Altec Lansing A7's 50's model

I can only speak to your first topic. You need to remember what the things were designed for, and that was not music in the home. They project exceptionally well, with not much subtlety, but very efficiently. Just the thing for filling a theater space. IMO, they're hard to beat for reproducing the horns in the triumphal march in Aida.

The sectorial horn was available in two sizes, 511B and 811B, with 500 and 800 Hz crossovers, respectively, though both used the 802D driver. The low frequency driver should be an 803B.

As a stab at topic 3, the actual A7, as I knew it, was pretty much an open box with the LF driver mounted at the end of a small front loaded horn, a sort of quite open bass reflex arrangement below, with either the 511B or 811B and 802D mounted on top. There were so many of these in commercial use that I would expect servicing to be available.

We used A7s mostly in the lab, but I did have one at home for some time.

db

Altec still supplies parts(diaphragms/woofer re-coning kits) for the drivers to all their authorized repair/warranty stations. Waldom Electronics supplies re-coning shops everywhere, and parts that will make the woofer LOOK original, but it will lack the edge-wound aluminum voice-coil(and quite a bit of performance). SO- Yes, thet are easily serviced/supported. The sound: They're LOUD! Comparison with modern horn-loaded theatre systems: They're LOUD too! Some people like LOUD and don't mind the horn colorations/crazy response curves that go with these systems. If you can get them cheaply enough: See if they fit your tastes(they'll be great, if you have neighbors you hate, or for a home theatre system).

Here's a link to the system's PDF manual: (http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/A7-8G%20VOTT%20Speaker%20System%20Manual.pdf) and these guys do the authorized repairs: (www.greatplainsaudio.com)