Levinson 20.5 monos - Time for a Refurb?

I bought my Mark Levinson 20.5 pure class A mono blocks new in 1990. I loved them for their sound and still do. They have been 100% reliable and I have never had them back to the Levinson or my dealer for anything.

However, they are 16 years old now and except for my Magnum Dynalab tuner, they are the only thing I have not replaced in my system.

Being pure class A amps they run pretty hot.

Question is, is it time I should consider having them checked out, refurbished, capacitors and the like replaced, etc?

If so, who should I consider for this work? Levinson? They are not what they used to be when they designed and made these amps, and I'm not sure they are up to the same quality work they did back then or whether I should trust that their parts will be as good as the original. Someone else? But who?

Has anyone been through this or does anyone have any thoughts about this they can share with me?
Talk to this guy:




(same fellow)
Hey I talked to that guy, and what a turn off! I own Audio Research classic 120's, and by the time our conversation ended He made me feel like my amps were a total joke and were nothing more than than 150 lbs of garbage!!!!! not to mention the fact he wanted to make a good weeks pay on the parts he was talking about replacing. Levinson is top shelf stuff too. My recomendation would be contact ML directly!!! Like most great manufactures, they will advise and handle your great amps better than anyone else. Good Luck
I have a Levinson ML-3.....even older than your 20.5's.
Same situation, it has never been in need of service, these days, it's a backup amp that I light up and run once a month to keep the caps exercised.

Me, I'm gonna leave it alone. There's an old saying: "If it works, don't fix it".


Paul :-)
I agree with Beemer. Unless it can be improved with some updating, it should be fine.
I too agree with Beemer, if it works don't fix it! I know alot of folks would say after ten years its time to replace them caps, especially on pure class A amps. But I would guess that it would depend on how often in them ten years they are on/played.
Thanks, guys.

I think I will talk to Levinson.

Well, Phd, they have been played at least 2 to 5 hours a day almost every day for the last 16 years.
Cipherjuris, since that is the case, it will be to your advantage to call Levinson and go from there. Let us know what they have to say.
I would second or third the recommendation to send your 20.5's back to the Levinson repair department, if you think that they might need attention.
I have, on occasion, had to send both a cd transport as well as my 332 amp(that I shorted out and blew the right channel) back to the guys at Levinson, or the Harmon Group, their parent company.
There are guys in the department that have been there for many years.
There is probably a flat rate for replacing or upgrading the amps.
Trust me, they will do a great job.
But, "if it ain't broke....."
"if it's not broke don't fix" will only take you so far. What about preventative maintenance.? Your car runs fine but you change the oil every so often.

Electrolytic capacitors lose capacitance, start to leak DC, and have an increase in ESR as they get older. At some point they will begin to fail. The big question is when.

There is no definitive answer to your question but after 16 years it is reasonable to consider replacing them. Pretty much any competent tech can do the job. The hard part might be finding caps that are the same capacitance, rated voltage, and physically close to the same size.
I totally agree with Herman. It was very funny to see so many "if it ain't brokes" when other guys on this site will replace perfectly new caps to get a "tweak" improvement and not even think twice about it! Hilarious.

From an electrical engineering standpoint, those caps most definately need to be replaced - there is no question. Those amps run super hot and after 16 years, I bet there are even cracked resistors in there. The amps will definately benefit from an overhaul: Power will return and with it will come improved acceleration, er, I mean, dynamics, and bring along everything else that entails.

I am glad to see you following your gut instinct. Go ahead and send it back to ML and be sure to let us know if your sound improves. Get a quote though because it may take a very healthy dose of sentiment to pay the bill. :) Arthur
will cost at most $950 via Harmon Intl.

I have a ML#27.5 which has gotten alot of use and also
is left on 24/7. I just started noticing a slight buzz
from the left channel tweeter along with occasional
static/crackle. Kinda like AM radio during a thunder
storm. Obviously not that loud, I need to get close
to the speaker to hear it. It can be heard from my
listening postion during very quiet times. Is this the
sign of a cap going bad?

