The central seal between the lower box and the box with the mid/bass driver is critical. The seal must be complete with no gaps in the sealant. It must also be about the right thickness all the way around. Don't forget to put a smear of washing up liquid all the way around the foam so you can get them apart again if you need to move them. If the foam has gaps in it then get a replacement and stick it on. If there are any gaps then the bass will be crap.
The middle box must put its weight only on the lower box, not on the seal. To do this you must ensure that the spikes on the middle box do not sink too far into the lower box. To do that you cannot use one of the existing holes in the aluminium pads, all the spikes must be on unbroken parts. When you've done that then you give the middle box a well judged thump on top to drive the spikes through the pads by the right amount. I know the right amount only because my dealer showed me. It's probably about the same as dropping a 1lb bag of sugar on it. If the spikes end up too far through the pads so that it's the seal supporting the middle box then the vibrations of the mid driver won't be sunk through the lower box, through the spikes and into the floor and it'll sound crap.
Be careful when you're putting the top box on not to whack the middle box with it when you're tightening the bolts. I dunno if leaving exactly the right gap between the top box and the middle box is that critical.
If you ever need to move them then you'll almost certainly have to take them apart and start again, even for the shortest journey in your Citroen SM. Dealers were supplied with their own custom made lifting trolley so they could move them about in the shop. They then had to be put back in exactly the same place so they were level and couldn't rock.
These points are all taken from Naim's own dealer instructions and Naim wrote them in capital letters because otherwise it would result in 'loss of sale'.
After that you need to wash your hands with that hard green soap six times, left hand then right hand whilst facing in the direction of Salisbury. Pivot on one leg when reaching for a green towel. Then go and get some CBT therapy to cure you of the OCD.
Before I bought my SBLs someone on this forum kindly said that they'd give me a demo of theirs. I turned up and he then admitted that he'd replaced both drivers with something completely different and hadn't bothered sealing the boxes together. They sounded crap.
Incidentally my SBLs blew my Linn Keilidhs out of the water.
