Project Description


Spiral Groove’s Centroid Tonearm sets the new standard for performance as well as easy, precise setup. Its exceptional rigidity and low inertia keep the cartridge stable while allowing the stylus to move freely through the record groove. The materials and construction of the Centroid were developed to provide rapid energy transfer from the cartridge to the turntable chassis, so spurious vibrations are not “echoed” back to the stylus. These are two reasons our tone arm delivers unsurpassed speed, dynamic energy, and tonal purity. No other tone arm available today dispenses with wayward energy more effectively than the Centroid.

It is also exceptionally well balanced. Spiral Groove used computer modeling to better understand the forces exerted on the arm as the cartridge tracks the record. Being able to locate, measure, and visualize these forces means that we didn’t guess what the arm experiences when tracking the record. We know. We call our process Balanced Force Design™ and it gives the Centroid near-perfect tracking and optimizes cartridge performance.

Like Spiral Groove turntables, the Centroid is user-friendly. If you can’t achieve precise adjustment, the potential of quality cartridges cannot be realized. The Centroid allows adjust of overhang, VTA, azimuth, anti-skate , and tracking force, with remarkable precision. Better still, achieving these adjustments requires far less time thanks to Spiral Groove’s patented mirror gauge and setup system, that is included with each tonearm.

Centroid SG Integrated

For use with the Spiral Groove SG1.2 and Revolution turntables. Includes Spiral Groove arm board. The Bayonet Mount is included with the turntable for SG1.2 application. Additional Bayonet Mounts may be purchased.

Centroid Universal Integrated

The Universal Integrated is for use on all non-Spiral Groove turntables. The Universal Integrated mounting system provides a lightweight platform for the Centroid to perform on any turntable while s till maintaining the critical parameters and ease of setup to achieve optimal performance from the arm.

  • Balanced Force Design™ approach results in minimum torque on the cartridge for superior tracking.
  • Patented Counterweight design minimizes moment of inertia.
  • 10 inch pivot-to-stylus distance
  • Matched Swiss sapphire cup jewel and hardened steel upper bearing
  • “Zero tolerance” Unipivot bearing design
  • Multi-layered, damped arm tube from low mass, high strength aluminum/carbon fiber
  • High purity copper internal hyper-litz wiring
  • Overhang, VTA, Azimuth, Zenith, Anti-skate and Tracking Force easily adjustable
  • Precise mirror set-up gauge included

Turntable Art and Science

Vinyl remains unsurpassed for reproducing music. To convey vinyl’s rich, nuanced potential, a turntable must have precise speed control and operate without producing mechanical or electronic noise. The goal is an un-compromised signal emerging from a silent background.

Noise Control

In the turntable body aluminum is the first-line of defense against errant vibration, storing and releasing energy in predictable ways. Assembled into a sandwich of differing thicknesses and separated by proven damping material, the result is a dense, stiff, and silent platform. The sound-absorbing, mechanically solid, yet isolated layers (i.e.: the motor, turntable bearing, arm-board, etc.) is found in SG1.2.

The platter is where the music begins. Spiral Groove’s platter is belt-driven at the contact plane of the bearing to eliminate wobble or oscillation. Both the SG2 and SG1.1 platters utilize a 14 inch drive ring of either aluminum or stainless steel to guarantee exceptional speed stability. Spindle and bearing are decoupled yet precisely aligned. A thick phenolic layer forms the bulk of the spinning disc, topped by layers of vinyl and graphite. These materials act together to dissipate the energy generated by the stylus in the groove, all but eliminating the “stylus talk” common to most turntables. Threaded record clamps, made of stainless steel or anodized aluminum (depending on the model), snug the record to the graphite to create intimate contact for vibration transfer. Together, these features dramatically reduce the turntables’ noise floor, giving unparalleled depth and specificity of image.

Stylus Talk

Pops and clicks on records occur when the stylus encounters a piece of debris in the groove and “plays” it as if it were part of the record. Such encounters also generate energy that, in some platters, is reflected back into the vinyl, moving the stylus and sending a second signal milliseconds after the first. This “echo” is so close in time that the pop or click is not heard as two pops, but as a louder and longer single event.

And, reflected waves don’t only come from dust or dirt in the grooves. The movement of the stylus through the groove also sends energy into the record which, on insufficiently damped platters, comes back through the record to the stylus, causing a higher noise floor and coloring the sound.

Spiral Groove spares no effort to prevent mechanical-electrical feedback. SG platters are carefully engineered and constructed to dissipate energy. And they do: SG platters dissipate reflected energy so it can’t get back to the stylus. Vinyl is a lot quieter and the music clearer when played on Spiral Groove.

Speed Control

All of our turntables use a 20 volt, AC synchronous motor driven by our proprietary outboard motor controller. The controller transforms AC wall current to DC and generates its own sine wave with switchable frequencies and adjustable phase to precisely control the motor. At startup the motor runs at full torque until it reaches speed when the current is reduced for smoother and quieter operation. The LED speed indicator flashes during start up, becoming steady when 33⅓ or 45 RPM is reached. Speeds are independently adjustable by 10% with 18-turn pots accessible on the turntable.

Please note: there is no further adjustment, calibration, or “tweaking” required to make the SG1.2 perform as designed. Once the table has been leveled and the speed checked for accuracy, it stays set up indefinitely. Get right to setting up the tone arm and cartridge (even these operations are easier and faster with Spiral Groove’s Centroid tone arm) and enjoy a new level of reproduction from your favorite records.