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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
stevemcx
166 posts
 
Under equal conditions, the DNA-500 will run cooler than the DNA-225 simply because it has a *lot* more heatsink surface area. Many DNA-500 owners have commented that it only gets warm - never hot.

SM
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!
fplanner2000
616 posts
 
My DNA-500 has never run hot, only warm after lots of hours, seconding Steve's comment above. I have Whisper speakers which are pretty efficient, but nevertheless have lots of big drivers. Never had a problem with heat. I would suggest maybe trying out a DNA-500. Altho I have not heard the 225, I would say the 500 is one of the best solid state amps made under $15K. The sound should get lots better and the heat should go away, right Steve?
kartracer OP
37 posts
 
Steve - help! I've lived quite happily with the sound of my DNA-225 for 6 months now. Speakers are now Von Schweikert VR-4jr's; speaker cable is (don't laugh, I'm just entering cable hell!) Home Depot 10-gauge solid copper shotguns made by yours truly, about 8 feet long. Balance of equipment, just for reference, is Bel Canto Pre2P, Music Hall CDP 25.2 (modded by Underwood), VPI Scout with Dynavector 10x5. IC's are Signal Cable silvers and PC's are Signal Cable; shielded for CDP, otherwise for otherwise.

The equipment is less than 10 feet from my breaker panel. I've had two dedicated circuits installed (I believe the electrician used 12 gauge wire) with a 20-amp breaker on each, outlets are Porter Ports. 70% of the time when I switch on the DNA-225, the breaker STILL trips. As before, the only other thing on that circuit drawing power is the pre- and it's what, maybe a couple dozen milliamps to power the LED and some transistors in standby?!?

What tests can I do to find and resolve this problem. With all the great reviews, I was considering a Silver upgrade. Don't make me buy a Class D amp!! Any advise would be greatly appreciated, thank you all.

Mike
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