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Bonded Naim SBLs

O

onlyconnect

pfm Member
Well this intrigues me:

https://www.ebay.co.uk/itm/16509869...d=link&campid=5338728743&toolid=20001&mkevt=1

"naim SBLs. Which have been restored by Alan Clark of Kralk Audio around 3 years ago. They were totally rebuilt from scratch including a new sub frame with improved dampening to the cabinets and 2 new tweeters, then finished in Gloss Black. The speakers themselves have been bonded between the base and bass module so no more air leaks or gasket repairs. The velcro for the grills has been removed and new magnetic grills have been fitted."

So no more "Separate Box Loudspeakers"?

I would be interested to know how they sound without Naim's interesting design by which the middle box makes an airtight bond with the lower box but also rests on spikes rather than being tightly attached.

Tim
 
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I fear the bonding may just be a load of grip fill who knows. I am also interested in the idea the subframe was recreated, surely its all welded steel?

Could be interesting just for the crossovers which look nice.
 
Colonel_Mad said:
I don't want to go all Mick Parry, but it does make me laugh when people bodge a bit of kit and expect people to take their word that it is massively better than the people who spent millions developing it could do.
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I doubt Naim spent millions developing the SBLs!
 
IanRB said:
I doubt Naim spent millions developing the SBLs!
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I take your point. How much money would you estimate they spent? These things don't fall out of the sky. I'm sure permanently bonded boxes were tested and rejected for a reason.
 
Colonel_Mad said:
I don't want to go all Mick Parry, but it does make me laugh when people bodge a bit of kit and expect people to take their word that it is massively better than the people who spent millions developing it could do.
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You’ll be getting a complaint about that name.
He gets touchy about being named on here.
 
Colonel_Mad said:
I take your point. How much money would you estimate they spent? These things don't fall out of the sky. I'm sure permanently bonded boxes were tested and rejected for a reason.
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They certainly don't fall out of the sky.

I seem to remember, but it was a long time ago, that the two boxes were used to avoid colouration passing from one driver to the other. Or it may just have been marketing fairy dust.

Anyway I wouldn't use Grip Fill to join the two, Puraflex is far better.

Development costs? Bet it was less than 100K, bet it was less than 50K. Although for accounting purposes a higher figure would not be out of the question.
 
I loved them and have to believe the point behind the gasket was that it offered compliance between the two boxes with the PIR or what ever it was called controlling movement, The gasket presumably allowing for vibrations between the two, a tiny amount of movement. Bonding the two together negates the whole point as far as I can tell. Perhaps marketing ****ery, but they are a special speaker and deliver a very clean sound with at the time naims obsession with how to remove resonate box noise.

As I say though the cross over looks interesting?
 
IanRB said:
I seem to remember.. that the two boxes were used to avoid colouration passing from one driver to the other.
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Yes, that's right, but then they stopped building their speakers that way and then they stopped building speakers altogether. So maybe let's not get too gooey eyed about how brilliant Naim were at designing loudspeakers?

As for gluing the boxes together, we can't say much about it as it will depend on how it's done. The only reason the gaskets were not stuck to the box before was to allow easy removal of the box. If you used a similar consistency of silicone I don't see any reason why it wouldn't work as designed with them stuck together. You'd just have to cut the silicone to separate the boxes and peel the residue off. Bit of a pain but I can't see it being too big a deal.

But I agree. I don't want a product that has been modified simply because you do not know if it sounds right or not. It might sound better, it might not, you don't know. That alone would stop me. Well, that and not being a huge fan of SBLs even when they are working properly ;0)
 
Mr Pig said:
The only reason the gaskets were not stuck to the box before was to allow easy removal of the box.
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As I recall, the gaskets *are* stuck to the box. Then the silicone bead goes on the gasket, then the top box rests on the spikes and the bead (but more on the spikes).

The design remains a bit of a mystery to me but they sound very good. I find it hard to believe that easy removal of the box was a goal, what is the advantage? Compared to the immense hassle of having to disassemble and reassemble every time you move them, other than around the house.

Tim
 
Only bit I don't get is the gasket and silicone? If the tolerance was that tight the gasket alone should have provided the seal alone?
Likewise the gasket is porous and not fully compressed so would not provide an airtight seal unless firmly clamped between flat surfaces.
If the idea was to have no mechanical connection like the tweeter then i fail to see the advantage. I assume it is made to all the energy from the driver to dissipate into the lower well damped enclosure. The engineer I me thinks if this was the case a better solution would have been a small duct or port to bridge the gap with the neoprene gasket attached on the inner bore of the lower box to any hard surface contact.

Something like this would be easier to set up and more consistent.

Unless there is a benefit that I am not understanding then just looks like poor design, not in terms of sound or concept but in user interface. The fact dealers openly admitted they had issues setting them up correctly says a lot.

Seems odd they go to this length then fit crossovers with cheap components in a nasty looking vacuum formed plastic box.

It just seems like the budget ran out on r&d and basic solutions rather then well worked. The foam grills for example. By the tim we SBL's were made the issues with foam degradation were well known. I accept foam was part of the design feature for the tweeters, yet other contemporaries of the time have traditional peg and frame or magnetic light weight frames. The foam and velcro seems a Friday afternoon job.

Saying all this I still bought a pair, so not slagging then off in that sense just trying to understand the the engineering design process to some of the choices
 
I have SBls bought second hand about 10 years ago and the seals are tightly bonded. I've moved them many times and they don't budge. I'd probably damage the cabinet if I tried to split them! I did worry that I wasn't getting the 'Naim' sound when I first bought them and intended to split them apart and redo the seals, but the drivers moved in and out correctly, and I was fortunate enough to be able to listen to them on a friends system who already his own SBls, so we could compare, and neither of us could tell any difference...so either we are both deaf or maybe it's not so critical.. so I stopped worrying about it...they've never been split and still sound great, at least for me in my system...used actively now.
 
say it as it is said:
Saying all this I still bought a pair, so not slagging then off in that sense just trying to understand the the engineering design process to some of the choices
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I agree it is not really clear what the design is aiming for. I am speculating; but we know from the term "Separate box loudspeaker" that Naim had in mind a degree of isolation between the three boxes. The tweeter cabinet has an air gap. The bond between the lower and middle box though is different and my guess is that the result is the outcome of a lot of listening tests and that the science was secondary. I suspect that it sounds quite different with a stronger bond, just as it sounds off if the bond is too weak and too much air leaks.

Tim
 
say it as it is said:
Seems odd they go to this length then fit crossovers with cheap components in a nasty looking vacuum formed plastic box.
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The Naim crossovers were purposely held back to that level of performance. The SBLs were introduced at a time when Naim was pushing active systems so that they could sell the extra boxes needed to do so. They needed to maintain the upgrade ladder. It's been proven that upgrading the Naim passive crossovers alone with better equivalents brings much better performance out of the SBLs. Some say you don't need to go active after all.
 
Even when evil Naim tried to squeeze the last penny out of our pockets for their greedy selves by tempting us on the neverending upgrade ladder, a simple Nait 3 into standard SBLs sounds mighty fine.
 
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