To re-cap or not to re-cap? That is the question

I definitely recommend a re-cap, (my preamp is currently in the factory for that..) but preferably from someone who knows your specific equipment and the wide variety, cost and sound of available caps out there in that equipment. Cost does NOT necessarily correspond to what will sound best. When  you talk to the designer / tech doing the work, try to get an idea of what they think sounds good, what speakers they like, etc., so beyond their expert advice and experience, you have a sense of what they consider 'good sound'. Caps can to some degree tailor your sound... Some will promote ear fatigue in some systems, some are more laid back, etc...Caps are just one piece of a big puzzle.

My passionate response is that it sounds reasonable to me...

All right, one final word, at least from me. And please: I promise I'm not trolling. 

I just got off the phone with the electrical engineer who repairs audio equipment in my community. I've worked with him for decades; he used to be the head of the tech team at the university where I teach before he started his private business as "The Audio Doctor." And, not irrelevantly, he describes himself as "a recovering audiophile." 

He insists that he has almost never seen capacitors fail, and that worrying about them "blowing up" and destroying the entire amp is plain silly. Active components like transistors, switches, and so forth constitute 95% of his repair work, he tells me. Moreover, he says that some electrolytic capacitors have "weep holes" that can leak electrolyte, and he has seen this problem (generally, the customer discovers some damage to the shelf on which the component with the leaking cap sits). Even with a capacitor that is leaking electrolyte, measurements will be within about 5% of what they should be. Furthermore, he says, circuits are very tolerant; most other components have normal functioning tolerances of 10% or higher. Bottom line: re-capping, he insists, will not improve my sound at all, nor am I risking a catastrophe from an old capacitor blowing up.

Now, I'm not saying he's right. But...I do trust him, he has 35 years of experience in the business of repairing audio equipment, and one would think he'd be motivated to suggest that I should replace my old capacitors, since I came to him wanting to do that, and he could have made money from me merely by agreeing to my wishes.

One more thing. My right speaker is more than 30 feet from my amp; the cable must go up and over a stone arch in my living room. The left speaker, however, is only a couple of feet from the amp. I've run 14 AWG copper wire--nothing special, that is--to both speakers, using the amount of wire I needed to reach the speaker. He insists this is completely fine, and gave me a long explanation of why I don't need to worry, which I'll spare you all. But I'm pretty sure just about everyone on this site will think I'm making a mistake not to buy expensive cable, and to run identical lengths of cable to both speakers.

Chances are, this thread is sleeping now. But it will be interesting to see if these remarks provoke a passionate response.

Mid40sguy--   I was being a bit facetious, but I guess the serious point was  that this is not step-wise?  (Perhaps someone can help me here).   I assume there is no difference between (1)  'break in' and  (2) 'aging' or 'degradation' (let's just talk tubes since no one doubts the aging process there).   It's just a slow degradation from the moment you turn them on until they wear out completely, with an (arbitrary?) period in the middle where we like them the best?   Not arguing here.  Just trying to figure out what happens.  Or are some arguing that once things get 'broken in', then they hit some steady-state of (perhaps finite) perfection?  

This comes up with all kinds of things,  just in my experience--physical books,  Mason jars, cars, sails, hair brushes, engines.    Is the process that electronic equipment is subject to different in any significant way?  (I would assume for some components it might be:  they either work perfectly or not at all, but in that case, there really is no 'break-in' period.).  Again, not arguing.  Just asking what audiophiles and electronics experts believe is happening.

Thanks, everyone. Lots of well-informed advice here. I know what I have to do.

You got great answers on the caps. Safety trumps sound quality and those electrolytic's are past their expiration date. Quality modern electrolytic's are significantly better that vintage ones so they need replaced.

Jdane; Caps tubes cables do break in. The time varies in my experience. I've found at 50 hours things are settling in. After 100 hours you should hear little or no changes.

You can pretty much leave all the film capacitors intact, unless they are showing any sign that they may have a problem.  If you MUST change them, a good brand is Mundorf.  But you dont have to go too fancy.  Some of them are ridiculously priced and you really do not need them.

As for electrolytics, after about 5-10 years, it is best to replace them all.  And when you do replace, if you can, substitute film capacitors into their place or choose higher voltage & temperature rated ones, if you can.  This may not be possible for larger caps since they just cannot make film capacitors of very hi capacitance values, but change as many as you can.

