Over heating NAP250DR

Allante93 posted:

Richard Dane posted:

{It's less about lack of power} and more about thermal dissipation.  The NAP250 uses the case as a heatsink.  When it works hard in warm weather it can begin to get hot - once it reaches 70 degrees the thermal trip is activated and this protects the amp.  How much circulating air do you have around the amp?  close confines within a rack can be a problem.  Cooling the case with circulating air from a fan can help.

I guess it's only so many topics one can discuss, and trust me, During Mr. Richard Danes Tenure, he's heard  them all, tenfold!

But never the less, when your Naim's iconic 250, shuts down, its darn right frustrating!

Can't recall the thread this exact moment, but I've probably got it archived.

But winging it:

Naim's Achillis Heel, is it's Lack of Power!

Naim's answer is an upgrade path with increasing power.

Nap 200 ~ 70 watts

Nap 250 ~ 80 watts

Nap 500 ~ 140 wat......

But some  members replying on this very thread, have suggested that they prefer the 300 over the 500.......

MONKADILL, Enjoy Your Music!

JMHO!

Allante93!

Found it, From one of our Esteem Press Members:

"just to be controversial... my ordering in increasing quality is:

500, 300, 300DR, 500DR

Going from a 300DR to a 500 seems to me to be a significant backstep. 

Now people will squeal that the 500 is better than the 300. Its bigger, more powerful, but it simply doesnt time as well. However, it doesnt matter what you think of 500 or 300, and the relative qualities of both -- a 300DR is streaks ahead of either."

So I would imagine:

205.2 < 250DR < 500 .....

@ Monkadill, I listen to my music from afar also! 

Music throughout the House!

MM > Airport time capsule > 3 x Airport expresses.

Hence, the Volume, of all three Systems is more like 7:00 or 8:00 o'clock, I guess!

I don't know that decimal  conversion!

Allante93!

PS. Baby Boomer

Allante93

I own a 250 dr,and have never had it shut down on me ...and I have played it at 60 on my 272 for 10 to 15 minutes maybe.Now if you want to talk actual SPL levels on a real RadioShack SPL meter(which I have),as you said,my active Dynaudio XD 600's,I hit 113 DB peaks,holding the meter about 1 meter away from the speaker.

No quarter posted:

Allante93

I own a 250 dr,and have never had it shut down on me ...and I have played it at 60 on my 272 for 10 to 15 minutes maybe.Now if you want to talk actual SPL levels on a real RadioShack SPL meter(which I have),as you said,my active Dynaudio XD 600's,I hit 113 DB peaks,holding the meter about 1 meter away from the speaker.

I think you have put a lot of  thought in implementing your System!

All this talk is interesting. Similarly I have not experienced any amp shutting down since I started with this hobby. Perhaps I was lucky, or maybe I wasn't listening loud enough. The NAP 250 DR is quite a robust amp so I am surprised that the Ovator S400 can cause the amp to shut down during a listening session, considering the speaker is not that "difficult". Personally I would think that high listening levels is more likely the culprit than weather / room temperature. Poor ventilation can be a possibility though the OP would be able to gauge if this would be a concern after the amp was moved to an open-air placement.

All the speculation about the OP listening at high levels and the subsequent hearing damage comes up quite often these days. The size of the room isn't really the key factor. It's the listening distance from the speakers that will usually indicate whether listening levels are too high. Typical listening distance from speakers is usually 2.5m to 3.0m but you would never know if the person is seated 6.0m (or more) away from the speakers with far field listening, The best way to find out whether you are listening too loud is to use a proper SPL meter. Or just use your ears - by your own judgment.

Allante93 posted:

RICHARD DANEADMINISTRATOR
6/20/143:17 AM
Mike,
 
it's the thermal trip operating on your NAP250.  It shuts down when the temperature of the casing exceeds 70 degrees C.  
 
A few things can cause this: unsuitable cabling or cabling; connection or cable fault; "difficult" speakers with complex crossovers driven at high level; high ambient temperature with not enough air movement for the heatsink (casework) to expel heat.
 
