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Those Maggies make my heart sing

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology
 

Simple gray rule


Those Maggies make my heart sing
 

By Al Fasoldt

Copyright © 1986, The Syracuse Newspapers

It is easy to create the sounds of music and speech. All you need is a piece of paper rolled diagonally into a cone. Stick a coil of wire at the small end of the cone, hold the other end in some kind of support, and as soon as you send some AC current through the coil you will have a working loudspeaker. Of course, bass drums and violins and 4-year-olds reciting poems don't make sounds the same way. They form them in what you might call a natural manner, and that is one of the main reasons most loudspeakers don't sound quite as realistic as we'd like them to. When the cone of the speaker goes back and forth, it often adds its own signature" to the sound. This comes from the material used to make the cone.

A further problem comes from the size of most loudspeaker cones. In order to make loud sounds, they must pump their cones back and forth over a distance of an inch or two. This can cause Doppler distortion, in which the sound changes pitch as the object that is sending out sound waves changes speed relative to the listener. (This is why sirens rise in pitch and then suddenly fall when an ambulance speeds past us.)

Are we stuck with such a state of audio affairs? Not to Jim Winey and his band of devoted customers. He is the designer of some of the most successful flat-panel speakers ever made, and he would be delighted if the only cones anyone ever saw were holding up scoops of ice cream. Winey's company is Magnepan, of White Bear Lake, Minn.

For years, Magnepan has been manufacturing expensive loudspeakers that use thin, flat membranes to create sound. These speakers, called Magneplanars, are so tall and thin that they look like room-divider screens. Magneplanars which everyone in the hi-fi business fondly calls "Maggies" - work by using the electric signal to vibrate a diaphragm rather than a cone. The diaphragm doesn't cause any noticeable Doppler distortion, because it doesn't move back and forth very far. (You can barely see the diaphragm vibrating when it is playing.)

How then can it play very loud? By using the principle of equivalent force. You can get the same sound volume by doing a lot of pushing against a small amount of air, as with a cone speaker, or by doing a small amount of pushing against a large amount of air, as with Winey's Magneplanars. Other speakers on the market use a similar method, but Magneplanars are the only American-made flat-panel speakers in wide distribution.

Unfortunately for music lovers with tastes bigger than their bank accounts, Magneplanars have been the proper playthings of the rich and famous, having a typical price per pair of $2,000 or more. These megabuck models are still in the line, but Magnepan is finding an entirely new market among non-wealthy sound lovers with its model SMGa speakers, which sell for $535 a pair. Magnepan sent a pair of SMGa's for review.

Except for wooden runners on each side, the SMGa speakers are entirely covered by an off-white cloth. They are 19 inches wide and 48 inches high. The screens themselves are less than an inch thick. Bench tests showed that the SMGa speakers had the type of sound typical of dipole sound radiators speakers that project equally well to the front and rear, but not to the sides. They were bass-shy in the region of organ pedal notes, but otherwise tested out with a remarkably smooth frequency range.

But it was in the listening that the little "Maggies" really stood out. Nearly every type of sound was reproduced with a clarity uncommon even in loudspeakers twice or three times the price of the SMGa's. Response to ultra-brief start-and-stop sounds was especially good, and string instruments, the bane of many speakers, took on a natural sheen that I have heard few other times.

However, these listening results came at a small penalty. The Magneplanars sounded good only when they were toed in slightly toward my listening chair, and I found that turning my head a few inches to one side or the other sometimes made the sound seem muffled. This beaming of high frequencies seemed a relatively minor inconvenience most of the time. Magneplanars are sold only at specialist retailers.

If you cannot find a store near you that sells them, write to Magnepan, 1645 9th Street, White Bear Lake, MN 55110.


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