I’d be a little bit careful of what sticky stuff you guys put into it.
The tweeter replacement is also something that one needs to be careful about. You need some hylomar blue which Naim supplied in a syringe with the MATCHED tweeters. The little tweeter fastening bolts are “fingers tight” with a tweak or if you are lucky enough to to have a flash torque wrench that goes as low as .85Nm, that bit is very important. Do not over tighten as the tweeter diaphragm is easily distorted and cracked! Best to get Naim or a competent dealer to do it or somebody that knows not to over heat the tweeter posts with the iron and cook the tweeter coil.
2 Likes
Hi Soundsfaber
Was that specification posted about the SL2 foam on the dbl thread, or elsewhere?
That would help to explain why mjkent found the 12mm thick Wilmslow Audio Acoustic Foam Laminate Panel worked so well.
But then why did the foam I removed from my SL2s measure about “25mm thick and about 11 x 14 cm in size”?
I can see that NeilS helpfully posted this on a thread about Allaes:
“FYI: The specification of the foam is 12.7mm thick reticulated foam 80ppi
Regards
Neil.”
Is that where you found it?
thanks
Jim
Thanks @JimDog
I just got a nice pair a few months ago. Replaced the tweeters last week. Sounded amazing before. Now they are almost spiritual. Exciting to think there is even more performance to be had. I did notice when I assembled them that the foam was starting to crumble.
1 Like
When I asked my dealer here if the crossovers were serviceable, the response that came back from Naim was that there were no parts available any longer.
I assume that if you know the component specifications, it would be possible to service them yourself, although there’s always the risk that the new bits would be a different physical dimension and wouldn’t fit
There is at least 1 3rd party crossover that has the same specifications, so really it’s a matter of deciding if the cost is worth it. And the aesthetic downsides of having a crossover that doesn’t hang off the back of the speaker like the SL2 one does
2 Likes
Yes that’s it. No sure why yours is different. It may be that somebody’s else had a play in the past. Or naim changed the spec over the build period of the speakers. Only Neil or Richard or Jason may have the answer to that. Im waiting anticipation for an answer!
My foam is horribly crumbly on one side especially. Wilmslow audio order placed for 12mm sheet, will report back.
Bruce
2 Likes
Any idea roughly how thick the original foam was?
Closer to 12mm or 25mm?
In case anyone is interested, I just came across an informative summary of speaker damping materials and issues on the site of ‘QTA Systems: DIY Loudspeaker Components’.
Haven’t had time to read it all yet, but here is a snippet:
“All vibrating objects produce sound pressure waves. These can act as a form of airborne interference and spoil the overall listening experience. For best cabinet acoustics we require a speaker cabinet to be acoustically dead and a number of designs exist to meet this criteria with varying degrees of success. […] A variety of materials attached to the interior of the cabinet can also modify it’s response. […] Vibrating panels effectively act as large speaker cones with a small peak amplitude. These have selective modes of vibration, (resonances), and can be of sufficient amplitude to colour the overall sound. In addition the rear radiation from the speaker cone may be reflected around the inside of the cabinet and then back out through the speaker cone. This all contributes to a background noise which tends to distort the listener’s sound experience and give rise to what’s known as a ‘box sound’.”
They sell materials in small quantities, including ‘Sound Absorbent Foam’:
“Used for Loudspeaker cabinet damping, this sound absorbent foam is an ideal contender for damping the higher frequencies in speaker enclosures. Coloured grey, it has a closed cell construction, is easy to bend / fit into a variety of loudspeaker enclosures and may be cut to shape using a sharp scalpel. This sound absorbent foam provides a cost-effective and clean method of installing speaker enclosure damping to your home project. Nominal thickness 16mm. Supplied in rolled sheet format, 550mm * 1200mm = 1 piece.”
But not sure I like the sound of “rolled sheet format” as the foam needs to end up dead flat.
The SBL, Allae & SL2 all shared the same bass/mid cabinet foam - 12.7mm.
There were 3 stacked sheets inside each SL2 bass/mid box.
Hope this helps
Neil.
1 Like
Neil
Thank you so much - that’s extremely helpful.
If you have time, please let us know:
When you say 3 stacked sheets, does that mean 3 on each side of the box - so 6 in total in each cabinet?
’Stacked’ in the sense that the sheets were pressed into the side walls next to one another, but not bonded together in any way?
Best wishes
Jim
No, just 3 per cabinet, not bonded together, just 3 on top of each other held vertically bent into a horseshoe a pushed in through the driver hole, so that they covered the sides and back leaving the airflow through the PAR unobstructed.
Regards
Neil.
Thanks again, Neil.
That is very useful info.
Sorry to be a total pest, but may I just ask:
Did the horseshoe curve up the cabinet sides and across the roof, i.e. one foam panel each on the left and right walls and one panel across the roof?
Or was it one panel on each side, and one at the back, but mainly above the rear hole where the tweeter assembly enters the cabinet?
Best wishes
Jim
Hi Jim,
I’m struggling to think how better to describe it.
I’ll try to knock up some sort of crude diagram later on when I’ve got a bit more time.
Regards
Neil.
1 Like
Ah - now I see that you are all talking about the tweeter cabinet foam & I didn’t read the whole thread!
Tweeter foam is 25mm thick and there are 2 per cabinet.
Apologies
Neil.
1 Like
Thank you again, Neil.
Apologies for not asking you a clear question on my part.
All the best
Jim
I am just astonished at what a difference the Wilmslow foam has made. If I hadn’t chanced upon the DBL thread, I’d never have checked the foam in the tweeter cabinet. Listening to the Proms last night, the clarity and feeling of ‘being there’ was astonishing. As somebody above has said, almost spiritual. It’s great that with a little love and attention we can keep these wonderful speakers performing for years.
2 Likes
Another worthwhile tweak for aging SL2s is replacing the spacers that sit on the pins between the upper and lower cabinets. In my case, the tiny bumps that provide the air gap had completely flattened. Got the official part through Chris West at AV Options; I believe TomTom also sells them.
1 Like
Folks, apparently SL2 drivers are no longer available. In thinking about replacement options (should the need arise), is it true that SL2s use the same drivers as SBLs and Credos?
1 Like