Ayre Acoustics • MX-R Mono Amplifiers

by Marc Mickelson | November 30, 2010

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You know you've listened to a lot of audio gear when you begin to create personal lists of the best speakers, CD players, turntables, and so on that you've heard. Such codifying is a natural exercise, and a fruitful one. It reminds us what we value most about listening to music reproduced at the highest level. It also helps set the standards by which new products will be evaluated.

Of the personal lists I've made, the one for amplifiers is easily the most interesting. It seems to lack a unifying principle other than that it collects the amps that have most impressed me. On that list are single-ended (the mighty and expensive Lamm ML3s) and push-pull tubes (the Convergent Audio Technology JL2 Signature Mk 2), a high-power output-transformerless design (the last version of the Atma-Sphere MA-2 mono amps I heard) and a high-power solid-state (the massive Luxman B-1000f monoblocks). That these amps sound different should come as no surprise. Collectively, they are a lesson in the immutable law that no amp -- indeed, no audio product -- does everything better than all others. They also illustrate how many different paths there are to producing sound that can be called both realistic and extraordinary.

Even with the diversity of my amplifier best-of list in mind, the Ayre MX-R monoblocks are distinct. The solid-state MX-Rs are neither class-A power hogs nor class-D powerhouses. Their diminutive size will have some thinking that they must utilize puny readymade amplifier modules, perhaps in concert with a switch-mode power supply, neither of which is the case. Instead, the 300-watt MX-Rs are the manifestations of some creative answers to the question of how to create the ideal amplifying device -- the same question that the people at Lamm, CAT, Atma-Sphere and Luxman have attempted to answer in wholly different ways.

Of immediate notice is the chassis -- its overall compactness and longer-than-wide orientation. The MX-R chassis (and that of the matching KX-R preamp) is machined from a billet of aluminum. Its petite size was, first of all, a way to keep costs down, but that created a problem of space -- there simply was no room for banks of vertical heatsinks. Then Charles Hansen of Ayre made a discovery: "I had always assumed that heatsink fins needed to be vertical, as on all of our other amps. But then I found an article that said (assuming certain rules were followed) you only lost about 10% of the cooling efficiency with a horizontal orientation." Thus, the chassis became the amplifier's primary cooling mechanism, the heatsinks running horizontally along the top. This certainly didn't harm the way the amps look. The MX-Rs would be right at home on a shelf at Tiffany's, their gleaming casework drawing admiring stares and curious touches. I had seen the amps only in silver until the review pair arrived. The satiny black may, in fact, be more lovely. The amps' size belies their weight. Each MX-R weighs over 50 pounds and feels like a solid mass.

The tight space inside the chassis became another design challenge. "For months Ariel (our other engineer) and I would sweat bullets trying to gain 1/16" here and 1/32" there," Charles said. Again, some clever thinking was essential. For example, the MX-R's two transformers -- one that supplies the positive voltage and one that supplies the negative -- provide no performance advantage. "We were just trying to fit ten pounds of stuff into a five-pound bag," Charles admitted, and using two smaller transformers in the place of a single larger one was a matter of necessity. The transformers clear the top and bottom of the chassis by a mere 1/32".

The MX-Rs follow Ayre's well-known design ideals -- a fully balanced circuit with zero feedback and great care paid to the power supply -- and add some new wrinkles in terms of parts. Whereas the company's previous top amplifier, the V-1xe, had a JFET input stage with MOSFETs for the rest of the circuit, the MX-R has a similar JFET input, but the rest of the amplifier uses bipolar transistors, which lower the amp's output impedance and improve its ability to drive tough loads. The ON Semiconductor ThermalTrak output devices have a heat-sensing diode within each transistor. This eliminates the lag between the time during which the device heats up or cools down and the time the bias circuit compensates for the change. The bias is, therefore, in Charles Hansen's words, "significantly more stable," including while music is playing.

More bits 'n' bobs. The circuit boards use a substrate that is twenty times more costly than that used for other Ayre products, and the transformers are decoupled from the chassis with a special foam that retains its loft -- and isolating properties -- permanently. Input is via XLR only, although Ayre sells adapters if you must use the amps with a single-ended-only preamp. The speaker binding posts are the clever ones from Cardas that use a single knob for tightening both the positive and negative connections. I like them. You can torque down on the spade lugs (or bare wire) with little effort.

