Lifespan of a quality solid state amplifier?

I listen with Audire equipment.  A power supply capacitor failed in the Diffet preamp and was replaced.  But the almost 50 year old Model 2 amplifier soldiers on without fail and sounds amazing.  

Sorry to jump on such an old thread, but it was certainly an interesting discussion. Through a series of unexpected events, I ended up getting pulled back into home audio through the portal of the legendary solid state Crown commercial amps of the ’70s and 80s.

After reading all the lively fan chat about these legendary rock and roll work horses, I’ve been having fun building robust mid-level home stereos around two bargain early ’80s PS-220 units - one with, and one without, rack handles.

It appears that both of them were used in churches, based on their home-made user stickers and eBay seller descriptions. FWIW, I scored one for $125 and the other one for $85.

Built a 6U rack around one of them for our cottage, with high-end 1U TASCAM media player/bluetooth device, modest 1U three-pot preamp and a 1U surge protector power strip. It powers a set of 1990s Cerwin Vega bookshelves and a vintage Jensen powered sub.

The other one, I went the opposite way, with a goal of experiencing a lean rat rod rig in our living room with only a BLT2 DAC into a Shiit un-powered two nput switchable pre-amp, sitting right on top of the amp with ample clear rubber feet :) New mid-price towers and a sweet REL T/5i finish this deal.

To the point of the thread, the PS200 for the rat rod had a lazy red "SPI light" on the left channel, so I sent it away to AE Techron, the Crown mother ship, manned by long time techs and engineers from before the company was purchased by Harman Kardon. It was a great experience in customer service. They replaced the Main IC Dual Op, two 4.7 uf 50V caps and an axial diode. $2.50 for the parts and $255 for the service diagnostic and repair...and I scored a really nice sturdy shipping box from them in the process. It was like one of their babies came home for check up. Very professional.

Both amps have performed very well, can’t really sense a big performance gap between the serviced and un-serviced one, but they are in two different systems in two different homes.

So, yes, these bits can go south, and may need serviced over decades of use, but these old Crowns sound like a million bucks in carefully placed settings in our two houses...for pennies on the dollar!

I too will post my last comment. Even though I know squat about electronics, I repeat what I posted before. I own 2 vintage Crown "back-up" amps from the 70s. The darn things are bomb proof. Even though I have sent them to the Crown factory every once in a while for a check-up, the factory always winds up replacing a few out of spec electrolytics or resisters. The parts cost a buck or two a piece, but the point is they GET replaced. Like US, they AGE. My point is that I love my old Crown amps. I don't care how they sound compared to current stuff. They are 100% USA built, top build quality, and I'm proud to own them. The fact that a couple crappy little passives needs to be replaced every couple years to keeps the amps working at barely measurable distortion levels is AMAZING. That's why I own all ARC gear. It's 100% USA built with probably 100% USA built passives. Even though I pay a heck of lot more that if I bought some foreign built stuff, I'm proud to own it, proud that I can support American CRAFTSMEN/WOMEN. And so far, I can say that other than an occassional bad tube or bias resister, the stuff is bomb proof just like my back-up Crown gear. So THERE!! HUH!! G-d Bless America!!!!!!!

...I will not be responding further since you clearly have no intention of accepting the overwhelming body of evidence that contradicts what you say...

No, caps age. The thread was how LONG and how WELL and amp can sound as it gets older. To go to some of the extremes in this thread would be to toss out an amp as soon as time changes. The discussion was NEVER that caps don't age (you seem to be hell bent on thinking I don't know that), it was how gracefully they age. Nothing contardicts what I say. A fifteen year or older amp can sound pretty darn good. Remember too, that caps are selected to provide the best service and sound where they are used. SS is a wonderful thing...for a long time.

Had a PS Audio 200C amp years ago and it began sounding lifeless with a cracking sound audible. Called PS Audio and the tech said that after about 20 years the caps are pretty much shot. Which led to my purchase of a Belles 350A.

You graduated in one day? Damn!

I attended Harvard...it was a Thursday.

Maybe he attended Harvard.