After shutting down the pre-amp, the noise continues.
I guess that eliminates upstream components. I'm hoping
not to go through yet another repair cycle.
Here's my update. I talked with ML via Harmon. As expected the phone tech (Jaime) said that if they are 16 years old and have never been serviced, they should definitely come in for inspection and maintenance. He said they recommend that you send them in about every 10 years.

There is a Guaranteed Maximum Price of $1,140 per amp or $2,280 for the pair. If the actual work is less, then they will charge less but if it is more you will still pay only $2,280.

All he needed to issue me an RMA# in addition to my name, address, etc. was the SN of the amps.


Cipherjuris, that is alot of money. Have you considered putting the money towards new mono blocks/ different technology, maybe the Nuforce 9s or are you determined to refurbish the Levinsons? If you are, thats excellent as well. An example only, I took a car one time in for a tuneup and the dealer told me I needed an engine rebuild. Turned out to be a loose spark plug after I checked myself.
Joe, you might want to check/clean/replace the 2 fuses on your amp first. They are sometimes a source of noise after many years -- not really bad, but dirty or marginal. Ditto your signal connections (at both ends.)

Since these amps sound fine, I fail to see what cleaning,checking & replacing fuses & connectors will accomplish that a Santaria ritual & the requisite chicken blood won`t.
I would use them til they show signs of needing work. Of course if you can have them updated to the 20.6s, it may be worth it to you.
Even though the 20.6 update was only one circuit board, Levinson no longer provides the update.

To be clear, as far as I can tell by listening, there is nothing wrong with my 20.5s. However, as I said I love them and 16 years of Class A heat is a long time and a lot of wear on the caps, if not resistors. These amps cost $12,000 in 1990 (that's like $35,000 in todays $$) and even Levinson no longer builds amps like these are built.

I just want to get them checked out and get anything replaced that needs replacing before something goes wrong and does some damage to them. Other than my Magnum Dynalab, which I don't play very often, the 20.5s are the only component in my system that I have not replaced in the last 10 months.

Thanks, guys

Common thinking, (old wives tale?) is that caps are good for about 20 years. The look-see price seems more than a bit steep. If your amps seem fine, perhaps the maintance is a bit premature. I'd suggest waiting a little while and then if you still want the amps, have them looked at. That is, unless of course they begin to dissapoint or flat out fail.
Get the Nuforce 9, listen to them about 20 seconds and you will decide the $2,280 to get ML20.5s up to shape is a real bargain!
I would check caps and resistors myself, not really brain surgery...
Common thinking, (old wives tale?) is that caps are good for about 20 years.

What does that mean? Do you think they don't last that long or that they last longer.

For all naysayers, if you do a little research you will find there is indisputable proof backed by numerous studies that electrolytic capacitors deteriorate over their lifetime losing both capacitance and suffering an increase in effective series resistance. It is also true that the rate of deterioration is directly proportional to how hot they get. There are also other components that can shift in value after operating in a hot environment for so many years.

The fact that this deterioration happens very slowly means that it is very difficult to discern how it affects the performance of the amps, but I guarantee they are not performing as they did 16 years ago. I have rebuilt many vintage guitar tube amps which mostly consists of replacing all the bypass and power supply electrolytic caps along with any carbon composition resistors that are out of spec. The resistors tend to increase in value. The owners, who though their amps sounded pretty good before the service, are consistently amazed at the transformation.

Given the fact these caps have been operating for at least 16 years in a hot environment, and the owner places great value on the amps, it seems reasonable to have them serviced.
Herman: Hey, I need to get two vintage tubed guitar amps serviced for new filter caps (at minimum) right now. But I will say that most of the original caps in each of these lasted about twice Unsound's 20 years.

Porziob: The useless comments from you just keep on coming, don't they? Nsgarch wasn't responding to the threadhead in the post you criticized, he was addressing Joemt's concern from 8/2. It's a little thing called trying to help somebody, and pseudoscience wasn't involved. If you can only get your thrills from predictable negativity and weak sarcasm, the least you could do is take the trouble to read what you're attacking first.

