Getting back to the configuration used in the Watt/Puppy and others, it's a very intelligent way to meet several design goals.
One thing designers often try to do is minimze the baffle width. Midranges are narrower than woofers, and tweeters narrower than midranges, so this configuration is an elegant way of keeping baffle width to a reasonable minimum for the various drivers.
Another consideration is ease of construction - it's hard to build a cabinet that's straight-sided for the lower half and then has a kink and tapers for the upper half. Two separate enclosures, with differently-angled sides, are much easier to build.
Building two separate enclosures allows optimizing each cabinet's construction for its frequency range.
And finally, two admittedly fairly heavy enclosures are easier to ship and move around than one bigger and even heavier enclosure.
It's not surprising that several manufacturers converged towards very similar configurations. I don't think it means that anyone is copying anyone else. My own limited experience leads me to believe that speaker designers do not aspire to copy - they aspire to be original, and will do something that resembles a competitor's product only if they have very good reason to believe that that's the best approach.
Duke
One thing designers often try to do is minimze the baffle width. Midranges are narrower than woofers, and tweeters narrower than midranges, so this configuration is an elegant way of keeping baffle width to a reasonable minimum for the various drivers.
Another consideration is ease of construction - it's hard to build a cabinet that's straight-sided for the lower half and then has a kink and tapers for the upper half. Two separate enclosures, with differently-angled sides, are much easier to build.
Building two separate enclosures allows optimizing each cabinet's construction for its frequency range.
And finally, two admittedly fairly heavy enclosures are easier to ship and move around than one bigger and even heavier enclosure.
It's not surprising that several manufacturers converged towards very similar configurations. I don't think it means that anyone is copying anyone else. My own limited experience leads me to believe that speaker designers do not aspire to copy - they aspire to be original, and will do something that resembles a competitor's product only if they have very good reason to believe that that's the best approach.
Duke