Look at it this way. Move the stylus and that movement is detected by the magnetic circuit contained in the cartridge body and thus produced as signal. But that signal depends on the movement of the coil relative to the stationary magnet (or vice versa in a moving magnet cartridge) so an accurate transcription depends on holding that magnet stable. But as the stylus is moved sideways by the record groove modulations, it will tend to drag the cartridge and tonearm in the same direction, creating inaccuracy in the signal: This is why designers refer to the closed loop between platter, arm and cartridge and place such emphasis on the rigidity of their arm bearings. And yet, herein lies the biggest conundrum of all. The arm must dissipate mechanical energy that would otherwise move it in sympathy with the stylus and it must do so without creating dominant resonant peaks that would themselves be read as signal. Yet at the same time, it must allow the cartridge and stylus assembly the freedom to read microscopic variations in a groove and trace those grooves across the surface of the record, making lateral or vertical friction absolute killers when it comes to accurate reproduction.
You can tackle these issues in a number of ways involving the structure of the arm and its physical arrangements, moving potentially harmful resonance outside the audible band, damping the structure of the arm itself. But the fact that the Rock sounds so different to other turntables tells its own story.
The Rock solution is to place a fluid-damping trough right next to the cartridge, allowing slow, gradual movement, but resisting faster or more sudden deflections. At the same time it effectively offers a far shorter route to close the mechanical loop between platter and cartridge. You just need to remember that damping one end of the arm will encourage the other end to flap about, so you can’t afford to skimp on the bearings there, even if the frontend damping carries some of their load. Once you’ve engineered the practicalities of the design (allowing the trough to move for placing and replacing records, fixing the arm’s arc of travel and thus effective length) the rest of the deck can rely on established engineering principles. As I’ve already suggested, these have varied over the years, dictated by price and technology as much as anything else. However, to really understand the Rock V, we need to look at the stillborn Mark IV, or Rock Reference Master.