I've tried a couple of things. First, I checked the
batteries in my crossovers ( Vandersteen #5 ), they were
good till 2009. Next disconnected the subs and ran
direct. Still had the noise. I've now plugged the amp
into a Line conditioner and things seem better so far,
I'll continue to listen. Still have a slight buzz, but
that's with my ear up to the tweeter. The crackle seems
to have died down. The other speaker is dead quiet. If
it is electrical noise, why only one channel? I'm on the
East Coast, everyone running AC's. My one power
conditioner reads just under 100 volts. The other
conditioner ( for the front end components ) gets power
from an Exact Power unit first, it ALWAYS reads 121 volts.
I can't reach the Exact Power unit with amp chord.

Hope things cool off by the weekend, perhaps it's all
due to dirty electric and low voltage. I will clean and
check all the connections as well, can't hurt.

Joe T.

To re-confirm the obvious, do replace those caps and also check other vulnerable components as suggested above.

I also VERY strongly recommend you find/purchase/otherwise obtain the SERVICE manual for your amps. Had you had that now, you could have changed caps (usually no big deal) yourself as well as checked all the tests points to see if anything else needs looking into.

Lastly, low voltage caps & resistors cost very little. Of course, the "safety factor" of having Harman service yr amps is very important; however, given a service manual, a competent & experienced electrician -- or experienced & knowledgeable diy friend could do the actual job just as well.
Zaikesman, you say the caps "lasted about twice Unsound's 20 years."

What that really means is they lasted that long without a catastrophic failure, either shorting out or losing so much capacitance that your amp started to hum. The amp works but it is impossible for it to be working as well as it did when it was new. The situation in tubes amps is also worse because the caps have much higher voltage sitting across them than a solid state amp, and the amount of capacitance even when new is much lower than a solid state amp.

I used to hear all of the time that a player didn't want to replace his caps because the amp would no longer be original. That is equivalent to saying that you don't want to replace the original tires on a vintage car. Things wear out and need to be replaced. If you don't do it the object (amp, car, etc) will eventually become worthless for its intended function.

What amps do you have?
Joe, from your further explanation, it might not be your amp (or any other component) at all. First thing I would do is swap the signal leads to your amp and If the "noise" stays on the same speaker, then it's the amp -- but not necessarily something wrong in the amp! -- it could still be powerline noise. So get a really stout (12AWG preferably 10 AWG) shop type extension cord (just long enough to reach you EP-15A -- fabulous unit BTW) and plug your amp into it. You'll know right away if it's something actually IN the amp, or lotsa line noise (which interestingly enough, can sometimes manifest in only one channel ;--)

Okay, you guys have done a really great job of giving me the pros and cons of going ahead or not going ahead with sending my 20.5s to Levinson for their first ever checkup and any parts replacement necessary to put them back on spec. I really do appreciate your time and thoughts whichever side of the argument you came down on.

That was a really great suggestion about the Service manual for the 20.5s. That never occurred to me in audio. I used to do a lot of my own work on my cars and I always used to get the service manual whenever I bought a new car. Levinson no longer has the service manuals available for their older discontinued models. Does anyone know if they are available anywhere else?

I now have the RMA #, so I now have 3 options:

1. I can send them to Levinson next week or the week after. The Levinson tech guy said that the turnaround time would be 2 - 3 weeks. In audio, I have found that manufacturers always take 2 - 3 times longer than they tell you to deliver the product. That means I will likely be without my amps for 6 to 9 weeks. I would not want to have my system down for that long. Any thoughts on something I might pick up on the 'Gon and resell in 2 or 3 months for at or near the price paid?

2. I can pull the top covers off and inspect the caps for leaks, cracks, etc., and then decide whether to send them in now or not.

3. I can replace the 20.5s and invest the money I would have spent on the maintenance as well as the sale price of the 20.5s in new or newer amps. I was thinking about replacing them next year with Ayre's new monoblocks anyway. Alternatively, since I have always been an ss guy, I could buy a pair of used tube amps on the 'Gon and try them out with the option of selling them for little or no loss if I decide I want to remain an ss guy. If I went this route I would want to get tube amps that are a good fit with my new Ayre K-1xe preamp and Wilson Sophias, meaning in part that they would need to be balanced and accept a balanced interconnect cable from the preamp.

