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

As a supplement to my previous post, I might mention that I "graduated" from the A7 to a pair of AR3a speakers in the early 60s, i.e. from monaural to stereo. In our psychoacoustics lab, A7s were driven by the lab standard Mac MC 60 amp, but the efficiency of the A7 suggests that was overkill. I much preferred the big 511B horn with its 500 Hz crossover to the 811B.

Although the 511B and 811B are sectorial horns themselves, the A7 isn't a LF horn design in the sense of the large corner horns in vogue in the time of monaural, e.g. those from Paul Klipsch, JBL, Electrovoice. These were mostly rear loaded LF horns designed to be placed in a corner where the walls could act as extensions of the horn. Their popularity went out with stereo, because you could rarely find a configuration of corners that would work for stereo, and taking the speakers out of the corner removed a major design parameter. IIRC, the smoothness and frequency extension of the dome tweeter of the ARs contributed to the demise of the HF horns.

I looked in the Audiogon Blue Book and didn't see anything about the early A7s, so I'd guess following the ads is the way to figure out what's a fair price.

My impression of the sound of the A7s, with over a 40 year gap, compared to my KEF Reference 104/2s, is that the A7s lack refinement. But then that was not the design goal of the A7s, spreading a lot of sound over a large area with high speech intelligibility was. Usually, A7s were hung close to the ceilings in theaters and auditoriums.

db

Ginas,

You should find them a very easy speaker to drive. You haven't mentioned whether the A7s have the 811B or 511B sectorial horn. In looking over an Altec brochure from that time, I see the A7 spec is for the 811, although we had both in the lab. I hope you are aware the A7 is an industrial looking box intended to be custom finished for residential use. Their top of the line residential unit at the time was the Laguna, with two 803B LF drivers and a 511B horn with 802D HF driver. List price was $599; list price of the A7 was $299.40. By the way, one of the features mentioned in the brochure is ease of driving the speakers without the need for high powered amps.

I also have an interesting booklet by Badmaieff, Altec's chief acoustics and transducer engineer, in which he discusses speaker enclosure design principles. In my high school days, I built a few enclosures based on Altec designs and populated them with Altec drivers.

db

Hey, Ginas, I'd take the comments of Spl and Learsfool with a grain of salt. Finesse and texture are not terms that come to mind as I recall the A7. One only has to consider their design aim and common application: Auditorium sound. You might like them, but honky comes to mind. Of course, I've mostly heard them with Mac MC 60 amps -- we balanced the tubes on those very closely; as a grad student that was one of my jobs.

db

Learsfool,

I am one of those people who used an A7-500 and MC 60 in my home, when I was a graduate student and the A-7s were being surplused. As I previously noted, hard to beat for the horns in the triumphal march of Aida, but not my choice for a string quartet.

db

And so it goes. Enjoy your A-7s.

db