Expectations after re cap of power-amp

Dear PhD
Thank you, great suggestion.

Jon Soderberg of Vintage Amp Repair used to work for Threshold back in the day and still works on repairing and upgrading Threshold, Forte, and other brands of amps. He does excellent work. He replaced the power supply caps and the bias pots on my Forte amp. There was a substantial improvement overall. Here is what I want to tell you. Given the age of your Yamaha M-2 (nice amp by the way) you also want the tech to replace the bias pots with the newer superior enclosed bias pots. Better to do it now while you are replacing caps.

Re-cap the Adcom for use in the second system?

Interesting post. Names of my components withheld due to persecution. I recently purchased new $8000.00 speakers. A well respected dealer in Milwaukee suggested that I replace my 20 plus year old Adcom GFA 555 II amp after heavy use powering my old Infinity Kappa 8's which are known as power hungry speakers. He mentioned for the money it would cost it would be better to buy something new. I'm all set with my system now but thinking of a 2nd system since I have an old not being used pre amp and CD player. Just bought a pair of speakers from a friend for $500.00, new they were $2000.00, handle 250 watts. Dealer said to run them with my Adcom until it fails. If it damages the speakers I'm not out much. What are your thoughts?  

Yes agree, if the caps are laid out cleaning, its nota  difficult task for the DIYer,,,The Cayin CD17, was not simple, required the board to be dis assembled and soldered from bottom....,,so if the caps are laid out as ~~Scaffold~~~ design, anyone can make the mod, just clip the wires, solder on new caps, But if on a  tight preassembled baord, like jprrp1's Marantz mod , and my cayin 17 mod, these mods require a  tech who is WILLING to take it on. 
Some tech guys won't touch it, or will cost ya, My Cayin mod cost me $250 just labor. Worth it? I'd say yeah, Caps were like $300 and tech fee $250,,yeah, i now have greater dynsmics/sonics. 

The 2 ~~coffee can~~ sized caps, must be the M Supreme SGO caps,,,Yes?
I have a  apir of 10 UF sitting on my shelf waiting to go in a  new xover for my SEAS Thor speakers xovers...anyway,,,there is a  YTer,,~~AudioSurgery~~ who displays his work ina  series of vids, showing off his recapping on various amps, Uses M top line caps,,I can  actually hear the sonic improvements on his mods.
I have my Jadis Defy in the shop, for something stupid i did to the unit,,and will have the tech swap out some critcal caps for new M SGO caps,,,I can only say from my experience on my  cayin cd17 Mark 1 player, with 8 new M caps , noted a  nice gain in sonics, dynamics. Subtle, but notable. I expect more  Notable gains in the jadis recapping., vs the cd player recapping
https://www.youtube.com/watch?v=HGWcXN_zsR4

I know a few professionals who won’t go near a Marantz vintage receiver 

If you can do the work yourself, the cost is quite minimal.  That's the route I took, but I am comfortable with a soldering iron, and the particular component had nice access to the capacitor leads for de-soldering (the hardest part!).  I opened up a friend's '70's Marantz receiver to see if I could pep that one up, and it was way too hard to get at the stuff, so "no go".

I had my 35 year old Krell KSA-80B refurbished about a year ago.  It was completely recapped as well as other components replaced.  It wounded wonderful when I got it back.  Its in hard service driving Apogee Scintilla One Ohm's--but I expect it to heat my music room for many years to come.  I would definitely do it again.  Had the work done by the factory and was treated very nicely by all.

I will repeat myself because I think sincere gratitude needs to be expressed. All the generous feedback has been very encouraging and because of it I now feel far more confident in my project. All these responses are not a trivial blessing in my case.

If recapping is a fool’s errand why bother? Better to use the money toward newer amps. I needed to know. I may do both but I would like to express that the Yamaha M-2 was well respected back in the day. It is still possible that I may yet invest in some Classe gear after recapping the Yamaha.

I have some Dahlquist DQ10 speakers I spent $2,000 on rebuilding them before I retired them.  I still own them. Even though I seldom use them I’ll argue that I owed them something for their decades of faithful service.

Ever own an old faithful dog? Nothing was too good for my Christopher.

I just had a Krell KAV 250 refurbished which I believe was mostly new caps and while it always was a touch tad or pinch ( not sure which) better than its KAV 250/3 partner in my system to my ears after the refur it does sound “fresher and cleaner”
and like the Krell svc mgr and several here have said it should give me another 15+ years of the Krell sound I enjoy.  By the way of the 675 or so cost the vast majority- not a complaint just a observation- is the labor.  I’d do it again without hesitation. 

Well, couple of things are at play.

Modern electrolytics are usually much better. Longer life, lower inductance, and lower equivalent resistance, means better power supply but..

how much of this, if any translates into sound quality is very much design dependent, so I wouldn’t try to oversell it.

Oh, also, make sure to replace any decoupling caps near the amp boards too, not just the big oil cans next to the transformer, as well as using higher temp caps.  That can increase their lifespan.

@jl35 

you are correct, this was my exact answer.

 You should expect a much better presentation and open/airy ness to your sound.

enjoy

it will sound much better...but don't expect it to sound nearly as good as the Classe amps you really want...but definitely worth the cost to recap...

My worst fear would be that the amp would sound worse not better and I might waste the money invested and butcher what was once a well respected amplifier.

Done well, the worst thing you should expect is 30 years of trouble free use.

If your caps were compromised; it should sound better, soon as you get it back.      Chances are good; it will sound(increasingly) better, as the new electrolytics, "form", their oxide layer. https://en.wikipedia.org/wiki/Electrolytic_capacitor

@timothywright  If you like the amp that price to repair is reasonable. And a lot better than what can happen if a filter capacitor eats a power transformer or explodes! You'll hear the improvement right away- anything built that long ago has ailing capacitors!

The responses have all been very encouraging, thank you so very much.  My worst fear would be that the amp would sound worse not better and I might waste the money invested and butcher what was once a well respected amplifier.

 

I don’t want to throw good money away but after the responses I received I don’t think that would be the case.

 I was shopping some expensive (and powerful) power amps and everything I looked at was $5k - $7k. So if I can get my old Yamaha back to ship shape for anything like $500 I am all in.

Assuming nothing else has aged, yes.

I've heard good things from some who have had these caps replaced, meaning they experienced tighter, better bass.  If nothing else you'll have another several decades of listening to look forward to.

  Fact is, that if the capacitors are not replaced, there is a (small) chance of big trouble. I am not trying to incite worry here, it is just a fact that capacitors do age. Normally, it is just the overall performance that suffers, but just like other components can, and might, fail in a way that is a game changer. Specifically if a component fails and then shorts out, all bets are off as to how much damage is accomplished. If on the other hand, the component goes open (no circuit connection), chances are better that no further harm will be done. 
 I often compare the care of audio equipment to a classic car. If you don't replace spark plugs when you should, it is not a good overall result for the engine. There comes a time when much more should be done to preserve that performance and value of the car itself.
 

I replaced all the caps in several vintage amps with Elna Silmic and Nichicon FG caps and the improvement was significant. For the $50-75 I invested it was well worth it. What amp could you buy for $500 that would compete power wise with the Yamaha?

Replaced all the electrolytics in a tube amp with 15 (hot) years on it, and it made a very nice sonic improvement - - all upside, no down, and no dramatic change in the overall voicing of the amp.  I hope you will be as pleased with your recapping.

My caps were not expensive high temp, low ESR Panasonics, FWIW.

Depends on the quality of the caps used. Could be quite a bit better than new. Talk to the tech, ask about how he selects caps. There is a huge range of performance- and yes you do pay for better.