Magnepan 20.7 Loudspeaker

Unprecedented Full-Range Planar Sound

Equipment report
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Floorstanding
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Magnepan 20.7
Magnepan 20.7 Loudspeaker

Audio reviews today are rife with proclamations that a product sets new standards, is the best the reviewer has ever heard, perhaps the best in the world, and the like. Because so many products are system- and room-dependent, and because so many older products are still so good, I normally would be reluctant to reach such sweeping conclusions. Nevertheless, after living with the Magnepan 20.7s for over three months, I have no choice but to report that, in my opinion, this speaker does indeed set new standards as to the capabilities of a flagship planar transducer.

Most readers of this magazine are familiar with the overall design concept of a planar loudspeaker. Instead of using cones or domes or horns, planars use a very thin diaphragm of some type to reproduce music frequencies. Generally, the larger the panel or panels that are used, the greater the low-frequency extension and bass output of the speaker. Because of the relatively small excursions of most planars, the low frequencies require a lot of panel surface area. Some manufacturers of electrostatic or other planars (such as MartinLogan and Eminent Technology) are often able to use smaller planar panels because they augment the bass with traditional dynamic bass drivers. This works, but sometimes at the expense of continuity between the planar and cone drivers. It’s all in the execution. Unlike electrostatics, Magnepan loudspeakers utilize proprietary ribbon and “quasi-ribbon” magnetic transducers. One of the major advantages of this approach is that the speakers do not need to be plugged into an AC outlet and there are no transformers to alter the sound. In my experience, the Magneplanar designs will generally play at higher sound levels, without breakup, than most electrostatic designs. On the other hand, most listeners would agree that electrostats probably offer the very last word in microscopic detail.

Planar loudspeakers are dipole by nature, in that the rear sound wave of the panels is generally equal to the sound wave at the front of the panels. This equal generation of sound may require somewhat more care in placement of the speaker, but the rewards are a generous soundstage and ambient field that are difficult, if not impossible, to obtain with traditional dynamic speakers, particularly those that are smaller in stature and use a limited number of drivers. Still, I have heard fans and owners state that they prefer the “more direct” sound of dynamic and horn/cone hybrid systems. They are not wrong that these other technologies may provide a more “upfront” sound, which may be somewhat more dramatic on rock and jazz recordings. I too have always enjoyed the music reproduction of good cone and horn loudspeakers, particularly with their very specific instrumental focus, solidity of image, and ultimate bass slam.

Yet, as an owner of Magnepan 20s and 20.1s for over 20 years (that’s a lot of 20s), I can unequivocally state that once set up properly and with the right amplifiers and associated equipment, the large Maggies can do a remarkable and very satisfying job of projection of instruments into the room. If not quite the equal of large cone or horn systems in that regard, they come surprisingly close. Plus, the large Maggies can provide real-sized instruments on an (almost) real-sized stage, something even many or most of the large cone-based systems cannot do. Planars are also known for the high definition of their bass output. But if all planars have had a traditional weakness, it is in the reproduction at higher volumes of midbass and low bass with slam and authority.

Before discussing the specific qualities of the speaker itself, a few words about Magnepan are in order. Founded by legendary designer Jim Winey in 1969, Magnepan is located in Minnesota where all of its products are made. A recent visit to the factory was enlightening in that it revealed the tremendous amount of skilled hand-labor involved in making each speaker. While Magnepan is justifiably proud of the reasonable prices and high value offered by its products, it seems incredible to me that the company can maintain its prices when so many of the steps in building the speakers are done entirely by hand. I tried my own hand at putting together part of a panel—it would have taken me many hours to perform an operation done in a few minutes by Magnepan’s technician. Not surprisingly, they made me no job offer. Although Jim Winey is now retired, he still offers some design input and the company continues a program of improvement to its entire product line. Jim’s son, Mark Winey, and Magnepan’s long-time marketing manager, Wendell Diller, continue to advance the Magnepan flag.

Magnepan understandably strives to emphasize the relative value of its products. Personally, I believe they understate the competitive performance of their flagship loudspeaker compared to dynamic or horn systems at any price, including those in the $80,000 to $150,000 range, or more. Yes, it is that good. The 20.7s may not do everything a speaker in the $100,000+ price range can do, but they come close in many respects and are arguably superior in other important respects. It is a system of trade-offs, often won by the large Maggies if the user is prepared to drive them with appropriate associated equipment and if the user is prepared to accept these relatively large (but thin) monoliths in a position at least four to five feet (more is even better) away from the front wall. The user must also be patient enough to accept a long break-in period, more about which below.

