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.
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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