To someone with an engineering bent, the Kronos contra-rotating platter design makes perfect sense: Think of the 1982 Kamov single-seat Ka-50 “Black Shark” or 1997’s two-seat Ka-52 “Alligator” helicopters. These Russian-made attack helicopters were the first production non-fixed wing aircraft to feature a contra-rotating coaxial rotor system, employing a pair of rotors mounted one above the other on concentric shafts with the same axis of rotation, but turning in opposite directions (contra-rotation). This configuration affords several serious advantages in an airframe application, the most significant of which is the elimination of torsional forces.
Helicopters using a conventional single set of rotor blades exert a tremendous amount of torque (rotational force) on the helicopter fuselage. This torque causes the fuselage to rotate in the direction opposite the direction that the rotor blades turn, resulting in the necessity for a second rotor, the anti-torque, or tail, rotor. This second rotor’s sole purpose is to counteract the main rotor’s torque, opposing and countering, not defeating, the tendency for fuselage rotation.
Coaxial-mounted, counter-rotating rotors solve the problem of main rotor torque by turning each set of rotors in opposite directions. The opposing torques from the pair of rotors effectively cancel each other. Further, by eliminating the need for the torque-countering tail rotor common to all single-rotor, non-fixed-wing aircraft, up to 30% of the engine’s power can be recovered to the motor’s main purpose, providing greater lift and better maneuvering, with no increase in weight or displacement.
On the greatly reduced scale of our turntable application, the elimination of torque unloads the torsional forces that would otherwise be loaded in the turntable’s suspension system, and, as we shall soon learn, allows for the unleashing of a wealth of fine detail, tonal purity, and resolution that were, in my experience, previously unobtainable.
The Kamov helicopters are a clear analog of the reduction of adverse energy that this two-platter, contra-rotating turntable configuration affords. If, in the larger scale of a non-fixed-wing aircraft, employing just one rotor requires nearly one third of the motor’s power merely to try to counter (but still not eliminate) the torsional forces being transferred into the airframe, imagine the potential damage that might be done by that rather significant, yet unnecessary and undesirable, energy being stored in the suspension of a highly sensitive playback platform like a turntable!
According to Kronos literature, the energy produced by the torsional forces of a typical single-platter suspended turntable manifests itself as a natural tendency for the sub-platter frame to rotate in-sync with the platter. Although this rotation is controlled and absorbed by the suspension springs (or some similar elastic suspension mechanism), with the suspension maintaining this much more highly energized state of equilibrium, the slightest vibration coming from the stylus as it transcribes the LP groove is echoed back to the stylus, but out of phase. This, according to Kronos, results in a blurring and distortion of the stereo image. In essence, critical musical information is permanently destroyed.
An entirely different approach, one that has wantonly abandoned the more widely accepted suspended design methodology championed by a large number of manufacturers, favors building massive, rigid turntables, completely devoid of any suspension system whatsoever. Seemingly endless research into, and application of, alternative constituent materials has further elevated the sonic performance of this group of mass-based turntables. My reference Redpoint Model D is a prime example of this kind of thinking, and, overall, is a highly effective approach, especially in the lowest octaves.
But such “suspension-less” designs are still susceptible to the vibrations produced naturally by other mechanical components and other vibrations disturbing the listening environment. Those sympathetic vibrations can be fed back to the platter and tonearm, causing yet another type of blurring and distortion of the music signal, one often perceived as having a harsh, aggressive, and edgy sonic nature. As you may have come to realize, both approaches have their own set of advantages and detriments. Like everything else in our hobby, it often comes down to a choice of compromises that are least offensive to the individual listener.