The Evolution of the NAP 250

Hi Alonso,

Others are better qualified to advise on the evolution of the 250 than me but I can say having just taken delivery of a 250DR it is a superb amplifier - rich and intoxicating sound, with sublime timing and rhythms.  I have started a seperate thread on my findings.

One thing about all the Naim reference level power amps is that they really need a high quality pre-amp to provide a big enough soundstage to give of their best and indeed quality source. In my view the 250 (of any model) really requires a 282/HC or 272 minimum.

Sorry!!

Regards,

Lindsay  

Hi !

The "old" 250 was cased in the olive case and was produced till the year 2002. The 250.2 is the current version (the case has the same design as your Nait XS but has a height of 8,7 cm. as all the classic series). This year Naim introduced the DR upgrade which is based on the same circuit design of the 250.2 (and has the same case). This upgrade includes the  NA009 transistors  (taken from the Statement amp) and the new discrete regulators. Some fellow forum members that bought the new 250DR say that this upgrade is a huge step up in sq. If you buy a used 250.2 take care of 3 important things:

1) every 10 years or so the Naim amps need a recap that is not so cheap (so a 250.2 from 2003 should have a different price as a 250.2 of 2014);

2) the 250.5 can be upgraded to DR specifications (starting from 2016) but the cost has not been jet published by Naim (but some say it could be around 1.500-2000 Euro)

3) the commercial name of all the 3 versions of this amplifier is NAP 250 so pay attention that you get what you pay for (the used prices of the 3 versions  are very different from each other).

Hope this helps. 

Hi Alonso, I was in a similar situation to you recently - I had a supernait and was looking to move to seperate pre / power combo. I tried my supernait as a pre with a 2012 250.2 (non DR) and it sounded great. Added more definition and control, especially in the low end when things got very busy. I moved to Naim from lesser hifi about 8 years ago and what drew me in was the lack of colouration and "smearing" of music in more complicated tracks. For me adding the 250.2 to the SN did more of that. 

Ultimately I managed to part ex most of my kit, including CDX2 and managed to stretch to a 272 as source / pre and a 250DR power. The DR option is a step further up the ladder to what I (poorly) describe above.

Having said that, I would have been happy with the non DR with a view to having the DR upgrade done when funds allowed. And i think it would have proved cheaper to buy a used 250.2 and pay for the update later. But I'm a sucker for box fresh!!

im afraid I can't give you any reliable detail in the 250 prior to my experience with the 250.2 but I'm sure there will be many here who will be able to give great detail on its history and I look forward to reading about it.

I was reading an old thread about this, and what the NAP 250 bought to the table when it was first released was that in those days, many speakers had loads of 15 ohms, and any speaker with a 6 ohm load would kill most of the amps of that era. The NAP 250 was one of the first amps that could easily drive a 4 ohm load, and was stable to 2 ohms.

But times have moved on and nowadays 4 ohm speaker loads are common, and my NAP 200 also drives 4 ohm loads quite well, and is also stable down to 2 ohms.

I am not sure about this but there is an opinion elsewhere that the regulation seems to work best at low frequencies (hence most of the comments about the 250.2 and 250 DR seem to be about how well it controls the bass), but it seems a capacitor smoothed amp like a 200, 180 or 140 seems to regulate the midrange and HF better. Certainly the unregulated amps seem a bit more airy to me in the treble.

Again I never heard a 250 DR, and it entirely possible that the 250 DR upgrade addresses this one last remaining reservation - there have been some debates where plenty of people here preferred the NAP 200 compared to 250.2. There is even a thread called 250, a slow amp? on this forum

But now the comments seem pretty much in favour of that the 250 DR is better than the NAP 200.

I would agree that the big 3d soundstage starts at 282/HCDR level. When compared against 202, it is quite a huge jump upwards, and I would advise anyone to go for a higher level preamp like 282 or 272 before even considering a change in power amp.

282 with a Nait XS as power amp will sound much better than Nait XS preamp with a 250 DR

Alonso, as you are interested in the later NAP250 (sometime called the NAP250.2) then I'll just explain the internal difference between this and the earlier NAP250.

Basically the arrival of the "new" NAP250 in 2002 saw a complete change in just about every area;  A new look - the current triptych casework; a much bigger transformer - now 1020VA; completely revised internal layout with lifted resistors, stable hemispheres for close temp matching of componentry, and Naim's custom 007 transistors throughout for both regulation and power stages.

