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How hot should a McCormack DNA-225 get?

I recently picked up a 6 year old one that was just factory checked. The heat sinks get pretty hot with no signal, and with music at moderate levels (feeding Infinity 8 Kappas, nominally 6 ohms) for half an hour, get almost too hot to touch! I'll call the factory and ask, but thought a voice of user experience could be more "honest." It is on a bottom shelf of a cabinet with open front and large openings in the back. At the time nothing was above it (over 2 feet of air.) The DNA-225 is replacing my 20 year old Adcom GFA-555 which would only get "hot" after a good while of cranking out some tunes.

Also, in a different room, the amp is tripping a 15-amp circuit breaker at turn on. Nothing else is on at the time. The original location may have been on a 20-amp circuit, I'll have to check.

Both these things make me wonder if the factory missed something. Ticket said they just biased some transistors. Any owner expeiences would be greatly appreciated.

Thanks,

Mike
kartracer

Showing 2 responses by christobyl

christobyl
15 posts
 
Your mccormack should be biased more towards class A operation than the gfa 555. If true, then it will always run hotter. I believe mccormack is owned/designed by conrad johnson..they are into high class A operation last time I checked.
An other possibility is that you have excessively long (20ft or longer) runs of thin gauge speaker wire which will increase resistance and heat up the amp..or your speaker wire is corroded which will do the same thing. I have seen corroded (green copper) wire even blow fuses in amps. NAD in particular..since they are high current designs.
Thirdly, if your supply voltage is lower than 120V then the amp will draw more current..which will make the amp run hotter and can cause the wall breaker to trip.
christobyl
15 posts
 
OOO. I didn't read all of the replies before I spouted out. It seems this amp design Jesus hath spoken. So, while all my spouting applies.. his responses should be more educated than mine, needless to say I suppose.

WooHoo to great equipment Steve!
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