Dbl refurbishing LF cabinet acoustic foam


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Reinstalling the really heavy drivers back into the cabinets and getting the soldering right without damaging the delicate membranes is another issue … :rofl:

First attempt to come up with a stable and safe positioning of the bass driver before soldering …
There is room for improvement still :shushing_face:

Thank you for the info Charlie.

I only noticed the different bolt lengths later in the day, so checked the other driver and found that they too were different lengths. Bottom left and Top right were short and Bottom right and Top left were long.

I can`t see that it can be that important, but I usually try and put the same Bolts or Screws back in the same holes they came out of.

Can somebody please remind me of the Torque settings for all the Drivers.

Mid range and bass have the same torque Settings … I think it’s 3.6 nm but will double check

Tweeters are „loose“

Will check again on the bolt lengths here from the mid drivers …:wink:

Mid and bass are indeed 3.6nM, while tweeter is 2 nM.

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Information I got from Naim in June…


Here is the additional information concerning your question.

DBL Tweeter to Plate, 0.8 Nm.

Tweeter screw to the cabinet, no torque setting, just do up until the grommet is held against the cabinet with no movement, must not be compressed.
Should be Hylomar applied around the tweeter edge between it and the plate, just a thin bead.

Kind regards


Now that is strange :hushed:
I got my torque numbers also confirmed by Naim A few years back (and by a reputable dealer).
Below the exact wording for the tweeters:
2 nM torque is to be applied on the Allen bolts, while the screws are to be tightened just enough to hold the plate flush against the rubber grommets.

I don’t want to create confusion

The italicised part of my post was a direct copy and paste from the email from Naim a couple of months ago.

Maybe @NeilS can investigate and shed some light on what the correct value is? 2Nm or 0.8Nm.


With respect to the tweeters there are two separate connections

  1. drivers screwed onto the slit plates -ie those inner four screws with internal edges -Allen bolts - which are attached tight so most likely those 2nm

  2. attachment of the plate onto the wooden cabinet with rubber grommets fixed just tight enough that the plate can not move freely and for instance sink towards the lower lip and touch the wooden cut out, yet loose enough that the rubber grommets are not squashed, so probably those 0,8 nm

The information I received did associate the 0.8Nm value with the tweeter to spring plate interface though there seems to be more of a concensus around 2.0 Nm for that. Hopefully we can have a definitive value from Naim directly.


Hi Guys,

I’ll see what I can find out regarding the torque settings.
I recall that the NBL was shipped with an aluminium plate with a cork gasket mounted over the mid range driver using two of the (diagonally offset) mounting bolt holes, in order to prevent the wooden leaf springs breaking under inertia from the driver weight. So these two bolts were longer - I wonder if this was also the case for the DBL?


Sounds like I have opened up a can of worms asking about the Torque settings!

Charlie I did try and get the foam for the pillars in without removing the Plates, but soon realized it was not going to happen. In the end I used a longer Screw placed a block of wood up against the Cabinet and used a Claw Hammer and they both just popped out. I see that they are sealed with Hylomar. I used the 340 Foam and pushed it up to the Plate and it is just level with the bottom of the Pillar and have put the two ends together at the back.

Willy, the plate on the Tweeters. Should they be perfectly flat? Mine are slightly bent.

I downloaded the manual from “manuals lib”. Have it as a pdf. Here’s a screen grab of what they have to say on the tweeter plates…

If you can’t find the manual online then get my email address off Richard, ping me and I’ll forward a copy.



Ok, I have spoken to the chap who used to build DBLs - the bass & mids are torqued to 3.6Nm & the tweeter to plate 0.8Nm, plate to cabinet enough to not squash the grommets. He thinks the confusion may come from the direct tweeter to cabinet (e.g. SBL) being 2Nm?
He also confirmed that the longer screws in the mid range drivers are indeed due to the transit plate (as above).






Thank you Willy. I have found the online manual so now can sort that little problem out.

The information from Neil on the Bolt length and Torque settings also solves that mystery.

Getting those beasts back inside their box :wink:


Been following this with great interest. An excellent and innovative use of a Fraim shelf.


Glad you liked my innovative (ab)use of a fraim shelf. I needed to come up with a stabilized position for the heavy drivers while doing the soldering. Somehow I thought that the cut out of the fraim would give a perfect recess to prevent the driver from slipping away. I used some of the foaming for further stability. Also the wooden block was rounded to accommodate the heavy magnet of the drivers .

The fraim is ok and back to its normal place meanwhile …:wink: