How hot should a McCormack DNA-225 get?

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.

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!

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?

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

Hi Mike -

I confess that I am puzzled by the fact that your breaker continues to trip when turning the amp on. The DNA-225 has a fairly large power supply, but tripping circuit breakers has never been more than a rare thing. I can't really imagine anything that could be wrong with the 225 that would 1) cause the breaker to trip, and 2) not show-up in some other obvious way - fuse blowing, amp not working, etc. Did the electrician check your AC system Earth ground? Problems with your power system ground might cause some sort of seemingly unrelated issues like this. I do feel that something unusual must be at work because this is just not a problem normally.

For what it's worth, the "ARC-2" upgrade option does have the effect of being a sort of "soft-start" circuit (even though that is not its intended function). This might eliminate the problem if you decide to have the upgrade work done, but otherwise I don't know what to suggest.

Please give me a call if you want to talk this over.

Best regards,

Steve McCormack
www.SMcAudio.com
760-732-0352