Quality counts!

Without wishing to contest the general assertion that Naim makes quality equipment, I don't quite share the enthusiasm for the NAP 250, and in fact believe that Naim should have modified or retired it long ago.

Someone on this forum once provided a quotation from the devloper of the 250 (and founder of Naim) to the effect that he didn't design the amp to drive difficult loads. And indeed, the 250 has terrible heat-dissipation problems, and the speakers that it was commonly paired with after about 1980 (Linn Isobariks and Saras, e.g.) will cause it to shut down after a short period at loud volumes. This fact has been discussed and complained about regularly on this forum, as you may know.

What's frustrating is that the 250 (which at $3600.00 is hardly cheap) was never changed to rectify this problem, DESPITE the fact that everyone knew by the early-80's that most of the better speakers were hard to drive and gave the 250 trouble. Why a (relatively inexpensive) heatsink/fan arrangement such as appeared in the 135s was never added to the 250 is unclear. But unless there are pretty good reasons for not putting a fan in the 250 (reasons which I for one have never heard), then I think the fact that it was never modified to correct the overheating problem is actually one of the more disappointing chapters in Naim's product history.

Let me add that when I and others have complained about the 250 frequently shutting down at volume, we were sometimes accused of placing unreasonable demands on the amp. I categorically reject this claim. My ex-250 would regularly shut down driving Linn Isobariks at even moderately loud volumes with bassy music. "Moderately loud" in the sense that you could comfortably talk over the music (and yes, the 250 was recapped by Naim and the 'Briks were in good order, with Naim cable and the rest). I am very certain that these volumes were well within the 250s power handling capacities and that it wasn't clipping or breaking up; it simply couldn't handle low-impedence loads for more than 20 or 30 minutes WITHIN its power rating without thermal tripping. Someone might say that the 250 wasn't designed for such loads, but then I reply that if so it was OBSOLETE decades ago, because such loads long agoe became a fact of hifi life. And if the 250 was supposed to drive lower impedence loads, then it was born with a design fault. Naim doesn't look so good under either alternative.

Anyway, as I said I don't wish to deny that Naim makes great quality stuff, but the 250 is about the worst example I can think of for making the point

I had a circa `90 old style 250 used with saras for over 9 years and never once did it shut down nor did it ever have a problem. I now have 135s driving linn 5140 speakers and the fans have never gone off. I have a very large room and my 82 volume control is usually around 9 0`clock and sometimes up to 10 (with cd player). Face it the 250 is a fine example of elegant engineering and I wouldn`t hesitate to buy one if I didn`t want to spend for the 135`s. david.

some (bad) habits are hard to break. Those mark levinson towering inferno monoblocks have, like, 73 output devices per amp. They don't shut down do they?

I don't know why naim didn't modify it sooner but i suspect they didn't give too much a damn about "the reality of hifi speakers". Running the 250 on their speakers is just fine and really, active is where the amp is happiest it seems. A many hands makes light work approach. Brilliant, I think. Long live naim.

Connon

Just so no one thinks I'm making this up .

Here are a few threads found on this forum from a search on 250s overheating. Some threads have several complaints about this from different people driving different speakers, including some electrostatics, Epos 22s, various model Saras, and (of course) 'Briks:

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=4111964912

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=3961910543&r=7171903743#7171903743

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=3761998943&r=8031965053#8031965053

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=990192024&r=907193024#907193024

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=4671991605&r=7301914605#7301914605

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=2851961483&r=9191917583#9191917583

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=4111964912&r=3421984912#3421984912

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=222193736&r=548199988#548199988

http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=131196593&r=852196593#852196593

The various suggestions to attach a computer cooling fan to the 250 are kind of cute, in their way. But maybe not what you want to hear after plunking down $$$$.$$ for one.

The 250 does great things when it's not shutting itself off, as I'll be the first to admit. But it's still got problems.

Put it this way, if I paid many times the average price of a new car for a high performance model that would outperform the others, only to find that it chronically overheated when I started pushing it in the ways (power, say), that it was supposed to distinguish itself from its lessers, I'd be, well, disappointed. If I was told that people who only drove the car as they would an ordinary, pedestrian sedan, didn't have a problem, I'd be disappointed and irritated. If I found out that the manufacturer had been making this model for decades without bothering to install a cooling fan to fix the problem, I'd be, well .... .

My upset was mitigated by my excellent Naim dealer, who basically bought my 250 back from me after:
i. It had been serviced by NANA;
ii. It overheated in his own shop on gear similar to mine;
iii. He admitted that overheating had always been a problem, and even told how he used to get people out of his demo rooms at closing time by intentionally cranking the 250 until it quit (Time to go!).

quote:

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Now correct me if I'm wrong here, but Isobariks are, due to their design of basically being two independant speakers in one box, 2 ohm devices when driven passively.

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I think more like an honest 4 Ohm.

FWIW I ran a NAP250 into SARA for some years and never cooked it.

Perhaps its a combination of excessive room sizes and limited power output? Or poor ventilation around the base of the case where the temperature trip is placed?


Paul

Hi ejl:

Before I left good old blighty I had a 32.5/Hi-Cap/250 and original Saras and never got the 250 to shut down, even at high levels.

On the other hand, I do have a bit of theory as I have managed to get my newer 250 to shut down driving my Credos. I honestly believe that the power supply to the 250 is critical in this area. I now use a PS Audio PowerPlant AC regenerator and along with better sound quality, the 250 runs much, much cooler and has never shut down since.