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Oh my, you are quite the clever one aren't you? I'm so glad we have such a quick witted forum policeman on board.

attack?
putrid?
rants?
denigating? (the correct word is denigrating. If you want to impress us with your vocabulary you should check your spelling)

Hold on a second, your idea that using low-fi, antiquated equipment to prove caps don't deteriorate is rightly, politely refuted and you consider this an attack? There is no "mine is better than yours attitude" in that. It is a simple statement of fact.

Your rants full of insults and abuse is much more denigrating than what you rant about. Probably one of the most ironic posts I've ever seen here.

Thanks for entertaining us.

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Thanks Cathode for being a member of the "non-negative" group. Unfortunately, there are always members who are obligated, predisposed by personality to inject their conflict driven thoughts in conversations where conflict wasn't sought. They enjoy this denigating activity too much to refrain and seek out places like Audiogon where their alleged "knowledge" gives them some kind of entree. Some also actually bring some "useful" information to the discussion. Too bad the "salvageable element" of their post is tainted by the putrid grime of detritus ridden tendencies. Others just blurt out their childlike venom like they use to do at recess. Either way, the members not predisposed to or baited by this type of obvious and weak behavior, continue on here engaging in discussions with reasonable and like minded people. School's never out for some.

Ah, luring the arrogant, denigrative tendencies out of those who simply can't resist the temptation/obligation to grace these pages with thier personality dysfunctions, the holier than thou, "higher end than thou" is a pleasure. Gotcha!:) They can't resist an opportunity to prop up thier pithy, fragile self esteem with yet another childlike attack, "mine's better than yours!" Your mission is not accomplished but mine is! Baiting curmudgeons is easy. Reveal yourself for all to see. They think they gain power thru these inconsequential immature rants. The inner weakness drives this behavior. They remain: WEAK...awww

But- you won't want to listen to lofi all that much either...

"How would you know if your self described "low end" systems have deteriorated when they don't sound that good in the first place"

You have just put your finger on one of the best things about going sub lo-fi. They never break and if they did, you wouldn't be able to tell the difference. Lo-Fi Rules!!

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How would you know if your self described "low end" systems have deteriorated when they don't sound that good in the first place.

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2 old "low end hifi" SS amps chugging along: 1. a Hitachi receiver SR 2000, circa 1981, 70 W per channel continuous, inherited from my now deceased mother-in-law, has operated without a problem. I use it in my home office. It is on now playing blues..:) 2. my Hafler 9180 purchased in 1995 for $477 has never malfunctioned or shown any sign of sonic degradation.....:)

electrolytic caps have a limited life span.
No way around it.
500k hours I think. Average use 25 years or more. Some caps can last up to 50years. It depends on the environment too.
My 26 year old kenwood sounds like I am listening to a low bitrate mp3.
This is due to electrolytic breakdown.

Routine maintenance, inspection and repair is required for any high-end piece of equipment. The same logic you apply to upper quality cars, home, etc. should apply to delicate, high end equipment. If you find a quality older high-end amplifier for example, send it to a qualified service technician for inspection and maintenance. If the amp is older, then they should automatically tell you that the caps should be replaced on general principle. However, also, checking the wiring, connectors, boards for burned traces and wear is automatic. I already posted comments regarding transistor, insulator and thermal heat sink compound replacement. This is automatic for a qualified technician. For someone that isn't properly trained, they wouldn't know what to look for or how to fix it. But, again, it depends on the equipment and whether there is inherent value in it. My earlier example was if at a "fire sale" you find a pair of Mark Levinson 20.6 amps. Absolutely, I would do whatever is necessary to bring them back to top shape and keep them. Capacitors, transistors, etc. But the other example whereby you have a 30 year old low to mid fi panasonic amp. It probably isn't worth it to replace anything. For high voltage power supply rail capacitors for example, they are really expensive. Large TO3 Motorola output power transistors are about $10 each. If your amp has thirty of those, well things start to really add up, incluing labor charges. I find it fun to repair and upgrade older 70's receivers because they are really nice, especially the huge ones with wood grain panels. So repairing them is okay for me. Caps, transistors, the whole thing. But the original poster said "quality solid state amp" Therefore a ML 23.5, ML23, Threshold, Bedini, etc. Yeah! I would inspect and maintain them. As for sound quality of capacitors, well if they are in the signal path, definitely, they affect the sound. But, everthing loses value over time. Older resistors change value. Don't believe me? check it out. Caps, transistors betas change over time and with heat and long term use. it isn't just the caps that would do this. So the argument about caps affecting sound is really not the point. The point is, on an older quality amp, what is the lifespan? The answer is, it depends on what you do to it. And that is proper routine inspection and maintenance, and that totally depends on the knowledge and experience of the qualified technician performing the work. Also, this also applies to older quality tube amplifiers. Proper inspection and maintenance.

