The guys at Naim NA used to decribe the NBLs as ‘passive aggressive’…in that it was very difficult to tame in the passive mode. It really needs to be taken active. I have listened to my dealers personal pair quite a while ago. It was pretty drab in the passive format with a 250. Things got very much better with a brace of 135s and a Snaxo.
1 Like
I’ve heard that the passive crossovers was not the
main priority,the most important thing was that they sounded very good with a Snaxo.
I run my NBLs passive with 500 DR series, swapping the 500 out for a 250-2 removed much of the bass resolution but it had more weight if anything.
For placement I found, with solid render behind them, 5.5cm was the magic number, neither 5 nor 6 was quite there measured between the wood and plaster after levelling, this held for both my 16m^2 and 42m^2 rooms, though they appreciated the greater breathing space. The distance between tweeters had quite an impact on the sense of scale but I didn’t play with it much in the first room, in the larger it optimised at around 1.4m.
Moving to a 36m^2 room with insulation backed plasterboard walls changed the rules on placement. Here 5.5cm meant no bass worth the name, that came at 33.5cm and the tolerance wasn’t much different. Optimum distance between tweeters was largely unchanged.
Cables are standard Naim, a Hiline for the ND555, Lavender for the superlines supercap and NACA5. I used Herbie’s Gliders for positioning trials in the two large rooms with tiled floors and have left them in place for convenience. The first, smaller room, had thick carpet and repositioning spiked NBLs on that with precision was no joke.
4 Likes
IIRC, the NBL was developed almost entirely in active form, with the passive X-over being developed later. I don’t think anyone was ever totally happy with the passive x-over, hence the revision to it midway through production, which I gather improved things, but still it’s a speaker probably best heard active. I preferred the SL2s to passive NBLs, but my brief time with NBLs active showed me what they could really do. For all that, SL2s have a sense of top end coherence, openness and naturalness that are rare to find anywhere, and not in NBLs or even DBLs, whether active or not.
5 Likes
It’s nice to see someone else agree with my opinion of the SL2’s Richard. Once heard, never forgotten.
1 Like
You aren’t the only one PB, and I don’t mean just you and me either.
2 Likes
I know, there are a number of people who will never let their SL2’s 
Since the demise of my then SL2s the ATC SCM20PSLT have filled the void.
I never liked the sound of sl2s, particularly after nbls. However if a pair comes up at a reasonable price I may try again.
Doug always preferred NBLs to SL2s, not helped by the fact that he had probably the worst SL2s I ever heard. It took ages to get to the bottom of it. We swapped everything until one day I brought in my own top boxes and swapped them over, and… they sang! Roy inspected the original top boxes and felt that there was just a little too much glue used which probably affected their rigidity. Hornslet mostly got it right but every now and then…
3 Likes
It is always the small things Richard, that seem to have the biggest impact 
1 Like
I have used SBLs and SL2s active and passive with 552 DR and 2 x 300 or a single 500 in my listening room. The room is very “lively” and I tamed it as far as possible using furniture and wall hangings. The results were different but active proved to be hit and miss due to the complexity of cable dressing and the tendancy to sag over time. IME the biggest change in sound depended on whether the door to the room was open or closed.
I am now using NBLs with 52/135s and find that the most musically satisfying combination. The realisation that listening to musical performance and not minute differences is a big factor but the sheer simplicity of set up helps a lot as does partly closing the door??
FF
3 Likes
I have re-installed my NBL’s, active with 3x Olive 250’s as I wasn’t happy with the sound of my system post-factory visit.
I have now got to the root of the problem and I have to say, the NBL’s sound absolutely superb.
I will now have to reinstall the Kudos 808’s which would have not been sounding their best either…
(The issue was that one of my helpers had very helpfully dismantled, cleaned and reassembled my Fraim and failed to reconnect everything 100% correctly….)
1 Like
Years ago, my dealer had a pair of SBLs that never sounded right.
Changed all 4 drivers….still sounded horrible.
I brought in a CDS1, 52, 4x135, Snaxo, Supercap (they only had CDX/82/Hicap/250 in stock) and maxxed them out-well as far as maxxing out went in the late 1990s.
Still no good.
A pair of passive tukans ran on the 135s sounded better in every way than the SBLs did with an active 4-pack.
Maybe it was faulty cabinet construction, as the drivers and electronics were all substituted.
2 Likes
It could well have been Ron.
2 Likes