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Post by bobbyt on Apr 13, 2021 1:56:36 GMT -5
Hi Keith, hoping to get your input on my Airmotiv6s which have served me well the past 8-9 years (connected to an XDA!). The right one recently developed a low 60hz hum, and when I pulled the amp board I saw a little staining on one of the big caps. So I'm curious if you have any concerns/cautions about replacing them. I figure it makes sense to do both while I'm in there (woofer seems fine and second cap has no visible issues), but will it matter to have a significantly newer or different brand cap in one speaker vs. the other? Other thing I wanted to mention is that I've had these on smart plugs the last couple years, so they get power cycled a couple times a day and spend hours on & idle. I've never considered this a problem and figure the cap blew from age, but curious whether I might've cooked an otherwise fine cap -- ie am I good for another 8-9 years or am I going to be back here in another year? Thanks!    |
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Post by vcautokid on Apr 13, 2021 5:50:13 GMT -5
To be honest with you I would recap it completely both speakers and you should be golden. If that big filter cap went bad, how far out are the rest. IMHO.
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cawgijoe
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"We made too many of the wrong mistakes." - Yogi Berra
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Post by cawgijoe on Apr 13, 2021 6:01:51 GMT -5
To be honest with you I would recap it completely both speakers and you should be golden. If that big filter cap went bad, how far out are the rest. IMHO. +1 |
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Post by audiobill on Apr 13, 2021 6:15:47 GMT -5
Shouldn’t it read QC-Fail?
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KeithL
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Post by KeithL on Apr 13, 2021 8:36:42 GMT -5
All types of electronic components fail occasionally. And, to be quite honest, electrolytic capacitors are not known for remarkably long life expectancy compared to many other types of parts. (But a capacitor of any of the types that are known for super long life, of similar circuit value and performance, would be the size of a soda can.)
Running electrolytic capacitors at especially high temperatures does shorten their life. However running them at normal temperatures shouldn't be especially bad for them.
Many components "age" over time due to the normal temperatures they operate at... And many components also age due to "power cycling" and "temperature cycling" when you turn them off and on. But you won't get much USE from a part that's stored in a refrigerator and not connected to anything.
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KeithL
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Post by KeithL on Apr 13, 2021 8:45:52 GMT -5
No.
(That would suggest that there's something wrong with the part itself.)
Parts occasionally fail...
It's simply "component failure"... Shouldn’t it read QC-Fail? |
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Post by bobbyt on Apr 13, 2021 11:24:43 GMT -5
Shouldn’t it read QC-Fail? Obviously Emotiva chose capacitors to fail at the 9.5 year mark -- planned obsolescence! No.
(That would suggest that there's something wrong with the part itself.)
Parts occasionally fail... It's simply "component failure"... Shouldn’t it read QC-Fail? Thanks Keith, saw your very detailed response in the other thread and will probably try replacing both caps in this speaker, then run them a while. |
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Deleted
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Post by Deleted on Apr 13, 2021 11:27:24 GMT -5
Shouldn’t it read QC-Fail? Obviously Emotiva chose capacitors to fail at the 9.5 year mark -- planned obsolescence! No.
(That would suggest that there's something wrong with the part itself.)
Parts occasionally fail... It's simply "component failure"... Thanks Keith, saw your very detailed response in the other thread and will probably try replacing both caps in this speaker, then run them a while. A lot of manufacturers especially in the auto industry will design a part to fail say 1 in 100. If only 1 in 200 fail the following year the parts will be selected in order to reach a desired fail rate of 1 in 100 to save money. In auto racing though this is quite different. A part can be made to last not only the duration of a race but an entire season but it will "weigh and cost so much in performance" that it isn't desirable. So a team will select cutting edge specification to only survive a single race. Though a part will be reduced in reliability the weight savings etc of a simple bolt or nut equals performance. How that design factor comes into play w/ electronics in the audio industry I have no idea but just putting this out there. Perhaps the season is 10 yrs where it isn't desirable to go any longer? I mean, Emotiva might hope and even "encourage" upgrades in new purchases at a certain price point.  |
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KeithL
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Post by KeithL on Apr 13, 2021 12:34:13 GMT -5
MOST things are designed with a tradeoff between service life and cost. Do you think your car's engine will run for 10,000,000 miles? Do you expect the door handles and seat covers to last fifty years? How about the plastic on the dash board?
Did you buy "20 year shingles" or "30 year shingles" or "shingles guaranteed forever"? And how often to you replace the paint or siding on your house when it fails?
We absolutely could have chosen capacitors that would last five times as long. However, in order to do so, we would have had to significantly increase the cost of the speaker. (They would also have had to be significantly bigger and heavier .) Older speakers had paper surrounds - which eventually became brittle and fell apart.