Design Advantages of a Large Dipole Loudspeaker
I am not an engineer (so please bear with me) but I have had so many years of experience with the Magnepan 20 Series that I believe I can state some of its main design advantages with some accuracy. Besides, many of these points are made by Magnepan on its website, and I am not afraid to crib when needed. The 20.7 is approximately 29 inches wide, 79 inches tall, and 2 inches deep. It is a hybrid design utilizing a tall but narrow true ribbon tweeter, a “quasi-ribbon” midrange consisting of a very low mass Mylar diaphragm suspended between rows of magnets on both sides and a larger quasi-ribbon Mylar woofer panel driven by opposing magnets. One of the design successes of the 20.7, compared with earlier versions, is that the integration of the three planar drivers is now totally seamless. The entire speaker seems cut from the same cloth, or at least the same aluminum and Mylar, as the case may be.

The design parameters of the 20.7 offers a number of advantages (and a few disadvantages) when compared to a dynamic or horn system. First, the speaker is not in a box. All drivers are suspended by a sturdy perimeter frame, with an open front and back. No box means no box colorations to the sound. Manufacturers of the more expensive dynamic or horn speaker systems often go to great lengths, and great expense, to make as rigid and acoustically “invisible” an enclosure as possible. Their goal is to eliminate box-related colorations, which are automatically eliminated in Magnepan’s boxless designs. No box means no box resonances to control, or colorations to eliminate. I think it is fair to say that a lot of the substantial additional cost of competing loudspeakers is devoted to the design and construction of the enclosure. Indeed, if Magnepan were required to build box enclosures to the same quality level as Rockport, Wilson, or Magico, as a few examples only, the 20.7s undoubtedly would offer far less of a price advantage when compared with those speakers. I believe this is an important concept to keep in mind. It is not that Magnepan set out to build a “cheaper” loudspeaker. Instead, it is because its planar design does not require the construction of a very expensive box enclosure that it enjoys the design advantage of being able to offer competitive (or superior) sound at a much lower price.

Another major advantage of the Magnepans, and all planars, is the low mass of its drivers. It is obvious that the lower the mass of the driver, the more quickly it can respond to electrical input. The signature Magnepan true-ribbon tweeter is an ultra-thin aluminum foil approximately five feet long by ¼-inch wide. The Magnepan website points out that it is 1/10th the thickness of a human hair. Hence, it is extremely low mass and responds accurately to even the smallest of signals. I have listened to and admired a huge variety of tweeters through the years, but I still believe this ribbon tweeter to be one of the finest made today. I have not heard a smoother or more extended high-frequency transducer. The quasi-ribbon midrange and bass drivers, while not of the vanishingly low mass of the true ribbon, are still of a very low mass design. Very thin aluminum strips are bonded to thin Mylar panels, which in turn are tightly stretched between the perimeter frame and suspended between carefully spaced rows of bar magnets. The musical electrical signal passes through the thin aluminum strips, which in turn moves the Mylar panel as it is attracted to or repelled by the magnets. While I was at the factory I observed that proprietary devices are carefully attached to the panels to minimize resonance. These ribbon and quasi-ribbon drivers are of much lower mass than competitive dynamic drivers.

Another design advantage of the 20.7s is their ability to offer a more uniform output of sound energy throughout the room, often called “power response.” Magnepan states, and I have read concurring technical articles, that a dipole’s bidirectional radiation pattern contributes to a power response flatter throughout the listening room than a front-firing dynamic speaker. These authors indicate that the taller the line source, the better the power response. With this in mind, Magnepan states it would offer floor-to-ceiling speakers if it believed its customers would buy them. Further, the 20.7s dispersion characteristics produce a more-enveloping sound field, like real music in a concert hall, and often minimize adverse interactions between listening room and loudspeaker. Even though one-half of the sound is radiated rearward, the direct sound from the front of the speaker reaches the listener first and allows for excellent imaging, although in my experience well-designed dynamic and horn systems may offer even superior imaging. That is one of the tradeoffs with a dipole transducer. The reflected sound and life-size instruments allow more of a “you are there” immersion in the sound, a feeling of being there, at a slight expense of imaging precision. Yet I have never heard super-precise imaging in the concert hall, so this point has never been an issue for me. Opinions vary. In my listening room I have slightly reduced the amount of midrange and treble energy reflected off of the front and side walls by “upholstering” parts of the walls in a thin layer of cotton batting, covered with a silk cloth in a neutral color. One cannot tell they are covered without actually touching the walls. It seems to me that the net effect has been to make my 25' long by 16' wide by 8' high room, reflection-wise, slightly larger than it is.

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