TMA 500.1

Have a quick question on this amp ..

The owner says he can play 2 songs by that time he said the amp is so hot you cannot touch it ..

I had another friend test this amp in his car and he said the same thing .

The ohm load on the first car was 2 ohms. The ohm load in the second car was 4 ohms ..

I tested this on the bench for 30 mins and it never got hot for me the ohm load was 2 ohms ..

They both said in a car it was to hot to even touch without getting burned ..

Any ideas what might cause this ?
If it was the same as the amp below, you were not running it hard on the bench. In 15 minutes at full power it will get very hot.


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Perry Babin

Paid Member
2003-11-20 11:01 am
Most amps shut down before 200F. The thermistor is in one of the coolest parts of the amp. If it heated up quickly, the thermistor may have been cooler than the hottest part of the amp.

The owner may need a fan. This isn't a class D amp and when driven for extended periods of time at moderate to high power, it's going to get very hot. The fan would need to blow over the outside of the amp. A fan shroud would be helpful since the amp has almost no fins to increase surface area for cooling.

How long did it take to get that hot?

Did the idle current remain about the same as when the amp was cold?

Did you confirm that the ohm load was correct with a meter?

Was the amp mounted where air could move freely around it?
The amp was mounted so air could move around it ..

Trunk lid was open the entire time ..

I measured with a meter and it was a 4 ohm load ..

It took about 5 mins to get warm then about 15 mins into playing songs that's when the amp got to 220/230 degrees and shut down ..

The idle current stayed the same the whole time ..

Can I extend the leads on the thermistor and put it closer to the outputs or will that cause problems like the amp shutting down to
Soon at a certain temp
After the amp got around 200 degrees we unhooked it and put it back in the bench when it was that hot and the idle current was still only about 1 amp..

Then hooked it back into the car and played it til
It shut off ..

Not sure on the history of the amp the first time it came to me I replaced 1 of the driver transistors in it and that was the only thing I noticed that was bad everything else checked fine no shorted or leaking outputs ..