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by George M. Graves
Air-bearing turntable and tonearm. Prices: review unit, $645; deluxe air pump, $150; optional lead platter, $195; Audio Technica AT-160 cartridge, $260.
MANUFACTURER: Maplenoll Inc., 3797 Eleazer Rd., Xenia, OH 45385.
Straight-line is the only kind of disc track ing that provides perfect tangency at all times. Unfortunately, straight-line arms are difficult to design because they require frictionless bearings-which do not exist! The lower a cartridge's tracking force the more deleterious the effect of a given amount of tonearm friction. The significant relationship here is the ratio between the tracking force and the bearing friction at the stylus tip. When friction is a very small percentage of the tracking force, cartridge performance is unaffected. As friction rises, the distribution of tracking force between the two groove walls be comes unequal, and, when the force drops below the minimum needed for intimate groove-wall contact, distortion results.
With a conventional pivoted arm, the length of the arm provides leverage which reduces several grams of friction at the bearing to a small fraction of a gram at the cartridge. A straight-line-tracking arm has no such leverage, so all friction in the arm bearing is transmitted directly to the stylus recently, the technology did not exist to produce very low friction bearings, so straight-line designs have had to rely on a servo-controlled motor to drive the cartridge across the disc. Servos are inherently unable to maintain perfect tangency at all times, since they rely on tangency error to drive them: the arm loses tangency until it actuates the servo, then the arm regains tangency. This error-correction-caused error would at times permit more error than a conventional pivoted arm; sometimes the errors would cause step-like image changes as the record played.
The last couple of years has seen a plethora of new schemes for linear tracking without traversal drive, all from small specialty manufacturers. Most of these arms are purely mechanical, taking advantage of recent developments in low.
friction bearing designs. Some designs, typified by the Souther SLA, use rolling bearing technology; the second design approach, employed by Eminent Technology, Dennesen, and Maplenoll, uses a cushion of compressed air. Maplenoll carries this technology a step further, by using com pressed air to float the turntable, as well.
Maplenoll is a small company whose products are refinements of those initially marketed by a firm named Colony., The Athena combines Maplenoll's air-bearing turntable and arm in a naturally-finished solid oak cabinet. With its smoked Plexiglas lid and small brass plaques ("Athena" by "Maplenoll"), this is a very handsome unit indeed. No one will ever mistake this beauty for mass-produced.
The motor board is a laminate built up from a 3 / 4 -inch piece of high density particle board, a 1 / 4 -inch thick sheet of lead, and a Y4 -inch thick piece of oak plywood. The turntable platter itself is made of a piece of cork and two sheets of aluminum separated by a rubber-like substance. There is even an
------------ Not to be confused with Old Colony, which is the merchandising division of The Audio Amateur magazine.
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extra-cost optional turntable platter available, made of solid lead bonded to an aluminum plate.
The headshell is also a laminated affair, made from six layers of lead, copper, phenolic resin, and black walnut! The idea behind all this is to damp out or isolate all resonances. It sure is successful on that count: this baby is acoustically dead! The drive motor is AC synchronous, coupled to the platter by an elastic belt.
Most belt-drive 'tables use what is called a thrust bearing, in which the platter is attached to a precision-machined hard steel rod with a pointed tip; the whole assembly rotates against some smooth surface (e.g.. carbide steel, sapphire). The small contact area results in very low rotational friction.
Good bearings of this design, though ex pensive to make, can work well, having the advantages of reliability and low maintenance.
The bearing on the Maplenoll consists of two carefully machined metal plates about 8 inches in diameter. The bottom plate is bolted directly to the motorboard and re mains stationary. Near the center of this plate is a hole through which is fed pressurized air from a pump. The top plate is kept centered over the lower plate by a short "nub" which fits into a hole in the center of the bottom plate. When air is pumped between the two plates, air pressure forces them apart, so that the top one is free to rotate with almost no friction above the bottom plate. This type of bearing effectively isolates the turntable platter from the motorboard, thus eliminating yet another path for structure-borne vibrations and motor rumble. The obvious disadvantage is the required air pump.