enjoy

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Once again, I don't have the energy to read through your dissertation.

Despite whatever you said it is well documented that caps do age and I've replaced enough of them to know they do have a profound effect when I do.

If you google "electrolytic capacitor aging" you will find a ton of information that contradicts your position including Nelson Pass who's equipment you list in your system.

I will not be responding further since you clearly have no intention of accepting the overwhelming body of evidence that contradicts what you say. Believe whatever you wish. It is certainly cheaper than properly maintaining your equipment.

Take care

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400 Years or maybe 300.

You have no facts, just "faith" that can't be proven wrong, even with the FACTS!

First, the thread was, are older amps, or SS in general, serviceable and good sounding at older ages? YES, they are.

I offered how old? Even thirty years old! I have an APT 1 power amp S/N E02248 and use it all the time, as is the PS IV pre-amp S/N 1718 purchased in 1981. Besides, I lied, they are both OVER thirty years old. I'll send "proof" to anyone who wants to see the receipt! I have the shematic if you want to count the number of electrolytic capacitors in the amp! The circuit is a very statistically valid representation of OLD electrolytic life span.

You're invited over to my Mom's house to listen to this "junk" on thirty one year old B&W 801's (S/N 001364 , 001363) and guarantee you you will NOT want to go back to your boom box.

Go to this thread and READ IT! This is measured FACT on cap circuits and parts.
http://sound.westhost.com/articles/capacitors.htm

Until an amplifier circuit of any sort get well outside the passband requirements to pass music (slew rate, frequency response, current delivery ETC) the sound is still acceptably good. Especially at the level music is listened to 85% of the time (which should be 3dB or more below the amps peak output capability).

Proper electronics use capacitors that remain benign to aging where required (poly or Teflon in audio path as an example). Or, excessive requirement can be built-in up front to provide a useful life (HUGE electrolytic cap banks in amplifiers due to ESR increase). This is pretty straightforward use of materials and cost trade-off.

A so called DPA (hey, this MUST be audible if we have an acronym!) analysis is 100% meaningless until such time the double blinded tests PROVE age related degradation is audible in a GIVEN (not any other, they are all different) design. I see no facts here, just wishful thinking.

As long as we see invisible elephants in the room, there is no fact but faith providing fiction. Everyone is afraid to NOT see the invisible elephant, so the audio art gouges those who can see (or hear) the invisible elephant trumpet.

Sorry everyone, I'm not taking the bait to be like the rest of you. I DO NOT hear my older equipment sound "profoundly" bad...just the opposite, it sounds profoundly good for its age. All hundred or so electrolytic caps still seem to be doing their thing in the amp and pre amp (when the old preamp SWITCHES are clean, but that isn't the caps!).

Silly lines applied WAY outside this thread are unproven, too. What is your invisible elephant’s size or time frame? Oh how loud does it trumpet before you can hear it be profoundly different, or unacceptable? You make it up as you go.

"...Caps do matter...
...Caps do have a profound effect on how an amp sounds...
...Caps do age and affect the sound...."

Caps matter if you don't have one (utter failure) way less so if you do and they are used right, and they are simply older. An amp can function very well in this state...mine is. This statement is so utterly obvious to be meaningless (or why would we have caps at all?).

Profound? No, that's an utter garbage statement that is a great sounding adjective, but it holds no double blinded FACT. If it is PROFOUND, like a light switch turned on and off, this thread would answer itself. Someone PLEASE tell my old amp and pre amp to become "profoundly" bad.

