AVS Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
74 Posts
Discussion Starter #1
Over the years, I have noticed that longevity issues are not necessarily addressed by reviewers, either professional or individual. Some recent layouts I have seen are quite poor.

One glaring example is what heat can do down the road of time. Some parts, such as electroyltic capacitors, are very sensitive to heat, their life can be halved by as little as 10 degree centigrade (approx 18 F) increase in temperature.


For example, a 20 C rise could reduce electroylitic capacitor life to just 1/4 its normal life. A 30 C rise in temperature to 1/8 normal life. So 20 years of life may become just over 3 years.

Electrolytic capacitors generally have a maximum temperature of either 85 degrees centigrade (185 degrees F) and 105 degrees centigrade (220 degrees F). Film capacitors also have fairly low maximum temperatures depending upon the dielectric material used.

Besides adequate ventilation, parts layout within the component is crucial.


For example, electrolytic and film caps should be adequately spaced from heat sources such as large heat sinks in SS amplifiers and especially large vacuum tubes.

Vacuum tubes operate at much higher temperatures than SS devices and their associated heat sinks. Large octal types such as outputs and rectifiers generate more total heat and temperatures typically run 300 degrees F plus.

Besides direct heat, there is also infra-red heat to contend with. Place one's hand within an inch or two from a light bulb and one can gain a sense of both, and the problem. And do not rely on convection around the tube to keep the parts cool. And yes, 1-2 inches has been observed.

Placing electrolytic and film capacitors near hot heat sinks or a large vacuum tube is just asking for premature catrostrophic failure, expensive repair, and possible downstream component failure.

If possible, look inside, check out photos on the internet and check for placement of parts. You may just save yourself a ton of money and grief down the road.
 

·
Registered
Joined
·
703 Posts

Quote:
Originally Posted by Steve Audio /forum/post/14343114

Over the years, I have noticed that longevity issues are not necessarily addressed by reviewers, either professional or individual. Some recent layouts I have seen are quite poor.

Most of the time they rarely have the component long enough for it to matter to them . . .
 

·
Registered
Joined
·
74 Posts
Discussion Starter #3
Very true Mike.


Unfortunately, most have no education or experience in designing and will not see a problem when inspecting the insides, the layout.


This leaves the purchaser to experience the pain and expense when the component fails, and possibly the following component fail as well.
 

·
Registered
Joined
·
3,188 Posts
Most pro gear (good pro gear
) is designed to run 7/24 and I believe they do take these things into the design consideration. One company in particular offers a 20 year warranty on their products so I trust they must consider these design elements. Their products have built a solid reputation for reliability. I believe just as important is using quality discrete parts. A few years back many computer manufacturers were hit with a rash of bad caps on their motherboards where they would fail after a period of time. Something similar happened to my Buttkicker amp - the large filter caps blew. Buttkicker acknowledged the bad caps and replaced your amp if it was in a certian serial # range. Problem is 99.9% of the consumers wouldn't be able to tell a quality cap from a cheap one or would be opening up their components to find out.
 

·
Registered
Joined
·
15,247 Posts
I'm a fan of ventilation.
 

·
Registered
Joined
·
74 Posts
Discussion Starter #7
Hi EC,


But not every product. Good to check for proximity to heat sources like heat sinks and tubes before purchase and save a headache. I saw one not to long ago that is an accident waiting to happen.
 

·
Registered
Joined
·
703 Posts

Quote:
Originally Posted by Chu Gai /forum/post/14357051


I'm a fan of ventilation.


One of the best and funniest short sentences I've seen in a long time.
 

·
Registered
Joined
·
667 Posts

Quote:
Originally Posted by Chu Gai /forum/post/14357051


I'm a fan of ventilation.

Classic "Chu" !!


Don't forget Class A amplification can give off heat that rivals alot of tube set-ups, except for maybe the ARC 610T's !!
 

·
Registered
Joined
·
15,247 Posts
I wonder if Al Gore would buy a Class A amp?
 

·
Registered
Joined
·
74 Posts
Discussion Starter #11
Hi Twitch54,


Yes, agreed, total heat output is quite high in Class A SS amps.


54, I was thinking more of the absolute temp of the tube with nearby part vs heat sink temp or overall temp. For instance, the heat sink of a Class A ss amp might approach 140-170 degrees F(?). Correct me if I am a little off with the temp. The tube's temp will generally be 300+ degrees F. Near the vicinity of the tube, esp octal tubes, a part would reach a higher temp.


Thanks for your point 54. Much appreciated.
 

·
Registered
Joined
·
2,399 Posts
Seriously though, how much detected sound deterioration of a regular integrated amp can happen in 10 years? So far a lot of people mentioned their old amps are just as good as new ones in the market. Well, except when comparing to a class d...
 

·
Registered
Joined
·
74 Posts
Discussion Starter #15
Hi Veda,


Good question. It depends upon how close the part, electrolytic, film capacitor(s) is to the heated part. Most have no problems, but it never hurts to inspect and see. For instance I saw one brand that had a 185 max degree electrolytic and film cap within 1 inch of a hot 300+ degree octal tube. And it was a 5 grand component. That part is not going to last 10 years by any means.


This is probably unusual as no compitent manufacturer would place a 185 degree part that close to a 300+ degree tube, but it can and does happen. And it could cost one big time as the component will not necessarily sound different, it may just short out the supply, or even explode. And the electrical pulse created could travel through the output and harm a down stream component.


I am just suggesting to be careful and check to make sure one does not purchase some unusual component that might fail. A quick inspection makes good sense.


Thanks Veda, good question that needed answering.
 
1 - 15 of 15 Posts
Top