NBL Tweeter, “Hylomar”

When I replaced the blown tweeter on my one of my NBLs (and its twin) there was what appeared to be blue Hylomar between the suspension plate, tweeter and ring. As they were apart by then and I didn’t have any I torqued (0.6Nm) the new ones in place without joining compound. Now I come to consider rectifying this I see there are 3 grades of Hylomar blue (I’ve always used Wellseal on my bikes). Does anyone know which grade to use?
The manual assumes the tweeter comes ready attached to its suspension and doesn’t mention it.

Three grades of hylomar!
I did a lot of " research" about 15 years ago to make a piece of plant at work " leak free". We used hylomar and contacted them for advice. In short the three grades are the same. The difference being how much solvent is in each one. The " heavy" grade having the least.
And non of the grades performed differently anyway. Just use the standard grade.

Thanks for the input. No one else seems to know anything and it may not matter except I can’t see Naim using it if it didn’t. Hylomar give different film thicknesses after drying for the three grades.


Temperature range -50°C to +250°C (-58°F to 482°F)
Film Thickness 0.015 mm
Typical Surface Finish 2.0 μm Ra
Area covered by 100g 1.875m²
Product coverage after drying 2mg/cm²
Film Thickness 0.03 mm
Typical Surface Finish 3.0 μm Ra
Area covered by 100g 1.275m²
Product coverage after drying 4mg/cm²
Film Thickness 0.09 mm
Typical Surface Finish 3.5 μm Ra
Area covered by 100g 0.56m²
Product coverage after dying 12mg/cm²

It’s probable the same is used on SL2, allaes etc.
Is it there to couple or damp? There’s nothing to seal.

I would argue that in that it’s there to seal the drivers to the cabinet so the precision air gap between the cabinets can work at their optimum. Naim once told me that they preferred the older adhesive based Hylomar as opposed to the more recent silicone based variants, and so bought up all the older stocks.

This was from before I replaced them and shows the back of the faulty tweeter secured to its plate, note the cuts between the main plate where the tweeter mounts and the four outer corners that attach to the cabinet, these provide suspension for the tweeter which is itself a sealed unit. The blue gunge was between the tweeter and plate and tweeter and the mounting ring visible. This was I think a Naim original tweeter, the other one didn’t have the s3 sticker and it’s soldering was somewhat poorer than what I expect from Naim.

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