The only feature on the clean front panel is the combination indicator LED and standby/on pushbutton. The LED changes color depending on the amp's operating status. After one of the amps shut down, the result of a hiccup from a tube in my preamp, I discovered that one of the color options for the LED was violet. A few minutes later -- and with no fuses to change -- the amp was up and running again. I've never experienced a more elegant shutdown from a power amp.

Extreme Ayre

Ayre warns of a break-in period for the MX-Rs that's "100 to 500 hours" long. Fortunately, the amps I received were well-used demonstrators, and this may account for the immediate impression they made. The MX-Rs were preternaturally quiet and spacious-sounding from the very start. Each recording was utterly individual, as if it had been somehow remastered in a way that didn't just reduce noise but eliminated it, leaving nothing but the music and the sonic signature of the venue in its wake.

Impressed and delightfully perplexed with what I was hearing from those first few recordings, I listened for a few more hours, and then a few more days, pulling out familiar CDs and LPs just to experience them in what seemed like a new realm of reproduction. Dimensionality dominated in both the spatial and interstitial senses. Insight into the size of the venue was equaled by the way the amps separated instrumental lines and delineated the music from the atmosphere around it. There was a deep-space-like quietude, every note emerging from a place that seemed previously unreachable, and air was in abundance.

The MX-Rs came in especially handy as I was compiling my CES demo CD-R -- picking tracks that will help me understand not only what a system is about, but also what heights it can reach. The guitars on "Pretty Bird" from Jenny Lewis's Acid Tongue CD [Warner Bros. 508668] were rife with slashing intensity, but even more impressive were a pair of bonus tracks on the Rhino CD reissue of Elvis Costello's My Aim is True [Rhino R2 74285]. Among the half-dozen tracks labeled "Honky Tonk demo" are early versions of "Mystery Dance" and "Blame it on Cain," whose loose feel comes not only from the stripped-down arrangements but from the odd use of stereo. Costello sings discretely in the left channel, while he plays guitar in the right. What makes these cuts demos is their live-mike-feed immediacy. They were astonishingly direct with the MX-Rs, the silence between the channels casting an almost eerie presence.

In tandem with this ability to reveal the qualities of recordings was unequaled transient fidelity. By this I mean that the MX-Rs propelled drum strikes and cymbal flourishes with catapulting speed and snap but without crispy highlighting or edgy exaggeration. In this way, they were tube-like in the very best sense. They energized the ancient blues of David Johansen and the Harry Smiths' CD Shaker [Chesky JD236], which has wondrously spacious sound, as most Chesky recordings do. However, the music doesn't sound distant or lack force, at least when played on a full-range system that can do it justice. It's a CD with SACD's fine-lined resolution, and with the MX-Rs, turning up the music past the point of good sense brought on a more impactful version of what's heard at lower levels, with no grittiness nor hardening. Sharply plucked strings and drum thwacks displayed great speed in their attack, along with decay that trailed off not into the noise floor, but oblivion. Interestingly, while the MX-Rs are very powerful amps, they never sounded that way. Some multi-hundred-watt amps put their power forward, imparting a uniform forcefulness on the music. The MX-Rs possess too much refinement and grace for this to happen, although they can certainly thunder when the music demands.

These are 300-watt amps without a point past which you will regret pushing the music, and because of their inherent noiselessness, they are just as satisfying at low levels. This, as you may have already surmised, means the MX-Rs have an especially wide dynamic envelope that, when coupled with the space they can portray, gives them a special way with orchestral music. A few years ago, I was lucky enough to find at a garage sale one of the most iconic RCA Living Stereo LPs ever produced: Arthur Fiedler and the Boston Pops playing Gaîté Parisienne [RCA LSC-1817]. The copy I bought for 25 cents has a needle drag across the first side, which may have scared others off. After cleaning, however, the record plays beautifully, with no audible aftermath from that scratch. This was one of the first LPs I played with the MX-Rs in my system, as I wanted to hear the vaunted Living Stereo soundstage through amps that were absolute champs in this regard. Yet, it was the dynamic range of this over-50-year-old recording that was most impressive (along with the string tone, the orchestra's scale, the overall vividness of the performers, etc., etc.), the music building from a point of near inaudibility to Offenbach's famous crashing climax.

