M & K MP-4512 surround speaker system
M&K feels your pain. They've come up with a clever alternative for cramped systems by putting not only the front speakers, but the rear speakers as well, into a single compact enclosure that can fit comfortably atop a 20-inch direct-view monitor. Combined with M&K's K-10 subwoofer, the MP-4512 would seem to be a panacea for space-challenged home theaters. But does this diminutive system really deliver the sonic goods?
It's a Small World
Stuffing a complete array of surround-sound drivers into one box is nothing new. At the 2002 Consumer Electronics Show, Nakamichi demonstrated their one-box Niro system, a technology that later formed the basis for Sound Matters' $300 Mainstage product. But unlike the Mainstage, the MP-4512 uses M&K's proprietary Tripole Surround Matrix system. This works much like a mid/side (M/S) microphone pattern in reverse, creating a coherent surround soundfield from a single physical location. Also unlike the Sound Matters system, which includes a minuscule amplifier and some rudimentary digital signal processing, the MP-4512 is driven by your power amplifier.
The MP-4512 is the home theater equivalent of M&K's MP-45 system, which was created for professional broadcast and film postproduction studios; the MP-4512's driver complement reflects the rigorous demands and requirements of those original applications. Its tweeter, M&K's own Z-26, is basically a neodymium version of the company's professional tweeter. To deal with high sound-pressure levels, the tweeter has a ferrofluid-cooled voice coil and an integrated heatsink. According to M&K, the Z-26 can handle a THX-certified amplifier with ease, even though its low-frequency crossover point is around 2kHz.
The MP-4512's long-throw midrange/woofer, built in Denmark, combines remarkably linear frequency response with excellent power-handling capacity. Like the tweeter, this coated paper cone has been used in M&K's professional monitors for a number of years, and can cover frequencies from 2kHz down to about 100Hz (although it's –2dB down at that point).
Traditionally, crossovers are measured and optimized for one point in space, usually 1 meter in front of the speaker. M&K has pioneered the use of multiple measuring points to create their proprietary Phase-Focus Crossover. With this method, they can optimize not only the crossover's electronic circuitry, but also the physical locations of the drivers in relation to each other and to the speaker cabinet, to minimize the lobing effect that is often a problem with 2-way speaker designs, and thus obtain a larger "sweet spot."
The MP-4512's cabinet has an understated profile, in order to be as unobtrusive as possible. Its matte-black finish lets it almost disappear when placed atop a direct-view monitor. Also available, from a company called OmniMount, are various kits that can be used to mount the MP-4512 above or below a flat-panel display.
Unlike most speaker systems that employ a 1-inch dome tweeter and a 3.25-inch midrange woofer, the MP-4512 doesn't use ports to enhance its bass response. For the smoothest overall frequency response, M&K recommends using an even higher crossover than the 80Hz THX standard—such as 120Hz, or even 200Hz. That's good advice. Crossed over at 200Hz to a subwoofer, the MPS-4512 has a fighting chance of achieving THX volume levels.
It's a Small Sub
M&K also sent me their K-10 subwoofer. This compact sub contains a single, long-throw 8-inch cone of treated paper (the same as the one in the company's MX-700) in a sealed cabinet, driven by a 75W class-A/B amplifier. M&K claims that the diminutive K-10 can produce frequencies down to 35Hz (–3dB). Along with continuously variable crossover settings between 50 and 125Hz, the K-10's rear panel has an adjustable level control, a 0/180° phase switch, a pair of line-level inputs, and a pair of speaker-level inputs.
To reduce distortion at high levels, the K-10's circuitry includes M&K's Headroom Maximizer circuit, which functions as a limiter by controlling the maximum voltage to the power supply. This vastly reduces the amount of dynamic compression caused by the circuit while retaining its protective capacity.
A Home Theater Microcosm
Rather than set up the MP-4512 in my large or medium-size home theater room, I put it in a more real-world situation. I used one of the smallest rooms in the house, which measures about 9 by 12 feet and usually serves as my workroom. I placed the MP-4512 atop a 20-inch Mitsubishi direct-view monitor and arranged my viewing-and-listening position so the sweet spot would be about 4 feet away. The K-10 subwoofer ended up on the floor about 4 feet to the right, near the front wall.
