Need Help! My Class A Amp Is Running Very Hot

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

what kind of speaker cables are you using?  I about roasted a Classe CA200 20 years ago using Goertz spkr cables.....caused the amp to oscillate and overheat....can't remember what the tech explanation sorry 

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). Both models weigh about 63 pounds. The amp’s heatsinks are entirely enclosed within its metal cabinet, and are immediately adjacent to the side-panels, as can be seen here: 

http://www.luxman.com/asset/product/L-590AXII/gb4.jpg 

So the escape route for the heat corresponding to those power consumption numbers is almost entirely via the vents on the top, supplemented to a small extent by radiation through the side panels.

Given all of that it seems to me to be very possible that what you have described is normal, but it’s hard to say for sure. Perhaps another owner of one of these models will chime in.

@three_easy_payments, I believe the OP’s reference to "cabinet" pertained to the metal enclosure of the amp itself.

Regards,
-- Al

Hi there, 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 

Actual temperature? "Burning hot", is very subjective! No one can(possibly/correctly) answer your question, without that fact/measurement. Not even the manufacturer. btw: your amp has a protection circuit, that will turn it off, if it senses over-current, abnormally high temperature, or DC drift(per the first page of the Owner's Manual).

Although others hear are diagnosing your amplifier with positive, absolute, definitive assessment they cannot know what might/could be wrong with your amplifier without a firsthand inspection or more information than you have provided it may well be functioning completely, fully, and entirely within the manufacturer's intended operating parameters at the very least/minimum you need to measure the temperature of the unit itself.

Have you talked to your dealer? What did he say?

@almarg 

I believe the OP's reference to "cabinet" pertained to the metal enclosure of the amp itself.

Ah yes, I see I likely misread.

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). Both models weigh about 63 pounds. The amp’s heatsinks are entirely enclosed within its metal cabinet, and are immediately adjacent to the side-panels, as can be seen here:

http://www.luxman.com/asset/product/L-590AXII/gb4.jpg

So the escape route for the heat corresponding to those power consumption numbers is almost entirely via the vents on the top, supplemented to a small extent by radiation through the side panels.

Given all of that it seems to me to be very possible that what you have described is normal, but it’s hard to say for sure. Perhaps another owner of one of these models will chime in.

@three_easy_payments, I believe the OP’s reference to "cabinet" pertained to the metal enclosure of the amp itself.

Regards,
-- Al

You probably shouldn't have it placed inside of a poorly ventilated cabinet. My Class A amp is warm but not burning hot to the touch but I choose place it on an amp stand, not even within a rack.  Ventilation is important.

How hot is too hot, how hot is burning hot?

Measure with a thermometer !

Contact the dealer or manufacturer directly and explain the situation.

This is not normal.  Don't take any chances.

Doesn't matter what the problem is, and there is a problem.  If you aren't prepared to fix it your self, then an authorized service center or the manufacturer is the way to go.

It appears to me that the bias is way off. However, a simple solution (not the best) is to adjust the bias back to where it should be.  However, what caused the bias to float way off in the first place.  This is not normal.

enjoy

the cabinet over or around the vents  it is burning hot , I even feel the heat on the sides of the cabinet,

Can you measure with a thermometer?