Magnepan Magneplanar MGIIIA loudspeaker

Anthony H. Cordesman & Martin Colloms, April, 1986

I must confess to a certain sentimental affection for Magnepan products.  An early version of the Tympani did more to rekindle my interest in audio than any other speaker I can think of.  In a world which seemed doomed to finding out just how small and dull it could make acoustic suspension boxes, the Magnepans reminded me that speakers could produce a large open soundstage, real dynamics, and musical life.

Both box speakers and electrostatics have gotten far better since that time, but Magnepan has continued to steadily improve its planar speakers.  It also has introduced some superb ribbon tweeters, and while some might argue that the Decca ribbon was a serious product in the US, I still feel Magnepan should be given the credit for introducing the first successful US speaker—the MGIII—to use a ribbon tweeter.

The Magnepan MGIII, introduced several years ago, may have been ahead of its time.  Few US reviewers and audiophiles had any real experience with ribbon drivers, and there was a natural tendency to treat them like any other tweeter.  In practice, this often meant too little attention to problems in source material and to the need to readjust cables or VTA/SRA; the MGIII was too revealing of details in the highs.

While the MGIII has since become a relatively popular speaker, many listeners initially found the highs to be too quick and detailed, and reviewers complained about the imbalance between tweeter and midrange.  These complaints were and are legitimate, in part: there is still a slight discontinuity between the ribbon and midrange panel.  Experience with other ribbon speakers like the Apogees confirms the suspicion that ribbon tweeters which measure flat often seem to have too much treble energy.

Magnepan solved some of these problems shortly after the introduction of the MGIII by offering plug-in resistors to slightly attenuate the highs, even though many user and reviewer complaints were not caused by the speaker (see above).  The MGIII’s ribbon tweeter was simply revealing more about the input from recordings and electronics.  Being audiophiles, other users ignored the manufacturer’s instructions (which are about as simple and useful as instructions can get), failing to give the speakers enough space from the rear and side walls to operate properly, or to aim the tweeter ribbons towards the listening area.

These points are worth mentioning because they still apply.  The MGIIIA is not a dramatic change from the MGIII.  In fact, the basic change in the speaker is not acoustic, but stylistic: it is simpler and more attractive.  The new feet for the base and new wooden frame create a speaker that disappears nicely into the room, but retains enough style to be very attractive, joining the Acoustats and Apogees in being close enough to sculpture that most wives can live with it quite nicely.

As to any other improvements in the MGIIIA, I am not sure how much they really affect the sound.  My acoustic memory is scarcely perfect, and I have had a great deal more experience with ribbon speakers since I first encountered the Magnepan IVs and IIIs.  I was able to get significantly better performance out of the IIIAs than the IIIs, however.  Years of fiddling with cables and interconnects, acquisition of tonearms with rapid VTA/SRA adjustment, and added experience with speaker placement all helped—which indicates that new owners are likely to benefit from the kind of dealer who will set up the speaker or come by to check it out and offer advice.

The highs, as before, were superb.  I did end up using the plug-in resistor-fuse assemblies to slightly attenuate the highs, but this is a matter of personal preference; I could easily live without them.

With a really good cartridge and electronics (I used the Clearaudio and Monster Alpha 2 cartridges, the Audio Research SP-11 preamplifier, and the Audio Research D-250 II Servo and Counterpoint SA-4 amplifiers), the upper octaves provided excellent detail and transparency, superb coherence, and outstanding air and sweetness.  Every bit of quality in the front end is mercilessly revealed, but when the “going in” is good, the “coming out” is excellent.



There were very slight problems apparent in the transition from ribbon tweeter to planar midrange.  They were far less apparent than with all but a handful of cone speakers, and compensated for by very wide dispersion, and a midrange sound which was open and live without making the listener feel the usher had just dragged him into the front row.  The overall timbre was excellent, with no change from the midrange up to the limits of my hearing (and that of assorted family females).

Getting the best transition from midrange to bass, and overall bass energy levels, required careful amplifier choice and speaker placement.  A couple hours’ listening and fiddling, however, was enough to set up the MGIIIAs quite well, with good-to-excellent bass and lower midrange performance.  This is not a speaker with deep, powerful bass, and the lower midrange is slightly analytic, but the bass line is well-defined down to about 42Hz, and deep bass energy is surprisingly good.  Anyone looking for good orchestral bass will not be disappointed.  The MGIIIA goes much deeper than the Quad ESL-63, and as deep as most cone speakers.  They just are not rock-digital, cannon-power, or organ loudspeakers.

You also will find that once the Magnepan MGIIIAs are properly placed, they are freer of lower midrange and upper bass resonance than most cone speakers.  The result is a clearer and more realistic lower midrange, and bass which is free of the peaks and valleys that often make powerful bass a curse in real-world listening rooms.  I found this to be particularly rewarding with bass strings, piano, and the lower woodwind notes.  Natural bass is far better than powerful bass if you are really going to listen to music, which is one reason I’d never use this speaker with a subwoofer.

Dynamic coherence—the ability to convincingly reproduce sudden small or large shifts in the volume of music without favoring some instruments over others, or loud passages over low—was very good.  The MGIIIAs definitely benefit from a powerful amplifier, however, particularly one that brings out their lower midrange.  Lower-powered amplifiers are acceptable, but a clean, high-powered amplifier is necessary to really open them up.

The soundstage had excellent, well-defined imaging, an open character, very good height and width, and reasonable depth.  In fact, the soundstage of the Magnepan MGIIIAs compares interestingly with that of the Quad ESL-63s.  The Quads give you a soft midhall perspective, but one that seems a bit rolled off in the highs compared to the Magnepans.  The Quads have a more stable soundstage in terms of listening area or listener movement, but it’s not as detailed.  Both speakers are slightly lacking in the illusion of depth, but not seriously so.  Accordingly, the MGIIIAs held up against one of the best soundstages around.

I did not find that they benefitted from biamplification.  Even with two identical high-quality power amps, I preferred the sound coming from one truly top-quality amp.  Mixing amplifiers for upper and lower frequencies made things worse.  The best coherence and most convincing music came from a single amplifier in every case, with the exception of a few really loud selections.

In summary, the MGIIIAs require a little love and care, but the sum is then as good as the parts.  They offer natural musical life with a wide range of music.  They do not favor one type of voice over another, orchestral music over baroque, or guitar over violin.  You’re never jarred by the feeling that the sound is coming from a small box, or by an unrealistic combination of timbre and apparent hall position.  Like most really good speakers, the Magnepan MGIIIas allow you to ignore the compromises speaker designers must make to produce real-world products.  You can simply sit back and listen to the music.—Anthony H. Cordesman



Martin Colloms wrote about the MGIIIa in January 1987 (Vol.10 No.1):

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.

Sound Quality
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



Sidebar 1: Measurements

Fig.1 is a “snapshot” of the forward axial response, showing some lift up to 16kHz.  The mid-treble is linear and well integrated, while the bass is more or less level to 40Hz, in good proportion with the rest.

Fig.1 Magnepan MGIIIa, response on listening axis.

The response in the listening room (fig.2) was remarkable at first sight, although the upper treble was just too good to be true.  In addition, the moderate prominence at 60-80Hz could ideally have been avoided.  This curve confirms both the inherent neutrality of the IIIa, and its new found extension to 25Hz in-room.

Fig.2 Magnepan MGIIIa, spatially averaged, 1/3-octave response in MC’s listening room.



Sidebar 2: Specifications

Magneplanar MG-IIIa