Space...the Final Frontier page 2
Fig.3 Acoustic Energy AE3, spatially averaged 1/3-octave response in JA's listening room.
Fig.4 Westlake BBSM-6F, spatially averaged 1/3-octave response in JA's listening room.
Though the Westlake again has the smoother balance, its more limited lateral dispersion in the treble gives an in-room response that slopes down, even when compared with the Acoustic Energy, which, despite its greater treble energy in-room, also has an overall downtilt to its response. Coupled with the shelved-down bass, this results in a very midrange-prominent in-room balance, which is what I perceived (footnote 3). (Remember that all my measurements are done after the auditioning.)
Coupled with a high dynamic range, this balance is appropriate for a "monitor" speaker, of course; the engineer needs to hear midrange detail thrown forward in order to make optimal judgments concerning edit points, miking choices, and background-noise problems. But for music reproduction, I found that, in the longer term, this vividness sounded unnatural and was fatiguing.
The Westlake's bass could be usefully reinforced by placing it near the wall behind it---or in the studio, it would be placed on the recording console's meter bridge, which would have the same effect. But the irony, then, would be that its already rather shallow, somewhat smeared imaging would be further degraded by the strong reflection from the close boundary (as I explain in an earlier sidebar).
To sum up my reviews, I felt that neither speaker sounded particularly neutral, which is perhaps why neither is still manufactured (footnote 4). The BBSM-6F's high dynamic range, a necessary design choice for a true monitor speaker, was not a significant factor in my own listening. However, for me, the Acoustic Energy's better, more accurate soundstaging offset most of its faults, while the Westlake failed to do enough of what I judged important. But to respond to JGH's general point, which could be condensed to "the better the soundstage, the worse the loudspeaker," I have to say, "Sorry, Gordon, I think you're off-base on this one. Such speakers (if they are neutral) are the ones that give me goosebumps."---John Atkinson
Footnote 2: I average 120 individual 1/3-octave response measurements---six in each of 20 microphone positions---for the left and right speakers in an approximate 3' by 8' region centered on the listening position. The analyzer is an Audio Control Industrial SA-3050A, and the test signal is pink noise at an approximate 80dB spl.---JA
Footnote 3: The only other US reviewer of the BBSM-6F, Don Keele (Audio, December 1991, p.78), also felt it to have a rather midrange-forward balance with reduced bass impact. Don did like the Westlake's imaging specificity more than I did, however, and was impressed by its dynamic range capability.---JA
Footnote 4: I understand that the BBSM-6F has been replaced by a new Westlake model, the BBSM-6VNF, which uses the same well-engineered drive-unit complement in a vertical array. This should correct the "vertical venetian blinding" I noticed with the earlier model and should, all things being equal, result in better focused imaging.---JA