Hi All,
Try
http://quarter-wave.com/ I recently received an email from Martin saying that he'd finally cracked the XL enigma; haven't checked it out yet, though.
I currently have two pairs of XLs: a 30 year old pair of ESS AMT-1 towers which now have the Seas woofers used in the A25, and a pair of d'Appoilto/Seas Thors I bought from Madisound 5 years ago.
As much as I love the A25s, the towers are now the speakers being used in the reference system. I've never heard any speaker design that equals the ¼ wave for reproducing the bottom octave so effortlessly and not sound like a speaker.
I had a dog in the '80s who was ultra mellow except when it came to Fourth of July, New Years, shotguns and (especially) thunderstorms--which we don't have all that often out here. I was playing some records for a friend down from Oregon who'd never heard the towers. He asked me to play "One Stormy Night", an otherwise Godawful record that had a really neat thunderstorm playing in the background and between cuts. I played it and my dog freaked and tried to get under the bed (he was an 85 lb yellow Lab). My friend turned to me and said "Dogs don't know how to lie" and found a used pair when he got back to Portland. He traded them in for a pair of Wilson Watt-Puppies, which are fantastic speakers (at $18,000 a pair, they'd better be), but even they don't have that jet-engine-clearing-its-throat low end that an XL has. He's been whittling on me to sell him either the towers or the Thors, but I ain't budgin'.