The arm on the Maplenoll Athena is very similar to the Eminent Technology One2 found by DO to be a first class performer (Vol. 7, No. 5). In both, a large-diameter brass cylinder is mounted on the subchassis behind the platter and parallel to the turn table's front. A highly polished, tightly dimensioned tube slides freely back and forth within the cylinder. The actual "arm tube," cantilevered forwards from the right-hand end of the inner tube described above, extends forward just enough so that the headshell, which is locked in place by a set screw, traverses the record's radius.
----2 No wonder! It was designed by the same person.
Bruce Thigpen. ---
Slots in the headshell accommodate various cartridges.
Counterbalance is provided by two brass discs threaded onto a shaft, also attached to the inner tube but extending towards the back of the 'table. The discs can he threaded in and out, and locked against each other, to set stylus tracking force.
When my sample Athena arrived, its Plexiglas arm rest was broken (a little superglue fixed that), there was no platter mat, and there were no output cables for connection to the preamp. Checking with the factory.
I found that, although the 'table normally comes with a turntable mat. Maplenoll feels (and rightly so, I think) that most users would rather use their favorite cables in stead of any supplied.
In spite of comprehensive instructions, the Athena is not easy to set up. I recommend having your dealer set it up; if he won't, find one who will. Otherwise, you should be good with tools, and patient.
The set-up of this 'table will make the difference between good performance and great performance.
According to the instructions, the factory set air valve on the bottom of the motor board should never need adjusting; it turned out to be fine for the standard platter, but the optional lead platter bottomed out on the stationary lower plate. Fortunately, adjustment of the valve is covered in the instructions.
Next, the book says that the suspension is also factory-set, and should never need attention. Not so: with the standard platter fitted, the top of the arm-bearing manifold rubbed firmly against the underside of the Plexiglas cover. Fitting the lead platter stretched the springs enough so that the bearing manifold cleared. The book does tell you how to adjust the suspension, but it is not an easy adjustment to make. (The sample reviewed had been used as both a demo at shows and as a review sample for others; maybe that explains its state of maladjustment.) When assembling the turntable air bearing, the instructions say to apply grease to the centering nub. No grease is supplied, however, nor any type or brand recommended. I had some silicone grease left over from my damped unipivot tonearm days, and it seemed to work, , but I would have felt better had some mention of the proper lubricant been made.
The tonearm set-up is fairly straightforward, but, again, a couple of comments are in order. First of all, the headshell design is marvelous. You can remove it easily to mount the cartridge, and it is threaded to take the mounting screws:, The cartridge hook-up wires are captive with the arm tube, and each is a single, unbroken length of Litz wire from the gold-plated cartridge pin sleeves to the gold-plated RCA jacks on the rear of the cabinet. Because Litz wire is so fragile, Maplenoll has placed a piece of color-coded shrink tubing over each wire where it emerges from the arm tube. This really facilitates the handling of these fragile wires by all-thumbs klutzes such as yours truly. A nice touch.
The arm tube itself is secured at the rear by a single Allen screw. The mounting hole for this screw is a vertically elongated slot, allowing for considerable VTA adjustment.
My only complaint with the arm is its in ability, in stock configuration, to accommodate some of the heavier cartridges due to insufficient counterweights. Maplenoll tells me they will gladly supply additional counterweights for cartridges weighing more than 10 grams. (Free, I suppose.) Maplenoll has come up with an ingenious way to set "overhang" (actually, the point of a straight-line tracker is that there is no overhang). Supplied is a long ruler-like piece of aluminum with a hole in one end and a slot in the other. The hole fits tightly over the platter spindle, and the slot fits over a brass rod which plugs into a precision "socket" mounted in the motorboard just ahead of the arm tube. There is a line in scribed down the center of the "ruler", and the headshell is adjusted until the stylus rests on that line. If the stylus remains over that line when you slide the arm across the platter, you know the tangency is perfect.
--- 5 This was a poor choice: its viscosity is too high. I am surprised it didn't slow down the platter. -JGH ---
----- 4 This is good-except for use with Dynavector cartridges. which are themselves threaded. Better to use bolts and nuts. I fed. though admittedly less convenient. -LA ----
If it isn't, you loosen the bolts which hold the air manifold in place, and adjust the arm until it's square. Neat, huh? With the air pump off, lifting the arm from its rest requires enough effort to strike fear into the heart of any audiophile! With pump on, though, there is effortless movement both vertically and across the record; the arm literally floats on a cushion of air. For all intents and purposes, there is no friction.
