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M&K Sound S150 Monitor and X10 Subwoofer

M&K Sound S150

Allow me to set the scene: You’re a young audiophile, living in Los Angeles in the 1970s, an avid reader of a new high-end journal called The Absolute Sound. So far, you only have the budget beginnings of a high-end system, inspired by reviews in the pages of TAS—an entry-level Thorens deck, an ADC XLM cartridge, a McIntosh integrated amp, JBL L100 speakers (orange egg-crate foam grilles, thank you very much). But thanks to TAS, you’ve already begun to fantasize about upgrading. 

Where did you go to hear these mythic dream systems you’d spent afternoons reading about? The ARC D150 amps, the Goldmund LP rigs, the SME and Forsell tonearms, Quads, Magneplanars, even a full Infinity IRS system. The store was Jonas Miller Sound in mid-town LA. Miller with his partner Ken Kreisel were the founders of M&K Sound. 

And that young audiophile? Well, that was me.

This was where I first encountered M&K’s satellite/subwoofer system. The demo being played on one afternoon was a big band record, a challenging choice (I thought) for the smallish stand-mount speakers to handle. (I only later learned that this direct-to-disc LP was produced by the M&K subsidiary RealTime Records.) So explosively dynamic and immediate was this recording that it brought collective gasps from the audience. A trumpet solo midway through the track materialized in the room with startling immediacy, electric with brassy intensity. With our eyes centered on the small stand-mounted satellites, no one could understand how these speakers were producing so much dynamically weighted punch and gobs of deep tuneful bass. They weren’t, of course. It was an M&K subwoofer, inconspicuously located in the room, that was doing the heavy lifting. At the time sub/satellites were a unique approach, although I later read that electrostatic or ribbon speaker owners had been deploying subs to augment their bass-limited systems for some time. As history has shown, subwoofers were quickly validated in the nascent home-theater market, where the sub/sat-term “.1” became part of every cinephile’s lexicon. 

Today’s Miller & Kreisel Sound Corporation is an entirely new entity. The original factory closed its doors in 2007, after a solid run of 34 years. Its assets were purchased by a Danish group led by Per Becher, who remains the principal owner today. His new M&K company has concentrated on the refinement of core models like the S150 (reviewed here) and the S300 and X-Series subwoofers, all the while expanding in-wall and on-wall solutions for the high-resolution multichannel market.

The M&K System 

The system that is the subject of this review comprises three loudspeakers—a pair of S150 stand-mount compacts and an X10 subwoofer. Total cost about $8000 plus stands. The S150 is a two-way, five-driver monitor of squarish dimensions, roughly a foot tall. It’s an acoustic-suspension design of better than average sensitivity (92dB), with dual 5.25″ mid/bass drivers and a trio of soft-dome tweeters in a short vertical line array. Among the virtues of a line array is controlled vertical dispersion that is meant to reduce reflected sound, for example floor or ceiling bounce. Of course, there is also the advantage that three tweeters don’t need to work as hard as one, and collectively possess greater dynamic headroom. As I soon observed, with five voice coils per speaker, power handling was never an issue. Construction quality is rock solid. Cabinets are heavily braced MDF and tight as a drum. The finish is impeccable. Giving the enclosure a classic knuckle-rap test yielded little to nothing in the way of enclosure resonances. The cabinet is, how shall I put it, quite dead.

M&K Sound S150 Monitor and X10 Subwoofer

The X10 subwoofer is equipped with dual push/pull, long-stroke 10″ drivers (a total surface area equivalent to a single 15″ driver) in a sealed (acoustic-suspension) enclosure. The surround on these woofers is massive, to allow long-stroke cone motion and provide a high degree of damping. The two-inch coil-diameters ensure extended, linear cone movement, extraordinary power handling, and thermal stability. The woofers employ open, rigid, cast baskets for free air circulation, resulting in minimal mechanical distortion and improved heat dissipation from the motor system for reduced power compression. X10 also sports aluminum AC shorting rings in the magnet system and aluminum pole spacers above the pole piece.

The X10 combines a switch-mode power amplifier of 350 watts RMS with M&K’s proprietary analog “front-end” input stage. Paul Egan of MK Sound America, pointed out that “350 watts RMS doesn’t sound like a lot of power given its output, but the dual-driver push/pull configuration gives us an additional 6dB of output versus a single-driver unit. And this driver alignment gives us an additional halving of acoustic distortion compared to conventional subwoofers.” 

The back panel houses a bevy of two-channel or LFE (low-frequency effects) cinema settings, which are outlined in the specifications section. This is a THX-certified subwoofer, which means that it can play back at the same reference output levels that were used to mix the soundtrack—the way it was meant to be heard in theaters. Ultimately, after cycling through various room settings, I ran the sub in a way that suited my stereo listening preferences—with the crossover setting fixed at 80Hz and the variable volume control active, rather than set at the fixed THX reference-level. 

