Hi there Giorgio,
Just seen your post regards the AR-LST cabinets for sale on Ebay, I saw the ad. earlier today, a very good deal, I live quite close to the items for sale around 25 miles or less and thought what a great offer, only issue is the drive units for these are expensive, the LST's can sell for quite a lot, maybe 1000 GBP or more, the 12" bass unit would cost 100-150 GBP each, you would also need the tweeters, midrange and crossover and bear in mind these speakers have multiple mid & treble units.
The only use I think would be for someone who wanted to replace their cabinets, but then you would have 30 or so spare pairs.
Looking at the quantity of cabinets available I would think these are left over items from the old AR Houghton Regis site, this site was around when I bought my AR-2ax speakers in the late 70's, seems a bit odd they are for sale now 40 years later. Only an assumption though.
I now have a pair of AR-3a Improved speakers, they need recapping and cosmetics done to the cabinets, nice speakers though.
Regards
Steve Hoare