Thus, if a recording sounds lackluster or downright nasty, the MX-Rs will not be to blame. Tonally, they're evenhanded and a touch sweet in the treble, offering high-frequency extension and timbral realism without a sonic penalty to pay. So many of the amps that are notably quiet and portray space especially well also have a treble region that runs the gamut from clinical to unforgiving. The treble of the MX-Rs is again reminiscent of tubes, giving the music glints of color where they reside, putting the amps on a different tonal plane from much of their competition. They revealed the truly sophisticated treble of my Dynavector XV-1s stereo and mono cartridges all the better. Miles Davis's muted trumpet on six-eye mono [Columbia CL 1274] and stereo [Columbia CS 8085] copies of Porgy and Bess never sounded more extended and pure, nor have the differences between the two LPs been more obvious. While the stereo spread gives this music an enhanced sense of stature, I prefer the directness of mono. My Audio Research Reference Phono 2 phono stage has a curve specifically for non-RIAA Columbia LPs, and it is especially effective with Porgy and Bess. The MX-Rs made its effect plain.

The bass of the MX-Rs doesn't have the extreme weight and slam of some solid-state bruisers, trading ostentation for a more natural rendering of the lowest frequencies. Jenny Lewis's Acid Tongue has some growling low frequencies that the MX-Rs portrayed with their unique energy intact, if not with the heft and crushing power that an amp like the Luxman B-1000f can muster. Yet, I'm not sure the MX-Rs would be improved if their bass were equal to that of the Luxman amps. Putting aside the issue of integration with the rest of the sonic spectrum, there is the matter of the amps' overall voicing and what added prominence in the low frequencies would do to that. Voicing is a matter of quality -- the combination of individual traits that make up a sonic personality -- and I would worry how bass in seemingly greater quantity would affect the delicate balance the MX-Rs have. I suppose this is a roundabout way of saying I'd change nothing about these amps.

MX-R vs. M1.2

Putting aside the difference in physical footprint between the Ayre MX-Rs and my Lamm M1.2 Reference monoblocks ($22,290/pair) -- the pair of MX-Rs could probably fit within the chassis of a single M1.2 -- the amps' circuits share little in common. The M1.2s are hybrids, mating a tubed input stage that features a single 6922 to a solid-state output stage. The M1.2s are said to deliver all of their power in class A; a switch on the back panel adjusts the supply voltage and idle current of the output stage, ensuring that the M1.2 Reference is able to provide its full output of 110 watts into any speaker load. Due to this, power consumption is high: over 300 watts for each amp. In contrast, the Ayre MX-Rs output nearly three times the power while consuming less than one-third the AC.

"In contrast" is also the phrase that comes immediately to mind when considering the sound of the Lamm and Ayre amps. The sound of the M1.2s is more about tonal saturation and image solidity than the Ayre amps, delivering a denser and duskier view of the music. I've never thought that the Lamm amps sounded intrinsically dark; in fact, I think their tonal balance is just right, imparting a natural weight to music that competing products, including many that are thought to be exceedingly neutral, don't equal. There is no question that the MX-Rs sound lighter and less corporeal than the Lamm amps, but their ability to convey tonal shading, along with that touch of sweetness in the treble, ensure that they never become bleached or lean. Both amps sound natural -- supple, lithe and graceful both tonally and harmonically -- but they arrive there through different means.

There is no question that the Ayre amps portray the space in which a recording was made with greater insight -- width, depth and even height -- than the Lamm amps, which subordinate space to imaging presence. Keith Richards' Main Offender CD [Virgin V2-86499], which I've mentioned in many of my reviews, makes this distinction obvious. The Lamm amps emphasized the quick impact of the drum strikes and throbs of the kick drum on "Words of Wonder," while the Ayre amps, ceding nothing in terms of speed or impact, gave a much more realized view of the space around and between the musicians. This also translated into greater understanding of image placement and its relationship to the truly panoramic spread of the soundscape.

