How's the cooling capability?

[GJgo]

Ok final word from Mesa, they did some testing to back up what I was saying & passed on some technical details- very cool of them. They got the same basic surface temps & also measured internal temps which were of course a little higher.

Basically, it's not a problem, however I'm still going to point a fan at the back when running CabClone because it's free insurance.

Technically, all the components are UL rated for a lot more heat than this & the surface temps are high but in spec. For example the circuit board is flameproof, and the midi microprocessor IC (which is within an inch of the load resistor) is rated to 257°f when in use. :shock:

Carry on!

 

[bandit2013]

The aluminum chassis will transfer the heat since the load resistor is mounted to it. It will get hot as it lacks the surface area needed for cooling (heat sink).

As for rated temperatures, depending on the UL certification requirements, may only be for a short time at its maximum temperature and should not fail (burst into flames or cause cotton test fabric to catch fire). Without having read through the UL standard that is applicable to the amp or related equipment it is hard to make an accurate statement. In general practice and in my experience with UL testing of line voltage products: being UL certified only indicates that when the component fails it will do it with grace vs causing a fire or other safety hazard such as electric shock. Especially if the test is termed as destructive meaning the product will no longer function after the test is concluded.

Use of an external fan may help to some extent if you can keep the chassis a bit cooler with forced air at least it will pull some heat from the resistor. It the amp had an internal fan that would only run with the speaker turned off would probably be a better solution or if there was a heat sink on the chassis that had good thermal transfer for the load resistor. I had to look at the manual again as it was easier than walking to the other side of the house to look at the amp, Never really dawned on my that this Mark amp does not have Variac power. Makes me wonder what it would sound like with a spongy mode or reduce voltage mode like most of the other Mesa amps. Not that it matters to me but most would argue it is not a IIC+ if it had it. :|