Listening #64
By Art Dudley   •   April, 2008 Today, as every Saturday, I brought my daughter to the stables where she has her riding lessons. But this time was different. As we pulled up the long gravel driveway, we found ourselves dodging a riderless horse, moving at a trot across our path. It turned out that the very cold weather had caused a latch to malfunction—"gate won't close, railing's froze"—and five horses had gotten loose.

The situation was messy but not unpleasant. I had fun catching one of the older horses—a small, good-natured Arabian who apparently wanted to go back inside—and within a few minutes the stable hand and the adult riders had rounded up the others. Then, because the five escapees celebrated their short-lived freedom in that most elemental of ways, I grabbed a shovel and went to work mucking the yard in front of the barn.

To view the scene with the jaundiced eye of some audiophiles—elderly train-whistle recordists, for the most part—would be to wonder why horse enthusiasts go to such trouble just to travel from point A to point B and back again. As far as it goes, they have a...point. Automobiles, which I also enjoy, require less work, less training, less exasperation, and a great deal less expense per mile traveled. And after a ride in the car, you don't have to clean up a lot of excrement. (That's for the next generation to do.)

But people who ride horses don't love it because it's easy or unexasperating or economical. They love it because they love it—because it's a process that gives them something they need. Those who would disdain horseback riding as impractical or uneconomical are rightly seen by the rest of humanity for what they are: pedantic, unimaginative killjoys who have some degree of intelligence, yet whose character flaws—inculcated, no doubt, by painful adolescent years of not fitting in with others—reduce them to drooling pinheads when confronted with pleasures, usually of the aesthetic variety, that they can't understand. Not to put too fine a point on it or anything.

A simple love for doing things in a certain well-worn way: That drives those old nerds right around the bend and over the cliff. And I'm here to help.

SET in my ways
Fly-fishing, haiku, quilting, caning, canning, writing letters with pen and ink, hunting with a muzzle-loader, hot hide glue, dovetail joints, waxable skis: It's not that these cultural artifacts are superior in every way to their more modern counterparts (though they often are), but rather that they engender the kind of love to which phosphorescent plastic worms, e-mail, white glue, and waxless skis can't aspire. I'll let you in on a secret: The people who love those things tend to be happier, not to mention a lot damn smarter, than everyone else. (No condescension intended: I prefer Smuckers blackberry jam to all else, I can barely get around on even waxless skis, and if I had to hunt for my own meat I'd probably choose an assault rifle.)

Why would anyone want to play an LP record instead of an MP3 file? Neither you nor I will ever convince the world of the former's technical superiority, so let's just say: We do it because we love it.

Analog isn't that hard a sell, especially to audiophiles with a materialistic or fetishistic streak. (Never a shortage of those, is there?) But other things certainly are—such as horn loudspeakers and low-power amplifiers, which tend to require a great deal more patience, understanding, and involvement on the part of the hobbyist than anything short of wax cylinders and windup gramophones.

Thus, in recent years, have we gained an entire new class of manufacturers. I can think of at least a dozen loudspeaker companies in particular that started when a lone tinkerer was bit so hard by the single-ended-triode bug that he felt the need to deliver the flame to the rest of us, Prometheus-like. I'm thinking of people like Eric Thomas of Beauhorn, Ed Schilling of the Horn Shoppe, Tommy Horning of Horning, Bruce Edgar of Edgarhorn, and Jacob George of Rethm.

Rethm, which takes its name from the Sanskrit word for harmony, is an especially interesting case. Founder and chief designer George is a native of southern India who lives and works (as an architect) in the US, and who has elected to slay more than one bird with a single stone: bringing a practical full-range loudspeaker of very high sensitivity to the marketplace, while also bringing a few jobs to the people of the area he calls home.

His first commercial loudspeaker—the Second Rethm, which debuted in 2000—used a Lowther full-range driver in a rear-wave horn made of a combination of wood and PVC, in which the labyrinth also functioned as a tuned, quarter-wave pipe. All subsequent Rethm models have been variations on that theme (footnote 1), up to and including the new Saadhana ($7850/pair; see www.rethm.com).

Yet the floorstanding Saadhana breaks from Rethm tradition in two significant ways: Its front-firing driver is a Lowther DX55—nearly 2" smaller in diameter than the English company's standard-bearing full-range models—and it gains bass reinforcement from a pair of 6" non-Lowther drivers, driven by a built-in solid-state amplifier. Well!

PVC and parchment
Although the enclosure of the Saadhana seems deep, the speaker is actually supplied as two separate cabinets, arranged front to back. Each of the four cabinets in a stereo pair is also marked left or right, although this is less a matter of sonic performance than of ergonomics and décor: the routing of the signal wires, the placement of the speaker-cable connectors and power switches, the positioning of the Rethm logos on the speakers' side panels.

The frontmost enclosure for each channel contains a three-part labyrinth intended to augment the low frequencies. The Lowther driver's rear wave is channeled into a curved PVC pipe, from whence it travels down for about 30", then turns around and goes back up for another 30" through a PVC pipe with a mild flare and an opening at the top. Because the flared pipe is contained within a larger tube of constant cross-section—which is the part you can actually see from the front of the Saadhana—the last portion of the labyrinth also takes the shape of a mildly flared horn, enhanced by a wedge-shaped "diffuser" just below its mouth. Jacob George says that the overall effective length of the Saadhana's loading labyrinth is about 7'.

The single Lowther DX55 is modified in a number of ways. A cone-shaped plug of expanded polyurethane covers the whole of its rare-earth magnet at the rear, giving the miniature Lowther a somewhat papal look and shaping the throat of the horn for the right amount of compression (and prevention of backwave interference). A ring of very light foam batting is tucked between the frame and the perimeter of the backside of the cone, to help tame the driver's upper-midrange peakiness. And the DX55's stock phase plug is replaced with a much longer one, machined from a light hardwood and ringed with a perforated paper diffuser cone that resembles the Lowther's own treble whizzer—and the headgear worn by dogs who've just had their ears bobbed. Again, the aim is to tame: "There are peaks in the smaller Lowthers," George says, "occurring between 3.5 and 5.5kHz. I wanted to minimize their impact upon the music, and the only way I could determine what was right was to make a bunch of cones and measure their effect. I made six different cones every day and measured them—that went on for several weeks—using different combinations of three variables: cone length, cone angle, and perforation pattern." George says he made and auditioned over 125 different cones before settling on these.

The Saadhana's rearmost enclosure is home to a pair of 6" paper-cone drivers, mounted in a plywood labyrinth and connected together in an isobaric loading scheme: One driver contributes to the loudspeaker's output, while the second driver, moving in response to the same signal, acts on the volume of air inside the otherwise sealed cabinet, effectively fooling the first driver into thinking it's loaded with a cabinet of infinite size and thus allowing it to function down to its free-air resonant frequency. The bass drivers, which have paper cones and impregnated cloth surrounds, are custom-made for Rethm by Peerless of India, and driven by an onboard 75Wpc power amplifier of proprietary design. George describes the low-pass filter as a simple passive circuit that introduces no more than 15° of phase shift. There are control pots on each Saadhana bass cabinet for crossover frequency and bass level, hidden beneath a removable cover that contributes to the visual illusion that the Saadhana, like earlier Rethm loudspeakers, has a second tuned pipe coming straight off the back of its main driver.

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Footnote 1: Art reviewed the Third Rethm in May 2003.—Ed.