Vinyl remains unsurpassed for reproducing music and high-end turntables are something every audio fan should have in the system. The SG1.2 from Spiral Groove is one those things every audiophile would like to see in their collection of superb devices.
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The SG1.2 body is comprised of four aluminum layers in two independent constrained-layer platforms. These two mirror-imaged assemblies, separated by four carefully positioned elastomers, function as a single platform. The feet, with Strange Attractor technology and low frequency damping, are attached only to the bottom layer. The second layer, which is separated by rigid damping material, provides a stable platform for the motor. The upper half of the SG 1.2 body isolates the platter and tonearm in a similar fashion.
The bearing/platter assembly attach to the 3rd plate from the bottom. The top plate, which is separated by a rigid damping layer, provides the tonearm mount. This allows motor, platter, arm, and the furniture the turntable rests on, to remain isolated from each others' vibrations while maintaining critical alignment between them. The unique Spiral Groove bearing is made from the same case hardened steel used for an F1 racing car's crankshaft.
Utilizing material made for high heat, high speed, high wear applications might seem unnecessary for a turntable bearing, but, it's actually ideal for several reasons. For one, it allows us to machine an extremely small bearing gap for superior platter stability. Secondly, since both bearing components are made from the same material, the clearance between bearing parts remains unchanged by temperature variations. In bearings made with dissimilar materials, varying rates of expansion and contraction result in variations in the stability of the platter.
The Spiral Groove bearing incorporates a steel ball and sapphire thrust plate so the entire weight of the platter rests on the very small contact area between the ball and sapphire. This spot is vulnerable to wear and is a source of noise. To further insure the bearings durability and smooth operation we use a custom designed magnet system that reduces the weight on the sapphire to about 2 Lbs. This is a major contributor to its smooth operation and low noise. The SG1.2 exudes an authoritative calm that is a window into the soul of the performers. ■