Caps, depending on the type and headroom can "maybe" degrade enough to effect the sound. If the amp is several times faster, cleaner and more dynamic than the passband information, it may well be THIRTY years before the amp gets noisy or clips enough to be "profoundly bad". Clipping is the power supply DC voltage rail capability in an amplifier, which does vary with transients / load modulation. But, is the change enough to be “profound” verses a much “softer” degradation? In big amplifier power suppliers, ESR is important, but it has to degrade to a point you HEAR it, not just measure it. I do not concur that a change, any change in ESR, is audible. Where is the fact in that? Can some designs eventually get “weird” as ESR goes up? Sure, but this is happening WHEN not that it doesn’t EVENTUALLY happen. We're talking about how LONG a design capacitor ages, not that it doesn't fail...eventually.

We use HP analyzers at work that are a decade old, and are checked regularly each year. They get a 100% bill of health with minor bias adjustments (which can be done on any amplifier). They make measurement orders of magnitude more critical than an amp playing music.

We all seem to be so aggressive to hear "anything" that we forget it is also OK to hear NOTHING between components. But no, we all take a drag on the same joint and ask each other if you feel high. When the “group-think” mentality says so, than we are high even if we made it up (no one venture fourth that they AREN'T high for fear of not being cool!)

So no, I'm not in this peanut gallery that "hears" the equipment age every day simply because 24 hours passed by. When I hear it I'll make comment on it. Do caps change? Yes. Can you "measure it"? Yes. Are the measurement so profoundly different all of a sudden you wretch away the minutes listening to them? No. Can some thirty-year-old amps (and even speakers) age so gracefully as to sound good at thirty? Yes.

One last thing, who CARES if a cap all of a sudden vaporizes at 32 years? You’ve had your use from the unit so why the FUD when it does die? Oh it surely will...and THEN that big elephant in the room is...well crap, he's silent. If that scares you, just change them at fifteen years.

Some time this site reminds me of Forrest Gump when he stopped running. One poor guy spoke for the crowd and said, "great, now what do we do?" We'll, use your ears and stop pretending to hear everything simply because someone else says what, when, where and how much.

That silent curtain of "faith" is so easy to hide behind. It replaces real knowledge and that's a shame. Hearing a difference is not knowing what made the difference. Enjoy what you hear, don't make-up what you know. And use your own noggin.

I've seen corrosion at the terminals open up computer grade caps that were only 5 years old.

It is true that heat will shorten the life of an electrolytic. But even if there is no heat, to continue to operate an electronic piece with 30-year old caps in it (even if it seems OK) is asking for trouble.

Rower30 if you were to do a DPA (destructive parts analysis) you would definetly see what 30 years of use can do to a capacitor and it will have a audiable affect when being used in audio equipment
What Herman says is spot on in and is what I see at my military customer sites who do this procedure using sems (scanning electron microscopes) and highly accurate test equipment.

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Rower,

Sorry, I just don't have the energy to read your dissertation. I glanced at it and despite your lengthy denial you are in a word… wrong.

Caps do matter.
Caps do have a profound effect on how an amp sounds
Caps do age and affect the sound.

No point in debating it further since you clearly don’t want to be bothered with the facts.

Believe what you want but if you would bother to do a little research you would find an overwhelming body of evidence from hobbyist as well as manufacturers of amps including the maker of your Pass and those who make caps.

Take care

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Like most of the bozos on this bus, I get bored and sell things eventually...while they still work...clearly a large part of the fun of this hobby along with discovering new stuff. I'm sort of looking forward to my Forte' seeming to need sonic improvement as that's my incentive to get all those cool-man upgrades to it...if I don't sell it first.

I gave you the thread on CAPs in power supplies and circuits. Read it. Unless the caps are real bad, it isn't a "major" thing at all as they age. The "rant" is easy to "listen" to. So many want to read till they agree with the "words" and never listen.

How many of you even HAVE an amp that is thirty years old to listen to? Most here that do have a twenty to thirty year old amp seem to say the experience is like mine which is not too bad. And, Like I said for the third time, big caps do age in the power supply and are easy to change out. The cans face "up" with the leads on top, usually, so inspection is easy. If you have a twenty or thirty year old amp you want to keep, simply change them out.

