Do amplifiers "fatigue" as they age?

V

vivaveloce

Audiophyte
#1
Question for the Audioholics community. I have an old Rotel RB-986 MkII 5-channel amplifier at the center of my home theater system. Lately it seems that we need to increase volume on shows and movies more than we did in the past. I'm wondering, do amplifiers have a "half-life" where their poser output declines over time? I've had the amp for 20+ years and wonder if it's time to retire it.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Ratings
7,535 17 25
#2
Question for the Audioholics community. I have an old Rotel RB-986 MkII 5-channel amplifier at the center of my home theater system. Lately it seems that we need to increase volume on shows and movies more than we did in the past. I'm wondering, do amplifiers have a "half-life" where their poser output declines over time? I've had the amp for 20+ years and wonder if it's time to retire it.
They really fatigue in that sense. Caps do tend to age, but that would not likely cause that fault. If the loss of gain is occurring at the map, then it would most likely mean that a voltage regulator is getting out of spec at some place, reducing gain.
 
davidscott

davidscott

Senior Audioholic
Ratings
307
#3
They really fatigue in that sense. Caps do tend to age, but that would not likely cause that fault. If the loss of gain is occurring at the map, then it would most likely mean that a voltage regulator is getting out of spec at some place, reducing gain.
How long does it take caps and voltage regulators to age? Just curious.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Ratings
7,535 17 25
#4
How long does it take caps and voltage regulators to age? Just curious.
How long does it take caps and voltage regulators to age? Just curious.
Well, they may not. The rate at which caps age, very much depends on manufacturer of the caps and materials used more than anything else, and usage. Long periods of disuse can also accelerate the problem.

The failure of other components is random on the whole, although with a tendency to fail when new more often than not.

In this case, I was just purely speculating on the likely cause of a loss of gain. If that happens to an amp it generally means there has been a loss of voltage to an area of the amp.

And of course no evidence was provided in this case that this issue, was actually a problem with your amp, and not another piece of equipment in the chain.
 
davidscott

davidscott

Senior Audioholic
Ratings
307
#5
Well, they may not. The rate at which caps age, very much depends on manufacturer of the caps and materials used more than anything else, and usage. Long periods of disuse can also accelerate the problem.

The failure of other components is random on the whole, although with a tendency to fail when new more often than not.

In this case, I was just purely speculating on the likely cause of a loss of gain. If that happens to an amp it generally means there has been a loss of voltage to an area of the amp.

And of course no evidence was provided in this case that this issue, was actually a problem with your amp, and not another piece of equipment in the chain.
 
davidscott

davidscott

Senior Audioholic
Ratings
307
#6
Thanks I have a HK3490 receiver circa 2010 or so with no problems. I sold a 2001 Technics receiver to a friend with no issues either. Nice to know about the long periods of disuse. I play my receiver at least once or twice a week. Thanks again.
 
H

Hetfield

Audioholic Chief
Ratings
299 3 5
#8
I have a Parasound amp I hadn't used used in probably 10 years because I didn't have the room until about a year ago. I actually contacted Parasound and got the founder and owner to respond to me and he said there is nothing to do in preparation for hooking it back up and using it again, everything should be just fine and guess what, it was. It's a tank of an amp and sounds fantastic. Really powers my Def Tech's nicely.

Sent from my Pixel using Tapatalk
 
L

Leemix

Full Audioholic
Ratings
123
#9
Question for the Audioholics community. I have an old Rotel RB-986 MkII 5-channel amplifier at the center of my home theater system. Lately it seems that we need to increase volume on shows and movies more than we did in the past. I'm wondering, do amplifiers have a "half-life" where their poser output declines over time? I've had the amp for 20+ years and wonder if it's time to retire it.
It could be setup changes, room changes, your hearing or different sources/tv channels.


Sent from my iPad using Tapatalk
 
davidscott

davidscott

Senior Audioholic
Ratings
307
#10
It is not always about playing it or not, often it is about being unplugged as certain components of an amp should stay charged.
It stays plugged in to a surge protector so its always in standby mode. (Unless I unplug it during particularly nasty thunderstorms) Thanks again!
 
