Mark Levinson 23.5

I was at my local dealer yesterday because I am considering purchasing some cables down the line. He gave me 2 brand new sets to audition and told me since they are brand new they would sound best after the burn in of about 30 hours or so. I plugged them in to my Mark Levinson 23,5 and its been on playing all day (about 10 hours) at a normal to lower volume. My thought is, I'll just keep the system on and audition the sound periodically in between. I don't know if I've ever had my amp on this long. It seems to be getting very hot. Everything sounds absolutely fine. Does anyone know if these amps normally run hot after extended hours of play. It's not even being driven hard. I'm concerned because I just got the amp out of the shop last week after being in there 4 weeks the first time and then 9 weeks the second time. When I received it back the first time, I received it back with a noise issue. Nothing has changed impedance wise. Any thoughts out there?
3a4e1df6 59ac 4e6e 8a27 f6591e7fd810luvrockin
luvrockin, I have a no.334 dual mono. I’ve had it for a very long time. Actually I bought it new when the no. 334, 335, 336 series was released. I leave my amp on for extended periods. Days- weeks even. Unplug when it rains or to switch equipment or cables. Mine only gets warm to the touch even when I push it.

No way would I leave my 23.5 on 24/7.  I would connect those cables to something else to burn in, or,  I would burn them in while listening.  If you had a tubed REF 6 pre-amp brand new would you leave that on constantly for 600 hours while burning it in?  I definitely wouldn't. Most people suffer to the slowing bettering sound of their new equipment while burning it in.

Also, the cables shouldn't sound bad while burning in anyway, and it is interesting to hear the sound get better over time.

My recommendation, is you are asking for trouble leaving a 23.5 on.


I use an old Oppo DVD player to burn in new cables. I run the Ayre IBE disc and a stereophile test CD for the most part. I normally don't  like the sound of new cables initially. If the cable is used, it goes into the system immediately.

However my Levinson normally stays powered up most of the time. 

I owned a Classe' CP35 and a CP60 Preamp and they did not have a power switch.

I wonder if the bias was changed when it was in for service.
The 23.5 runs in Class AB and there is enough idle bias which results in the amp being warm, not hot.  Former 23.5 owner.
Guys, thanks for your input. I actually turned off the amp last night. After a couple hours after this post I felt it's running way too hot, not warm for comfort. Years back, I burned in cables leaving the amp on most of the day and I don't remember anything like this. They must have done something. My dealer is closed today but I will definitely be calling them tomorrow morning.
Good luck, keep us posted in your 23.5.

