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Old 11th December 2006, 04:14 AM   #1
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Default Capacitor lifespan and audio quality

What happens to audio quality as capacitors -- and, notably, aluminum electrolytic capacitors -- approach and exceed their rated lifespan? Should one be as concerned about replacing them as, say, vacuum tubes?

(see this link for Elna's take on this issue)
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Old 11th December 2006, 10:59 AM   #2
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Depends on the age, the amount of ripple current the cap is regularly subjected to, and the ambient temperature in its environment. All of these contribute to the aging of the cap.

My own rule of thumb: if it's 15 years old or older, replace it. When it is in doubt, replace it. If something weird is happening on that board, replace it.

New low ESR caps (Panasonic FC and FM and Nichicon PW and HE) are so much better than anything used in older gear that the reasons NOT to replace them pale in comparison to the benefits.
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Old 11th December 2006, 12:20 PM   #3
AMV8 is offline AMV8  United Kingdom
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Hi

I have been rebuilding some equipment that I originally built in 1980 at which time I used Elna electrolytic capacitors and also ALS20 electrolytic capacitors.
I found a slight improvement from chaging the elna capacitors. I did not find any change from changing the ALS20 A capacitors. In fact in one power amp I put the ALS20 capacitors back in as they sounded better.
Plastic capscitors ( such as polcarbonate, polystyrene etc ) do not seem to age but electrolytic ones do seem prone to drying/leakage.
If possible I use 105 degree capacitors and not 85 degree capacitors. The higher temperature rating gives them a much longer useful life as they are operating so much more within their temperature rating. I think that is why the ALS20A capacitors were still working fine after 20 years.
The last caps I bought were Kendeil and they have a rated life of 10,000 ours at 105 degree. So as long as they do not dry out ( in central heating ) they should last some time.
When storing capacitors at home,before use,I store in air tight plastic bags to avoid drying out if possible.
I hope this helps.
Don
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Old 11th December 2006, 04:37 PM   #4
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Quote:
Originally posted by AMV8
Hi

I have been rebuilding some equipment that I originally built in 1980 at which time I used Elna electrolytic capacitors and also ALS20 electrolytic capacitors.
I found a slight improvement from chaging the elna capacitors. I did not find any change from changing the ALS20 A capacitors. In fact in one power amp I put the ALS20 capacitors back in as they sounded better.
Plastic capscitors ( such as polcarbonate, polystyrene etc ) do not seem to age but electrolytic ones do seem prone to drying/leakage.
If possible I use 105 degree capacitors and not 85 degree capacitors. The higher temperature rating gives them a much longer useful life as they are operating so much more within their temperature rating. I think that is why the ALS20A capacitors were still working fine after 20 years.
The last caps I bought were Kendeil and they have a rated life of 10,000 ours at 105 degree. So as long as they do not dry out ( in central heating ) they should last some time.
When storing capacitors at home,before use,I store in air tight plastic bags to avoid drying out if possible.
Thx for your reply.

I have some equipment that is on all the time. Some feel electronics perform better/"last longer" this way. But with respect to electrolytic caps, I'm not sure always-on is such a good idea. A lot of us may have upgraded/sold/traded-in equipment long before cap lives are "expired". This is especially true for rapidly-evolving technologies, such as DACs and CD/DVD players. But some of my equipment -- notably amps and pre-amps -- is modular and does not become outdated very quickly. So cap longevity may be more of an issue here.
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Old 11th December 2006, 04:55 PM   #5
AMV8 is offline AMV8  United Kingdom
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Hi

I think that the life of a part, especially a capacitor or semiconductor is considerably extended by running at low temperature and at below the current rating. For example a capacitor in a class a power amp may run at 50 or 60 degrees centigrade. If its life is rated at 85 degrees it will not exceed its 85 degree life by much. However if it is life is rated at 105 degrees it will be working long after its rated life.

Don
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Old 18th September 2012, 01:44 PM   #6
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Default Elna capacitors recommendation for Beogram CD 5500 CD player

Hi experts, Can you please recommend the best possible and correct Elna capacitors for my Bang & Olufsen Beogram CD 5500 (CD Player). It was manufactured in 1987

Looks as Silmic II (RFS Series) Electrolytic Capacitors or Silmic ARS series with Silk fiber are the BEST I could think of.

