Cheap tweak from Virtual Dynamics:

I was surprised that with all my strength I was unable to tighten any of the screws on six woofers that I checked.

Albertporter (System | Threads | Answers)

I did not take away from the VD video that getting the screws the tightest thay can be is necessarily the goal. I was under the impression that somewhat looser is better (not loose, but looser than cranked all the way until they cannot be tightened any further), and that all the screws be equally torqued.

Albert,
Maybe you can check with your Dali dealer or ask a factory technician about the torque. They might pre-torque these to factory specs and then, as you mentioned, they might put some lok-tite on the screws to keep them from loosening with time. It made me cringe to see that you couldn't tighten them with " all my strength..." You don't want to break off a screw or strip the wood out.

Having been around audio for a long time and a past filled with car racing and engine building, when I say tighten with all my might I should have clarified the situation. Torx can be set up to fit two screwdriver handles or a ratchet drive. For something like a woofer I deliberately used the small handle Torx that limits leverage.

I don't know the exact amount I'm able to exert with the small drive, but it's like tightening brass parts on a carb when assembling an engine, you don't want to overdrive it and ruin the whole assembly.

I believe Dali must have used a locking compound on the screws, keeping the torque uniform over time. I have no proof but this behaves that way in my opinion.

No question that the ratchet handle and reverse motion could break the bond if a driver needed replacing, but I think they have it right where they want it and it was planned that way during assembly.

Albert,
You would make a great candidate to do the brass for steel swap out. Lotsa drivers lotsa steel. I performed that surgery on my Dunlavy 4's some years back. I used brass machine screws intead of wood screws. The machine screws had a higher number of threads and they extended all the way to the head unlike the wood screws. Made for a more tuneful sound that was also less noisey. Tom

Interesting thought, I don't doubt you. All materials have a sound and brass is definitely more friendly than steel.

Maybe I should contact the tech guys in Denmark for advise, the same ones I spoke with when I redesigned the crossover.