I do have an older amp, and it runs fine and the caps are physically sound (no bulging, leaking. ETC). No, the caps won't test the same as new, but the amp is far from "major" different to newer reference equipment relative to the APT one's ability in the first place. The supply can still deliver OK bass transients and the amp is very quiet.

My "one" amp is FULL of large caps, so the statistics are in the favor of caps doing well over twenty plus years if they are of good quality. If it was ONE cap it would match you smoker anlogy. I have statistics on several in the same amp under the same stresses. This is called a large sample population. HEAT is the major enemy of electronic parts. A 10C difference in service temperatures can add an easy ten years to a components life. And, this isn't the ONLY unit I have that is older and working fine, and they have caps, too. So say bye-bye to the lone cigarette man.

When is an amp "true" to you? Since you don't accept that an older amp can sound fine, not like new, there is no truth other than what you read. When do you "decide" your amp is all of a sudden "MAJOR" different? It just all of a sudden goes "major" does it? Do you have an identical new amp that never ages to reference it to? You'll need one as the sound quality does diminishes slowly.

I find it interesting that so many reference what we "read" and not so much, if any, on what we hear. I'm as sober as can be and SS amplifiers and lesser audio circuits age very well with good quality parts. They don't "massively" change except for total loss / leakage.

I have NEVER had a SS unit die from capacitor failures. Transistors, yes. Diodes, yes. Resistors, yes. These parts have been replaced and all upstream and downstream components have been fine (except failed output transistors, they over current lots of parts). It might be fairly argued when more than one component fails, it's hard to point to the one that started it all. But, Phase Linear 400 amplifiers in the day blew outputs all the time and I NEVER saw the capacitors replaced.

So again, someone decides my "position" that power supply caps don't matter is simply silly. Sure they matter, but much less so over time than people want to "read" verses "hear". Most good supplies are well over the design spec of their peak current ratings to provide headroom. As the caps age, the headroom does diminish. But it is still "servicably" good after decades of service to sound nice. Most amps run far under their design limits, so transients are still reproduced well.

But, if an amp ages and simply goes "major" all of a sudden because we simply read that they do at some point in time, than many people will be happy to buy these amplifiers!

The near end of "major" is fifteen years and the far end of "major" is thirty years. Your service temps are far more important to service life than any other variable except the quality of the part. My ears say so, and so does inspection of my equipment. You can't be any more sober than that.

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He's a little more specific than "LONG time."

From the X150.5 manual....

Hardware Facts.. So how long will this hardware last? It is our experience that, barring abuse or the odd failure of a component, the first things to go will be the power supply capacitors, and from experience, they will last 15 to 20 years before needing replacement

So you are at the lower limit of 15 years with a 1997 amp. Better start saving up for that cap change. If you agree with Pass then you must agree with my point above that caps 30+ years old should be replaced.

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In the manual for a Pass Labs amp, Pass says in the most common sense no bullcrap manner something to the effect that it will take a LONG time for caps to fry, and the caps let you know when they're dying so you'll have plenty of time to get 'em fixed. I've inspected my circa 1997 Forte' amp and it looks fine, sounds GREAT, and sure, I'll send it to Soderburg eventually...eventually...

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sorry................

your rant is just about impossible to follow

Sober up and then formulate a response.

Your position that power supply caps don't matter could not be further from the truth. They are the heart and soul of the amp. I build my amps and can assure you from experience that caps do affect the sound in a major way.

Taking one incidence (your old amps still work) to justify your stance makes as much sense as saying smoking is good for you because you know someone who is 95 and smokes a pack a day. There is a huge amount of data that says otherwise.

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No, you just push statements you're trying to justify making using my post. Do it on your own, please. I did NOT say counter to what want to say, I did say the effecets are less severe than MEASUREMENTS would lead you to believe! READ it again. If the caps aren't looking bad and it sounds good, keep on trucking.

If you keep electrolytics out of the audio path, a power supply has less effect on the overal "sound" than touted if the supply was decent to begin with. Older electrolytics aren't the same as new, but the FUD is overblown. True, gross failure not withstanding. ESR change in a electrolytic capacitor in a good circuit doesn't doom an amplifier to a severly limited lifespan.

Large electrolytic capacitors are GROSSLY variable right out of the box. But, on the power supply side it makes little difference to the sound. People LOVE to talk ESR, but know little of how it effects a circuit..it just "sounds" good to pretend any change is audible. We also take RF circuit design and pretend it works at audio (basically DC realtive to RF).

http://sound.westhost.com/articles/capacitors.htm

YOU need to read-up on facts about types of caps and degradation and why, not to mention their sound, or lack thereof. There is more snake oil in audio than in snakes.

When I say the amplifer sound fine, I mean it. As good as a new Mark Levinson? No, of course not. But to simply say it is older so it can't sound fine is nonesense. I listen to it (fact), and you simply read about it (no fact at all!). I also have New KISMET ODYSSEY amps running C4's, so I do happen to have a new reference.

So I LISTEN to this amplifer which goes a LONG way to saying the older caps are plenty servicable, still. "Comments" of differences in sound are pretty baseless since you haven't even listened to the amplifier. True, I don't take out the caps and measure them all but the point of the post is OLDER amps can still sound fine. Mine does. Are the caps the "same"? Of course not.

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Rower

What you say is just plain wrong.

Unless it is bulging or leaking fluid it is impossible to visually inspect a cap and determine if it has deteriorated. The capacitance drops and ESR goes up and they leak current and you have no way of knowing if or how much just by looking at it. You can delude yourself if you wish but all electrolytics slowly deteriorate in ways you cannot see.

All electrolytics have a limited lifetime. Take a minute to google the topic and you will get hundreds if not thousands of hits discussing this phenomenon.

It is impossible that your 30 year old caps function as well as new ones. To deny this is to deny that which has been studied extensively and is well documented. Your amp may sound "fine" whatever that means but that does not mean it wouldn't sound better with fresh caps.

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I have an over thirty year old APT Labs amplifier that is still running a pair of old 1979 B&W 801's! Yes, it's a 100-watt amp into 8-ohms and runs near clipping all the time. It sounds fine.

Electrolytics are no better than +/- 20% tolerance so that wear is less sensitive than you might think to sound. Caps in the more sensitive audio path that are non electrolytic give you a better circuit life if anything. There is no "proof" that exotic caps sound better over just last longer (at a price). Large electrolytics in the power path are cheap to service, too.

Most smaller electrolytic caps, if mounted right to lower lead inductance, often have the lead end (where they leak) SHORT and right to the PC board. You can't see the caps leaking when they do go till it's too late. Large power stage electrolytics are faced "up" with the terminals using screws. Inductance isn't as important in the DC path. You can watch these for signs of deterioration.

I am in the same boat with Ralph as the mallory caps I see in 5v200amp switching power supplies also have the greyish white vent plug positioned half way between the plus and negative terminals on the cap;they will start to push up and show signs of leakage.Once the electrolytic gets on a pcb it damages the board and shorts seem to start occuring thus rendering the mainboard unrepairable.

Thanks Atmasphere; you are entirely correct and I also replace caps if I notice the bulging plug. I forgot to mention it. Again, for those interested, this is part of routine inspection and service. For expensive high-end electronics, this is something that I definitely recommend.

enjoy all

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Minor I would have to disagree with "it is only too late if it fails" when it comes to audio. The statement may be true with power supplies for some equipment, but since they typically affect the sound of an amp long before they fail they have to be replaced sooner if your goal is optimal sound.

I do agree you should only replace caps in really old amps when necessary, but if we take 30 or more years to be really old then IMHO it is necessary in all of them. Bulging or oozing or not those caps have deteriorated. They need to go.

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Most electrolytic caps used in power supplies will show some signs of failure before they start to leak. Most such capacitors have some sort of plug on the terminal end that will show signs of bulging prior to outright failure of the part.

Its a judgement call as to how much of that you want to put up with, IMO if you want to be safe, any electrolytic that has a bulging plug should be replaced.

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Cathode, I don't feel it is being negative to correct a mistake. Electronics is a branch of physics. It is science. We use specific terms with specific meanings to avoid confusion. Why anyone would insist otherwise baffles me.

