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Post by pre65 on Apr 17, 2015 9:59:58 GMT
well made caps not constantly used with a small fraction of their tolerances will probably last a human life time .
What tolerances ?
Using a higher temp rated cap than necessary would be a good example, what are the others ?
I'd like to learn from you.  |
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Post by danielquinn on Apr 17, 2015 10:08:35 GMT
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Post by pre65 on Apr 17, 2015 10:19:42 GMT
Thank you Daniel.
Still not sure you understand though. 
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Post by danielquinn on Apr 17, 2015 10:26:47 GMT
Then take issue with what I have said .
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Post by pre65 on Apr 17, 2015 10:38:36 GMT
Then take issue with what I have said .
I'm off to get some empirical experience of using the GK-71 as a pentode (rather than in triode mode) so may be away for a while. |
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Post by danielquinn on Apr 17, 2015 10:45:36 GMT
not sure what saying something empirical is ?
however , I must be more intelligent that i give myself credit for [ and i give myself a lot of credit ] if a man of your empirical experience is unable to take issue with anything I have said in what as always are my very opinionated posts .
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Post by Deleted on Apr 17, 2015 10:53:55 GMT
Capacitors today especially electrolytic are far more advanced then they were say 10 years ago, much low ESR's, improved temperature range, great ripple current rejection, long lasting Improved TAN's etc.
I still replace capacitors after 8 years regardless as components do degrade over time, weather their are in spec or not.
Leaving equipment on, you have thermal equalization to take into account on many pieces of equipment both solid state and valves.
These days, I switch off my power amps, but leave all low level equipment on stand by.
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Post by MartinT on Apr 17, 2015 11:17:15 GMT
thus to say you understand "capacitors dry out" is not the same as saying in my experience I have seen capacitors dry out . In my experience with both valve and solid state equipment, electrolytic capacitors can dry out or blow their tops and should be replaced, especially if they are approaching 25-30 years old.
In my experience, said replacement usually either renders equipment working again or dramatically improves their sound provided you use good quality replacement parts.
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Post by danielquinn on Apr 17, 2015 11:26:36 GMT
Yes martin but your experience leads you to believe £800 mains leads and £100 fuses have beneficial effects on SQ and thus I am somewhat skeptical in making generalizations upon it and when i say this I make no claims to accuracy or truth , merely as humans we subjectively assess the information given to us with reference to what we know about the person giving it and thereafter assess it accordingly . |
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Post by MartinT on Apr 17, 2015 12:35:34 GMT
Fair comment, but I wasn't umming and ahhing. I try very hard not to pass opinion on things I don't understand or have no experience of, but the listener can't necessarily distinguish that from opinionated crapulence.
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Post by gazjam on Apr 17, 2015 19:22:19 GMT
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Post by gazjam on Apr 17, 2015 19:44:23 GMT
I don't think you'll regret that, Gaz. I'd have regretted NOT doing it! Had the volume pot and input selector renewed too. |
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Post by MartinT on Apr 17, 2015 21:03:24 GMT
The take-away from that is what has been stated here already: "the service life decreases as the temperature increases". Power amps, especially, can be quite hot environments.
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Post by Deleted on Apr 17, 2015 23:03:24 GMT
Comes down to the Arrhenius equation for reaction rates en.wikipedia.org/wiki/Arrhenius_equation , and since an electrolytic capacitor is a chemical device its lifetime follows an Arrhenius temperature dependence. Higher temperature = higher reaction rates = lower lifetime. Arrhenius mechanism has been known for well over a century. Craig |
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Post by canetoad on Apr 17, 2015 23:35:43 GMT
If age isn't an issue for caps why do the manufacturers supply the life expectancy figures in their specs. As manufacturers they think the caps have a finite lifespan too.
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Post by danielquinn on Apr 18, 2015 5:41:19 GMT
We're do manufactures supply life expectancy figures of capacitors?
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Post by ChrisB on Apr 18, 2015 6:13:46 GMT
That's an excellent typo there DQ! - I read it as "weirdo manufactures supply life expectancy figures of capacitors"
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Post by stanleyb on Apr 18, 2015 7:00:42 GMT
Slightly off-topic I know... Last year I took my 'old' Sugden A21a to Sugden's for a service. I asked the headman (Patrick) about recapping. He laughed out loud and said, yes, he could do them, but it would be a complete waste of time and money. Capacitors were meant to swell and buckle a little under use; this recapping malarkey was exactly that. These are the sort of things that make a lot of British audio servicing technicians look out of touch. Capacitor technology has advanced a lot from being just another component to the status of a critical component for sound quality. |
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Post by Deleted on Apr 18, 2015 8:40:59 GMT
Here you go guys, how to calculate the lifetime of an Aluminium Electrolytic Capacitor  and to make it easier for you... Capacitor Lifetime Calculator(s)It also does "film" and "ceramic" caps. Yes, I know it's not "definitive" but you can now have fun desoldering all of your caps and reading the info on the sides so you can enter it into the calculators on that site, oh, and don't forget you'll need to know the ambient temperature of the operating environment too. Fun for all the family.   Ah - I missed this post. That is the Arrhenius equation applied to capacitor lifetime. |
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Post by AlanS on Apr 18, 2015 8:50:03 GMT
Slightly off-topic I know... Last year I took my 'old' Sugden A21a to Sugden's for a service. I asked the headman (Patrick) about recapping. He laughed out loud and said, yes, he could do them, but it would be a complete waste of time and money. Capacitors were meant to swell and buckle a little under use; this recapping malarkey was exactly that. 1. These are the sort of things that make a lot of British audio servicing technicians look out of touch. 2. Capacitor technology has advanced a lot from being just another component to the status of a critical component for sound quality. 1. How do you know about this large(?) number of technicians? What number and proportion of the total are you referring to? To you have access to a survey of all audio engineers? That us a very ambiguous statement to my eyes, I can accept you may speak with them about DACs, your products in particular, but do you review all their areas of work to include PSU capacitors 2. Surely capacitors are as critical as the original designers design made them. They haven't gone throgh some mystical transformation according to your statement. They are what they ever were. If a bad design or choice of supplier was made that is true from day 1 of the product. If well designed and spec'd product was used they are no major issue. |
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