Bookshelf Speaker Reviews

It's not uncommon for a company to come along and make the claim that they've reinvented the wheel in audio or video. In fact, every year at the Consumer Electronics Show, I chuckle when some yahoo representing one of these companies comes up to me and begins to peddle their wares. Sure, there have been several advancements in audio engineering over the last few decades, but let's face it—no one has truly reinvented the wheel.

The endless search for that perfect speaker to suit all my needs is what makes my job both boring and fun (depending on my mood). In wading through all the hype, I've come to believe that, if you make a claim, you'd better be able to back it up.

Surprisingly, M&K's S-150P THX speaker came along relatively quietly. There was no Don King-type PR rep breathing down my neck, and M&K made no claims initially...yet, for a change, the speaker itself seems to warrant plenty of hype. Read on and discover how.

For those of you who may not be familiar with the benefits of a self-amplified speaker, let me explain briefly. For years now, professional recording studios have used self-amplified speakers almost exclusively. This is due in part to the exceptional accuracy each individual speaker can propagate while working entirely independent of every other speaker—not only in the studio, but within its own enclosure. This is accomplished through the internal amplifier (or amplifiers), which has the luxury of only amplifying the sound or individual frequency being input into it. In other words, if a signal contained within the frequency bandwidth of, say, 17 kilohertz is input, the amplifier will only produce that signal for however brief the amount of time. On the other hand, a standard two-channel amplifier powering a pair of speakers would still need to deliver alternate or identical frequencies to the second speaker simultaneously. Apply this to a five-channel application, and you can imagine the kinds of problems that could occur.

The S-150P THX speaker incorporates a 180-watt amplifier with a frequency response of 80 hertz to 20 kHz (since those are the only frequencies required of the speaker in a THX application). It actually integrates two identical internal amplifiers, which is an optimum application because it allows one amplifier to drive the tweeters while the other drives the woofers. This design enables the output of the amplifier to match the full rating of the drivers. The amp will deliver its full 180 watts to the woofers, as long as no high frequencies exist. In theory, the result is a pure, untainted sound that doesn't compromise details—this is due to the lower distortion and higher damping factor (the amplifier's ability to control the cone movement).

The speaker measures 12 1/2 by 10 1/2 by 16 inches and weighs a hefty 45 pounds. There are three 1-inch soft-dome transmission-line tweeters and two M&K-reference 5 1/4-inch polypropylene woofers. All of the drivers are magnetically shielded. The grille used to cover these speakers is attached via four small Velcro patches and is as distracting as Bill Clinton at a NOW (National Organization for Women) meeting. For the life of me, I can't see why M&K decided to use this fastening method, as it is in no way related to the rest of the speaker's fit and finish. M&K assures me that they will eventually incorporate the use of pin-mounted grilles, but not in the near future. After all, the M&K motto has always been, "There's no grille like no grille."

On the back panel, you'll find both balanced (XLR) and unbalanced (RCA/low-level) inputs, as well as a bypass output for connecting an extra speaker or subwoofer. Additionally, there's a switchable, electronic, 80-Hz, second-order, Linkwitz-Riley high-pass filter, which forms a forth-order filter in combination with the speaker's acoustic rolloff and uses a selectable level control with variable and fixed (THX) settings. The speaker comes with a custom stand that adds a very nice touch to the overall look—it also places the speaker at ear level for optimum on-axis response.

The subwoofer I used with the S-150P THX is no stranger to the editors in this industry. The MX-350 THX has been making bass waves for nearly two years. It features a built-in, 350-watt amplifier that drives a duo of 12-inch woofers mounted in a push/pull, sealed enclosure that measures 23 by 15 1/4 by 19 5/8 inches and actually maintains a rather small footprint for a dual 12-inch design. The sub's back panel incorporates enough features to blend into any system, with variable crossover and gain controls marked for THX reference levels. There are also low-level inputs and outputs for daisy-chaining additional subs.

Setup of five S-150Ps and the sub was a snap—it was probably the easiest setup of any THX system I've used so far. The average consumer could set up this package and obtain pretty good results without the help of a certified THX specialist (although I'd still recommend it for optimum performance). Here again, the stands made placement a breeze, and the only things left to connect were the low-level input and power cord. Using the Parasound AVC-2500 THX preamp/ processor, I was able to quickly calibrate the M&K ensemble using the auto-calibration feature and microphone. From unpacking to playback, the system took a record 45 minutes to install in our Los Angeles sound lab.