The Recently introduced NAP250DR brings improved "DR Technology" regulation, and Naim's custom 009 transistors from the Statement project.  Improvements to the circuit board and heatsinking are also made.

Here is a picture from the 'net of the insides of a NAP250 (a mid to late '80s extruded case "Chrome Bumper" unit - detail changes but similar layout until end of production in 2002);

Here is a picture from the 'net of the insides of a

NAP250.2

Here is a picture of the insides of a NAP250DR;

Hi Richard

The capacitors on the 250.2 and 250 DR seem quite different to the ones on the old CB 250.

It is quite clear from the pictures that the 250.2 and 250 DR are very different league of amplifiers compared to the older 250.

Capacitors have improved considerably since the design of the original NAP250 - smaller in size and better in performance.

The transformer in the NAP250.2 and NAP250DR is about twice the size of the one in the original NAP250.  

For all that, the original NAP250 is a bona fide classic whatever the age or version and can still perform extremely well in a modern day system and setting.  It introduced Naim's first custom output device, the Naim 001.  It's also an iconic piece of hifi equipment.

Messier insides these days...

there are some good deals on older NAP 250, but after looking at these pictures, the 250 DR really seems much more capable an amplifier

No way around that - space (or lack of it) mean't that the ultra neat wiring layout of the earlier NAP250 couldn't be replicated.  Also, it was found that in some areas it sounded better to have fewer cable ties and to allow the wires greater freedom.  Getting the wiring form right is a longer process than many understand.  It is all about listening to the prototypes over many months and experimenting with dressing and cable tying of the wiring before a final wiring buck is approved.  After that, all others copy the wiring and cable tie layout exactly.

Wow - look at the engineering in that.

Amazing Richard, thanks for clarifying. That also helps me understand the provenance of my 32.5 a little more, given the etching on the circuit board 'experimental board'.

The new 250.2 is epic, as are all the newer amps. However, the Classic 250 is unbelievably good, a very sweet, tuneful sounding amplifier and a legend. A classic 250 is Naims SET amp, simple paths, great organic sound.

Blimey. From the look of those pics, the DR upgrade involves swapping out both of the main PCBs which is half the amp. That is quite a change.

Err, that would be the Regulators, I think - so yes - half the amp.

Guys, thank you SO MUCH for such illuminating responses.

To conclude, I wanted to ask, where was the power amplifier section inside the SuperNait (1 or 2) 'lifted' from? I.e. In loose terms, will one find a NAP200 or a NAP250 (sans casing) 'inside' Supernaits or SuperUniti? 

The SN1, SN2, SU all have unregulated amps similar (in some way) to the NAP 200 

The regulated amps start at NAP 250. 

inside the old 250 you can see 4 boards. 2 boards are the left/right channels, and 2 boards are the regulators. basically 2 amplifiers in one box !

...but also some elements taken from the development of the Nait 5i.  

Richard,

This makes me think that the only way the 250 and 250.2 are related is in the name!  Is it fair to say that the .2 was basically a complete redesign and they then "borrowed" the 250 name, much like Porsche has done with the 911 for 40 odd years.

Graham, well, the basic design is carried over; i.e. it's still a regulated power amplifier utilising Naim's own custom transistors.  The last of the Olive NAP250s moved to using NA007 transistors in the regulation stages, so those are also shared with the NAP250.2  Otherwise, yes, a new and much larger Tx, a move from NA001 to NA007 output devices, use of the temperature control hemispheres (the black lozenges) on the matched pairs, lifted resistors, different capacitors and lots of other little detail changes. As you say, it's a bit like when Porsche went from the 993 "911" to the 996 "911" - an easily identifiable evolution of the original, but mostly all new.

@Graham Clarke - I love the Porsche 911 comparison - !! Which IMHO is spot on. 

Like the current 911, the 'new' 250 isn't a 250 at all. The original 250 was a 2 by 125W into 4ohms amp. Hence the designation. The '-2' or DR is a bigger amp, but still called '250'. Same or similar architecture, but bigger. 

I will stick with my Classic 911.... Err, 250....

Which 250 has more of the Naim boogie factor? (not soundstage, clarity, treble, none of these qualities are relevant here, just boogie factor )

250 CB, olive 250, Nap 250.2 or 250DR?

CB & Olive are the same (original) design, differing only in detail.

-2 & DR are the new design.

Plenty of boogie with a CB or Olive.

Hi Ian,

in terms of the 72/140 compared to your 82/250, which one boogies more ?

sorry to hijack the thread