Need Help! My Class A Amp Is Running Very Hot

just want to be sure it’s ok since it is a preowned unit

Obviously, most amps will survive life with higher input voltages but it's not necessarily good for them, best to ask the manufacturer run at 122 Volt continuously for the L590AII is OK!

Did you ever call Luxman or your dealer? What did they have to say?

Chill off rod man
First time I experienced with class A Amp 
just want to be sure it’s ok since it is a preowned unit

Does your amp perform/function/sound as is should? Do you believe Luxman actually might know how/might possess the competence, to design and manufacture a device, that can protect itself from overheating? Has it EVER exhibited the first signs of malfunction? Why are you entertaining so many alarmists? Oh, wait; THE SKY IS FALLING! THE SKY IS FALLING(just being consistent, with the other contributions)! 

Thanks for the clarification hififan.
Currently I have the 590AII model so I guess it is running within spec
I had the 550AX before it doesn’t run as hot but the 590 sounds a lot better more dynamic and detailed 
Happy Thanksgiving!

I just did another reading from the Killawatt
Standby =1.1W
Idling power on with no input =318W
With input and music playing =326W
60Hz Volt 122

I did some google search and found the following:
L-590A / L-590AII power consumption is 280 watts at idle,
L-590AX power consumption is 220 watts at idle,
L-590AXII power consumption is 260 watts at idle.

If OP’s amp is a L-590A or L-590AII, power consumption is 280 watts at idle at 115 Volt, according to calculation based on ohm’s law, the power consumption at idle at 122 Volt it should be 316 watts. So it is well within spec.

If it is a L-590AX, the power consumption at idle at 122 Volt it should be 248 watts. IMO, it should go for a check-up.

If that is a L-590AXII, the power consumption at idle at 122 Volt it should be 293 watts. Maybe it is best to ask the manufacturer if 318 watts is still within spec.

I have different brand class A amps in a custom cabinet with active ventilation. They are Krell Evolution 600 idle/listening moderately they are about 117 degrees when they are pushed approach 130. The owners manual of Krell lists the amps heat output in btu’s for each model incase one would buy it for a space heater as an alternate use. 

Yes I did, please  see the above reading 

DID YOU TRY DISCONNECTING YOUR SPEAKERS??

Contact your dealer or Luxman.

Thanks for the feedback 
I just did another reading from the Killawatt
Standby =1.1W
Idling power on with no input =318W
With input and music playing =326W
60Hz Volt 122

The back panel of the amp stated it is a 115 Volt /60Hz model

Oh!

Also, if you have a "separate" switch, use that, see if the power drops for any of these examples.

:)
Best,
Erik

At idle, the Watt meters are pretty accurate.

As I said above, it could be you have a signal you cannot hear, so it is important to try disconnecting the speakers. If you have an A/B switch that would work.

So would switching inputs to an unused input. 
Best,
Erik

Imhififan makes a good point about the possibility that the amp is a 100 volt model being operated with 120 volts. The voltage the amp is designed to operate with should be indicated on the rear panel.

Regarding the Kill-A-Watt meter, I have no experience with and no particular knowledge of such devices, but I wonder about what kind of accuracy it would provide when used to measure the power consumption of a power amp or integrated amp. I assume that what it does is to multiply together a measurement of voltage and a measurement of current. But are those measurements "true rms," or something else?

And if they are not true rms, given that an amp draws current mainly during a small fraction of each 60 Hz period, when the instantaneous voltage of the AC at the output of the power transformer approaches positive and negative peaks and exceeds the voltage stored on the filter capacitors by enough to cause the rectifier diodes to conduct, that would seem to raise questions about how meaningful the measurement is.

Also, given the inductive nature of the power transformer and the capacitive nature of the filter capacitors, perhaps voltage and current aren’t quite in phase with each other, which would also result in some inaccuracy if the device calculates power consumption by simply multiplying the two numbers together. With the inaccuracy being in the direction of overestimating the number of watts.

Perhaps one of those having experience with these kinds of devices can comment on these questions.

Regards,
-- Al

Where are you located and what does the back of your amp say about voltage? Is the voltage on the back the same as your standard voltage where you are located?

As I noted, disconnect the speakers, and all inputs, and measure again.

If it's still 330, and you are sure you are running a US model, contact the manufacturer.

They are pretty responsive.

Hi I checked the reading it is about 332 Watts at idling with no volume and the same with music on

Yeah, running a 100V model at 120V will absolutely cause this problem!

If OP's (khmyjy) amp is L-590AX and not the AXII, there's a possibility his amp is a 100v japan model.

The L-590AX is spec’d as consuming 220 watts at idle (310 watts max). The L-590AXII is spec’d as consuming 260 watts at idle (330 watts max).

http://www.luxman.com/
I don't know why peeps don't rely on manufacturer's websites. :)

Per this, it should be ~ 260 at idle, and ~ 330 at full power.

