How hot should a McCormack DNA-225 get?

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

Getting on this topic late so maybe you have looked at or have already been advised of this. Since you have a dedicated line to your equipment you probably don't have this, but on the newer houses, I guess for newer codes, some of the circuit breakers are now equipped with a quicker shut off. Even though they are rated at the 15-20 amp constant load they will flip when seeing a real quick spike, this especially holds true in the high lightning storm areas. I have my listening room on a dedicated circuit line and when I had my electrician install my line he told me he had to use this type of breaker to stay within code, if/when I wanted to change it he would supply me with the breaker but would not install so as not to jeopardize his licence.

I have two amps that are doing just what you are complaining about, a vintage Krell KSA 100 and a highly modified little 2A3 SET amp. The krell I can understand why it is tripping the circuit, it has no protection circuit and goes right to the very large capacitors. The 2A3 amp has had a lot of bi-pass capacitors added to the power supple as well as in the signal path. When it is turned on it either trips the breaker or takes out one of its fuses. Issue 2, has you amp been modified? My solution was to have on outboard slow start for all of my amps and the problem was solved. I started with a variac but it degraded the sound so I modified a Welborne filter with a 3 step slow start circuit, problem solved. I leave the amps switch turned on all the time (saves the amps switch) flip the first switch on the out board filter wait about 10 seconds, flip the second switch wait for the bias to build (2A3 amp) (about 30 seconds) flip the third switch which than is direct and enjoy. This has worked for me for the past 4 years, a little trouble but well worth the effort...............

Again, if this has already been suggested sorry for the redundancy......Bob