Instead of a great big he-man power amp, I used a Teac Esoteric AV-H500D 5-channel integrated amplifier with a conservative power rating of 50W RMS for each of its five channels. The source was an EAD DVDMaster DVD player, its multichannel analog outputs plugged directly into the Teac's 5-channel direct inputs so that the EAD handled all the speaker crossover settings and output levels.
I checked the speaker levels using the Video Essentials test DVD. Because the MP-4512 also includes the surround channels, I didn't need to adjust the delay settings. In their instruction manual, M&K recommends that the surround speaker levels be set 4–6dB higher than the front levels. I found that 4dB worked well in my setup.
O Solo Mio
On first listen, I was impressed by how articulate soundtracks and music sounded through the M&K system. Although relatively inexpensive and quite small, the MP-4512 didn't sound as if its design was a compromise. Unlike many comparably priced home-theater-in-a-box systems, the MP-4512 had no pinched or plastic resonances when played at moderate to high volume levels. My wife commented that, even from upstairs—more than 40 feet away—the M&K system sounded remarkably clean and clear.
Harmonically, the MP-4512 shared many of the traits of larger M&K systems. Its overall harmonic balance sounded quite matter-of-fact, with no artificial warmth. Its small size and small-diameter drivers mean that the MP-4512 alone can't be expected to fill out the sound in the lower midrange and upper bass. Judicious blending with a subwoofer such as the K-10 can work wonders in solving this problem.
Following M&K's recommendation to use 200Hz as a crossover point not only resulted in more dynamic range and better power handling, it also garnered more energy in the lower midrange and upper bass. In my initial setup, I was limited to 80Hz as a crossover point, as will be most users who tether the MP-4512 to an AV receiver. The result produced a slightly lean harmonic balance. At the end of the review period I installed the Lexicon RT-10 universal player as the source, which permits higher crossover points. Setting the crossover at 200Hz nicely warmed up the lower midrange and upper bass.
Most moderately priced speakers force you to choose between a top end that's extended and one that's smooth. The MP-4512 gave me both. Flutes, piccolos, and violins had presence and air without getting shrill. This suave-sounding high-frequency presentation made even slightly abrasive soundtracks, such as School of Rock, completely listenable.
Often, when a manufacturer forces a 3.25-inch driver to handle a wide frequency range, the results are less than stellar. The MP-4512 managed to avoid egregious sonic problems. Not only did the midrange blend harmonically with the tweeter, it also exhibited no noticeable dips or peaks through its upper registers.
Given the close proximity of its drivers, I expected the MP-4512's lateral imaging to be compromised. This was not the case. Although the image width was less than I've heard through speakers that are physically separate from each other, the specificity and stability of the image was surprisingly good. Even when I changed positions from dead center to somewhat off-axis, the image remained stable, not collapsing or shifting drastically to one side.
Most speakers in small boxes with small midrange drivers can't play very loudly without producing signs of audible distress. The MP-4512 proved a singular exception, keeping its cool even during bombastic soundtracks at THX levels. If you like to listen to This Is Spinal Tap with your volume level set at "11," the MP-4512 will let you "smell the glove" with maximum verisimilitude.
The last major question about the MP-4512's performance revolves around the speaker's ability to create convincing surround effects. In my small room, the surround speakers produced a successful surround "bubble" roughly 60% of the time. Video Essentials includes a test in which a male voice cycles through all five speakers of a 5.1-channel surround setup. The MP-4512 did a fine job of creating a semblance of surround, the voice clearly describing a full circle around my listening position. But with DVDs such as Pearl Harbor, the planes and explosions never really came from behind, as they do with a regular surround system.
After talking with designer Ken Kreisel, I realized that, for optimum surround effects, you must set up the MP-4512 equidistant from sonically reflective sidewalls. My test room lacks this ideal configuration, so surround effects were not as convincing as they could have been. Still, even in a less-than-ideal physical setup—probably the situation in many homes—the MP-4512 successfully created surround much of the time.
The Power of One
Home decorators and interior designers often demand that home-theater speaker systems play a role subservient to that of domestic décor. Usually, the result is bad sound. M&K's MP-4512 offers videophiles an alternative to in-wall or microscopic lifestyle systems, one that delivers substantially superior sound at an affordable price while blending into the environment. Coupled with M&K's K-10 subwoofer, the MP-4512 makes it feasible to assemble an elegant, articulate surround speaker system in situations that used to be sonically impossible. That is very cool indeed.