Disconnect all inputs, and outputs.  You may have some ultrasonic oscillations going on. 
If that does not drop the power, contact the manufacturer.

Best,
Erik

@khmyjy,
Is the 332 to 340 watts with the amp idle, not playing any music but powered on? That’s how I’d recommend you test it, because the power draw should be “only” 260W in that case. If 332-340 is at idle, then It seems prudent to question the heat output. Do you have a local shop you trust to look at it?

Thanks I just bought the Killawatt and plug the L590 to measure, the reading is fluctuate between 332W to 340W 
I assume is within specs?

+1 @ramtubes and erik,

Plug in the L-590 to a KILLAWATT to verify if the bias as specs

Power consumption 330W
260W (under no signal)

We're cooking a roast tonight. How many kilowatts should it be?

Get a KILLAWATT AC power measuring device for $20. It will tell you how many watts you are drawing. End of story. Its a very useful device, logs yoiur KWHr, time, voltage current, watts VA. I have 6 of them

OP, all amps are different, so don't be sidetracked too much by remarks about other products. As some above have recommended, I would first want to find out how hot your amp actually gets. Terms like 'hot', 'burning hot', etc, are all subjective.That being said, I own the L-590AX, and was concerned about heat before the purchase. After owning it for a couple of years now, my assessment is that the amp gets what I would describe as "pretty warm". Certainly nothing approaching burning hot, I could put my hand on it anywhere, for any amount of time.Good luck, please let us know what you find out.

OP--for a definitive assessment on operating parameters by someone who is really going to steer you in the right direction whichever situation unfolds---Join Luxman vintage yahoo group. The moderator there Hans is invaluable for info on Luxman. He is an archivist and a wealth of knowledge on anything Luxman.
I had a vintage class A/AB Luxman once. It did not  get hot enough ---there is so called class A and then there is true CLASS A---which may all that is going on here and coupled with internal heat sinks most assuredly results in higher temp. Although I did not read enough to gather whether you bought this used .. As Correct bias is paramount. Contact Hans for his 2c. Actually not sure he is moderator but that doesn’t matter. He is based in Europe I think. One time ordered a manual from him if I recall correctly. Long time ago. Be sure though that you actually communicate with Hans himself.

I have four Class A amps. I run two of them bridged in one system and each one is over 100 pounds of radiating fury.  That system is not one I listen to frequently during a hot summer - they would drive you out of the room in a bit of time.  Great in winter, though.

I doubt that you have anything to be concerned about - that is just the way Class A normally works.

Different amps, different temps! I am using 2 mcintosh 2205s and noticed one running hotter on one channel of heat sink then all of the others. After a thermogun and amp meter, I reset the bias and found a dirty connection. Read true maintenance manual from manufacturers to get specs. If you are technically apt, do it yourself! If not, find reputable repair or service. 

I have a 100 watt per channel pure class A Threshold SA/4e. There are large heatsinks along both isides of the amplifier. The heavy front face of the amp, and the large rack handles, are also part of the heat sink system. After it's been working for a half hour or so, the heat sinks get up to about 114 degrees F. 

My WA33 woo runs extremely hot to ... to the point where if I put my hand on the chassis it will burn my hand ...literally...  I bought a fan to cool it off so it runs warm all the time now....

I'd still be interested in having you take a few temperature readings at various locations using an infrared thermometer.

@khmyjy- Luxman has it covered. Just relax and enjoy your music.

I've had Class A amps for years so to me what you're describing sounds normal. Looking at a picture of the inside of the 590, each of those massive heat sinks is for only four power transistors. That tells me the designers expected all that heat.

This is a funny amp, @pbnaudio


Look at the power rating, and look at the idle/max wattage.
Tell me what they say to you. :)

https://www.amazon.com/dp/B07R4W5DS7/ref=sspa_dk_detail_6?psc=1&pd_rd_i=B07R4W5DS7&pd_rd_w=G...=

Get one of these - a properly designed Class amp should not run any hotter than 50 to 55 Degrees C  

Good Listening

Peter

You can check this with an inexpensive watt meter:

https://amzn.to/2nhr6Iv


Set it to watts and compare to your spec.
And yeah, class A gets very hot.

I replaced my Mc integrated with a Lux 590AX about a year ago. Wanted to try Class A. My equipment had always been in cabinets. That did not work with the Luxman. Even though the cabinets were pretty well ventilated the Luxman ran so hot that it would shut down after about an hour. So, I moved it to the cabinet top where it has lots of fresh air and I’ve had no further issues. Great sound and good looking unit with all the retro knobs but it needs LOTS of breathing space as it definitely runs hot. Maybe all Class A units do but this seems excessively hot to me.

My experience with this amp is exactly that, it runs like a house on fire. But it sounds pretty good too. As some note, Class A amps typically run hot.

