April 1, 2007

Mirage OM Design OMD-28 Loudspeakers

Mirage’s history dates back some 30 years, but it was 20 years ago, with the release of the groundbreaking M1 loudspeaker, that the company made its mark. The M1 was tall, wide, shallow, black -- as imposing as the monolith in 2001: A Space Odyssey. The novel thing about the M1 was that it had identical drivers mounted on the front and back. It was sort of like two speakers back to back, and because the drivers were wired in phase, they all worked together to launch soundwaves into the room. Mirage called their in-phase speaker technology bipolar, in contrast to dipolar, which describes speakers that radiate front and back but out of phase.

The M1 was tremendously successful, partially because it looked cool and had whizzy technology, but mostly because it sounded so good, with a spacious, room-filling sound that conventional speakers couldn’t match. Mirage followed up with smaller versions of the M1, including the venerable M3, which was thought by many to be the best of the M series -- it had everything the M1 had, but wasn’t nearly as big, and so worked better in moderately sized rooms. In fact, the M1 and M3 were so well liked, and were talked about for so long, that many, including me, consider them classics. However, such strong initial success can have drawbacks -- since the M series, no other Mirage model, no matter how good, has generated the same kind of buzz.

That could all change with Mirage’s new flagship speaker, the three-way OM Design OMD-28 ($7500 USD/pair), which showcases everything the company knows about the unique kind of loudspeaker technology they’ve been developing for so many years. The OMD-28 is every bit as exciting to look at and listen to today as the M1 was when I first heard it in 1987.

The Omniguide

Mirage no longer uses the term bipolar, and they no longer mount drivers on the front and back of their speakers; they call their current technology Omnipolar, and they use a nifty device, the Omniguide, to disperse the sound using a single set of drivers mounted on the top of the cabinet. The core of the Omniguide technology is the strange-looking saucer thingy atop the speaker, which works with the tweeter and the midrange driver.

Andrew Welker has been Mirage’s chief designer since the late 1990s. He and the Audio Products International research team (API, Mirage’s parent company, is owned by Klipsch Group) developed the Omniguide over five years ago and introduced it with Mirage’s innovative, inexpensive Omnisat speaker in 2002. I reviewed that speaker at our sister site, Home Theater & Sound, as part of a multichannel home-theater system. The use of the Omniguide in the OMD-28 is a unique case of "trickle-up" technology.

Here’s how the Omniguide works. In the OMD-28, the midrange driver is a 5.25" carbon-fiber cone placed atop the angled cabinet. The Omniguide’s convex reflector is mounted directly above and a short distance away from the cone, at a specific angle to the driver. The tweeter, a 1.1" titanium dome, is mounted atop the midrange driver’s reflector, and above the tweeter is another convex reflector, again placed a specific distance away and at a certain angle. These shapes, distances, and angles are all proprietary to Mirage, and part of their patent on the Omniguide technology. The midrange crosses over to the tweeter at 2.5kHz.

The shapes, angles, and distances result in the drivers’ outputs ricocheting off the saucers and being dispersed so that most of the sound is directed forward, with lesser amounts to the sides, and the least amount to the rear. Mirage thinks of this as a 360-degree radiation pattern with a forward bias. The goal of such a dispersion technology is the spacious, room-filling sound that evenly dispersing, 360-degree-radiating speakers are known for -- that is, speakers that put out equal sound in all directions, such as those from mbl and Duevel -- but with the imaging precision of a good conventional, forward-firing speaker. This is quite different from the original M-series speakers, the bulk of whose output was fired directly to the front and rear, and the least energy to the sides. Here it’s front, then sides, then rear, the output smoothly decreasing from front to rear.

The rest

The OMD-28’s two 8" woofers are crossed over to the midrange at 550Hz. Each 8" woofer has a multilayered carbon-fiber cone and API’s patented Ribbed Elliptical Surround, which is said to result in greater driver excursion with less distortion.

Both woofers are front-firing; i.e., their outputs aren’t bounced off of anything. One reason for that is that deep bass is inherently omnidirectional; the wavelengths of low-bass frequencies are so long that they essentially swamp the room. You can mount a woofer on the front, side, or rear of a cabinet, as you see done in various speakers, and your ears can’t localize the source.

The closer a bass driver’s output approaches 550Hz, the more directional the soundwaves become. However, because the OMD-28 is a forward-biased radiator, not an evenly dispersing one, Mirage has chosen a crossover point at which the dispersion characteristics at the woofers’ upper limit matches those at the lower limit of the top-mounted, Omniguided midrange driver.

Augmenting the woofers are two downward-firing ports, which shows another bit of ingenuity in this speaker’s design. The ports open into a bottom plate that’s separated from the main cabinet by attached aluminum feet. This nice touch conceals the ports yet still lets the air escape and, at the same time, finishes off the bottom part of the speaker by perching it on a bit of pedestal. Mirage rates the -10dB output level under anechoic conditions at a jaw-rattling 18Hz. Yes, full-range.

The OMD-28’s technical tour de force is capped off with exceptional industrial design and nice cosmetic details. Each speaker measures 46.5"H x 11"W x 13"D and weighs about 70 pounds. The MDF-based cabinet has a curved back, and I have no idea how they do that -- I’m guessing that it involves layers and/or slots, steam, glue, and plenty of time and skill. It comes in a veneer of black, rosewood, or burled maple -- all coated in a thick, high-gloss finish. My review pair came in rosewood, and they’re simply gorgeous.

200704_omd28_bp.jpg (16186 bytes)But because the whole Omniguide look is rather, well, unique, and perhaps won’t be a thing of beauty to some eyes -- some may wish to simply cover it up -- Mirage provides a big, rounded, removable grille that covers the entire top portion of the speaker to conceal it all (there’s another grille for the woofers). With its grilles in place, the OMD-28 has a rounded top to match its rounded back, but looks far more conventional overall.

Around back are three sets of large, gold-plated binding posts -- you can triwire the speakers should you wish, but you don’t have to; a jumper is also provided, for single- or biwiring.

Mirage claims that the OMD-28’s voltage sensitivity is 87dB, and that its nominal impedance is 6 ohms, with a 3.5-ohm low point. I’d say their recommendation of power amplifiers rated from 50Wpc all the way up to 300Wpc is spot-on. You need some power to get the OMD-28s going, and they also seem able to take quite a lot. The mistake you don’t want to make is to pair them with a small amp that might not be able to get enough of a grip on them to make them really deliver.

System

I connected the OMD-28s to a Simaudio Moon Evolution i-7 integrated amplifier with a 2m run of Nirvana S-L speaker cable. The i-7, an amazing-sounding integrated that’s rated to deliver 150Wpc, provided enough power to drive the OMD-28s to very high levels in my much-larger-than-average listening room.

At the front end of the system was my Theta Data Basic transport connected to my Stello DA220 D/A converter with an i2Digital X-60 interconnect. The DA220 was connected to the i-7 with 3m runs of Nordost Quattro Fil interconnect.

Setup

Normally, I have no trouble setting up speakers in my room -- I just plunk most of them down in my favorite spot, way out in the room, and they work fine. The Mirage OMD-28s weren’t too tough to set up, but they were more challenging than the rest because they didn’t necessarily like that sweet spot -- their unique dispersion characteristics mandate that they be placed reasonably close to wall boundaries, but not too close. Like me, you’ll probably have to experiment a bit.

The OMD-28s ended up about 5’ from my front wall and about 4’ from each sidewall. Usually, I listen to speakers placed up to 10’ from the front wall and up to 6’ from the sides. My setup might still be farther away than most people place speakers -- I’m sure you can get the OMD-28s closer to you if need be -- but my room is huge. This placement resulted in a good balance that let the Mirages’ output reflect nicely off the walls, which a design like this needs to do, without overloading the room with heart-stopping bass: the OMD-28 sure can kick down low.

Sound

From Bipolar to Omnipolar, from Paisley to Welker

Despite how well-regarded Mirage’s speakers have been, they’ve also been greatly misunderstood. For example, with the earlier models -- the ones Mirage referred to as bipolar -- many people, even many reviewers, couldn’t grasp the idea of the front- and back-mounted drivers all working in phase. It just didn’t seem to make sense to be sending sound ahead and behind. After all, aren’t speakers supposed to fire the sound directly at you? That was the conventional thinking -- if you didn’t understand how speakers interact with a room.

All speakers -- even conventional, front-firing ones -- splash sound all over the room, even if the drivers are mounted only on the front. The reason is that sound doesn’t radiate from the drivers in a straight line toward the listener’s ears. Rather, the soundwaves from each driver go off in many different directions. Furthermore, how they’re launched and where they end up are affected by many things: driver design, the cabinet itself, room boundaries, objects in the room, and on and on. If you don’t believe me, stand directly behind a conventional, front-firing speaker as it’s playing and notice how much of its sound you can still hear -- and, often, how different the speaker sounds from back there. There’s a lot more happening with speakers that meets the listener’s ear than first meets the eye.

Therefore, speaker designers must be concerned not only with a speaker’s on-axis response (the direct response in front of the speaker), but its off-axis response as well (the response everywhere else). It’s the complex combination of on- and off-axis responses that ultimately ends up at the listener’s ears. If the designer doesn’t pay attention to how a speaker radiates energy all over the place, by the time the sound actually hits the listener’s ears, it might be nothing but a mess -- and often is.

Mirage’s original designers -- most notably, Ian Paisley -- understood all that. In the 1980s, Mirage was heavily involved in the NRC research that brought to light the importance of speakers’ on- and off-axis frequency responses. That research resulted in recommendations that speaker designers try to ensure that the on- and off-axis responses were well controlled and similar, so that when all these responses finally reached the listening chair, they all blended coherently instead of being a mishmash of disparate sounds. That’s why Mirage’s original M-series speakers were designed with drivers mounted front and rear -- to evenly disperse the sound in front of and to the rear of the speaker so that the on- and off-axis responses were similar. Having front- and rear-firing drivers might sound crazy, but those speakers were actually designed to work with the room. Furthermore, delivering more energy to the rear also heightened that sense of spaciousness for which Mirage speakers are known. Some call that effect a coloration; others, like Mirage, feel that it better mimics what we hear in real life.

Enter Mirage’s current designer, Andrew Welker, who joined the firm in the late 1990s. Welker had his hand in some of Mirage’s final designs with front- and rear-mounted drivers. It was about then that the company ditched the term bipolar in favor of the trademarked Omnipolar, which they say better reflects the omnidirectional-radiating approach they were now taking.

Andrew Welker would probably have been in elementary school when the guys at NRC were doing the original research, but he’s more than caught up; he’s not only carrying on the Mirage torch, he’s advancing it. The newest Mirage speakers don’t have front- and rear-mounted drivers; they have what Mirage calls an Omniguide, which is described thoroughly in the accompanying review. It’s a Welker creation -- something designed to take Mirage’s Omnipolar technology to the level seen in the OMD-28.

...Doug Schneider
das@soundstageav.com

Once set up properly, the OMD-28s cast a magnificent, spacious soundfield with good center-fill, an often astonishing sense of depth, and nearly subterranean bass. It was the largest, most expansive, and, in some ways the most enjoyably musical sound I’ve ever experienced in my room.

Take Blue Rodeo’s Five Days in July [CD, Discovery 77013], for example. The album is wonderfully recorded -- it’s one of the best pop-rock recordings in my collection -- and it’s been one my reference recordings for more than a decade. The opening track, "Five Days in May," has a vast, expansive stage that some speaker systems stunt into something smaller, constraining the sound to the area between the speakers and going only a few feet behind them. Through the OMD-28s, the stage reached from left to right in a way that threatened to go beyond each speaker’s outer side panel. As a result, the OMD-28s basically "disappeared," leaving only the soundstage behind. It was the sense of depth, though, that bowled me over -- it went from the plane of the speakers to somewhere behind my front wall, which rarely happens. As a result, the vocals were center stage, just shy of the speaker plane, while the drums were way, way back. It was as if the band was in my room and finally had enough space to breathe.

I’ve been listening to Ennio Morricone’s soundtrack score for The Mission for 20 years now [CD, Virgin CDV 2402]. The chorus that dominates this recording is captured with impressive width -- regardless of which speaker system I use, it stretches from over here to way over there; there’s also a great sense of depth, if the system can convey it. With the OMD-28s, the depth was as good as I’ve ever heard. But what most impressed me was that the stage didn’t just fall back from the speakers, presented as a well-defined wall between and a few feet in back; instead, the chorus encased the front part of my room and, again, reached back beyond the front wall. More unusually, it spread to the room’s corners, creating the most spacious, enveloping stage I’ve ever experienced in this room.

That’s not to say that the OMD-28s are all about large-scale re-creation and soundstaging thrills -- they also performed extraordinarily well with smaller, more intimate recordings. I was particularly interested in how they would re-create the human voice; one criticism I had of the first-generation Omnisat was that it sounded a touch distant in the mids, which made me strain to hear voices, and sometimes had me itchin’ to turn the volume knob up and up. The OMD-28s had none of that. Voices were suspended in space at the speaker plane, and I had no urge to turn up the volume to bring them closer. These speakers could convey depth as can few others, but they didn’t recess the midrange in the process.

Chesky Records has released a compilation titled The World’s Greatest Audiophile Vocal Recordings [SACD/CD, Chesky SACD323]. If you’re into vocal recordings, or want a sampler of Chesky’s material, or if you just want something that sounds great so that you can impress friends with your stereo, get this disc. I play it a lot -- for all of the above reasons. I listen to many tracks on this disc, but I’m always drawn back to Livingston Taylor singing Stevie Wonder’s "Isn’t She Lovely." Through the OMD-28s, the richness and vibrancy of Taylor’s voice were startlingly realistic, with no chestiness or overhang. Furthermore, his voice was tight and focused, almost as if the OMD-28s had transformed themselves into smaller monitors. Whether called on to play big or small, the OMD-28s sounded spectacular.