Here is an excellent site:
https://www.partsconnexion.com/film-capacitors.html

Hi @elliottbnewcombjr

The issue with amps, and this varies a lot, is how much damage you can do if the electrolytic caps blow out.

With a preamp for instance, there's usually no more than +- 15V inside. At most you would blow a voltage regulator.

With an amplifier, with +- 60V or more, and high current, you can blow an entire amplifier board.  Maybe more important for solid state than tubes.

So, like Clint Eastwood's Dirty Harry, you have to ask yourself, "Do you feel lucky, punk?"

I have also consistently read from many that these upgrades are often quite beneficial sounding.

How much time is there between the end of a burn-in period (for caps, cables, and power cords) and the moment to think about replacing them?

Well now,

I have had a resistor or three replaced over the years, never anything more than that. Always checked out by pro when that was done.

Still, I always consider 'fixing' or 'upgrading' my vintage stuff, most from 1950's and 60's.

Problem is, they still sound great, they still are dead quiet.

I'm thinking, for my 75th Bday, I might have my McIntosh mx110z 'overhauled'. 

Yet, it sounds so damn good, I worry it might actually lose something.

Conclusion is always as you said, If it ain't broke, I ain't fixing it.

"On the principle "don’t fix it if it ain’t broke," I’m inclined to leave well enough alone."


Me too.

And yes we should try to leave politics out of this forum as much as possible.

It’s getting a little tiring watching reruns of Miller v the sheep.

Baaa!

please LEAVE politics out of the forum!!                                                                                                                  let’s talk about the issue at hand. a recap that is the question

"...would you like all the Chinese communist drivers that they’re built with?"

Only if they are just the right red. How else would I know they are not some knock-offs from the neighboring factory?

An election that was won in a landslide is being stolen in a so far relatively bloodless coup.

I don't believe they've stolen the election with the insurrection carry on. Even Mitch said so.

Make sure to allow the recapped amp to burn in before judgement.

You should replace any 40 year old electrolytic caps or else move on to newer stuff.  Period.  As has been mentioned, parts quality in 2020 is much better than what was available 40 years ago, and electrolytic caps don't last anywhere near 40 years. 

I will restrict my comments to speakers, since I don't have any actual experience working on electronics.  I can tell you that I am currently rebuilding a pair of ADS 1290/2 speaker crossovers.  I've been very slow and deliberate about this, replacing one crossover component at a time and evaluating the change after burn in one one crossover while leaving the other crossover stock.  I also had the tweeters and mids reconditioned.

 As has been mentioned, you can go overboard and change the character of a speaker, which you don't want to do.  If you wanted something that sounded different, you would just buy something modern.  

At this point, I've replaced about replaced about 2/3 of the caps and resistors in one crossover using good but not great parts.  I've left the inductors alone so far.  The improvement is not subtle.  The crossover with the old parts is quite veiled compared to the partially modified crossover.   But the character of the speaker has not really changed.  It is quite musical and is seemingly incapable of anything approaching fatiguing. 

Having gone this far, I am building a new crossover board that is point to point wired and eliminates the extraneous (as far as I am concerned) switches. 

This has been a great learning experience for me and  very rewarding.  I encourage you to proceed.  Just don't be in a big hurry and make sure you have your circuits understood before you start.  

Since I don’t want his Moabs, would you like all the Chinese communist drivers that they’re built with? 

I will bid for amplifier. Just to check what the fuss about tubes really is. I have no experience with Chi-Fi and this would be my chance.

Paranoia is the least of his issues.

You can replace the main caps fairly easily, but you may have a scattering of smaller power supply caps on the amp boards.  Usually 50 to 75uF or so. Those can like caps should be replaced at the same time.

Honestly, wet (electrolytic) caps in the 1980's were pretty crappy compared to the modern varieties.  Much more inductance and ESR than the average cap today, so you can improve upon the power delivery  and lower the noise a little by doing them too.

Say miller, when they come for you, can I have your stereo system?
I will of course keep everything but those hideous, eye sore speakers.

"...they'll be coming first after guys like me who have a clue..."

Is that a joke?

Seemingly mundane things like switches and volume pots should at the very least be cleaned.  