As always, thanks for your time and thoughts.

Ed, If you like the way the Sophias sound w/ the ML 20.5s, you're not going to find better ss amps for anywhere near $8K, which is what the 20.5 + refurb. at ML would be worth max. Unless you want to buy a used pair of ML 33Hs for ~$10K, or maybe a DarTZeel for what? $30K?

So I say door #1. Have it done right at ML, before they lose THEIR service manuals. They'll really go over them with a FTC, and probably replace a lot of little parts too. You'll get a limited warranty on the new parts, I believe. And I think they're better than most on meeting their time estimates. Also you might ask them if, while they're at it, they'd install some proper 5-way speaker binding posts and replace the Camac inputs w/ RCAs! A lot of 20.5 owners have had this done (although I don't know if it was done at ML.)
I told you it wouldn't be cheap. :) I think at this point, you have to trust yourself.
Herman: At the moment it's a '64 Fender Super Reverb and a '62 Ampeg Reverberocket that need attention. The Fender did have some parts replaced around 15 years ago, the Ampeg is probably still original. The Fender obviously wants filter caps, the Ampeg surely needs more -- not only doesn't it sound well, but the last time I used it the panel got way too hot. It's actually somewhat remarkable to me how good the Fender continued to sound almost right up until it crashed, even garnering copious praise from other players who were pressed into using it onstage. But then a pre-CBS blackface Super is an all-time great amp.
The last time I rebuilt a Super Reverb the guy kissed me after he played it. At least it wasn't on the lips. (I'll probably have one of those giant beer cans fall on me now) Find somebody who knows what they are doing and you will be happy with the results.
Herman, I don't have any strong conviction on an absolute length of a caps reasonable use. I am led to believe that caps can be reasonably expected to be reasonably servicable for 20 years. What do you believe the life expectancy of a cap to be? When is a caps qualitive use expired? How often should amps like the Levinsons require maintance? I suspect that the quality and value of the caps used in circa 1990 Mark Levinson products were appropriate for its intended use. Now, if HK believes that their products need service every 10 years, who am I to argue. Then again, I might be a little less cynical if that suggestion came from the original designers/manufacturers rather than a new holding company.
What do you believe the life expectancy of a cap to be?

That's the $64,000 question. I don't have a strong conviction either because it is impossible to put a number on it for any given capacitor. Naim recommends 10 years. Cynics say that is just to generate revenue, Naim devotees say it is essential for maximum performance.

I would agree that in many applications they can be "reasonably serviceable" for 20 years, but most audiophiles are not going to settle for anything reasonable.

If I intended to keep my $35,000 amps and they had 16 year old electrolytics I would have them replaced
"Most audiophiles are not going to settle for anything reasonable". LOL! Makes one question how "reasonable" audiophiles are?
Isn't it true that electrolytics wear out more quickly from not be used than being used everyday?
They don't wear out but can lose capacitance sitting idle. However, once you start to use them again the capacitance builds back up.

A cap that has been sitting with no charge for too long can short out if you apply full voltage all at once. This is especially true for old caps in tube amps because they have a relatively high voltage across them. This is why you see the recommendation to form these capacitors by slowly bringing up the voltage across them when turned on for the first time after a long period of being off.

I have a Citation II that I would like to get going again. Any advice?


If you stick with the old caps it is best to bring the voltage up slowly. You'll need a variac (variable AC) transformer to do this but unless you get a used one at a good price it will cost more than the amp is worth. http://www.iseincstore.com/index.asp?PageAction=VIEWPRODGROUP&ID=20