For example, your use of MTBF is simply incorrect. It is Mean Time BETWEEN Failures. It is not the same thing as MTTF.

Something is working.
It breaks down.
You fix it.
It works for some period of time. (this the "between")
It breaks again.

The mean of those "It works for some period of times" is the MTBF. It is not, as you stated, the length of time it takes for a certain percentage to fail.

That is not being negative. It is correcting a mistake.

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Thanks Herman; Actually, it is only too late if it fails, which I have never seen happen if the units are periodically inspected and serviced. Again, like a fine automobile, if units are routinely inspected and serviced this type of problem will be detected early enough to warrant replacement of parts before failure. Another warning other than visual leakage is lose of sound quality of other electrical issues. But, as I mentioned earlier, if the unit is routinely inspected and service, even these will be detected early enough and parts replaced before failure.

enjoy

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Rieff, we are systematically replacing all of the motherboards and video cards from the affected period.

Minor, so you mean physical leakage like stuff oozing out of them. The problem is they are performing below spec well before they start oozing. Since most don't have the equipment to test them some people recommend replacing after 10 years. I don't want to debate exactly how long is the right amount of time as that has been debated before but waiting until they ooze is a little too late.

take care
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Herman; Thanks for the response. Typically I don't measure a loss of capacitance per se. What I check for physically, visually is actual leakage that is noticible on the capacitors. It is obvious and very easy to see. Others have stated that what they do is simply replace all electrolytic caps. This is also another way to go. I can tell you most electrolytic caps aren't that expensive, but power supply filter caps can really get up there in cost if the rail voltages are high. This is one reason why amplifiers are so expensive. The others are 1) transformers (very high cost), transistors and tube, can get up there in cost if they are speciality devices in low production, 3) machining enclosures, that are well designed and built to eliminate vibrations (i.e. very heavy), rediculously expensive heat sinks, etc. But the only times I typically measure capacitance is when I'm reverse engineering something. or if I simply can't read the lables on the devices because they are so old. But the originally poster's question regarding lifespan of ss amps assumes that there is no routine maintenance of the equipment. Like cars, amps and electronic equipment (that you want to keep operating for decades do need maintenance.) a qualified service tech can do it for you. Replace caps with equal or better quality caps, replace transistors, resistors, tubes, diodes, heat sink compound and thermal insulators, etc. and you basically have a brand new and maybe better amp. But for regular people that don't have the technical background to do this, I recommend that they just enjoy. However, it depends on the equipment. If, for example one gets their hands on the older top-of-the line Audio Research, Threshold, Mark Levinson, Atmasphere, etc. equipment, I would definitely try to service it and get it working correctly and keep it. If going to a "fire sale" and I find two Mark Levinson 20.6 amps, I would do whatever it takes to get those working correctly and keep them. Some older equipment is as good or better then most newer amps today. believe me.

enjoy

I admit that I'm wrong for not being more adamant and argumentative with my opinions.

C'mon folks. There is room for precise teminology and room for metaphors/analogies that can be very useful and pragmatic for those that aren't familiar with the technical terminology and might be intimidated by it.

I'm with Herman on this one.

I'm with Cathode on this one.

Herman I repair 5v 200 amp switching power supplies and find that 70-80% of the fails are in the large filter caps used in the supply section;when I replace these caps I change all electrolytic caps in the supply as well as the fan.The supplies I see range from the 1990's and run 24/7 being used in large semiconductor test equipment;they are normally mallory 15000mfd at 7.5v and 4000mfd at 200v caps.
Did you company resolve their computer failures?

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No problem Ralph. I think it is a disservice to those who are trying to learn something here but If you are comfortable muddying the water with incorrect information then that is your choice. As one of the senior "experts" around here who comes from a technical background I would think you would strive for accuracy but your choice. I think from now on I'm going to refer to tubes as transistors since they transfer a signal and both words have trans in them. It's not correct but it's just as logical as your use of half life :>)

Like I said, it amazes me that nobody around here will ever admit they are wrong about something. When called on something they either don't respond, change their story, or do as you do and rationalize their incorrect responses. Actually, I find it a bit amusing.