An election that was won in a landslide is being stolen in a so far relatively bloodless coup. But don't worry, when it does get bloody- which it will! - they'll be coming first after guys like me who have a clue and stand on principle, and only much much later get around to all the rest of you. But do not worry. Your time will come.  

Think you're pissed off now? Just wait.

Oh you can perform many changes but that thing will sound different from what it does now. Not worse but different. 40 years is a long time and parts do age and by this time you got accustomed by its slowly degrading sound, normal. For start replace all electrolytics in amp, and speakers, that only will revive them. Same values, voltages, capacitance, temperature (especially temperature) for keeping at least the character of the units. If you want to go deeper and to unknown, some diodes, resistors, regulators. These changes are not expensive but require a bit of studying before any attempt. I recapped my 1978 tuner, did not alter anything, it only got better. Try to get amp's service manual, it would be the most helpful. Whatever you do good luck and have fun.
G

It seems more than a little frivolous to write about this, given what's unfolding in our nation's capitol at the moment. But...

Thanks to several of my favorite regular voices on this forum--especially Eric, from whom I've learned a lot, and Chuck Miller, who is always articulate and well-informed even when he pisses me off (which he almost always manages to do).

Good to know that the caps in my Teslas are probably OK. Accessing them would be challenging. And good to know that I really should replace the amp caps, after almost 40 years of constant use. 

And thanks also to Mr. Miller for the straightforward suggestion that I could do that myself. I'm pretty handy with a soldering iron, and I do value things I've done for myself more than those I've paid someone else to do. Besides, when I do it myself, I know exactly what has actually been done. 

Is there anything else I ought to do to renew a 40 year old amplification circuit?

I've got some very fine 1980s vintage equipment I love and don't want to replace.  

Well, that's it then, isn't it?

On the principle "don't fix it if it ain't broke," I'm inclined to leave well enough alone. I don't notice any audible deficit. But perhaps the system could sound even better?

Right. Changes that are slow and gradual, hardly anyone notices. The frog boils slowly story is there for a reason. Of course the system could sound even better. This is always true! Even right now, me with brand new Tekton Moabs, everyone telling me how much better they will be if only I am smart and replace the "cheap" caps and inductors. They're Mundorf, not cheap, but there are even better more expensive out there and so compared to those yes mine are cheap. Sigh. 

Its ALWAYS this way and so the smart thing it seems to me is instead of asking "is it worth it" which no one can answer the better one is, "what can I afford to spend on an upgrade if I KNOW it will be worth it?" Because it will. 

The difference is this way you take your budget, look at your parts, and divvy it up. Kind of like building a system. If you know you need 5 things and you only have $5k then you know it can't be more than $1k per thing.  

In fact its very similar because if you dig into it some caps the quality is more significant than others. Also its not just caps. Some nice fast hexfred diodes are relatively inexpensive yet make a huge difference.  

One really nice thing about this is its not something you even have to farm out and pay someone to do. Cap values are printed right on the cap. Shop around, find a better one, unsolder old, solder in new, done. Listen. If you don't hear it stop right there, probably never will. Odds are you are impressed just one cap can make so much difference. Keep going. Biggest problem usually is to find the room. Better caps almost always are physically a lot bigger, even though the exact same value they are huge, and there simply may not be room enough to do them all.  

You won't have this problem in the crossovers. Those are very simple circuits. Just sometimes hard to get at. But if you can - no high voltages, plenty of room, only a few parts - perfect place to start.  

My first mod was cap and diode upgrades in a Aronov tube integrated amp. Huge improvement. Will be for you too. Look at it that way. Plan your work. Work your plan.

The capacitors in a 80's amplifier will be dried out. No doubt about it.
re-cap it. It does not matter that most capacitors will measure ok.

Audio gear is like a rope under load. 

You can't allow any part along the way to fail, as a minimal failure in one part constitutes being a overall 100% failure.  Not the perfect analogy but close enough.

Speaker: Film caps in speakers can last forever unless over stressed.  The electrolytic caps, if any, are what dries out. Consider replacing with Axon film caps, if you can compensate for ESR changes. Replacing tweeter/mid caps can change the character of a speaker, so I do suggest you leave that alone unless you have good help.

Amp: With an amp of 1980's, you've had a good 40 years with the original power supply caps, all electrolytics. If you replace them now it will sound better, and you'll greatly reduce the chance of burning up the rest of it.

Best,

Erik