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.


I'm not familiar with MacCormack amps, but maybe someone with a DNA225 will chime in. The behavior you describe isn't at all unusual for power amps though. I had an Ayre V-3 that ran too hot to touch. I was speaking with Ayre tech support once and the guy said that's how they should run . . . "hot is good" were his exact words.
As for the rack position - I prefer to keep amps that run hot out (there are amps that run cool too) in the open (ie on amp stands, not in an enclosure), but as long as your rack is as open as you describe this may not be an issue. I would keep 2 ft above it open.

It's also not unusual for it to trip a breaker - especially if you have other equipment powered by that circuit. I imagine the amp is drawing maybe close to 10 amps on startup. If the amp is the only thing on that breaker - it may be worth checking out the amp again though.

It's worth a call to tech support, but it's possible this is all entirely normal
My 225 never gets hot even after several hours.. I have it plugged into a dedicated 20 amp circuit,and have no problems with breakers tripping either. cOntact Steve Mac., hes very helpful. Good luck
Hi Mike -

How hot your DNA-225 gets will depend on several factors, but I suspect that yours is behaving normally. The 225 runs on the warm side normally, assuming it is out in the open. Cabinets will restrict air flow more than you might think, and I feel that this is responsible for yours getting rather warm at idle - but this is not a problem. On the other hand, your Infinity Kappa speakers are known to be a difficult load, and may drop to below 2 Ohms at some point. This is undoubtedly why your amp becomes very hot with use. Under the circumstances, this is still normal behavior, but you might want to think about adding a small, quiet fan to circulate air in your cabinet. You may be surprised at how much cooler the amp will run if you push air into or out of the cabinet. Finally, the DNA-225 does not have a "soft" turn-on circuit, so its current demand at the instant you flip the power switch is quite high. Again, this is usually no problem - but if the circuit branch the amp is on is already loaded-down a bit (with lights or other appliances) or if the circuit breaker is "weak," or if there is a problem with the wiring, this may be enough to trip the breaker. The DNA-225 will not trip the circuit breaker on a normal 15A service, so if the breaker does trip, it may indicate a problem of some kind on that circuit branch.

Best regards,

Steve McCormack
when it's on for a while and not playing I registered 117 at heat sinks and about 95 or so on the faceplate. When I played music for an hours or so, the heatsinks get to about 128-130. Get a digital temperature reader and take measurment. i know the heatsinks are hot to the touch, but in reality, the temperature is not that hot....bit it feels hotter. Don't be alarmed. If it is much hotter than what I mentioned above, then be concerned.
Regarding this breaker; you can usually detect a weak spring in this breaker.---Turn it off and on---Then try and compare a different 15a breaker. You should be able to feel if they are equal or different in resistance.
All, thanks for your replies (especially Steve.) I replaced the breaker and that solved the tripping problem. I had time to have the system on for about 45 minutes last night and the amp seemed cooler (relative term) also. I have an infrared thermometer, so I'll take some readings, but based on your responses, feel confident the only thing cooking will be some hot tunes.

why doesn't dna225 have a soft start circuit?
Why not? Because they add cost and complexity, and I did not feel it was necessary in the DNA-225. Larger amplifiers like the DNA-500 are a different story, and it definitely must have a soft start circuit.

Best regards,

Steve McCormack
Is DNA-500 hotter than DNA-225? Think upgrade to a DNA-500. I have a DNA-1 deluxe and it is never hot.

I ran my DNA500 with a pair of Andra's for extended period of time, say 8 hours and maybe more during break-in period. The amp was out in the open on a decicated amp stand without any heating issues (In fact, I was surprised how cool (temp) it was). Thank you Steve McCormack for chiving in on nearly every email, if not all. You can always count on him to participate. Simply awsome knowing that your desinger is always there to help answer your questions.
I'll second that, you won't find better service anywhere than Steve's. Period. And to think that this is a McCormack of Virginia product (owned by Conrad Johnson) and Steve could just defer all issues to them.

My DNA-225 runs warm, but never what I'd call hot. Such was the case before and after I had Platinum upgrades installed. As an aside, even more than replacing the 15amp breaker - try to run your 225 on a dedicated circuit, if possible. It is worth the effort.
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.

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.

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
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
I'll make the assumption you bought your 225 used. If so, have you checked the main (externally accessible) fuse? Perhaps the amp developed (or always had) some kind of internal problem on power-up that kept blowing the line fuse so he simply replaced it with a MUCH bigger slo-blo fuse. Cheaper to flick a circuit breaker than keep replacing fuses. Checking the main fuse obviously doesn't fix the problem, but could be a clue to something amiss internally and/or something the previous owner never told you...
DNA 225 fuse rating at it fast or slo blo
Hello Hi5 -

I presume you are referring to the AC mains fuse for 220-240VAC, and these are always slow-blow. The fuse will read "T5A" where "T" stands for time-delay. FYI, the internal DC rail fuses are 10A fast-blow (F10A).

Best regards,

Steve McCormack
SMc Audio
I had a similar problem with a DNA-1 tripping a new 20 amp breaker. Some one suggested this and it solved the problem. It's a 20 amp breaker designed to allow a larger inrush of power. No problem since!!! Cheap too..only $20.00 from Grainger
I have just the opposite situation with my DNA225.

I moved into a condo in FL with one 15 amp outlet for all my audio and TV gear: DNA225, MAP-1 pre, Marantz SA11S1 CDP, Blu-ray DVD, 46 inch Sony LCD TV, Rotel 3-ch amp, PSA sub, SONOS, a couple of amps...and the breaker never pops open.

I am wondering if its working. When I go back this winter I'm going to fish a dedicated #12 wire to this area but it won't be easy opening all those walls.