The Levinson Sound?

I can remember the day, back in the late 70's that my Grandmother came home with her SX series Pioneer receiver. Grandma wasn't wealthy but she knew what she liked! That thing drove her over priced speakers into realms that, at that time, I could not imagine. Even my young untrained ears could hear a marvelous difference; a sound that I can only equate to "thick & full". It layered sound so well and did not leave voids in the spectrum as its predecessor did. Then a few years later I audition a Levinson setup and it drove the same chills up my spine that the Pioneer SX did, only on a higher magnitude. I heard a lot gear in those years but the ML got a hold of me. The Levinson badge was too rich for my blood back then but is definitely in my wheelhouse these days. A lot of older ML gear can be had for decent prices now. This is why I cherish the 332 that I have today. In fact it is probably the most unique 332 you will ever see. 

https://drive.google.com/file/d/0B0yvjhlC62G7SHVJczc2ZUV2OGs/view

I put a lot of work into that failing frame both electronically and aesthetically. But it must be said....this series is aging and in a lot of cases failing. If you get one it is silly to expect it to work as it was designed if it has not been seriously serviced recently. Yes, the larger caps are beyond their useful lives but you cannot ignore the smaller signal caps as well. As many others echo, Mark Levinson's service is one of the worst in the industry. THEY WILL NOT SELL YOU ANYTHING. THEY WILL NOT SELL ANYTHING TO AUDIO DEALERS. If you break a speaker binding, ship the 150lb monster and pay the minimum bench fee (a few hundred bucks). If you need any mundane part, ship and pay up. If you want an ML fuse, ship and pay up. Want to get bias adjustments, ship and pay up.

IMHO this series is now relegated to those users that have the technical skills, at the component level, to keep it running like new. If you are a casual consumer for vintage gear then your money could be better spent elsewhere (ie Bryston, Krell). I am not saying the amp is not worth it! It is worth every penny to me. The sound stage is astonishing and the power reserves make it drive the most complex loads effortlessly. What I am trying to do is prevent people from besmirching a fine name like Levinson when they buy an old  300 series amp and it blows the black electrolytic goo from the main caps on their $5000 Persian carpet a few months later. If the amp is overhauled then I say go-for-it. If you are unsure then buyer-beware and commit to it only if you have the skills, time and patience to bring it up to spec. Do not expect any support from ML.

@jafant Which ML repair facility were you referring as above?

I have been fortunate that my dealings with ML centers was minimal. I have not dealt with them anymore since I realized how they shut the world out for simple requests and simple parts. I have had to resort to sourcing parts from third party vendors and scouring both domestic and foreign ebay sites. I had to get documentation from underground sources in Europe. I got a Voltage gain board from a police-raid auction in the Netherlands. It is a little silly that one has to go through this to repair an amp.

I may be wrong but I believe there are only 3 U.S. based ML repair facilities. There is one at the ML headquarters, which I believe is in CT. Then there are 2 other "Authorized" facilities. I think one is in Texas; don’t know about the other. All of these centers follow the same doctrine however. You want anything, pack the monster up, ship it and pay up. Don’t have the original box? Be prepared to shell up big dollars for that. You cannot use an ordinary box with an ML amp. It will exit an improper box with great force under its own weight!
Very unfortunate that they treat the legacy equipment in this manner. I could understand protecting newer designs especially if it uses new techniques but spending 400-600 dollars to get a broken speaker bind post replaced is a little ludicrous. ML has great equipment, and the old stuff in the right hands will live a long time; you just need the patience and skills to grant it a second or third life.

@jafant Do you know if the No. 383 Integrated Amp has the cap issue like th other "3" series products?

I am not an ML expert by any means but my gut feeling tells me that this problem was limited to the 331, 332 & 333. The design of the electronics changes significantly with the later models. Most notably is the choice of moving away from T0-3 type power transistors. From a service perspective the newer design makes it so much easier to service. To remove a board that has T0-3 transistors requires un-soldering ALL the transistors because the legs of the transistors pass through the heat sink. (a real PITA). However, the newer designs with internally mounted transistors have a caveat. If they fail, they can fail violently and often will vaporize a board. I have seen pics of some of these boards. Not pretty at all. I think I said in another post that the ML amps are basically controlled lightning. They have massive power reserves that will destroy if unchecked.

The large caps on the 331-333 were problematic from a manufacturer perspective (Phillips). Oddly enough ML still chooses to install Phillips caps where most of the self-service community will install slightly larger Cornell-Dublier caps.

ML has identified a few counter-measures. One includes installing mylar strips on the frame of the chassis. I imagine the caps swell and contract, especially at initial power up. The caps are strapped to the chassis. I think the outer casing would eventually wear through the blue plastic coating causing the metallic can of the cap to contact the grounded chassis. If a cap is failing internally it would provide a path to ground for large amounts of current. This will heat up a cap quickly and then you get the black goo volcano. Don’t try to order these $0.25 "safety strips" from ML. They wont sell them. Don’t try and order large, small or so much as a decal from ML. They will not sell them.

Then there are a few other items that ML identified as failure points. These include soft-start resistors, small bypass caps and mid-level power supply caps at various locations.

I think by the time you get into the newer models such as the 336 and higher the cap problem had been well identified and fixes were already in place during assembly.