And, eventually, the cones themselves crumbled. Many newer speakers used foam surrounds - which also eventually crumble to dust. (Now we use rubber or other more modern surround and cone materials that last far longer.)
And the adhesive that holds most of the mechanical parts together isn't going to last forever either. But it does last a very long time - at least usually.
The bottom line is that, no matter how much you spend, or how great the quality is of the parts you use...
Nothing lasts forever... So something is always going to be "the part that's most likely to fail first"...
If I were AN END USER I would probably replace the same caps in both speakers at the same time. In this particular case (power supply) I doubt using slightly different ones will cause the speakers to sound different. However, once you find the right ones, and decide to place an order, you might as well buy two of each. (The parts themselves don't cost much, there are quantity discounts, and the shipping charges will be about the same.) And, likewise, the labor involved in changing two isn't that much different either. (You've got to get out the soldering iron, prepare a work space, clean up afterwards, etc...)
And, while I wouldn't specifically expect them to fail at the same time... It is statistically somewhat probably that identical parts, operating under identical conditions, will probably have similar life spans... (Since electrolytic capacitors do "age" the length of their lives isn't purely random.... as much as it is with resistors and semiconductors.)
Shouldn’t it read QC-Fail? Obviously Emotiva chose capacitors to fail at the 9.5 year mark -- planned obsolescence! No.
(That would suggest that there's something wrong with the part itself.)
Parts occasionally fail... It's simply "component failure"... Thanks Keith, saw your very detailed response in the other thread and will probably try replacing both caps in this speaker, then run them a while. |
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Post by audiobill on Apr 13, 2021 19:00:59 GMT -5
“ Rethinking the High End” I guess.....
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Post by bobbyt on Apr 13, 2021 19:42:23 GMT -5
MOST things are designed with a tradeoff between service life and cost. ... If I were AN END USER I would probably replace the same caps in both speakers at the same time. In this particular case (power supply) I doubt using slightly different ones will cause the speakers to sound different. However, once you find the right ones, and decide to place an order, you might as well buy two of each. (The parts themselves don't cost much, there are quantity discounts, and the shipping charges will be about the same.) And, likewise, the labor involved in changing two isn't that much different either. (You've got to get out the soldering iron, prepare a work space, clean up afterwards, etc...) And, while I wouldn't specifically expect them to fail at the same time... It is statistically somewhat probably that identical parts, operating under identical conditions, will probably have similar life spans... (Since electrolytic capacitors do "age" the length of their lives isn't purely random.... as much as it is with resistors and semiconductors.)
Thanks Keith, totally understand designing within limits and my comment was tongue in cheek. The Airmotivs have given me years of great service, and if a swapped component gets them running again, I won't consider it time wasted. Also appreciate your perspective on replacements -- I will probably order 4 but just update the 2 in the problem speaker to start. Maybe I'll have the other one open in 6 months or maybe you guys will release new actives before I find their lifespan... As follow-up, I de-soldered both caps, defeated the elastic stuff they were sealed with (biggest pain so far), and metered the "good" cap at +45 milliVolts and the "bad" one at -35 mV, which I figured was close enough to zero it might just be their discharged state. But after connecting a 9v (7.89V actual) to each for 30 seconds, the good one measured 7.86V and the bad one about -30 mV, so that seems conclusive. |
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Post by bobbyt on Apr 16, 2021 15:02:27 GMT -5
New caps arrived and were installed without too much pain. They had about 2v across them which made confirming polarity easy. With circuit board powered but no signal or speaker connection, the PCB leads the caps connected to showed around 51.7v, which surprised me since they're rated 50v.   Reconnected everything and powered up, noticed a faint hum (at about 6" away with no signal). Tried some music and the highs seemed a little faint or distorted, but I had the volume very low. Heat sink fins felt lukewarm, vs. the other speaker that was cold to the touch. Disconnected the speaker connectors and touched the metal bars that sit opposite the 4 transistors (under the board where the blue Xs are in picture below). Left one circled in red seemed to be warmer, but it was mild enough I held out hope, until the next discovery... The 4-pin molex connector circled in yellow sends signal to tweeter and woofer. With no signal or speakers connected, I measured 0v across the right pair (woofer), and about 17v across the left pair (tweeter), and noticed zero heat on the heat sink. So I think the tweeter DC was generating heat at the transistor and probably tweeter too.  So Keith I'm questioning whether it's worth trying to swap out the transistors (I can't locate any markings, not sure if they're under the elastic sealant gunk). Or if Emotiva might have a full board in a closet somewhere... |
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