One of the criticisms of the first-generation Mirage M speaker was that it could sound dark. It probably did. I do recall that its tweeter not only didn’t sound very "hot," it sounded a little turned down. That changed a bit in the early 1990s, with the metal-dome tweeters of Mirage’s Msi series. Still, no one would ever have called an M speaker bright. The right word was probably dark.

No one will call the OMD-28 "dark," or criticize it for being reticent up top. In fact, it seems that almost every criticism Mirage has received in the 20 years leading up to the OMD-28 has been addressed. The OMD-28’s highs were infinitely extended -- in fact, they sparkled. The OMD-28 was as extended as the best conventional speakers out there, and splendidly clean from the upper mids right through to the top. If you play a bright-sounding recording or have bright-sounding equipment, you’ll definitely hear that brightness. The only way you’re going to miss anything in the highs with the OMD-28s is if your hearing is gone.

Likewise for the low end. The OMD-28’s bass output was deep, tight, and forceful -- when the bass hit, I knew it, with no subtle swelling down low. When I played Johnny Cash’s American IV: The Man Comes Around [CD, Universal 077083], I was floored by this speaker’s downward reach. Nor was the bass fat, plodding, or sloppy. The OMD-28 had impact and weight -- real hmmmph-type stuff. It sounded as full-range as anything I’ve had in my room. However, this strong weight down low might be a concern for some, so I should caution you about some things.

First, understand that the OMD-28 isn’t a speaker for small rooms -- it needs space. As I mentioned, it needs to be some distance from the walls so that its output doesn’t reflect off a nearby surface. Nor should it be placed in a corner, which will only increase the bass output. (Bass increases when you place speakers close to a wall, and increases more when you place it close to two walls: i.e., a corner.) On their own, even way out in the room, the OMD-28s really hammered low notes home. Furthermore, they sounded best spaced fairly wide, and listened to from, say, 8’ to 10’ away. You’ll need a fairly large room to have the OMD-28s perform at their best.

Second, you’ll want an amplifier with rock-solid control in the bass. At one point, I needed to hook up the DK Design Group VS.1 Reference Mk.II integrated amplifier, which is claimed to deliver about the same output power as the Simaudio Moon Evolution i-7. However, when I used the DK, the bass was fat and lacked control, although the rest of the audioband was rendered respectably. When I reinserted the i-7, the bass was again tight, deep, and well-controlled. The difference wasn’t subtle; had I used the VS.1 to evaluate the Mirage, the results wouldn’t have been nearly as positive.






Finally, while the OMD-28s could create an uncanny, mind-boggling sense of space, and also presented images on that stage with good precision -- vocals here, guitars there, etc. -- they didn’t create that stage with the laser-like precision of some more conventional, forward-firing speakers. That’s not to say that Mirage’s speakers are vague -- their "forward bias" of output energy results in a credible degree of soundstage specificity -- but they won’t knock your socks off that way. On the other hand, I’ve never heard a forward-firing speaker, no matter how expensive, that can equal the OMD-28s’ sense of space, and in that department they probably will knock your socks off.

Conclusion

I was a big fan of Mirage’s original M1 and M3 designs. For years, though, I waited for the company to hit one out of the park again. During that time Mirage built what I thought were some very good speakers, but nothing that will be remembered the way the M1 and M3 have been -- they’re classics. It’s hard to know at this time if the OMD-28 will be remembered in the same way, but I think it deserves the same type of acclaim.

The OMD-28 appears to encompass everything the company knows about omnidirectional speaker technology, addressing shortcomings of the past and pushing through previous limits with their Omniguide approach. It’s built extremely well, and beautifully styled to make a visual statement commensurate with its performance. The fact that Mirage offers all this for only $7500/pair is as impressive as the speaker itself. The OM Design OMD-28 is a first-rate loudspeaker in every respect, and one of the best bargains in high-end audio today.

…Doug Schneider
das@soundstageav.com

Mirage OM Design OMD-28 Loudspeakers
Price: $7500 USD per pair.
Warranty: Five years parts and labor.

Mirage Speakers
3641 McNicoll Avenue
Toronto, Ontario M1X 1G5
Canada
Phone: (416) 321-1800
Fax: (416) 321-1500

Website: www.miragespeakers.com

 


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