caps preferably from well known manufacturers like Nichicon, Rubycon, Panasonic etc. However be aware of fake caps sold in the net under well known labels. Not from the stores mentioned above. There's even a dedicated forum to bad caps:

http://www.badcaps.net/forum/index.php

[reddinis]

Thanks for the help! That's what I needed to know.

This amp does run a little hot, that's why I was worried. But I'm going to put in strong ventilation and a fan, so I'm pretty sure the ones I ordered will be fine.

[Rhodesplyr]

Even tho 105 caps last longer at high temps, they do have higher ESR due to a different kind of electrolytic.

Are you certain? Panasonic EE series 105 degree long-life electrolytic caps have half the ESR of Sprague Atoms--and that's not just going by published specs. I've measured it with an ESR meter and with a professionally calibrated impedance bridge. I just recapped a Hammond B-3 preamp with these, and I think they're going to become my default choice.

[Chuck H]

Panasonic EE series 105 degree long-life electrolytic caps have half the ESR of Sprague Atoms--and that's not just going by published specs. I've measured it with an ESR meter and with a professionally calibrated impedance bridge. I just recapped a Hammond B-3 preamp with these, and I think they're going to become my default choice.

I don't think you can go by published specs. I've never seen any for Atoms!?!

I'm actually glad someone has taken the trouble to measure them. It confirms my recent doubts. In my last two of three builds I'm getting audible ripple that I never use to get and I'm using the same caps. "Same" being a loose term as I am only talking about the part number. I suspect shinanagins on Sprague's part and I intend to switch as well. And you and I aren't the only ones to mention it.

What do they think they're doing? Do they think that as long as their product is "axial" lead and the rep is good that we who make the amps won't notice a serious decline in quality? I guess so because they've been jacking the price too like they think they own the market. They're shooting themselves in the foot.