Older amp, upgrading capacitors

[TankTop5]

Not sure if this forum is the best place to ask as I don’t see these topics discussed much but maybe point me in the right direction.

My question is, does upgrading older caps to newer or better caps have real tangible results? Also, do caps fail slowly and are there signs to look for or is it sudden and amps are non functional?

 

[Verdinut]

Not sure if this forum is the best place to ask as I don’t see these topics discussed much but maybe point me in the right direction.

My question is, does upgrading older caps to newer or better caps have real tangible results? Also, do caps fail slowly and are there signs to look for or is it sudden and amps are non functional?

The answer is: IF IT WORKS , YOU DON'T HAVE TO REPLACE THE CAPS. You would be just wasting money.

If and when a capacitor fails, you will notice it and then you can replace it. Some amplifiers will operate for more than 50 years without the need for replacing power supply caps.

 

[PENG]

In my opinion and limited experience, I would say as a preventive measure against aging, it may be a good idea to do after 15-25 years depending on usage and general conditions. At that point there should be theoretical benefits but not likely enough to be audible. I have never experienced any audible degradation due to old caps.

 

[Out-Of-Phase]

After a visual inspection looking for bulging or leakage, they can be tested using an ESR meter.

 

[highfigh]

If it is very old and has been sitting idle for decades, it would be a good idea, but testing them is the best first step.

 

[M Code]

A big issue with aging electrolytic capacitors is that they tend to leak over time... But the major problem is when the leakage turns into a short than other damage can/will happen...

Just my $0.02...

 

[Irvrobinson]

A big issue with aging electrolytic capacitors is that they tend to leak over time... But the major problem is when the leakage turns into a short than other damage can/will happen...

Just my $0.02...

I agree, and it's not just aging capacitors; I've had capacitors fail on relatively new equipment more than old equipment. Based on my experience, and the analyses I've seen, capacitors are the biggest single cause of failures in solid state electronics. It's worse in digital electronics and integrated products (e.g. integrated amplifiers, receivers, etc.) because there are more power domains, so there are more capacitors. I've never seen the big power supply smoothing caps in amplifiers fail, it seems like it's usually the smaller ones on the digital or line-level stages that go, but if the smoothing caps age too much and their storage capacity is reduced you can get so-called voltage "sag" in the DC power rails, and that can limit amplifier output. Also, THD might go up considerably when that happens, but no one can predict audibility.

The most recent cap failure I've had was in one channel of my ATI AT3000 amp, and like M Code said it took out multiple components due to the resulting overload. I've also had my prized Levinson No39 CD player/pre-amp fail due to a cap failure on the digital board, which damaged the board so the entire board had to be replaced. IMO, capacitors are a PITA.

TankTop5, what make/model is this amp you're worried about, how old is it, and what sort of operating environment has it been in? Caps hate heat, so cooking in a cabinet can reduce their service life.

 

[Swerd]

On the subject of capacitors, I have often run into the general advice among audio fans, that one should replace electrolytic caps after about 20 years. On some forums, this advice is repeated very often, especially for caps in passive crossovers in speakers, but it could also apply to caps in aging amplifiers or other electronic gear. This general advice has been repeated so much, that it gets recommended for all types of capacitors, electrolytic or film-type, regardless of their construction or their ability to dry out or leak.

I wonder how much this advice is based on facts and how much it's been exaggerated into audio mythology. (Even though it's not directly related to this thread, I can't resist citing an example of how audio mythology has polluted the subject of capacitors.)

Please look over this Wikipedia page titled Capacitor Plague.

​

"The capacitor plague was a problem related to a higher-than-expected failure rate of non-solid aluminum electrolytic capacitors, between 1999 and 2007, especially those from some Taiwanese manufacturers, due to faulty electrolyte composition that caused corrosion accompanied by gas generation, often rupturing the case of the capacitor from the build-up of pressure.​

​

High failure rates occurred in many well-known brands of electronics, and were particularly evident in motherboards, video cards, and power supplies of personal computers."​

I'd appreciate comments from Irvrobinson, PENG, M Code, as well as any others qualified to answer.

My question is, did this so-called capacitor plague of 1999-2007 have too strong of an influence on our general opinion of aging electrolytic caps in older audio products.

 

[M Code]

On the subject of capacitors, I have often run into the general advice among audio fans, that one should replace electrolytic caps after about 20 years. On some forums, this advice is repeated very often, especially for caps in passive crossovers in speakers, but it could also apply to caps in aging amplifiers or other electronic gear. This general advice has been repeated so much, that I've wondered how much it's based on facts and how much it's been exaggerated into audio mythology.

Please look over this Wikipedia page titled Capacitor Plague.

​

"The capacitor plague was a problem related to a higher-than-expected failure rate of non-solid aluminum electrolytic capacitors, between 1999 and 2007, especially those from some Taiwanese manufacturers, due to faulty electrolyte composition that caused corrosion accompanied by gas generation, often rupturing the case of the capacitor from the build-up of pressure.​

​

High failure rates occurred in many well-known brands of electronics, and were particularly evident in motherboards, video cards, and power supplies of personal computers."​

I'd appreciate comments from Irvrobinson, PENG, M Code, as well as any others qualified to answer, whether this so-called capacitor plague has had too strong of an influence on our opinion of aging caps in older audio products.