Yes Woobie, will do. Its going back in Saturday. I just hope they didn't screw it up on me. I'll be really pissed because this is an awesome piece, age and all. We'll see!
Update, received my ML 23.5 back after I brought it back in for service because I felt it was running too hot, much normal than it use to. After another 3 weeks I received it back. The repair shop checked and adjusted the bias. They claim to have load tested it and basically abused the amp in their sound room. They said after this extensive use, the temp only got up to 128f*. I brought it home and set it up in my system. I'm using new speaker and balanced interconnects that I am auditioning. This should eliminate any issues with cables causing possible heat generation. I swapped left and right speakers as well in the event possibly one lost its impedance value. After having it on for a few hours and playing music at a low volume, the amp warmed up. I then sat down to listen for a few. After about 20 minutes of playing the amp a bit harder, the temp shot up to 132f on the right side and 122f on the left.  I refer to a bit hareder as my normal listening level. No way pushing this amp near 50 if not less. I'm not a blow your eardrums out listener. Ive had this amp for 15 wonderful and it never use to run this hot. And the fact the right side runs 10* hotter concerns me as well. I'm not sure what I should do. I don't know it they can do anything else with it. I love this amp and its sound. Although running hot, it sounds phenomenal. Should I push to have them look at it again or pay the freight to send it out to the east coast for repair or trade it for something different? My dealer mentioned trading up as an option to a Bryston 4B or Ayre Acoustics amp. Not sure which amp this may be but it retails for $9k. I'm not in that position right not, so that option sucks. Any thoughts?
You didn't mention how you measured the temperature but assuming a temperature gun, its possible to have 10 degrees F margin for error, depending on how you hold/point the gun or the specific point of measurement. Just a possibility.
Actually I measured it 2 ways. One using a Raytek infrared thermometer locating several different hit spots and the other using a Fluke 52 with a surface probe. The most hear is generated at the top of the rear heat sinks, which makes sense. But I can literally feel the temp difference with my hand. It's noticably different, much warmer.
I have owned a 27 and 27.5 and they never ran hot as you are describing.  Did your repair shop check the caps, resistors, etc?  Have you used Google to research this issue?  Personally I wouldn't use this shop any longer because they haven't found the issue plus I would be reluctant any way to take the amp back as they want you to trade up. To me thats a flag especially trading for a Bryston 4B. Not that it is a bad amp but the 23.5 IMO is quite a bit superior sonically. 
Samzx12, my 23.5 never ran hot either. Maybe a bit warmer when I pushed it harder. I may have worded my last post incorrectly about trading up. I was asking my dealer what should I do? In such a way like, wth, should I trade up or what are my options. This amp went back in to them 3 times in the last 4 months. Originally it has the left channel distorting which they corrected. I received it back with a short noise in the right channel which went away after 30 or 40 seconds. Either way it wasn't right, so it went back again. Immediately after I got it back is when I noticed it running hot. It went back again. It was suggested then in discussion and frustration that I asked wth I should do. That's when it was suggested the Ayre Acoustic amp would be my next jump up and sonically would wow me. It was also suggested I should audition the Bryston as technology has come a long ways through the years and I would be shocked that it supposedly out performs the Levinson sonically. That's a hard to me because I love everything about this amp including the classic BPA look. For now I have resorted to putting a 4" fan blowing on it to cool it plugged into it's own receptacle on a different circuit. It's actually a pretty quiet little fan and running this thing pretty hard is only about 115*. That's more like it use to feel. It just sucks because the original repair cost me over $800 and I know sensind it out east won't be cheap either. Sucks!!!
I loved the design and looks of the 23-27 series of amps and have heard the 23.5 was one of the better sounding of the series. OK I understand what your dealer meant now however, they aren't fixing the heat issue. It sucks your out $800 but it started running hot after they had worked on it. So I am not sure what your conversation was with the dealer are you sure they set the bias correctly and checked out everything else. I am guessing it sounds just like it did before?  Also, hopefully someone that knows amps can chime in here. 
Samzx12, yes, it sounds fantastic. I'm losing confidence in their repair shop. At one time pre-Harmon Ind days, they were a Levinson dealer and did a lot of service on ML equip as needed. It's just that since April, this amp was in their shop 12 weeks? The amp didn't run hot until they played with it. I may push that issue. The other option is I'll pick up the freight to have it go east for repair. They will absorb the repair cost. I asked them to check the bias when I brought it in last time. They said it was all ok when the checked it. I'm hoping someone that knows these amps may chime in as well. I may try to call Levinson myself and see if I could talk to a tech. I think that may be a slim to none chance but I'm going to give it a shot.
I would check with George Myers on the west coast he is very good with Levinson repair. 
68Pete, do you by chance have any contact info. I Googled the name with no luck.
Levinson would be Harmon International now and I ordered some parts for a ML 29 I used to have so I assume they are still in business?  However, a good repair shop should have no issue. Push your local shop and go from there. I feel its close to being back to normal. Great amp :)
This came up on the first search pass:

He's an authorized M. Levinson repair center.
I enjoyed an ML-29 for a number of years and kick myself to this day for parting with it.
tubegb yes its a sweet little amp and wish I could have kept it but had to use the funds to buy another amp. 
Thanks guys for the input. I called to Steven at Levinson this morning. He's pretty confident that either the amps bias is wrong or possibly there is another part that may be failed/failing. He confirmed both channels should run about the same temp rather than the 10° difference I have. I'm going to make some calls to the authorized repair centers as well. Maybe I can do the footwork for my local shop.