How observant you are! The speakers are Avantgarde Duo XDs. I've had them for 3 years now and before these I had 2006-vintage Duos and before that (in 2002) I started my conversion to horn speakers with Unos.What, please, are these?
And why does the construction differ between them?
You spotted they differ in appearance. Yes, the one on the right is how they normally appear, but I value the views from my floor-to-ceiling windows so I "slimmed down" the speakers by ditching the scaffolding and supporting the mid-horn with a cradle - as Avantgarde do with their Mezzo model. The base frame is simply rotated 90 degrees and they now have IsoAcoustic Gaia 1 feet in place of the ones shown in the photo. Avantgarde kindly sent a scale drawing to show the spec of the cradle I needed to get made and since then, their new Duo GT has also ditched the scaffolding and is considerably slimmer than the standard Duo XD. I'm very pleased with the slimmer speakers and there is zero compromise on sound quality. In fact the mid-horn is slightly better isolated from the bass enclosure now.