For clarification, this is a “true” sub/sat system, a system wherein the S150 satellites operate within a bass-restricted range and are designed to partner with a specified subwoofer, the X10. Contrast this with the more general mix ’n’ match approach of adding a subwoofer from one company to a speaker system from another. The fact is that some loudspeakers do not take to subwoofing one bit. They might have a midbass bump already built into their frequency response, or port resonances, or odd crossover-slope mismatches—even attempting high-pass filtering can degrade performance. The results can run the gamut from excellent to disappointing. Like going on a blind date, it becomes more a matter of trial and error. MK alleviates that issue; each speaker and subwoofer are pre-matched and designed for and with the other in mind.

An added advantage is that by isolating the woofer enclosure from the satellite cabinet there is less potential that the sub’s powerful internal vibrations will be transferred to and impact the midrange and tweeter. This gives the cabinet designer a free hand to optimize the satellite enclosure size and maintain a narrower front baffle to reduce diffraction. The satellite has the potential to play cleaner with fewer colorations, as I soon observed. And on the electronics side, since the main stereo amplifier no longer is required to produce deep bass, the amount of power needed to achieve a given output level from the main speakers is greatly reduced. 

Separate cabinets also give the owner more control over room setup. Even in the best of rooms, bass response and the rest of the frequency spectrum are often at odds with each other when it comes to optimization. For example, a listening position that may be ideal for imaging and soundstaging may be less than ideal for bass output or linearity. A sub/sat system opens up a whole new range of options in terms of placement.

In sonic performance, my first impression of the M&K system came down to these key elements: high-impact dynamics, speed, foundational weight, and superb resolution. The M&Ks possessed a slightly forward midrange signature that made soloists unreservedly present, and a personality that veered closer to the cooler, more clinical side—a balance that was not completely unexpected given its pro-studio-monitor heritage. This was manifested for me by an impression of images that were very ordered on the soundstage—uncrowded and distinct. Micro-dynamics were nicely realized with finer and finer volume gradients. During Harry Connick, Jr’s “A Nightingale Sang in Berkeley Square,” I found acoustic bass and sax cues fast and immediate. Perhaps the most stunning element in the M&K’s high-performance arsenal was its lack of congestion. There was an openness to the overall sonic picture—the macro side if you will—that extended down to the micro. The soundstage was wider than usual and evinced greater dimensionality. It had in many respects an enclosureless character. Power response into the room was also very good; listeners sitting a bit off-axis fully enjoyed the music and didn’t feel as if they’d been deported into some sort of sonic Siberia.

As acoustic-suspension designs, the S150/X10 combination shared a consistent quality of control and timing, which helped to define transient information and deliver wide-ranging dynamics at a level of resolution that, in my view, is best exemplified by the sustain and decay of the piano soundboard. Consider the closing bars of Norah Jones’ “The Nearness of You.” As she strikes a bottom-octave key to close the song, a bass-restricted system won’t cut it. Artistically, the song needs the pitch and decay of that deep fundamental note to resolve its ending. M&K brought it on in all its intensity.

An excellent voice speaker, the M&K handled male and female vocalists with equal realism. M&K’s upper-mid and treble performance was smooth, open, and without peaky misbehavior. Add to this the naturalistic transient attack and speed, and the tweeter became in some ways evocative of a ribbon transducer. Holly Cole’s airy vocal during “I Can See Clearly” was suffused with body and presence. At the other end of the vocal spectrum there’s Louis Armstrong’s throaty rasp of a performance on “St James Infirmary Blues,” a recording of such goosebump-raising immediacy that it nearly breaks the bonds of audio reproduction altogether. If your system is firing right, as the M&K most assuredly was, this track becomes a time machine in the way it draws the listener into another time and place. The images of the horn accompanists and the steady lament of background voices all seemed to occupy a ghostly space freely without encumbrance. In the best of all possible worlds, I would greedily have asked for a bit more air to underpin images like violin and to lift vocals a bit, but for this listener a dollop of dryness is preferable to warmed-over sonics that produce indecisive images and dimensionality.

As for system integration—always the elephant in the room—the critical blend of sub and satellite was as good as I’ve attained in my space, essentially seamless. No subwoofer localization, zero holes in frequency response, and no unfortunate mid- or upper-bass humps that ultimately cloud transparency in the lower octaves. The M&K system cast a continuous, stable soundfield across the width of my room. Of course, the best subwoofers never make themselves the centers of attention. They are the more or less silent participants, lying in wait until called upon. 

I was reminded of this fact as I listened to Renaud Garcia-Fons’ double-bass solo on The Marcevol Concert. Besides the virtuoso playing, this disc is highly revealing of timbre and pitch quality. However, the fullest realization of a naturalistic sub/sat pairing could be heard on wide-ranging acoustic recording like the Rutter Requiem. Unburdened of producing deep bass, the S150s were much more open on choral gradients and micro-dynamically alive, with the smallest cues from harp and cello unobscured. When this system is fully lit and reproducing a great, wide-spectrum dynamic recording like Copland’s “Fanfare for the Common Man,” I never had the feeling that anything was being held back. The M&K just gushes resolution and dynamic energy. Here, the unobtrusive nature of the acoustic-suspension design proved definitive, as it exhibited zero deep-bass overhang. I’ve never heard a sub/sat system anywhere near this price point as tight and expressive and as tonally and harmonically complex as the M&K. 

