MartinLogan Floor Standing Speakers
MartinLogan is an American speaker manufacturer (although its main factory is in Canada) long known for its hybrid electrostatic/cone loudspeakers. Readers will remember that several months ago this reviewer wrote about the company’s bookshelf Motion™ 4i speakers. The Motion series is a departure from MartinLogan’s traditional offerings in that this line of speakers does not utilize electrostatic drivers. Instead, the Motion series is a cone-based speaker system that employs Oskar Heil’s “Air Motion Transformer” (AMT) technology for it’s high-frequency driver unit. The AMT differs from conventional tweeters in that instead of using a piston-like diaphragm the way most magnetic tweeters operate, this technology works similarly to the way an accordion functions. In an accordion, when one squeezes the bellows together the space between the pleats goes away. When one pulls the bellows back apart, those spaces re-appear. If you place your hand close to the accordion’s bellows while someone is playing it, you will feel a rush of air as the accordion is squeezed together. The compressing pleats push air out from between the pleats as that space is eliminated by the compression. Of course, the same thing is occurring inside the bellows as well and that out-rush of air is what powers the instrument and vibrates the various reeds to play the notes.
The AMT works on that principle. The diaphragm in the tweeter consists of a pleated Polyamide sheet arranged so that the pleated area is facing the listener. The electromagnetic “motor” is arranged so that instead of moving a disc-shaped diaphragm in and out like a normal speaker driver, this one squeezes the pleats in a manner that is perpendicular (rather than parallel to) the desired air displacement. When the pleats are squeezed together, on one half of their cycle, they compress the air between each fold, displacing it and when the pleats expand again, on the other half of the cycle, they rarefy the air as it rushes in to refill the voids between each fold. When they do that at an audio rate, sound is produced. Dr. Heil invented this concept in the early 1970’s and applied it a line of speakers built by the firm of ESS in South El Monte, California. While ESS still makes speakers employing this technology (down to around 800 Hz), the patents have expired and many companies now build variations on this theme. Searching on the Parts Express web-site, I see that they carry a number of AMT tweeters ranging in price from about US$20 each to US$120 each. Judging by the number of speaker companies both in the USA and in Europe who utilize AMT tweeters, I’d say that the technology has become quite popular of late.
The Motion 40i
MartinLogan makes an entire line of loudspeakers employing the AMT tweeter, and they range in price and size from the Motion 2i, a small bookshelf model starting at $US200 each all the way up to the large floor standing “flagship” 60XTi at US$1750 each. For this review, we are interested in the next to the largest floor stander, the Motion 40i.
The Motion 40i is a tall, narrow “tower” speaker of the type so popular these days. Measuring 42.5" x 7.6" X 12.8"(107.9cm X 19.2cmX 32.6cm), it consists of two woofers in the bottom part of the cabinet and a midrange and tweeter in the top. There is a decorative strip between the lower part of the cabinet containing the two 6.5”(16.5cm) woofers and the upper part of the cabinet containing the single 5.5”(14cm) midrange unit and the 1.25 X 2.4”(3.2 X 6.1cm) AMT tweeter. A metal decorative strip separates the two fabric covered plastic grills, each of which is separately removable and held in place magnetically. With the top grill removed, the speaker looks like a typical small bookshelf or desktop speaker with the low frequency driver topped with the tweeter. The cabinet on the review sample is finished in very high quality red walnut wood and is available also in a gloss black or a matte white cabinet. On the back are four of the well-regarded MartinLogan proprietary “wing-nut” shaped, tool-less hand tightened 5-way binding posts capable of handling bare wires, spade lugs or banana plugs. Each pair of the four connection are strapped together but are separable via metal straps for bi-amping, (or bi-wiring if one believes in such a thing). At the bottom of the cabinet is a Helmholtz resonator (a round -in this case- bass-reflex port with an internal pipe connected to it). Each cabinet weighs 49 pounds (22.2Kg). There are no controls on the speakers, but the user has the choice of either spikes or flat pads which screw into the bottom of the cabinets at the four corners. For this review, the spikes were employed to pierce the carpet and make contact with the concrete slab floor. The Motion 40i retails for US$1199.99 each.
The MartinLogan Motion 40i speakers are rated at 40 to 25KHz ±3dB and are recommended to be used with amplifiers ranging from 20 to 300 Watts/channel and have a sensitivity of 92dB/2.83volts/meter. This three-way system crosses over to the midrange at 500 Hz and to the AMT tweeter at a surprisingly low 2600 Hz. Both the 5.5” midrange and the two 6.5” woofers have an aluminum cone in a non-symmetrical chamber format and a cast polymer basket with a rigid, structured dust cap to reduce cone breakup and any modal resonances. The crossover is a Precision Vojtko™ design sporting custom air core coils and low DCR (DC Resistance) steel laminate inductors. Polyester film capacitors are wired in series and low Dissipation Factor (DF) electrolytic capacitors are employed in parallel to maintain phase integrity. The Motion 40i speakers have a nominal impedance of 4Ω and are compatible with all solid state and most tube (valve) amplifiers as well.
