Art Dudley Listening

That said, I suspect that even the finest platter bearings—a category that includes the ones in both the Garrard 301 and the Thorens TD 124—are the source of at least some noise, given that none are perfectly concentric or perfectly frictionless. And because the metal bearing housings of all such turntables I've seen are directly and rigidly fastened to a metal chassis or frame, then it's a no-brainer: Noise is efficiently conducted throughout the whole of the thing. Thus, to cradle such a turntable in a large and massive but neither lossy nor mechanically lively structure is to give those vibrational noises an appropriate sink, I think.

Which material is best? On p.13 of their original (hard-bound) manual for the 301, Garrard said merely that the plinth should be "substantial"; Thorens said the exact same thing—and nothing else!—on p.7 of their manual for the TD 124. The traditionalists of today appear to lean toward birch plywood, various hardwoods seeming less popular if only because they cost so much. And then there's slate: an interesting dark-horse candidate, enduringly so, for as long as plinths have existed. On paper, at least, slate could seem almost ideal, being denser and more massive than most woods, and foliated (layered) in much the same manner as some solid woods (especially those grown in climates subject to seasonal changes) and all plywoods are. It may also please some to embrace the relatively organic origins of some slates—the stuff varies widely in color and density, given the locale in which it's mined—although one can say that about almost anything, I guess. Today's oil slick was, after all, yesterday's frolicking dinosaur. What could be nicer than that?

I've abandoned my base
Slate has even more nice qualities. According to my friend Jim Faliveno, whose company develops software for computer-controlled stone-cutting machines, slate is softer than marble, and thus arguably more wood-like. In years gone by the stuff was cut with a wire saw—like a fine-toothed barbed wire—doused with an abrasive slurry. But today's tool of choice is something akin to a computer-controlled Waterpik operating at over 10,000psi. With that sort of tool, according to Jim, cutting can be done with thousandth-of-an-inch precision, "limited only by the resolution of the CNC gantry." And that's precisely how it's done by Oswalds Mill Audio, using the characteristically dark, blue-gray slate that's harvested right in their own back yard, in east-central Lehigh County, Pennsylvania (footnote 1).

Oswalds Mill also distributes the excellent Thomas Schick tonearm, which I wrote about in my March column. When I first became aware of the Schick, I noted that OMA also does an apparently brisk business designing and selling custom slate plinths for classic turntables, including the great Thorens TD 124, samples of which continue to find me. (At the time of this writing, I had just bought the TD 124 used for 30 years by our copyeditor, Richard Lehnert!) Even during our earliest conversations, OMA's Jonathan Weiss and I decided that it would be a fine thing for me to borrow one of his plinths in the late spring, when the roads around here are finally clear of snow.

The plinth delivered in May by Weiss and his wife, Cynthia van Elk, is a gorgeous thing, admired in the days since by male and female visitors alike. It's about 24" wide by 21" deep—a little larger in both directions than the Box Furniture rack on which my favorite 124 sits—and rivals the lining of my aorta at just under 2" thick. The total weight of the OMA plinth, along with its three slate support trestles, is in the neighborhood of 80 lbs: more jealousy for my heart to endure.

I'd seen OMA plinths before, in person and in picture, but this one had something new: a detachable and adjustable armboard, also of slate, the height of which suited a Thorens TD 124 just fine, and the position and adjustability of which were ideal for the hobbyist who not only favors transcription-length tonearms but who tends to switch between A- and G-style pickup heads. Which would be me.

My favorite 124 usually sits in an open-frame beechwood plinth from Schopper AG (footnote 2), with an outsized (peninsula-style) armboard, also made in Switzerland by Schopper, in order to accommodate my 12" EMT 997 (owned) and 12" Schick (borrowed) arms. A fresh set of rubber "mushrooms" with metal washers go between turntable and Schopper plinth, the former using the shortest version of the Schopper's threaded height-adjusting rods.

With the OMA plinth, the idea is for the turntable's metal chassis to sit directly atop the slate surface, which is how I did it. I did, however, experiment with the Thorens's four threaded height-adjusting wheels, which can be lowered, singly or in combination, to a point where they lift the turntable's chassis up and away from the plinth. But doing so always made the sound worse: The best performance came from having all four just a bit loose, and not touching the plinth at all. Some day soon I'll try doing away with them altogether.

The changes wrought by the OMA plinth were clearly audible, and just as clearly for the better. I feel a bit sheepish describing the most obvious of all, if only because it is something of an audio-reviewing cliché: My record player had significantly greater bass extension and power with the slate plinth beneath it. Plucked bass notes on stringed instruments were especially lucky, gaining sonic prominence and musical power—as throughout Lhasa De Sela's moving and somewhat harrowing final album, Lhasa (LP, Audiogram AD-10222). Before the slate's arrival, this all-analog recording was enjoyable if a little fuzzy and unclear; with the OMA plinth, the string-bass notes were deeper and clearer, and stood in greater relief to the sounds that surround them. In fact, seemingly everything the performers would have wanted to emerge more clearly—downbeats, accents, playing nuances (including the very talented bass player's use of slides)—did so after the Thorens was cradled in the OMA base.

Speaking of clichés: There emerged, after Jonathan Weiss's generous visit, one of those chunks of time in which I played record after random record, just to hear how much better they sounded, and how much more music seemed to be written on them. The answer was always: lots.

I had only two problems with the OMA plinth, one unforeseen by the maker (forgivably so, I think), and the other of my own making. The first: Weiss's adjustable armboard, though adequate in most regards and aesthetically pleasing for some odd reason, didn't provide for a tonearm such as the EMT 997, which lacks a hardwired interconnect cable, and thus depends on being electrically connected to jacks mounted on an outboard plate. I typically bolt that plate to the underside or the rear edge of my wooden armboard, easily reachable by the fragile signal wires that exit the very bottom of the EMT 997's bearing pillar. But the whole of the OMA armboard is flush against the slate plinth, and the latter is simply too expansive to allow much slack in the signal wires, in any direction. (This occurred to me only after I'd made a routine adjustment in the OMA armboard's distance from the platter spindle, then realized there was no sound from either channel: I had moved the board too far and broken the solder connections at the jacks.) I recommend that EMT owners buy some 3M heavy-duty double-side adhesive to hold the jack to a point on the plinth's rear edge that's both close to the arm and movable, for when the need arises. That's what I wound up doing.

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Footnote 1: Oswalds Mill Audio. E-mail: Jonathan Weiss, jonathan@oswaldsmill.com. Web: www.oswaldsmillaudio.com.

Footnote 2: This is Schopper's economy plinth; they also make a heavy plinth of solid wood that I have yet to try.