NBL, Allae, active, passive results.

Posted by: London Lad on 01 May 2004

Hi All,

Those of you who read my thread “NBLs coming this evening (maybe)” will know that I recently acquired a pair of NBLs to replace my Allaes.

The Allaes were running active with 252, snaxo 242 and a pair of 250 Mk2s.

Having got the NBLs home it was my intention to wait for a snaxo 362 and 3rd 250 Mk2 to be delivered before I set them up to have a listen but of course I couldn’t wait and decided to check them out passive on one of the 250s.

The NBLs are big heavy speakers and although it would not be impossible to set them up alone I would highly recommend that you get someone else to help!

Two lifting straps are provided in the boxes that enable you to lift the speaker out of the box and lay it flat on its back while you fit the spikes.

The build quality is excellent and it is easy to see where the money went.

My speakers were supposed to be a 2001 pair purchased in 2002 and never used. Giving them a thorough inspection this appeared to be the case, no dust in any of the nooks and crannies and no marks or sign of wear whatsoever anywhere.

The NBLs have a rounded top and sides that taper towards the back. The HF and MF drivers sit in their own cabinet that floats within the top of the main cabinet on a 3-point spike suspension arrangement. The two opposed, side firing LF drivers are again fitted in their own cabinet at the bottom of the main cabinet, which they vent into via a PAR (precision acoustic resistance)

Once upright and levelled in the normal way the transit bolts and packing can be removed, 2 bolts at the rear of the HF / MF cabinet and an aluminium plate and some cardboard and foam from its front. 2 more bolts from the rear of the LF cabinet. Then you just have to centre the MF / HF box and make sure it floats properly. Tweeter set-up is the same as the DBL etc and the MF driver mounting bolts are set to a torque of 3.6Nm

Comparing the measurements given on the Naim site for the Allaes and NBL doesn’t prepare you for how large these things look in real life. The Allaes look like midget speakers next to the NBLs!!

The passive x-overs are huge and use large components that are well laid out on a high quality PCB. They screw to the back of the speaker in the normal way.

A quick bit of snaic and burndy swapping and I’m up and running passive.

(Now remember that I am comparing with active Allaes)

The first thing I noticed was the volume. The NBL is more efficient than the Allae and it shows. I would say that 9 o’clock on the volume control now gave the same volume as 10 o’clock had before.

More bass, lots more bass, not too sure I like it for some reason but lots more bass! The treble is better, cleaner and a bit sharper.

Ok make a cup of coffee, clear away the boxes and packing and move the Allaes out of the room while things settle down and then back for a serious listen.

There is a problem, although the treble and bass extension is far better than the Allaes the midrange seems very ‘back in the mix’ voices are less prominent and worst of all there is a ‘gap’ between the mid and bass, almost as if they are coming from two different pairs of speakers.

Before buying the NBLs I asked James of ‘New speakers for Mr. Tibbs’ fame for his opinion of them. One of the things that he pointed out was that if the side firing bass drivers were to remain non-directional then they would need to be crossed over at or below 150Hz and he suspected that the relatively small mid range driver would have trouble coming down to meet it.

I think he is right, although it must be said that these NBLs probably are unused and therefore not run in yet.

Moving these speakers about to try different positioning is slightly harder than normal, as you have to replace the transit bolts and packing on the HF / MF box to stop the box banging. However after a lot of moving about and a few days listening I was on the verge of thinking that I might not be able to live with this ‘gap’ between LF and MF……………then the new snaxo and 3rd 250 Mk2 arrived…

Well to coin a well used phrase, MY JAW HIT THE FLOOR.

Taking into account that the snaxo and the new amp (on the HF) were stone cold and the NBLs may well not be run in, the system sounded incredible, the bass and mids had integrated as if someone had swapped the speakers for a different pair overnight!

The voices were back where they belonged, the bass perfectly controlled, the treble sweet and all 3 drivers were working together. I’m a very happy boy.

If things improve more as the new amp and x-over run in then I will be an extremely happy boy!

In summary:

NBLs are big but you get used to them and I love their looks.

NBLs sound great active with 3 x 250 Mk2s

NBLs don’t sound good to me passive on one 250 Mk2


(I have recently been told that there was a passive x-over upgrade at sometime during the NBLs life. Maybe mine don’t have it!)

I will report further in a few weeks.

Graham.

Not a lad any longer and not from London!
Posted on: 01 May 2004 by Allan Probin
Graham,

Congratulations on the NBLs. As the NBLs are new I'm sure they'll get even better over the next few months. How about posting a few pics if you have them.

If you don't mind me asking, when you had the Allaes, what made you decide to go active with the 250's rather than, say, a passive 300 ?

Allan
Posted on: 02 May 2004 by London Lad
James:

Thanks!

Allan:

Thanks, pics to follow once I get a few work commitments out of the way.
I originally had the Allaes active with 2 x 150s and then went straight to 2 x 250;
I never considered a 300 at the time.

I’ve been a fan of active ever since I ran a pair of NAD amps into some 15 Tannoy monitor golds via home brew active x-overs some 20 odd years ago. Source was Sony’s first commercial CDP, a CDP-101.

Fredrik:

You have described my experience of the passive NBLs far better then I did with the phrase “where there seemed to be some discontinuity between the three drivers”

“Its nice when you find something that works out of the top draw and I believe the NBL can do that driven active”

Yes it is and I’m really enjoying the music right now.

Graham.

Not a lad any longer and not from London!
Posted on: 03 May 2004 by Greg Beatty
Graham -

If the bass/mid driver in the NBL is anything like the driver in the Allae, it will take months to run in. No kidding.

And the low end of it will be the last to arrive. One possibility is that the active configuration has the grunt to drive it even though it is "stiff" and not run-in. Passive cannot do this and so the holes in the frequency response appear.

Maybe active will shorten the run-in time and, if the fancy strikes, you could try passive again in a few weeks just for fun.

- GregB

Insert Witty Signature Line Here
Posted on: 03 May 2004 by Anders
I agree with Greg. It took my NBLs more than 6 months to achieve their full potential. A very frustrating period....Now they sing on the end of a passive 500.

Positioning is also extreamely critical. Changes small as 15 mm (sideways, back and forth) were clearly audiable and changed width/hight of sound stage and low end extention. I also found Mana sound bases improving overall performance.

Regards
Anders