In the old days with the original NAP250 driving tricky loads like Isobariks at high levels, some owners directed fans at the amps during the summer to keep them cool.  The NAP135 brought its own fan cooling, which is also found in the current NAP300. 
Like Reply (1 Like)

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Administrator
  
June 20, 2014 11:09 AM
Bert,
 
like 99.6% of power amps out there, the NAP200 isn't a regulated power amp and so when the going gets tough it just lets things slide a bit. A NAP250 isn't allowed to do that, so it has to work much harder (and gets hotter as a consequence). Remember too that there's much more inside a NAP250 - twice the transistor count for one thing.  For all that, unsuitable cabling will get a NAP200 hot.

 

Allante93!

PS. I'm with YOU, Analog

and Naim, and Mr. Richard Dane! 

That's All! 

Enjoy your Music Monkadill, and Analog! 

@ No Quarter & Ryder:

Lets just say, you guys done it right!

Mr. Richard Dane has seen & heard of a many 250s over-heating!

Allante93!

PS. Remember I dealing with Briks!

Passive Bi -Amped 250 & 200

250 shut down. As Mr.Dane pointed out, the 200 slipped on the job, It didn't shut down!

But Passive Tri-Amped Briks , with

(3 x 250.2s), No Problem!

Next Upgrade, SC & Snaxo!

Thanks Allante. Good information on speaker cables and "difficult" speakers causing the shutting down of the NAP 250. Perhaps the S400 is a difficult speaker :-).

Personally I would be more concerned about my speakers blowing up rather than the amp shutting down or picking up hearing damage when listening to music at high levels in a large room.

ryder. posted:

Thanks Allante. Good information on speaker cables and "difficult" speakers causing the shutting down of the NAP 250. Perhaps the S400 is a difficult speaker :-).

Personally I would be more concerned about my speakers blowing up rather than the amp shutting down(or hearing damage) when listening to music at high levels.

Speakers Blowing up! 

No, more like the Neighbors saying you got an live band in there!

Of Course, an respectable time of the Day!

But @ 10.5 & 11:00 o'clock, Sounds Great from across the Street, they are Diana Krall sounds Great!

Allante93!

PS. With modern up to date Speakers, like you guys got, and proper Cabling, the 250 is more than enough!

Allante93

i ended up ordering a full Fraim base,which is one shelf,with all the hardware and one piece of glass,so I could copy all the dimensions of the shelf to my Fraimlite shelves.The glass looks identical to what I got from that company.I am a machinist,so I set up a fixture on a CNC machine,then machined the sides away,cut in the recesses for the cups/balls and added the 250 diameter hole for the dowel,which stops the glass from sliding back(to my 5 Fraimlite shelves).Then I had them all painted black by a local wood painter,turned out really nice...anyway,back to the 250 shutting down.

And on the back of this thread I've just bought muso qb to go upstairs. That'll save unnecessary volume downstairs from the SN2. Makes a decent alarm clock too ��

Perhaps I'm over optimistic, or simply naive, but I'm quite certain that were overheating to be a regular and significant problem with the 250 Naim would have engineered into the design a preventative solution (300 style fan, improved heat sink etc.). The fact it hasn't done suggests this is a problem only encountered in rare circumstances for the reasons outlined above. I like my music played pretty loud, but the levels described by the OP are pretty extreme!! 

I've only owned two Naim amps (SuperUniti & NAP 250DR), with the latter driving speakers that can't be described as 'easy' (ProAc K6), but have never experienced any overheating or thermal trip. I believe ProAc have previously advised the few who experience such problems to consider buying a cheaper, more forgiving, stereo to use for their parties or BBQs rather than risk damaging expensive high end products that were never designed as rock venue PA systems!!

Timmo, it's rare (or at least should be).  I have had all sorts of NAP 250s of all variations, and still have an '85 vintage CB 250 and a fairly recent 250DR.  There has always been a NAP250 of some kind or other somewhere in one of my systems. The only time I ever had one trip out on me was many years ago when the NAP250.2 had just been released.  I had a pre-production unit and decided to try it in a high-end valve system I had.  That system used Kimber 8TC cabling and unfortunately it was not a good combination.  The NAP250 got very hot, very quickly.  A quick note to self - stick with Naim's recommended speaker cables.  The amp was fine thanks to Naim's thermal shutdown.  I've never had a NAP250 shut down on me since.