Best Regards,
Mark Dunnn

After many years wandering in the dark, I too am firmly back in the world of Naim. Grew up with a 12/110. In the intervening years, listened too and had various other makes. Everything else gave more mechanical trouble and less musical pleasure - much less. I too am back for good . . .apart from loudspeakers where I am still not quite a believer.

To judge Naim adversely just because of the problems of one amp with one type of speakers seems churlish to me. Undoubtedly, it would be a better company if 250 did not overheat. Given the range of achievements of the company and its consistency over the long run, I still think it deserves the word 'great', particularily when one considers the evolution of its long run competitors. JV should rest easy.

David

quote:

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To judge Naim adversely just because of the problems of one amp with one type of speakers seems
churlish to me.

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It would be churlish. Glad no one did it.

quote:

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I now use a
PS Audio PowerPlant AC regenerator and along with better sound quality, the 250 runs much, much cooler
and has never shut down since.

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Mark,

There was an interesting thread about these a while back. I think one of the concerns -- maybe you remember this -- was that the PS Audio wasn't feeding the amp enough juice. Do you still find speed/power in the bass, etc. with this installed?

Another concern was about a loss of musicality, but I guess you haven't found that to be the case.

It's surprising that the amp runs cooler with the PS Audio. Can anyone here explain why this might be

quote:

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Originally posted by ejl:
[QUOTE] To judge Naim adversely just because of the problems of one amp with one type of speakers seems
churlish to me.

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quote:

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It would be churlish. Glad no one did it.

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So, in that case the 250 runs hot is just a sidebar conversation to the overall thread?

...because Credos are reasonably easy to drive--a NAP 250 need not stretch to get these going; you'd probably blow the tweeters before you'd max out the amplifier.

David Q.,

The problem is with more than one kind of speaker, as I noted.

"Judging Naim adversely"; well, I granted at several points that Naim makes great products. If "judging Naim adversely" means that I'm criticising a product with a long-running problem, then I'm judging them adversely, and I think it's perfectly fair and correct, barring futher information from Naim about what's up. If "judging Naim adversely" means I think that they are a lousy company because of this problem, then I think I made my position clear.

The 250 is relevant to quality issues for the reasons I noted.

If the 250 had a fan there wouldn't be the same demand for the 135's. Naim are a business and it pays to have a genuine reason for your customers to upgrade. I am a very happy 250 owner and would only change it if I needed more power. I think the real problem lies in the practice of badly engineered speakers, surely audio designers should be aware of the real world problems caused.

A friend of mine had a really bad experience at a McDonalds burger joint once! Didn't fill him up you see. Server says he was wearing the wrong teeth and anyway, it's not eveyone who complains about the amount. Was told he should have had a McDouble burger. That would have sorted him out.

The Nap 250 has and will, as the thread starter indicated, give the vast majority of users great pleasure and give no problems interfacing with most loudspeakers. Why would we change the design to accommodate certain speaker models? They don't make Isobariks or Sara anymore. We still make the Nap 250. Are we doing something right.

Anyway, it's Friday (here) Have a god weekend one and all

Later

Doug

You should change it because Ejl is clearly unhappy.

He is very important in his circles, I think you should make an effort.

duh.

Hi ejl:

Re:

>There was an interesting thread about these a while back. I think one of the concerns -- maybe you remember this -- was that the PS Audio wasn't feeding the amp enough juice. Do you still find speed/power in the bass, etc. with this installed?
Another concern was about a loss of musicality, but I guess you haven't found that to be the case.<

I believe I contributed to that thread and I have found absolutely no drawbacks with the PP600 in my system. I think I pointed out though, that the larger Naim power amps may well draw more current than the PS Audio can provide.

>It's surprising that the amp runs cooler with the PS Audio. Can anyone here explain why this might be<

It beats the poop out of me too. The difference in temperature is certainly not subtle.

Best Regards,
Mark Dunn

quote:

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Originally posted by ejl:
It's surprising that the amp runs cooler with the PS Audio. Can anyone here explain why this might be

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Hi,

well, the only possible explanation I can offer is that the PS can't supply enought current for the amp to reach it's full potential.

I guess this would manifest as compression, which would make the sound smoother & cleaner, 'open' the sound up, and pump up the bass. You would tend to run at higher levels on the volume control to compensate, and this will bring up the low-level detail for the same peak levels.

Of course, these are attractive attributes, it's why Radio 1 does it to their output. Ultimately, though, it's better if you can set the system up so it works with the full dynamic potential available.

Note that I'm not saying the PS does this - I've never heard, or even seen one. I'm sure it achieves it's primary aim, to reduce noise on the mains input. I'm just suspicious that you're also losing something intangible.

cheers, Martin

Hi Martin:

I'm not sure why it runs cooler but in my system there are only pluses to its use and no drawbacks. With your 6x135s I don't believe it would be a good option unless you used multiple units.

I have a dedicated mains spur and dedicated ground in my listening room, so switching between the two power types is simple and using the PS Audio always proves to be far better than not.

I'm about as flat earth as they come and certainly wouldn't keep it if it had any deleterious effects on PRaT etc.

Best Regards,
Mark Dunn

entry in error

I also used to drive Saras and Isobariks at what I consider to be pretty loud levels. The 250 got slightly warm with the Saras but hardly budged above ambient temperature with the briks.

In fact I was puzzled why Naim thought it necessary to put fans in the 135's.

Steve B