That air pump is the source of one of my two major criticisms of the Athena. It is much too noisy, even in its newly designed "quiet" box, to be in the same room as the listener. Maybe the folks at Maplenoll agree: my sample came with about 30 feet of air hose . (The manual says 30 feet will not degrade performance as long as the hose is not kinked or asked to negotiate any sharp corners.) My second complaint concerns the lack of a lift lever. The high sides on the cabinet make it difficult to get one's hand in a position that inspires confidence when handling the arm. I know that this product was de signed to be affordable, but I value my re cord collection a lot more than the few bucks extra it would have cost to have a cueing lever included. How about it, Maplenoll? The Maplenoll arm has much more mass in the horizontal plane than in the vertical.
For this reason, it works best with cartridges of high mass and medium compliance.
Such a combination has its resonance at more or less the right frequency (8-10 Hz). I tried several cartridges with the Athena: the Adcom HC/VDH II Van den Hull, the Shure V-15VMR, the Grace F9-E Ruby, and the Audio Technica AT-160 (supplied as an option with the Athena). I settled on the Audio Technica as the best of the lot. I do not know whether this was because this cartridge is actually better, or whether it just mated better with the Athena; all I know is that the combination of A-T cartridge and the Athena is magic! With this cartridge fitted, and using the optional lead turntable platter (recommended), the Maplenoll turntable is an excellent performer. The bass is very clean, and sounds bottomless! It just goes down and down. (This same cartridge mounted in a Linn Sondek with an Ittok arm sounded much thinner in the bottom register.) The bass drum on the Telarc Hoist band suites (Telarc 5038) sounded like the CD for the first time! The combination of high lateral and low vertical mass contributes to this superb bass performance. Deep bass is all lateral on a disc, and placing the system's lateral resonance at below I() Hz puts it below the deepest signal on most discs. At the same time, the low vertical mass (and relatively high resonant frequency) makes the cartridge able to negotiate warps without producing subsonic interference.
The imaging of this combo is the best that I have ever heard from a phonograph.
On the Howard Hanson/Eastman Rochester recording of Walter Piston's "The Incredible Flutist" (Mercury SRI 75050), the image extends for a good distance out from either side of the speakers. The soundstage was also very deep, giving the illusion that the brasses were in the last row-where they're supposed to be. Percussion instruments tended to float over the orchestra in a manner that I'd heard only on some stereo miked master tapes, never on a phonograph record.
Not only was the image uncanny in its realism, but it was stable as well. Most phono systems that image well have some degree of image wander. This is due, in part, to the changes in tracking geometry (with a pivoted arm) as the stylus angle changes in relation to the groove. Another problem is most arms' inability to cope with record surface irregularities because of their great pivot-stylus length. The Maplenoll arm remains rock-steady.
This system has the smoothest massed violin sound that I have yet heard from a record. For instance, the string sound on "Ballet Music from the Golden Goose" by Hoist (Lyrita SRCS.44), simply sounds like violins in a good concert hall. The string sound hovers over the left side of the orchestra without any of the shrill metallic sound of many phono systems. The violins are neither dry nor dull, possessing that elusive "sweetness" that characterizes the real thing.
Maplenoll has tried to build a turntable which, at reasonable cost, overcomes many of the problems inherent in analog phono graph reproduction. They have eliminated floor-borne feedback so well that I was unable to induce it even when I placed the turntable on a shaky "TV tray" and set it directly in front of my Magneplanar Tympany IIIb woofer panels (flat to 32 Hz)! The Maplenoll has tried to build a turntable which, at reasonable cost, overcomes many of the problems inherent in analog phonograph reproduction, combination of the lead platter and the laminated, damped headshell create a record/player interface that extracts more from records than any other system I know.
I am careful to say "system"; it has be come apparent to me that, if analog records are to hold their own with CDs, a systems approach is necessary. It is not enough just to buy a turntable, pick an arm with a reputation for outstanding performance, then mate them haphazardly to some highly touted cartridge. It is an accident if such a system works decently, and most likely the user will still not get full performance from any of the three. To function well, a phono unit must be just that: a synergistic system with all components mated so that the whole is more than just a sum total of its parts.
Maplenoll has done this with the Athena, and I am impressed.
--
[based on a March 1986, Stereophile review article]
Also see:
THE HARMAN /KARDON T45 / T65C TURNTABLES
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