The Sound of The Motion 40i
If you go back to July 2, 2019, you will find that this writer favorably reviewed a pair of the MartinLogan Motion 4i, and small, compact bookshelf/desktop speaker. The major point of my review was the AMT tweeter used in this diminutive speaker. The same technology is evident here in the 40i. The AMT used in this speaker is identical in size. It crosses over at a slightly lower frequency but the result is the same – effortless ESL-like upper midrange clarity and high frequency extension.
When I unboxed the 40i’s for the first time, I was rather disappointed. I was replacing my beloved MartinLogan Aeon-i electrostatic hybrid speakers with these and found them thin and forward in the midrange with a slightly nasal quality. This was confusing because the note on the packing slip told whoever was in charge of dispatching these speakers to me to be sure to see that they were run-in for 100 hours and inspected before they were sent out. It seemed to me that 100 hours of run-in should be more than adequate to insure that, out of the box, these speakers would perform at their optimum. A phone conversation with Devin Zell of MartinLogan assured me that whatever run-in these speakers received at the factory, they undoubtedly needed more.
I played them more or less continuously over the next week (using the 192 kb/second MP3 Internet feed from WCRB Boston). Every time I sat down to listen I noticed an improvement. The first thing I noticed was that the nasal quality rather quickly disappeared. Next, the bass improved by leaps and bounds and the speakers’ overall balance became more neutral. Soon I was marveling at how good these speakers actually sounded! The new album by John Williams conducting the Recording Arts Orchestra of Los Angeles with Anne-Sophie Mutter, violinist, of Williams film music: “Across the Stars” has a cut called Rey’s Theme from “Star Wars: The Force Awakens”. This piece has a bass line that is truly spectacular. On good headphones, the string bass is truly realistic and totally natural sounding. With the 40i’s, the bass is deep and relatively well controlled for reflex bass. I have no doubt that these speakers have usable bass response down into the mid-thirties but, bass reflex designs, to me, have always been a bit wooly and these speakers are no exception. While my Aeon-i’s are likewise a bass reflex design, the bass seems to be a bit better controlled than that of the Motion 40i speakers. That’s not to say that the bass on these speakers is not satisfying, it is quite so, and gives the speakers a fulsomeness that is addictive to say the least in spite of not being as neutral as some.
Going up the spectrum the aluminum coned midrange is clean and well balanced. Vocals come across with just the right amount of weight and articulation. Astrud Gilberto’s vocal on The Girl From Ipanema from the “Getz/Gilberto” album on Verve (Catalog Number 80020749-02) has just the right balance with the guitar of her husband and Stan Getz’ tenor Saxophone has never sounded better. Back to Anne-Sophie Mutter’s violin on the Williams film soundtrack album, it is as sweet as a mother’s kiss with soaring highs and resinous bowing that sounds utterly realistic. The AMT tweeter is still the star of this show. On my own recording with the “San Jose California Symphony Orchestra” under Georg Cleve of Ravel’s Daphnis et Chloe ballet, the triangle floating over the left side of the orchestra has a clarity and an other-worldly etherial quality that I have rarely heard on a speaker. It’s even better than on my Aeon-i electrostatics! Imaging on this speaker, is almost uncanny. Again, it is the AMT that does the honors. Still listening to my own recordings, made with a pair of Sony C37P FET microphones mounted on a stereo T-bar about 8 inches apart at a 45° angle to each other and about 10 feet over the conductor’s head and slightly behind him, the listener can close his eyes and point to every instrument in the ensemble. One can tell that, for instance, the brass is behind the woodwinds (and slightly higher in elevation) and the woodwinds are behind the violas and cellos. This pinpoint image specificity and wide, deep soundstage is, as far as I’m concerned, the only justification needed to recommend true stereo miking on acoustic music recordings! The MartinLogan Motion 40i’s point out this incredible soundstage performance better than any floor standing cone-based speakers that this writer has heard in a long time.
The MartinLogan Motion 40i speakers are an affordable entry into a truly full range high-end speaker system. With it’s combination of usable, fairly well controlled bass down into the mid-30’s coupled with a low-distortion midrange driver, and an exemplary Air Motion Transformer tweeter, it’s hard to find a better pair of floor standing speakers for under US$2500.00. One could, contemplate the ElectroMotion ESLs for about the same price, but I have friends who have these speakers and as good as they are, in my opinion, the Motion 40i’s are a better value. If you are in the market for a new pair of floor-standing, small footprint, full-range speakers, put these on your short-list and try to give them a good, hard listen. If you are worried about the WAF (Wife Acceptance Factor) take the lovely lady along with you and show her the red walnut finished cabinets. That might just cinch the deal. They’re that pretty and surprisingly inconspicuous!
Dimension Drawings (ZIP 2.3MB)