Depends on the room's acoustics, speaker, listening location[s], signal source[s], personal preference, any WAF/SO considerations, etc..


Regardless, there's no truly 'full-range', flat amplitude and phase coherent Altec system and hard to get one 'close enough' over just the ~80-5 kHz critical speech BW with a horn system in an acoustically small room simply because we can't sit far enough away for it to look small enough to appear as a small point source, though many are satisfied with a well engineered Duplex system.


If I were to build one without resorting to designing/building a large three-way horn system, then a traditional three-way with a 755 'wide range' [preferably an 'A'] in a small WG with a 3000 series HF horn and 416 woofer all mounted to a properly contoured baffle to optimize physical TD offset to round it out will do an a pretty good job, but an 8" mid is a bit large for this type of system.


In either case, if pipe organ symphonies or other ULF sources are included, then add a separate multiple sub system spread around the room to handle the lowest ~2-2.5 octaves.


For high efficiency, then there's no such thing as too large a [mid] horn [system], just a point of diminishing returns, so as big as one can 'afford' and why if I'm ever able to do another one it will be dominated by large three-way Synergy concept horns coupled to a much larger multiple [sub] bass horn system. Actual Altec components [if any] will be limited to the HF compression drivers.

GM