Esoteric MG-20 loudspeaker
As I reported in my live coverage of RMAF 2007, spurred on by the performance of Esoteric's SA-60 universal player, a photo of which had graced the cover of our October 2007 issue, I had entered the room to give a listen to the company's new digital components. But my attention was drawn to two pairs of elegant loudspeakers sporting the Esoteric name: the MG-20 floorstander and MG-10 bookshelf models. The tweeters and woofers of both speakers have diaphragms formed from magnesium, a very light metal said to have an optimal combination of stiffness and self-damping, to make possible near-perfect pistonic behavior. Other than in alloys, I was told, magnesium had not previously been used in speakers because it rapidly oxidizes when exposed to air. However, Esoteric collaborated with a British company to develop an effective two-layer coating that keeps the metal in pristine condition.
The sound of the system had an addictive clarity, so I asked Esoteric's Mark Gurvey to put me down for review samples of the MG-20.
The Esoteric MG-20 is a slim, elegant tower almost 42" tall, and the front baffle of its trapezoidal cabinet is slightly wider than the rear. That front baffle is 30mm thick, and the rest of the cabinet is constructed from 15mm-thick birch ply, veneered on all surfaces (including internally) with American cherrywood. Solid American cherry is also used for the side rails flanking the baffle; in combination with the extensive internal bracing, this gives the speaker cabinet an inert feel. The enclosure is filled with long-hair wool, but, peculiarly, the lower third of the enclosure seems to be sealed off from the chamber that loads the woofers. Under the lower woofer is a flared, spirally grooved port 1.5" in diameter and 3.5" deep. Though the port tube is made of plastic, its outer surface is damped and reinforced with foam rubber.
The stars of the show, of course, are the magnesium-diaphragm drive-units. Two 6.5" woofers are used, one above and one below a 1" tweeter. The woofer is constructed on a diecast frame, its magnesium cone terminated with a substantial half-roll rubber surround. Pressed into the cone is a concentric ring to control its breakup behavior, and the dustcap is also made of magnesium. Special attention has been paid to linearizing the magnetic drive system. The tweeter also has a small half-roll surround, and uses a neodymium magnet and an aluminum voice-coil. The dome is slightly recessed into the shallow, flared front plate, and the rear of the diaphragm is loaded with a damped rear chamber. All three drive-units are rabbeted into the baffle and secured with Torx-head screws.
The MG-20's hardwired crossover comprises two inductors (one air-cored, the other with a core of iron laminate), two resistors, and four high-quality polypropylene-dielectric capacitors. (ICW Clarity capacitors are specified, though the caps I could see were marked "Bennic," a respected Taiwanese brand.) All components are hot-glued to a circuit board mounted on the inner surface of the terminal panel. This panel has five binding posts: one pair each for the tweeter and woofers, and a fifth that grounds the amplifier's output to the drive-unit chassis. Because I mainly used bridged amplification, I didn't connect this terminal, but doing so with conventional amplifiers is said to reduce the noise floor by shielding the voice-coils from RFI. The internal wiring is specified as being silver-plated copper from van den Hul, though this is of relatively narrow gauge.
The drive-units were designed by Esoteric's engineering department and are made in Japan by the Nippon Kinzoku company. The speakers are assembled by Tannoy in Scotland, under the watchful eye of Tannoy's veteran technical director, Alex Garner. While this manufacturing process is of undoubted high quality, in these days of the diminished US dollar, it inevitably makes the MG-20 quite expensive for a modest-looking, if beautifully finished, two-way tower: $9000/pair.
Though the MG-20 can be used standing directly on the floor, Esoteric offers an optional base plate, the STD-MG20. This comprises a rectangular sheet of aluminum 15mm (0.6") thick that bolts to the base of the speaker. On the base's underside are three self-leveling feet of stainless steel. These are complex, with an internal spike that couples to a captured circular steel bottom plate. While effective and elegant, these base plates are undoubtedly expensive at $1500/pair. Again, I suspect the dollar is to blame.
The MG-20s were used on their optional STD-MG20 stands. The speaker's grille consists of black cloth stretched over a fiberboard frame. I left them off. I single-wired the MG-20s with AudioQuest Kilimanjaro DBS cable, using the Esoteric-supplied jumpers to connect the two pairs of terminals. (Esoteric's informative handbook recommends that, for single wiring, the amplifier be connected to the tweeter binding posts for best sound quality.) Esoteric recommends toeing in the MG-20s so that the tweeter axes cross in front of the listener, but I felt this diminished the sense of top-octave air. I aimed the tweeters at my listening seat and, as usual, experimented with room placement to get the optimal transition between the upper bass and lower midrange. Pink noise revealed that the Esoteric was relatively tolerant of listening axis: my listening chair placed my ears about 3" above the tweeters, but slouching didn't appreciably change the tonal balance.