IMHO..
The primary problem came about as China began to take over the mass production of our audio products in the early/mid 80s... The audio brands needed a local China source for electrolytic capacitors but unfortunately the China suppliers had not yet mastered the design/production process for electrolytic capacitors. The previously built audio components largely from Japan in the 70s' used a better grade of electrolytic capacitors. The Chinese capacitor suppliers had lower pricing than the Japanese sources but had not yet achieved the art of delivering a longer, capacitor service life..

Just my $0.02...

 

[Irvrobinson]

IMHO..
The primary problem came about as China began to take over the mass production of our audio products in the early/mid 80s... The audio brands needed a local China source for electrolytic capacitors but unfortunately the China suppliers had not yet mastered the design/production process for electrolytic capacitors. The previously built audio components largely from Japan in the 70s' used a better grade of electrolytic capacitors. The Chinese capacitor suppliers had lower pricing than the Japanese sources but had not yet achieved the art of delivering a longer, capacitor service life..

Just my $0.02...

I agree with everything you've said, except for the implication underlined above, which implies that the "not yet" is past tense. Though it's just anecdotal evidence, the number of cap failures I personally see in LCD TVs, LCD monitors, various line-level HT products, and even a washing machine control board implies that the quality of relatively low-value electrolytic caps still stinks. Perhaps you really meant to say that.

Regarding Swerd's question, the problems I'm personally aware of are all with electrolytic caps, conventionally mounted to circuit boards (in other words, none with SMT caps of any type), and exclusively in the power supply portion of the circuitry.

 

[hemiram]

My general rule is if it's old enough to vote, it gets new caps, even if it works fine, and if it's close, it still gets them. I've had several cap kabooms over the years and all of them were on older stuff that showed no real signs of any problems until it happened. And don't get me going about the damn glue they use on some stuff to attach the caps to the board.

 

[Irvrobinson]

My general rule is if it's old enough to vote, it gets new caps, even if it works fine, and if it's close, it still gets them. I've had several cap kabooms over the years and all of them were on older stuff that showed no real signs of any problems until it happened. And don't get me going about the damn glue they use on some stuff to attach the caps to the board.

I've met a few folks who feel the same way you do about some cherished equipment. And the kaboom risk is real. If you're willing to pay, it's the conservative strategy for longevity.

 

[TankTop5]

TankTop5, what make/model is this amp you're worried about, how old is it, and what sort of operating environment has it been in? Caps hate heat, so cooking in a cabinet can reduce their service life.

It’s the NAD 705... my Denon 1910 after unplugging it and a reset is toast and I don’t think it’s worth fixing. The NAD sometimes sounds like the right channel is stronger but maybe it’s just how a sound track is mixed. That’s why I asked what I should look for if it’s failing. The 705’s sell for $200 for parts but mine sounds great, just trying to decide if and when it needs recapped is it worth it? The Yamaha A-S501 and the Marantz PM6006 look solid and can be had for a decent price if I shop. How do these modern amps compare to a vintage amp like mine if it’s recapped and performing at its best?

 

[lovinthehd]

It’s the NAD 705... my Denon 1910 after unplugging it and a reset is toast and I don’t think it’s worth fixing. The NAD sometimes sounds like the right channel is stronger but maybe it’s just how a sound track is mixed. That’s why I asked what I should look for if it’s failing. The 705’s sell for $200 for parts but mine sounds great, just trying to decide if and when it needs recapped is it worth it? The Yamaha A-S501 and the Marantz PM6006 look solid and can be had for a decent price if I shop. How do these modern amps compare to a vintage amp like mine if it’s recapped and performing at its best?

Test/measure with other than a particular recording/"hearing" session.

 

[TankTop5]

Test/measure with other than a particular recording/"hearing" session.

Well look what just came in the mail. I guess I need to pull out the laptop and do some testing.

 

[lovinthehd]

What software, REW?

 

[TankTop5]

What software, REW?

Honestly I haven’t even opened it yet and don’t know what I’m doing but I’m a lucky button presser

I just need to wait until my three noisy kids and wife gone for a couple hours to figure it out.

 

[Irvrobinson]

It’s the NAD 705... my Denon 1910 after unplugging it and a reset is toast and I don’t think it’s worth fixing. The NAD sometimes sounds like the right channel is stronger but maybe it’s just how a sound track is mixed. That’s why I asked what I should look for if it’s failing. The 705’s sell for $200 for parts but mine sounds great, just trying to decide if and when it needs recapped is it worth it? The Yamaha A-S501 and the Marantz PM6006 look solid and can be had for a decent price if I shop. How do these modern amps compare to a vintage amp like mine if it’s recapped and performing at its best?

The older NAD equipment is highly thought of, but I admit I'm not a big fan of re-capping receivers unless they're classics (like the monster high-end Pioneer and Marantz things from the 70s-80s). Would newer equipment sound better? Some newer equipment would probably measure better, mostly due to the improvements over the years in IC op-amps and output transistors. Are the better measurements audible by comparison? It's impossible to predict, but probably not.

 

[Pogre]

Honestly I haven’t even opened it yet and don’t know what I’m doing but I’m a lucky button presser

I just need to wait until my three noisy kids and wife gone for a couple hours to figure it out.

Might wanna budget more than a couple hours. When I go down that rabbit hole I can spend almost an entire day messing with it...

 

[Out-Of-Phase]

When in doubt, have the caps tested or test them yourself.