I have few reservations regarding the performance. Soundstage depth and general dimensionality were about average. The tightly controlled and cooler sonics may not be for everyone to the degree that they were for me. Some audiophiles prefer a warmer, more romantic, cushier signature. Fair enough.
A couple of final comments. Yes, in my experience, two subs are often better than one (I run a pair of REL S/812 in my larger system). But don’t be deterred. In smaller listening spaces and with thoughtful trial-and-error positioning to ameliorate acoustic peaks and nulls, a single sub can perform wonderfully well, as I discovered with the X10. Also, if your home is on a raised foundation with older wooden floors, low-bass energy can create floor resonances that will give the position of the subwoofer away, so you might want to place decouplers beneath the sub to prevent this from happening. Something like the very affordable products from A/V RoomService would be ideal.

Before my time with the M&K system came to an end, I decided to honor that long-ago moment in Jonas Miller Sound by once again cueing up my copy of “Take The A Train” from For Duke, the LP produced by M&K RealTime Records with Bill Berry and his Ellington All-Stars. My memory didn’t fail me, thankfully, for what I heard then I still hear today—the explosion of dynamic energy that seems to launch from the groove and send sparks flying from the stylus, the immediacy of the moment that even now places me inside the studio, an awesome LP that is arguably still the summit of direct-to-disc wizardry.

On one level, the M&K system certainly struck a nostalgic note and brought me back full circle to my earliest encounters with high-end audio. But as a tool for music reproduction, this system wasn’t living in the past. It’s a thoroughly contemporary and thrillingly musical take on a full-range stereo speaker system. It reminded me that the absolute sound has never been defined by the number of amps or speaker boxes or wires strewn around the room. One of the great pleasures of audio reviewing is when you meet a product that puts it all together in ways that allow you to get lost in the music as effortlessly and innocently as you once did—when it was only the music that mattered. M&K has produced such a system and at a price attainable for most of us. My recommendation: Time to think outside of the two-channel stereo box and consider what the power of three can do for you.

Specs & Pricing

S150 Monitor
Type:
Two-way, sealed-enclosure mini-monitor
Drivers: (3) 1.1″ soft dome tweeters, (2) 5.25″ fiberglass mid/bass
Impedance: 4 ohms
Sensitivity: 92dB
Dimensions: 10.4″ x 12.5″ x 12.2″
Weight: 25.4 lbs.
Price: $4398

X10 Monitor
Type:
Push/pull sealed-enclosure subwoofer
Drivers: (2) 10″ woofers
Power: 350 watts RMS/650 watts peak
Frequency response: 20–200Hz ±2dB
Phase: 0-180 degrees, continuously variable
Volume control: Continuously variable or fixed THX
Features: Switchable LFE, optional THX or MK EQ mode
LFE input: L/R line-level RCA & XLR
LFE passthrough output: L/R line-level RCA & XLR
Switchable low-pass filters: Fixed 80Hz/Variable/No lowpass
Dimensions: 14.7″ x 22″ x 17.3″
Weight: 62 lbs.
Price: $3499

MK SOUND AMERICA
PO Box 3035
Princeton, NJ 08543
(844) 204-8444
mksound.com
info@mksoundamerica.com
skb@mksound.com (international email)

Tags: LOUDSPEAKER STANDMOUNT SUBWOOFER

Neil Gader

By Neil Gader

My love of music largely predates my enthusiasm for audio. I grew up Los Angeles in a house where music was constantly playing on the stereo (Altecs, if you’re interested). It ranged from my mom listening to hit Broadway musicals to my sister’s early Bob Dylan, Joan Baez, Beatles, and Stones LPs, and dad’s constant companions, Frank Sinatra and Tony Bennett. With the British Invasion, I immediately picked up a guitar and took piano lessons and have been playing ever since. Following graduation from UCLA I became a writing member of the Lehman Engel’s BMI Musical Theater Workshops in New York–working in advertising to pay the bills. I’ve co-written bunches of songs, some published, some recorded. In 1995 I co-produced an award-winning short fiction movie that did well on the international film-festival circuit. I was introduced to Harry Pearson in the early 70s by a mutual friend. At that time Harry was still working full-time for Long Island’s Newsday even as he was writing Issue 1 of TAS during his off hours. We struck up a decades-long friendship that ultimately turned into a writing gig that has proved both stimulating and rewarding. In terms of music reproduction, I find myself listening more than ever for the “little” things. Low-level resolving power, dynamic gradients, shadings, timbral color and contrasts. Listening to a lot of vocals and solo piano has always helped me recalibrate and nail down what I’m hearing. Tonal neutrality and presence are important to me but small deviations are not disqualifying. But I am quite sensitive to treble over-reach, and find dry, hyper-detailed systems intriguing but inauthentic compared with the concert-going experience. For me, true musicality conveys the cozy warmth of a room with a fireplace not the icy cold of an igloo. Currently I split my time between Santa Fe, New Mexico and Studio City, California with my wife Judi Dickerson, an acting, voice, and dialect coach, along with border collies Ivy and Alfie.

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