In important ways, this music, which sounds best played loud, demands the dense energy of the Lamm amps, and yet the Ayre MX-Rs never disappointed. The choice between the two really comes down to what you're after: a more compelling portrayal of the music in your room, or greater insight into each recording. Even so, neither amp emphasizes its strengths to point of creating equal and opposite weaknesses. The M1.2s do reveal the qualities of the recording venue, and the MX-Rs do deliver the solidity that's one of the Main Offender's charms.

These are both stellar amps that offer divergent but valid views of the music. However, the MX-Rs' portrayal of space and their way with transients are truly special. I've owned the M1.2s for over four years, and I used various Lamm amps as references before them. I've felt at ease with all of them, as they have always sounded immediately right. If I owned M1.2s and MX-Rs, I'd surely use both. However, I wouldn't be surprised if the Ayre amps spent the bulk of the time in my system, and that's not something that would happen with many amps.

The accidental audio review

There's one bit of information about this review that I haven't yet mentioned: I didn't set out to write about the MX-Rs at all. I was supposed to receive Ayre's new DX-5 Blu-ray player for review, and the people at Ayre wanted me to hear it in the best possible context, so they shipped the MX-Rs and a KX-R to use with it. Well, the DX-5 was held up for months -- Ayre was selling more of them than they could make -- so I got to know the MX-Rs instead. And after a week of close listening, I knew I had to write about them -- even though they had been covered extensively already, even though my queue of review products was turning into a backlog.

So in the case of the Ayre MX-Rs, I didn't choose the subject -- it chose me. The MX-Rs' combination of unrivaled transient fidelity, acute rendering of space, extreme quietness, and treble sweetness made for sound that was truly compelling -- the kind that will urge you to rediscover your music collection. While the MX-Rs aren't physically massive, as some competing amps are, their jewel-like finish is more eye-catching than mere bulk, and their small size means they can be tucked out of sight if you're going for a minimalist aesthetic with your audio system. More than most audio components, the MX-Rs give the impression of heirloom quality. They convey uncompromising care and know-how in their design, their manufacture and especially their performance.

Which brings me back to where this review began. Do the MX-Rs make my best-of-the-best amplifier list? Oh, yeah. With ease.

Price: $18,500 per pair.
Warranty: Five years parts and labor.

Ayre Acoustics
2300-B Central Ave.
Boulder, Colorado 80301
(303) 442-7300
www.ayre.com

Associated Equipment

Analog: TW-Acustic Raven AC and VPI Classic turntables, Graham B-44 Phantom Series II and Tri-Planar Mk VII UII tonearms, Dynavector XV-1s (stereo and mono) and Audio-Technica AT33EV cartridges, AudioQuest LeoPard phono cable, Lamm LP2 Deluxe and Audio Research Reference Phono 2 phono stages.

Digital: Audio Research Reference CD8 CD player, Ayre Acoustics C-5xeMP universal player.

Preamplifiers: Allnic Audio L-3000, Audio Research Reference 5, Ayre Acoustics KX-R.

Power amplifiers: Audio Research Reference 110 stereo amp, Lamm Industries M1.2 Reference monoblocks.

Loudspeakers: Tidal Contriva Diacera SE, Thiel Audio CS3.7, Wilson Audio Sophia 3.

Interconnects: AudioQuest William E. Low Signature, Shunyata Research Aeros Aurora-IC.

Speaker cables: AudioQuest William E. Low Signature, Shunyata Research Aeros Aurora-SP.

Power conditioners: Essential Sound Products The Essence Reference, Shunyata Research Hydra V-Ray Version II.

Power cords: Essential Sound Products The Essence Reference, Shunyata Research CX-series (various).

Equipment rack and platforms: Silent Running Audio Craz² 8 equipment rack and Ohio Class XL Plus² platforms (under Lamm M1.2 amps), Harmonic Resolution Systems M3 isolation bases under digital gear.

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