Although my review samples had been used at audio shows, Esoteric's Mark Gurvey warned me that they'd need further break-in. Accordingly, he sent me the Isotek Full System Enhancer & Rejuvenation Disc, which he feels cuts total break-in time by almost two-thirds. "Make sure you run the full side repeat to finish the demag sequences," he instructed. "Run the full 110 minutes each time, or just do a side repeat over and over for 24 hours at a time. Then repeat daily until you hear the desired result." That's what I did. The combination of random noise and randomly occurring low-frequency blips and blops in the disc's first 10 minutes also had a curiously relaxing effect on me, though the subsequent jet-engine noises and chirps disturbed my newfound equanimity.
The sound was a little on the lightweight side at first, but after several treatments with the Isotek CD, the lower frequencies were more usefully fleshed out. Even so, the MG-20 will never be a bass-head favoritethe 1/3-octave warble tones on Editor's Choice (CD, Stereophile STPH016-2) audibly rolled off below 50Hz. But once the Esoterics were broken in, the bass content they did reproduce was perhaps the best-defined I have heard in my Brooklyn room. The upper-bass region was beautifully clearmy Fender bass guitar on Editor's Choice spoke with a clarity that I had been used to hearing only from the direct-injected instrument through Stax Lambda headphones. Jerome Harris's Taylor acoustic bass guitar on Duke Ellington's "The Mooche," on the same CD, was a little light in weight overall, but was again reproduced with wonderful clarity and evenness, and clearly spoke in a single voice across its range.
When, in 1998, I mixed the Jerome Harris Quintet's Rendezvous (CD, Stereophile STPH013-2), from which "The Mooche" is taken, I was monitoring on Revel Ultima Gem loudspeakers, reinforced with a Revel Sub-15 subwoofer, and checking what I was doing with my long-term references, the B&W Silver Signatures. With the generous upper-bass region featured by both of those speakers in my Santa Fe listening room, I was concerned that some listeners would find the bass guitar's level in the mix a little low. Yet when I then boosted that level, it filled in too much of the space between the drums, vibes, and horns. So I left the bass guitar's level a little lower than some might wish. Reproduced by the Esoterics, this wasn't a problem; the soft-toned instrument was superbly delineated in both space and tonal quality, and easily distinguished from the sounds of Billy Drummond's kick drum and tom toms.
Did I say that the MG-20's bass was lightweight? It actually seemed rather chameleon-like. Dave Holland's acoustic bass on Joni Mitchell's "Edith and the Kingpin," from Herbie Hancock's River: The Joni Letters (CD, Verve B0010063-02), was reproduced with a satisfyingly deep purr, and the electric instrument on The Blue Nile's seminal "A Walk Across the Rooftops," from the CD of that title (Virgin/Linn 7502-15087-2), had goodly grunt. Only recordings with true deep-bass content, such as Michael Murray performing organ works by J.S. Bach (CD, Telarc CD-80088), revealed the limits of the Esoteric's LF reach.
The MG-20's midrange sounded uncolored and natural. Classical piano recordings, such as Robert Silverman's performance of the two Rachmaninoff sonatas (CD, Stereophile STPH019-2), had a delightful combination of definition and clarity, not only in the left-hand register but across the frequency range. The highs were superbly clean and free of grain.
Dynamics were restricted, not so much by overload of the relatively small woofers at lower frequencies, but by a touch of "bite" developing in the low treble. This was at levels approaching 100dB in my room; the MG-20 will have no problem delivering sufficient loudness in rooms of normal size.
Stereo imaging was stable, with aural objects precisely positioned in space. Most times this benefited the music, but sometimes I was brought up short by what the speakers were revealingfor example, the perverse, 20'-wide piano on Herbie Hancock's River. But it's better that speakers accurately present what the producer has decided to put on the disc rather than to smear it all over. And perhaps I shouldn't criticize River on these grounds; after all, when I mixed Attention Screen's Live at Merkin Hall CD (Stereophile STPH018-2), I made a similar decision to spread Mark Flynn's drums across the entire stage.