You could take a chance and just turn it on.
Thanks Hermam,
I have been offered 1200.00 for it as is but I would like to use it in a second system.
oops, I had no idea it was worth that. A new variac is a few hundred. I would recap it if I was going to use it.
If you can find an older Spectral DMA180 it will give you adaquate power & dynamics and will resell easily. It will definitely benefit from a great power cord. Joe has an MIT Oracle AC1 for $850-a steal-and once you have it you probably won't resell it.
I am using Leak TL12.1 amps that are over 50 years old!
I have changed all signal caps to Mundorf silver-gold with great results, I am using the original Paper in Oil Can cap for the power supply, they are a bit low but sound wonderfull, I was instructed by a lot of "experts" not to touch them! If you are using your amps daily they should be fine, Try to get them measured before sending them off to get fixed!
I would say you will eventually need to change them so just decide which is the best time to do it! If you change them yourself or some technician close to you, you can decide which caps to use...these make a huge diference in sound, Do you want Blackgates, Elna cerafine for the Power supply? Do you want the original (20 year old design) caps for the signal path, will you just let HK put whatever they can get cheap! Do you want to try the latest in caps that add great resolution to your amp like the Mundorf Silver-oil or Silver gold, or the Teflon Vcaps, do you want a softer sound like paper in oil caps? Do you want a more crisp sound like Hovland caps? Are you confused enough already? This is a great hobbie go for it change them and play with the sound you like!!
I have an in circuit capacitor tester that costs about 100.00. It seems to work. I tried it on an Audionics amp that has a hum. The meter shows that one of the power supply caps is bad.
Guys, here's the conclusion to this story. As I was trying to decide whether to leave my still steller performing 20.5s alone or to spring for the $$, give them up for a month and send them to Levinson for a preventive maintenance refurb, I noticed a pair of almost new Lamm 1.2 Reference hybrid mono blocks for sale on the 'Gon and bought them.

They are already broken in so I have been having fun comparing them with the 20.5s. I also finally received my Silent Running Audio Craz Twin isoRACKS. Let me tell you that the sound is glorious with either set of amps!

The Lamms are better than the 20.5s (they should be), but not as much better as you might think. It is not an apples to apples comparison, however, because I cannot use the same speaker cables because the 20.5s take only camac connectors and the Lamms take only spades. So I am using my 8 month old Transparent Music Wave Ultra speaker cables with the 20.5s and almost brand new Purist Audio Aqueous Anniversary cables with the Lamms.

The Lamms seem more powerful than the 20.5s (and are so rated), definitely have more air and a better mid bass, mid-range and treble. They also resolve more. You can hear the lead singer on just about any CD take a breath. It feels more like the performers are right there in the room with you. The sound stage is no wider than the 20.5s but it is deeper. The 20.5s have a stronger, deeper base (at least with the Transparent cables they do), and are not shabby at all in the areas of soundstage, imaging, extension. I have never heard notes decay as realistically as they do with either amps and either speaker cords in the SRA Craz Twins.

Best to all and thanks again for your comments which ultimately led me to the Lamms though none of us knew that at the time.

Are you going to keep them both?
No, I'm going to sell the 20.5s sometime soon. I have just been keeping them to try to get a fix on the differences between the M1.2s and the 20.5s.

I'm glad you found something you like, but you have to ask yourself; Would the Levinson sound better than the Lamm if it were refurbed and didn't have those tired, old capacitors in it?

Why do you say the the Lamm's "should be" better?
Shut up Herman!! ;--)

I did get to listen to a pair of 20.6s at my dealer's that just came back from a Levinson refurb. They got better over a period of 72 hours of re-break-in and they did sound very good, but still recognizable as 20.5/20.6s. I can't say that they sounded better than before the refurb (Levinson refused to say that also by the way), but they certainly did not sound worse.

The Lamms are a 2004 or 2005 design and are Vladimir Lamm's reference state-of-the-art best that he knows how to design and build. Listening verifies that our best high end audio engineers have not stood still these past 16 years. They have actually found ways to improve their products. Also, some of us believe the tubes in the hybrid design do make the length and decay of notes more realistic while the solid state devices make the attack of the notes more realistic.

Lastly, it was not a question of finding something I like. It was a question of finding something I like even better than my 20.5s


Ed, I believe that would be 'tube' (singular), no? Do you know if there's somewhere Mr. Lamm explains the technical reasons for this particular design decision? I've always been curious about that.