SOTA Cosmos turntable Page 3
I would therefore imagine that new readers (of which there seem to be quite a few), on witnessing our continued fascination with high-priced analog playback devices, are wondering on just which planet Santa Fe is located. I would not be surprised if a majority of those new readers, probably also new to audio, have CD as their primary program source. Many likely do not even own a turntable. Fair enough, and probably not unreasonable given the current availability of analog recordings. But to those who already own sizable collections of LPs, or those willing to mine the substantial resources (and occasional bargains) available in used vinyl, sound reproduction by means of the "primitive" stylus-in-a-groove is far from a dead issue. And to a vocal minority of audiophiles it is still, given good playback equipment, the best source of reproduced music short of original master tapes.
I've been living for the past several months with two turntables that, if they don't redefine the state of the art, certainly compete strongly at that level. They do not sound alike, yet each in its own way will reconfirm an analog lover's convictions. And might even convert a digiphile or two.
SOTA Cosmos: $3750
A casual glance at this sleek turntable might lead you to believe that it's just a gussied-up, high-tech-looking Star Sapphire. That's what I thought when I first saw it at a CES last year, "Oh, great, they've put a Star in a marble base and doubled the price." Of course, I should have known better. Still, the physical similarities are obvious. The size is the same, the arm cutouts are identical and the arm boards interchangeable, and each is fitted with a vacuum platter. Both have heavy, suspended subchassis and overall weights guaranteed to give former Linn owners hernias.
But appearances here, as is often the case, are deceiving. The most visible difference lies in the Cosmos's polished, simulated granite base (footnote 1). The only visible controls are two pushbuttons which match the base material—one for power, the other for speed change. (The controls are unmarked on the reasonable assumption that the user will soon sort out the four possible positions.) Beyond this, a close inspection reveals a visible difference in the platters. Or rather in their integral mats. Both platters are built around the same damped, aluminum casting with a foamed vinyl intermat. The top mat on the Star is made of acrylic. The Cosmos incorporates what SOTA calls their "Vinyl-Format," a multi-step casting said to establish new standards in damping stray energy from the vibrating stylus (in conjunction with the vacuum clamping system) and preventing its reflection back into the record. SOTA is understandably a bit vague as to the exact procedures and materials used in casting this mat (footnote 2).
But most of the Cosmos's advances over the Star are internal. Its subchassis is a damped, carbon-fiber, honeycomb structure with an aluminum frame and inserts, and the armboard mounting block is 1"-thick machined aluminum (the Star subchassis and armboard block are lead-damped, laminated wood and fiberboard). The same 1" piece of aluminum used for the arm-block also forms the bearing block (the Star uses a separate bearing block bolted to its laminated wood subassembly). For bearing assemblies, both have sapphire-rod thrust plates, but while the Star uses a steel ball bearing, the Cosmos's is zirconium. In the Star, the motor is mounted, for isolation purposes, on the fixed portion of the base assembly separate from the suspended subchassis—the usual practice in this type of turntable since AR started the breed in the '50s. In the Cosmos, the motor is mounted directly on the suspended subchassis, along with the bearing, platter, and arm. This provides an unvarying geometry between the motor and the turntable. The Cosmos relies on its damped subchassis and multi-layered platter to isolate the arm and record surface from motor vibrations.
In theory, a vacuum clamping system is the best way to insure intimate contact between record and platter, not to mention flattening warped discs. In practice, it is complex and expensive. There has also been some evidence that, improperly executed, a vacuum system can damage vinyl recordings. SOTA minimized this problem when they introduced their vacuum system in the original Star Sapphire by using the lowest possible vacuum level. When first engaged, the vacuum pump operated on a "purge" cycle; after a designated time period, it switched over to a mode designed to maintain a continuous running level of 1.5" of mercury. SOTA continues to improve the system; in the Cosmos a vacuum sensor, not a timer, controls the change to the maintenance cycle.
An additional improvement was also made during the course of the review, which actually involved two samples of the Cosmos (footnote 3). With the first, I had some occasional difficulties, with certain records, in obtaining a good vacuum seal (pressing down around the perimeter of the disc with a fingernail generally, but not always, cured the problem). The pump on the first sample was also somewhat noisy, but not so much that I suspected a defect. From four feet away you could hear it shift from "purge" to "maintenance"—the latter was quiet, the former not annoying but definitely audible. In the second, later sample, the configuration of the outer, rubber seal had been changed (footnote 4) substantially reducing (but not entirely eliminating) the number of discs which required manual assistance to obtain a vacuum seal. In addition, the second pump was dead quiet in either cycle.
One added feature that I would like to see in the Cosmos is the addition of an indicator (an LED would do) to signal the transition to the maintenance cycle; ie, to let the user know when there is a good vacuum. There were just enough records which wouldn't form a vacuum without manual assistance (5 to 10% would be a good guesstimate) that I found myself sighting along the edge of each record on cue-up for the sign of a seal (the flattening of the rubber ring on the perimeter). This was a minor nuisance. Ironically, I had been able to do this by sound with the first, noisier version of the pump—listening for the reduction in pump noise which signaled the mode change.
One final difference between the Star and the Cosmos lies in their spring configurations. In the Star, the lead balance and damping weights are placed at the outer corners of the subchassis. The springs are inboard of this substantial mass. In the Cosmos, the springs are at the outermost corners of the subchassis. While the Star has a resultant tendency to wallow slightly when one is using the tonearm (especially noticeable with the SMEs, which require some slight force to free them from their armrests), the Cosmos feels far more stable and secure. It is doubtful if this particular change makes any difference in the actual sonic performance, but it creates an impression of a greater solidity in the Cosmos. SOTA makes a laminated armboard available as an option for the Cosmos. Constructed of several alternating layers of lead and different types of acrylic, this $250 option is available precut for the user's choice of arm, the total mass adjusted (by means of holes drilled in the bottom of the armboard) to match that required to balance the subchassis of the Cosmos. All of my auditions were performed using this armboard.
Footnote 1: This material is called Fountainhead and is made by Nevamar. The separate vacuum pump/drive electronics enclosure is also encased in this material. This plastic/ceramic resin compound—made primarily for use in countertops and very durable—is similar to the material used for the cabinet of the Wilson WATT.
Footnote 2: The Cosmos platter and integral Vinyl-Format are also available as a retrofit to existing Star Sapphires, or by special order on new ones, for those whose budgets and/or priorities are stellar but not quite cosmic. In either case it will cost you $800. We haven't heard this hybrid turntable, so cannot comment on it.
Footnote 3: There was no significant problem with the first sample of the Cosmos, but when the review ran into unavoidable delays, SOTA asked to borrow it back for a few weeks. The unit they returned was a new sample, with the revision noted here.
Footnote 4: The new seal is also furnished on the latest versions of the Star.