This however does not mean it cannot happen to ANY amp with large cans like the ML. As caps get older they start to become resistive. Resistance causes further heating and evaporation of electrolytic material. It becomes a run away train that cannot be stopped. If you have a ML amp with OLD large can caps by Phillips then be cautious and be prepared to spend a nice chunk of cash to make it right.

Thank you for the kind words Jafant.
I wish I could say this was a pet project for me. 
These legacy amps still command a good amount of cash.
If I could buy more of them I would but people know ML quality and hang on to them. I wouldn't touch a newer, recent, amp. You will not find one at bargain prices. You certainly won't find service manuals floating around. If I can't work on it I don't want to own it. I don't think any of the original innovators are involved with this line anymore either.

If I find a bargain I jump on it. For example I bought a pristine Adcom amp and preamp on Craiglist the other day for $100 with the knowledge that it was broken. With under $12 in mosfets and 2 caps, I brought them back to life. I jumped on it because it was a Nelson Pass design, I wanted to see it for myself and I knew there were service documents floating around.
My sensible side will not let me go too far off the deep end. 
I am more of a practical enthusiast, improving those things I can get my hands on at a decent price.

As for my listening impressions: I primarily use this amp in a listening room that also serves as a recording studio. Yeah I know, over-kill! But even studio monitors with 10" drivers can present a challenge in an environment where the source signal can be very raw. I spend a lot of time in that room so when not behind my console the amp is pleasantly working in the background providing rich, room filling sound. There is something amazing about an amplifier that does not have to flex its muscle. It will produce complex passages with no effort ,especially on the low end. The 300 Series produces a very musical, non-fatiguing sound. Those that have properly working specimens will not let them go. Those that do let them go often regret it. The only group that remains pissed off at ML are those that have a great piece of gear but find it unreasonable to spend $1200 - $1500 to get it serviced. A lot of audio shops turn the repair work away because they know they cannot get support, service manuals etc.Those that are in that situation, walk away quickly and trade in for newer, hassle free options. I don't think it should be that way. Look at all the old McIntosh, Krell, Dynas etc that remain in service today. They are like that because the respective manufacturers allow their gear to live in infamy with proper manuals, parts channels, etc made available to the public. I wish ML had the foresight to take down the wall of silence they put up. For those who live in other countries, I challenge you to call an "AUTHORIZED" ML service center and ask if you can buy a service manual. I really want to believe things in the ML world may be different in other countries.

@hk_fan And once again you are wrong. My 336 caps failed which I returned to Levinson for repair and was told that ALL 3xx amplifiers suffered the same issue. It’s not the caps themselves, it’s the way they are used in the circuit which shortens the life of them.

I can definitely agree with this. I believe ML knows this too. However the Phillips caps were a prominent weak point. Their service bulletins state that Phillips caps should be replaced with United Chemicon caps but I have read many cases where they replaced failed caps with Phillips caps again. Also these caps do have a finite useful life. If you have 10 to 15+ years on your amp then you should not be upset if they do fail. The amount of actual usage hours will affect this. When ML publishes safety bulletins (in an act of supreme irony they don’t publish safety concerns to the public) they are identifying areas of the amp that make engineers raise a brow. Three areas of concern were the Phillips caps, the contact points of the main caps and the in-rush resistors. The cap contact issue was rectified with mylar spacers The potentially violent failure of in-rush resistors was addressed by using open wound chromium wire resistors. Neither of these are parts they will sell to the public or 3rd party repair shops even though they are safety related. They will however automatically perform these fixes on any amp that comes across their service bench, at your expense. The main caps are punished every time the amp is started from a dead-off position. It is exponentially worse if one of the 3 in-rush resistors is failed open. One open resistor means the remaining survivors and the caps have to bear the in-rush; the next resistors will fail in short order. If your ML starts occasionally blowing fuses on power up, you potentially have a bad in-rush resistor or the main caps are going bad.

I will venture to say that those that keep the ML in idle (not off) when not in use will have longer cap life. In-rush current is not nearly as bad when turned on from idle. The problem with idle-off is you are burning approx 200 watts for absolutely no reason except to keep the output transistors at a nice toasty temperature. I for one am not going to watch my electric meter spin around faster with an amp chewing up 200 watts as I sleep or when I am at work. In fact I don’t know if I like the idea of keeping this hulking power supply of an amp alive at all when I am not physically home.

I cannot say the technology to bring the power supply up slowly with pulse width modulation was available at the time the 300 series was introduced, due to the current demands. I really wish it was. It would certainly make sense on modern equipment. These caps could really live a lot longer if they were slowly brought up to nominal voltage over the span of 30-60 seconds. I have even read of some guy trying to slowly bring these amps up to voltage with the use of large Variacs. The brute force approach of using single stage in-rush resistors with the Phillips caps that falter under this stress seems like an unfortunate mix.

Even with all of the above, which some might consider negative, I am here to say that the ML is still a superior product. 

@333jeffery Would a Levinson 20.5 amp that's been recapped be worth consideration? Do they produce high current into low impedance speakers?

Those are nice pieces and if taken care of are worth consideration, especially if the price is right. However I believe the entire front to back architecture of the 20.5 is full Class A. They are going to warm a small room. They will produce high current. Just Google the magazine article "Arc Welding with a Mark Levinson amp". I think they were using that series of amp in that punishing experiment.