A

Andrein

Full Audioholic
Ratings
75 8 1
#11
It is not always about playing it or not, often it is about being unplugged as certain components of an amp should stay charged.
What exactly are these components that should be always charged and are actually working while the amp is in standby mode?
 
killdozzer

killdozzer

Audioholic General
Ratings
721 6 12
#12
What exactly are these components that should be always charged and are actually working while the amp is in standby mode?
Here's a quote from a member I trust:
Amp - The capacitors should not be allowed to completely empty, so unit should be plugged in and turned on periodically (no need for signal). However, I have no idea how often this should be done or how long!
 
KEW

KEW

Audioholic Warlord
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5,099 22 9
#13
Capacitors are essentially batteries.
I am no EE, but I think looking at capacitors about the way you would manage coordless batteries (NiCad is my best guess) is reasonable. If you let them completely discharge, their capacity/life will be compromised. I would say a quarterly recharge (I have no idea how long, but 24 hours should definitely do it) would probably keep them working well. I have had amps unplugged for years that still seem to work fine, but that doesn't mean they are working like they should, it only means I am not putting enough of a demand on it to push the amp's capability!

I would trust TLSGuy's response as someone with more authority on this:
The rate at which caps age, very much depends on manufacturer of the caps and materials used more than anything else, and usage. Long periods of disuse can also accelerate the problem.
 
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highfigh

highfigh

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#14
Capacitors are essentially batteries.
I am no EE, but I think looking at capacitors about the way you would manage coordless batteries (NiCad is my best guess) is reasonable. If you let them completely discharge, their capacity/life will be compromised. I would say a quarterly recharge (I have no idea how long, but 24 hours should definitely do it) would probably keep them working well. I have had amps unplugged for years that still seem to work fine, but that doesn't mean they are working like they should, it only means I am not putting enough of a demand on it to push the amp's capability!

I would trust TLSGuy's response as someone with more authority on this:
Kind of. Capacitors that are connected parallel to the B+ are used to route AC away from the rectified DC voltage/current, as a way to 'clean it', not as a long-term source of power. They do keep the voltage relatively stable when demand increases, but only for brief periods- there's no Amp-Hour rating for these caps. NiCd and other batteries undergo chemical changes when they're discharged- capacitors usually don't. They don't like to be discharged instantaneously, though.

The voltage used and the cap's rating matters, too. A power supply that may have a way to slowly increase DC is a lot more gentle on the caps than just slamming them with high DC voltage- an amp that uses tubes and doesn't have a standby switch will slowly present DC to the tube plates as the rectifier heats but a solid state rectifier or an amp with a standby switch is the opposite- the DC voltage isn't there until the switch is flipped and then, it can go past 500V, depending on the tubes. Typical non-catastrophic failures in these usually comes in the form of hum, weird harmonics on low frequency notes or loss of dynamics.
 
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highfigh

highfigh

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Ratings
3,171 9 14
#15
Question for the Audioholics community. I have an old Rotel RB-986 MkII 5-channel amplifier at the center of my home theater system. Lately it seems that we need to increase volume on shows and movies more than we did in the past. I'm wondering, do amplifiers have a "half-life" where their poser output declines over time? I've had the amp for 20+ years and wonder if it's time to retire it.
Look into the amp, from the top- you will see some large capacitors that may or may not have a black rubber membrane on top; they may have metal that looks like it has a pattern of lines. In either case, the tops should be flat, not domed. If they're not flat and show an obvious curve to the top, they should be replaced- that's about the easiest way to tell if they're getting old without actually testing them.
 
Swerd

Swerd

Audioholic Spartan
Ratings
4,952 11 6
#16
Look into the amp, from the top- you will see some large capacitors that may or may not have a black rubber membrane on top; they may have metal that looks like it has a pattern of lines. In either case, the tops should be flat, not domed. If they're not flat and show an obvious curve to the top, they should be replaced- that's about the easiest way to tell if they're getting old without actually testing them.
highfigh is correct. I thought I'd add a few pictures to what he said.

Power supply capacitors in receivers or amps are large cans, often more than one, usually mounted vertically. They come in variety of colors and appearances, depending on the maker.
1550420483898.png


Here are two large capacitors. On the left is a normal cap. On the right, the cap is bulged and is on its way to failure. Look for bulging, or evidence of leaking – dried crusty deposits where the cap actually leaked.
1550420581592.png
 
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