Magnepan Magneplanar MGIIIA loudspeaker Martin Colloms January 1987
Panel speakers are back in fashion. After years of determined effort on the part of a few established manufacturers, the number of these designs has seen a marked increase, and many new exotic models have appeared. Stereophile has recently reviewed two leading examples of the genre, the $2780/pair Apogee Duetta and the $2490/pair Martin-Logan CLS, (both reviewed in Vol.9 No.7). To judge by the tone of letters arriving at the magazine's offices, those reviews generated heated controversy. John Atkinson asked me, therefore, to conduct an in-depth examination of the two models, to give a fuller picture of what these speakers are capable of. Lurking in the wings, and at present perhaps unfairly overshadowed, is the $1995/pair Magneplanar MGIII in its latest ("a") form; I decided to include it in the review, its influence being too great to ignore.
While the Duettas and the Logans position themselves at the extremes of technology and specific performance, the Magneplanar emerged as the classic, balanced, middle-of-the-road contender.
The well-established Magneplanar MGIIIa, based on a proprietary drive-unit in which a wire-conductor array is bonded to a plastic-film diaphragm, is probably the most durable of the three designs under test. The exposed diaphragms are at the rear, behind the magnet array; they are also sufficiently resilient to resist minor impacts. Magnepan's true ribbon tweeter is also well guarded. The fact that the MGIIIa is a three-way design has given its designer more freedom to balance its frequency response; it is arguably more successful in this particular respect than the two other models.
Other advantages of the MGIIIa include a truly extended, wide-directivity high end, plus a respectable 86dB/W sensitivity and well-damped film diaphragms, achieved via a lossy coating and the use of a special adhesive for the wire conductor bondings. Acoustically speaking, the bass and mid sections are not as transparent and unobstructed as the Logan or the mid-treble section of the Duetta.
This revised speaker was given the full review treatment by AHC in Vol.9 No.4, but for the sake of completeness, here are my brief notes on its sound. The treble was pleasantly pure, and very extended, directing a wide spread of "air" and "sparkle" into the room; a little too much so, in fact, for my tastes. The good treble added a sense of upper-range speed and delicacy that was somewhat lacking in both the Duetta and CLS. The MGIIIa mid has been improved, now sounding faster and more open, and setting a genuinely good standard. The overall tonal balance was close to neutrality and did not draw much dissension from me. Certainly the mid was not as pure or transparent as either the Duetta or CLS, but was no slouch for all that. The bass came midway between the two main contenders; at least it was present in better proportion, with pretty good extension, if not to Apogee standard. The MGIIIa was more tactile and articulate in the bass than the original MGIII, and in this respect, at least, has the CLS beat. Its bass was also of respectable uniformity.
It proved easy to drive, and handled high input power levels gracefully, never sounding strained. Even when the bass was deliberately overloaded with over 100W at 50Hz, no bangs occurred—just a gentle "blurring" of the bass tone.
For the record, the Quad ESL-63, while not able to play rock bass to the same level of any of these three speakers, was, in fact, the best as regards tonal balance and low-frequency uniformity. It was also consistently neutral to a wide range of sources.
The well-established Magneplanar MGIIIa has not suffered too greatly in these comparisons. Of eminently reasonable sensitivity, easy to drive, and possessing an essentially neutral tonal balance, it also has a notably wide frequency response, which survived well in my 20'-long, 80m3 room. In no way can it be dismissed as "old technology." Admittedly, the Maggie's mid did not reach the peak of the Duetta or the CLS but it was nonetheless good. In the long term, its overall engineering integrity told in its favor, to which must be added the ease of amplifier rating matching.—Martin Colloms