Hmm, 250.2 + Kimber 8TC, nice ultrasonic oscillator you built there!

There's nothing quite like experiencing these things for oneself...

There was only one instance when my Olive NAP 250 had a brief nap
We were driving QUAD ESL 63s at a reeeaaallly high volume via  6.5 m lenghts of NACA5. The amp didn't have a Quad-mod fitted at the time. One of the channels switched off. A brief re-set, 5 min wait and we were back in business.

I had my old NAP 250 re-capped and moded by NAIM last year - no further problems with it

Richard, did the tweeters survive?

Adam, did the Quads survive without arcing?

They were fine.  The whole experiment lasted only minutes...

Glad to see you take appropriate health and safety precautions in your experiments.

My Nap 250 would sometimes shut down due to overheating at high volume - switching to a pair of 135s cured it. My current Superuniti has never shut down even though I still like to play loud sometimes.

The worst thing is that the shut downs would happen precisely when you were most in the mood for rocking out, often with a few friends around. I just couldn't tolerate it !

Huge posted:

The SU won't shut-down when it gets too hot - it's not a regulated amp.

(Or rather if it does 'shut-down' I'll probably have blown up and need a trip to Salisbury for fixing!)

I'm not sure that's right.

"5.5 Amplifier Fault Warnings

In the unlikely event that a Uniti Series power amplifier is overloaded, exceeds its normal operating temperature or malfunctions, its output will mute and the front panel display will show a warning message."

Ah, OK it uses a different safety mechanism (by muting) - interesting: I'll delete my post.

All Naim power amps have a thermal cutout set at 70 degrees, not just the regulated ones.

In all my years of running 250s and 135s, in passive and active combinations, I have never had a 250 shut down due to over heating in the UK. I can sometimes bring on the fans on the 135s, especially on those driving the ATC bass drivers in the DBLs.

jon honeyball posted:

In all my years of running 250s and 135s, in passive and active combinations, I have never had a 250 shut down due to over heating in the UK. I can sometimes bring on the fans on the 135s, especially on those driving the ATC bass drivers in the DBLs.

I Guess Naim knew what they were doing, when they carried those fans over to the 300!

Jon, was it possible to detect when the fans were activated?

Also, what do you think about the following ranking?

250.2<250DR<500<300<300DR<500DR

Allante93!

PS . where would the 135s fit in ????

Perfectly possible. They whirr quite loudly. 

Re ranking -- i think it overstates the performance of the original raw nonDR 500 which we find to be boring.

Allante93 posted:

jon honeyball posted:

In all my years of running 250s and 135s, in passive and active combinations, I have never had a 250 shut down due to over heating in the UK. I can sometimes bring on the fans on the 135s, especially on those driving the ATC bass drivers in the DBLs.

I Guess Naim knew what they were doing, when they carried those fans over to the 300!

Jon, was it possible to detect when the fans were activated?

Also, what do you think about the following ranking?

250.2<250DR<500<300<300DR<500DR

Allante93!

PS . where would the 135s fit in ????

Allante

You have to take some things with a pinch of salt i.e. don't believe everything you read on this forum.

There has been a lot of hype about Sarum cables, very good they are indeed, but they are not the only game in town, compared to Vertere and Superlumina.

It has been claimed for instance that Superlumina speaker cables don't time well, but that is not the case to my ears - they are actually better than NACA5 in that department. They don't make NACA 5 sound broken, but improve on them and actually keep all the traits of NACA 5 while getting rid of the weaknesses.

I've heard 200, 250 300 500 many times, and 500 is much better than a 300 or a 250.

Of course everyone is entitled to their opinion, but in my experience with Naim when it comes to amplifiers they don't get it wrong. A 500 has no problems with timing, it got PRAT in huge amounts with a huge dose of power refinement, clarity, soundstage, just about everything - the best of Naim really.

I'm not a Naim fan of everything they do. I never liked their speakers for instance, just not good enough compared to the best of other companies.

The existence of Chord Hugo and Dave is also another matter, and well I like those a lot more and I have no Naim sources.