Westlake BBSM-6F loudspeaker Page 2
Though I wasn't particularly aware of any spurious noise from the ports during very loud musical passages, on pure tones below 50Hz wind noise could be heard at levels above 8V RMS. (The puffs of air could also be felt 3' away.) Hitting the speaker with high-level tonebursts with a fundamental below the port-tuning frequency also revealed a bit of dynamic instability from the woofer, the cone producing some well-damped subsonics as the toneburst cut off.
The more I listened, the more I became aware of more serious problems. The first is trivial, but mandates care being taken when setting up the Westlakes. The speaker sounded tonally balanced only when I sat facing the midrange and tweeter. If I could see the top of the cabinet, the sound became hollow in the low treble, with the extreme highs left peaky and exposed. Using pink noise, I heard this coloration even when listening to the speakers just an inch above the tweeter axis, which was a little extreme. There was also rather more than usual "vertical venetian blinding" audible. (By this phrase, coined by J. Gordon Holt, I mean that the sound can be heard to undergo numerous cancellations and reinforcements as the listener moves his or her head slightly from side to side, a distinctive comb-filtering effect.)
Though the BBSM-6's tonal balance seemed generally smooth, with good representation of instrumental colors, there seemed to be some resonant-type colorations that afflicted piano, for example, to a larger extent than instruments with more continuous sounds. The Steinway on my Chopin recording on the Stereophile Test CD, for example, acquired too much "clanginess" in the treble staff register, while some notes jumped forward out of the image. The piano on the Stereophile flute and piano recording suffered even more from this midrange coloration, acquiring a confused character that was nothing like the original sound. And recorded tape or microphone hiss sounded emphasized in the low treble, exaggerating its audibility.
The final problem involved stereo imaging. While there was good lateral spread to images, they seemed a little too broad in absolute terms. Gary Woodward's flute on Stereophile's Poem CD, for example, recorded with a Blumlein microphone technique, normally reproduces as a narrow, stable image, just to the right of center stage. Via the Westlakes, while the instrument sounded quite tangible, it occupied a significant spread of space that changed its overall position according to what note was being played.
This impression of image instability was reinforced by the lateral imaging precision test track on the Chesky Sampler CD (JD 37), where the spoken voice also lacked the pinpoint precision it should have (and does with minimonitors like the LS3/5a). The LEDR diagnostic test tracks on this CD were also reproduced with a fair degree of smearing, while the "Up" test, where the mono image of a sampled cabasa should appear to rise from the loudspeaker position (footnote 6), was completely destroyed by the BBSM-6. The image from just one speaker moved from the speaker position to the center and back again in a complicated and unstable manner. (Those dubious of this test should note that the cabasa sound has been equalized according to psychoacoustic criteria so that the changes in its tone color resemble those introduced by the ears' pinnae as a sound source rises in front of the listener. A speaker that has a response trend that tends to undo this EQ will therefore destroy the effect.)
The Westlake's presentation of image depth was also disappointing. While the voice and the tambourine on the depth-test track on the Chesky CD could be heard to get quieter and more reverberant as they moved away from the microphone, there wasn't the unambiguous impression of image depth created by, for example, the KEF R107/2s that I reviewed in May 1991. I suspect that this lack of image depth is more a function of the speaker's forward midrange balance than anything else, while the less good lateral and poor LEDR behavior reinforces the idea that the speaker has dispersion problems. I am also suspicious of that wide baffle area to the sides of the tweeter, something that my experience suggests also correlates with less-than-excellent image precision unless covered with some kind of absorptive material (as in Spica's TC-50 and Angelus models).
Given its pedigree, I had expected more from the Westlake BBSM-6F. Initially impressive-sounding, it increasingly irritated me as my listening continued. In the context of my preamble to this review, the Westlake's ability to form convincing acoustic objects is restricted to artificial recordings where not too much is happening. Then the speaker boogies! But let the mix get too complicated or the recording be minimalist and/or truthful to some original event—both implying that the recorded detail becomes more subtle, more fragile—and the speaker's limitations start to get in the way of the things it does do well.
While its midrange-forward balance, high power handling, superbly revealing presentation of recorded detail, and high dynamic range make it an obvious choice for monitoring of vocal and rock recordings, its shallow soundstage, rather imprecise stereo imaging, somewhat threadbare lower midrange, and lightweight bass make it a less optimum choice for naturally recorded classical orchestral music. While its levels of overall coloration are quite low, the problems it does have are not kind to piano recordings. Its balance will also be less than flattering to recordings that themselves have a forward tonal balance.
I suspect that within the basic formula of the BBSM-6F is a true high-performance loudspeaker waiting to be let out. In the meantime, though the $2500/pair Spendor S100 monitor will not play quite as loud, it is altogether a more refined design, offering a considerably more neutral tonal balance as well as a more extended bass register.
Footnote 6: See Bob Katz's article on these diagnostic recordings in Vol.12 No.12, December 1989, p.82.