In any case I'm done with it. Carry on.

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Does this conversation really need to diverge toward the negative? You’d think this was Audio Asylum or something. I frequent these boards because they’re usually (significantly) more civil. It doesn’t seem like we’re furthering much useful conversation on the original poster’s topic, just arguing about semantic minutia.

Regarding MBTF (or MTTF) of systems, caps, half life, etc, I want to clear something up. For the exponential failure rate distribution, which most electronics follow during the majority of their lifetime, MTBF is when 63.2% of the population has failed, not 50%. When the product / part begins to wear out (failures begin to occur at an increasing rate), the normal distribution is typically used, and MTBF is indeed when 50% of the population has failed.

And getting back to the original question, I agree that good SS amplifiers can last 20+ years. Electrolytics are frequently the limiting factor, followed by the semiconductors (transistors, diodes). Much of this depends on how much margin the designers used (how much the parts are derated for relevant electrical and thermal parameters). Personally, I wouldn’t worry about any maintenance unless recommended by the manufacturer. Bringing up an amplifier slowly with a Variac after it has been out of service for 6+ months isn’t a bad idea.

Hi Herman, I too have taught in technical schools and my stint in the service industry goes back to 1974. That's how I financed my way through the Minnesota Institute of Technology. The use of 'half life' is my own and simply comes out of experience - as a service tech I have repaired thousands of amps, preamps, receivers, tuners, tape machines, etc. I'm sorry that the use of the term bothers you but it works so well and is so easy to explain that I will continue to use it. I'll try not to use it around you :)

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Minor, sounds like you are a very thorough tech.

Question: you say you check the caps for leakage and replace only as needed. What about a loss of capacitance and/or increased ESR? The amp may function with these problems but well below it's potential.

Also curious what method you use to measure the leakage.

Thanks

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A couple of things. 1) most decent amplifiers have soft/slow start circuitry which prevents the on/off cycling problems that people mention here. Therefore for a decent high end amp, the cycling on/off damage they are talking about really isn't an issue anymore. 2). Electrolytic capacitors would be a problem and must be checked. They are like any other component in cars, etc. they give you advanced warning that they may probably fail. yes, yes, there are instances where something just simply goes out, but in most parts you can see leakage before they fail. So, take a good look inside or have a qualified technician inspect the unit to see if any problems may exist. If nothing is apparant, then leave it alone until some problem or possibility of problem presents itself. 3) apart from capacitors, the thermal damage due to the loss of heat sink compound that the transistors are using when connecting to heat sinks may be the major issue. Transistors fail for a number of reasons. a) people that short the outputs when playing with speaker cables are the number one reason. b) when the heat sink compound dries out, it presents a problem for loss of thermal conductivitity and also allows for the possibility of the transistor to come in contact with the heat sink, because not only is the heat sink compound gone, but the thermal insulator between the transistor and the heat sink may be damaged. Therefore, what I typically do with older amplifiers is to check the capacitors for leakage and replace if necessary (only if necessary) these suckers are expensive, and replace all pre-driver and output driver power transistors with the newest, latest and greatest more linear transistors and readjust the bias, which makes the amp much better sounding. This also allows me to replace the thermal insulators and the heat sink compound, thereby eliminating any possibility of the amp having issues. my "modified" amps are much better sounding then the original and also are much longer lasting because I have inspected and replaced capacitors where necessary and also I have replaced all pre-driver and output power transistors and their associated thermal insulators and heat sink thermal compound.

One last thing. I typically will add a slow start/turn on relay circuit to any amp that does not have it originally and I sometimes will modify the power supply to separate power supplies with regulators.

After all that, I guess what I am saying is for really old amps, definitely change the heat sink compound and thermal insulators at a minimum and if you can change all output transistors also and check and replace if necessary the electrolytic capacitors.

enjoy

True story: I had a 1960 Fender Deluxe guitar amp (brown tolex vibrato version...no reverb) that I thought needed attention (I'd owned and used it as a studio amp for 35 years or so) before selling it (mistake). It had old leakey caps...a reliable tech swapped 'em out for nice new ones resulting in my amp sounding exactly the same.