Read the paragraph under ’PROTECTION CIRCUIT’, on Page 1 of the Luxman AX590 manual: https://onahighernote.com/oahn/wp-content/uploads/2015/01/L590AX.pdfLuxman probably knows, how hot is too hot, for their product and have taken precautions.

Thanks for the info, it is very informative 
so many nice and helpful people here, love this site.

Perfectly normal. The amp has over temp protection. If it were abnormal it would be shutting itself off. This is what class A amps do. 

IMO it probably is running as it is designed to run.  I have a Luxkit amp that runs hot, very hot to the touch so you wouldn't leave your hand on the unit and it has open vent slots but small heat sinks.  The kit has been around 30 years and works fine, sounds fantastic also.  One of the best sounding amps I have ever heard or built myself.  Oh course mine is slightly modified by me!

BTW the Luxman will wipe the floor with the First watt amp so I wouldn't even consider that move.

Happy Listening.

Read the paragraph under ’PROTECTION CIRCUIT’, on Page 1 of the Luxman AX590 manual: https://onahighernote.com/oahn/wp-content/uploads/2015/01/L590AX.pdf Luxman probably knows, how hot is too hot, for their product and have taken precautions.

IF it is an used unit, make sure it is a 115v model ( not a 100v Japan model ) if you are in US otherwise a transformer is needed!

If you can hold your hand on it for 30 seconds, then it's not that hot.  Still, it's best to talk to the manufacturer/distributor if it really concerns you.

Given what you have reported and Al's usual helpful stats it sounds like the amp is operating at normal temps for a Class A design. This is the main reason I am not a big fan of some of these designs--it's not so much the heat they produce and the impact on room temperatures. I have concerns about parts longevity in an enclosure that produces so much heat. Things get stressed at those temperature levels regardless of what specs they might cite and the repeated heating and cooling as you power up and down will also likely take their toll over time. I feel the same way about tube units that are not designed to allow the heat to dissipate easily from inside the cabinet. One of the reasons I love a ZOTL design like my LTA Ultralinear is that it runs remarkably cool for a tube unit. This will likely contribute to less parts failure down the road.

If it is so hot on the vents that you would get burned, I find it hard to believe, that Luxman would use a material such as plastic, as vents. 

Questions: How much SPACE is open above the amplifier? How much space is under the amplifier? How much space is open behind and to the sides of the amplifier. Is it on the floor, on carpet? Is in on a hard shelf?     
Ambient temps? This is how HOT is your ROOM? If you live in the tropics or like me, regularly are at 80F/ 27C or higher, then the amp will be hotter. just the way it goes... If you room is at 74F / 23C that is not an issue.   
Does the 'too hot' mean if you left you fingers on it for thirty seconds you would have a second degree burn? Or just a bit of pain??    
If just some pain. then I say it is NOT too hot.     
I own a PREAMP that is a blast furnace. It gets really hot. I spoke to the guy who built them, and he said, normal.  
Things you can do: Raise it up a little higher off the shelf or floor. So small bits of wood under the feet. 1/2inch .. 10 to 15 mm is all you need. If the amp is on a shelt, it needs at least three or four inches free space above it. If it has less, you need to solve the lack of free space above it.    
All the "Danger Will Robinson Danger" nonsense spouted in other folks posts means nothing if the amp is designed to run that hot.

 Thanks for the feedback, to answer your questions, the Amp is placed on a  open wood shelf, the top and the sides are wide open, the room temperature is about 70 degrees. I can put my hands on the cabinet for a period of time no issue but when I put my hand on the vents it is very hot can’t hold it for 30seconds I will get burn

If you just bought the amp and are that worried, perhaps Class A isn't for you.  In that case, I would return the amp and buy the Class AB version instead.

the cabinet on the top temperature is 28C which I think is just a little warm but acceptable but when I put my hand on top of the plastic vents (over the heat shrinks) it is extremely hot, way over my thermometer maximum temperature of 50C

To add perspective, my Pass XA25 amp operates in class A and consumes an amount of power (240 watts at idle) that is very similar to yours. The XA25 is stated to be designed such that after it warms up to a stable temperature its heatsinks will be about 25 degrees C higher than the temperature of the room. (Elizabeth makes a good point about the significance of room temperature, btw. Each degree of difference in room temperature will make the same difference in the temperature the amp stabilizes at, following warmup).

So under typical room temperature conditions the heatsinks on my amp will approach 50 degrees C. Very significantly, however, in contrast to yours the heatsinks on my amp are on the outside of its cabinet:

https://www.passlabs.com/amplifier/xa25#lg=1&slide=8

The heatsinks on my amp also appear to have much greater total surface area from which to radiate the heat than the heatsinks that are inside of your amp.

So, again, it seems to me to be very possible that what you have described is normal, although I am not in a position to be certain about that.

Regards,
-- Al