Here is the link to Beogram CD 5500 Service Manual pdf
Beogram CD 5500 Service Manual pdf free ebook download from beomanuals.com

Also the link to its original Elna capacitors picture:
https://plus.google.com/photos/10396...74357282290481

These are the Elna capacitor details from what itís written on it:

Elna 470 (M) RE CE85C
8902
40v
8mm Width
24mm Length
HERE is the image: https://lh6.googleusercontent.com/-4...6/DSC_8537.jpg

Is this the right model?
capacitance (μF) / voltage (Vdc) / body dimension D * L (mm) / Price exc. vat
ELNAS-145 330 50 16 * 31 £3.25


This capacitor on this page: Elna Cerafine and Elna Silmic Capacitors homepage


Considering that my CD player Elna capacitor is 8mm Width I will need a gap of 8mm between this (above) capacitor. Would it be safe to band the capacitor pins in order to fit them into the circuit board?


P.S. Should I bother or consider this part as well? (I took a picture of it as well)
DIN 41253
25V-
ROE 4700 F.
W9


And


DIN 41253
EGD -40. 105 C.
25V-
ROE 2200 F.

Thanks for helping
Mykhailo
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Old 18th September 2012, 02:55 PM   #7
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AMV8,

electrolytic capacitor lifetime halves for every 10C temperature rise. and they are spec'd for a given lifetime at their max rated temperature.

so if you have two caps with the same rated lifetime & rippple current, but one is an 85C cap and the other is 105C, then the 105C cap will last 4x longer than the 85C cap in the same design.


an 85C cap at 55C has 2^[(85C - 55C)/10C] = 2^3 = 8x its rated lifetime

whereas a 105C cap has 2^[(105C - 55C)/10C] = 2^5 = 32x its rated lifetime

Echowars @ #2 is dead right. And as shown above, its downright silly not to use 105C caps. I'd also recommend Rubycon ZLH series caps - last I looked they had the best overall combination of lifetime, ripple current & ESR. only go to 50V though.

Note: there are some 125C and higher spec'd caps, but dont use them - the ripple current, esr & rated lifetime are not as good. However their electrolytes can take these higher temperatures without breaking down - unlike 105C or 85C caps, so they are used in certain applications where they get filthy hot.
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Old 18th September 2012, 05:10 PM   #8
RNMarsh is offline RNMarsh  United States
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The performance of the 105C caps are also usually better as well as longer life. The 105C are the only ones to use IMO. -Richard Marsh
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Old 18th September 2012, 07:54 PM   #9
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The problem with 105 deg C caps, is that there are 500 and 1000 versions sold. this tells me that the rubber sealant used in the short life ones is probably not as high quality as that used in >3000 hour caps. Oxygen never sleeps, it attacks rubber every day. There is red rubber, there is silicon rubber, look at the difference even as a caulk compound. I've had caps leak in their second powered up hour when the first hour was 22 years ago before I put the equipment away to wait for new tubes. If you're going to throw your equipment away in 10 years, fine, don't bother to look up the hours life specification. Most vendors make you download the datasheet to even see it. (Newark has hours life online). But my ST70 amp I've had to recap 3 times in 40 years, that is too often. And with new JJ 6CA7 tubes, it again sounds pretty good, and is putting out the watts it is supposed to again. Now that I can see the life spec with the internet, I'm buying >3000 hours caps myself, I might live 40 more years and I don't want to do this job again at 95.
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Last edited by indianajo; 18th September 2012 at 08:02 PM.
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Old 19th September 2012, 03:51 AM   #10
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Indianajo,

indeed. the temperature rating alone isnt enough to base a purchasing decision upon. And although it too is necessary, I maintain that high rated lifetime isnt enough either.

there are a lot of really crappy cap manufacturers. there are very few that make excellent quality caps. I've been designing industrial SMPS and motor controllers for 20 years, and will only use the following manufacturers:

Nippon Chemicon, Nichicon, Rubycon, Panasonic

there are some other high quality manufacturers as well (eg Sanyo) but the above four have the best parts - longest rated lifetime, highest ripple current, lowest ESR

In particular I would NEVER buy caps from a chinese manufacturer - and I have made plenty of money by solving problems caused by doing this. Samxon for example make lousy caps, and I dont believe anything their datasheets say wrt lifetime - I have personally disassembled some Samxon caps, and found the internal element OD to be 3mm smaller than the enclosure ID - on some caps but not others - a neat trick for identical components. this gives dreadful thermal performance hence much higher core temperature and significantly lower operating life.

something to be aware of also is specmanship - crappy caps often spec end-of-life at 300% leakage current, 30% capacitance drop. the good ones use 200% & 20%. the difference can be huge - the 300/30 points are a lot further along the time axis, making the spec'd lifetime appear larger.

I have yet to find a better cap than a Rubycon ZLH. any datasheet that purports to do better is probably lying.
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