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Westlake Audio BBSM6 Series2 Monitor

There probably is not a speaker made that yours truly is more familiar with than the Westlake BBSM6. I bought my first pair in the early '80s while working as a freelance recording engineer in New York City.

There probably is not a speaker made that yours truly is more familiar with than the Westlake BBSM6. I bought my first pair in the early ’80s while working as a freelance recording engineer in New York City. The BBSM6s were fairly large and heavy; consequently I had road cases built so that they could be carted around the studios in Midtown Manhattan more often than not by hand truck. They became a real reference for me regardless of what studio I was working in at the time, due to the fact that the tonal balance is right on. Most NYC studios back then used UREI 813s as main monitors and I never could deal with Yamaha’s NS-10s.
Product PointsApplications: Close and midfield studio monitoring

Key Features: Three-way design; twin 6.5-inch woofers; 4-inch midrange driver; 1-inch soft dome tweeter; heavily dampened; optional muffs

Price: $5,788 per pair

Contact: Westlake Audio at 805-499-3686, Web Site.


+ Accurate three-way design

+ Pin-point imaging

+ Amazing inner detail

+ Good sensitivity


– 2 to 4-ohm impedance make a serious amplifier a must

– Lacks deep bass

The Score: A highly accurate, no hype, low-distortion three-way studio monitor speaker.
During the mid ’90s the company that supplied the drivers for the BBSM6 stopped production on the 3.5-inch midrange unit, and designer Glenn Phoenix could not find a suitable replacement part. Westlake ceased production of the BBSM6 for almost five years because Phoenix would not compromise the performance by using a midrange driver that did not meet his criteria.

Over the years Phoenix has made dozens of small changes to the entire line of Westlake speakers, paying particular attention to enclosure resonance, crossover component orientation and internal point-to-point wiring. Collectively these tweaks have added up significantly enough to warrant the “Series2” designation.


The new Series2 BBSM6 ($5,788 per pair) is very similar in appearance to the original, even though it has all new drivers and benefits from all of the production tweaks Glenn has implemented in other Westlake models over the years.

A pair of 6.5-inch woofers flanks the new 4-inch midrange driver with the 1-inch soft dome tweeter positioned right above it. All four drivers are placed about as close as you could possibly mount them and still get front baffle rigidity, which I believe is one reason the BBSM6 images so well. Fourth order (24 dB/octave) crossover slopes are set at 475 Hz and 4.5 kHz, both frequencies a bit lower than the original BBSM6.

The nominal impedance is rated at 4 ohms; however, Glenn tells me that it is closer to 2 ohms from 100 Hz to 5 kHz. Needless to say, this is no place for a wimpy amplifier. Although sensitivity is high at 91 dB at 1M/2.83V, this overall low impedance can be challenging to some of the more pedestrian amplifiers.

The BBSM6 measures 11 inches high x 22 inches wide x 13 inches deep and weighs in at a whopping 70 pounds. Knocking anywhere on its bass reflex enclosure is a bit like rapping on a rock; this cabinet does not “sing” at all, because of the internal dampening — one reason for the weightiness. Frequency response is rated from 60 Hz to 20 kHz +/-3dB. A four-conductor heavy-duty barrier strip is used for input to the BBSM6 so that passive biamplification or biwiring is possible. The Westlake speaker cables supplied for this review are 4-gauge in a biwire set up. The four amplifier ends are terminated into a pair of large gold spade lugs that fit nicely into amplifiers with five-way binding posts. The speaker ends fan out to four gold spade lugs — one pair for mid/tweet, the other pair for the woofer.

The BBSM6s were also supplied with speaker muffs, which are large 4-inch thick foam pieces that surround the front baffle (see photo). The purpose for the muffs is to reduce the distortion caused by cabinet edge reflection, allowing the listener to hear more direct sound from the speaker and less from surrounding room boundaries. This also has a smoothing effect on the frequency response and localization within the sound stage; trust me, they really work. In trying to describe the effect, think of a cross between a pair of really good speakers and a great pair of headphones. The outcome is totally valid for professional monitoring since the goal here should be accuracy and not hype (I hate hype).

The largest and most obvious improvement in the new BBSM6 Series2 compared to the old BBSM6 is distortion. One of my main criticisms of the original version was a grittiness, especially listening to brass, which I mainly attributed to the steep crossover slopes used. I was wrong about that. The new version has the same 24dB/octave slopes but without a hint of grittiness or grunge. The overall tonal balance is still good like the old version, but with an added degree of openness and transparency only found in some of the most expensive high-end hi-fi speakers. For a guy who has been raggin’ for so long about crossovers and multiple drivers, I cannot think of any three-way speaker whose drivers integrate as well they do in the new Westlake BBSM6 Series2.

In Use

My auditioning setup consisted of the BBSM6s on 36-inch high RPG speaker stands driven by three very different power amplifiers. Listening at a distance of approximately six feet, I first tried the Bel Canto eVo 200.6 — a Class T digital amplifier (reviewed in PAR 8/02). From the upper bass (150 Hz or so) on up in frequency I could not find fault – smooth, open, airy, natural it had it all – but below 150 Hz it seemed a bit lean. Many speakers, especially ported enclosures, have a bump in the 100 Hz area that gives the impression of more bass. The Westlakes do not have a bump which may be why subjectively they seem a little lean.

Next I tried my trusty old Hafler 9505, which is a MOSFET design and not really designed to drive a 2 ohm load but still does a decent job in its price range. The bottom end was a bit fuller, not as well controlled, and it lacked the openness, depth and detail of the Bel Canto. Last, I tried the Thule Audio PA350B, which is what the company calls a “Virtual Class A” amplifier, not sure what that means, but this is a very nice sounding amplifier. The Thule shows off the great detail of the 6s, while having good low-end control, driving the BBSM6s with as much power as they could ever need.

Because the BBSM6s have so much inner detail, but are not so easy to drive, they become very amp-dependent, showing both the good and bad qualities of amplifiers. The beneficial side of this is that you have some flexibility matching up the BBSM6 with different amplifiers to suit your monitoring tastes. On the down side, if you are like me and want pristine performance, it means you are going to have to lay out some bucks for a really great amplifier.


The BBSM6s are not to be considered full-range monitors because of the lack of response below 60 Hz. If they only went down another octave or so on the bottom end, they might just be the ideal monitor speakers. To quote Glenn Phoenix, “The perfect speaker has yet to be built,” but it is safe to say the Westlake BBSM6 Series2 is a step closer.

Review Setup

Philips SACD 10-PE transport; EMM Labs DAC8 Mk IV D/A converter; EMM Labs Switchman Mk2 Bel Canto eVo200.6, Thule Audio PA350B, Hafler 9505 power amplifiers.