Bergisch Gladbach, Germany | 2020 – Thorens New Reference: Fully integrated active vibration isolation by Seismion.
The Thorens New Reference embodies our pursuit of the ultimate reproduction of music recordings. The turntable’s electrical signals arise from mechanical vibrations of the cartridge stylus as it navigates vinyl record grooves. These vibrations transform into sound waves.
Equivalent mechanical vibrations in the turntable cause distortions and undesirable effects. These vibrations originate from sources like structural vibrations, ambient movements, music-generated sound waves, and the turntable’s own vibrations. To prevent confusion between music vibrations and unwanted disturbances, these must be minimized.
Thorens’ design team, led by Helmut Thiele overseeing the new Reference’s construction and design, accepted this challenge.
The Thorens New Reference is the first turntable ever crafted and optimized from the ground up alongside a comprehensive active vibration isolation platform. Thorens collaborated with the globally respected German firm Seismion, acknowledged for groundbreaking active vibration isolators, to craft a turntable where vibration isolation is an integral system component. Seismion applied its active isolation system expertise, utilized in semiconductor industries and scientific laboratories, to create unprecedented turntable vibration isolation.
The active vibration isolation relies on piezoelectric acceleration sensors with exceptional sensitivity and linear electronic control circuits to produce remarkably low-noise, distortion-free control forces. This advanced mechatronic system utilizes Sky Hook Damping to isolate disturbances below 1 Hz, reducing them to less than 1% (-40 dB) at frequencies above 10 Hz. This outperforms other isolation methods (figure 1).
The active isolation core focus is to achieve unmatched music purity. It tackles vibrations down to nano and pico meters effectively using contactless actuators. The system swiftly follows high dynamic music transitions from soft to loud segments, thanks to active control forces stabilizing the system for near-instant isolation system stabilization. An adaptive leveling system maintains the turntable precisely level within 20 micrometers, complementing the active isolation system.
Impressive Platter Absolute-Velocity-Damping Drive by Seismion
The turntable’s drive unit aims to achieve consistent platter rotation speed precision. This includes absolute speed and modulation around the mean speed, known as wow and flutter.
The Thorens New Reference incorporates a top-notch German-made 3-phase synchronous motor powered by three linear power amplifiers with 120° shifted sine signals. The motor torque is transmitted to the platter via a belt (figure 3). The hydrodynamic bearing optimization uses lubrication theory equations, including the Sommerfeld number, for ideal lubrication film thickness and bearing diameter. A low Sommerfeld number means the bearing centers at low rotation speeds, minimizing wear and ensuring minimal eccentricity and whirl. The hydrodynamic bearing is manufactured and tailored in Germany.
Combined with the innovative active damping system, the belt-driven design presents notable advantages:
1. Unlike Direct Drive systems, the platter is separated from the drive motor by the elastic belt, efficiently utilizing the platter’s high inertia to maintain a steady platter velocity. Additionally, platter fluctuations from the motor are effectively suppressed by the platter/belt’s low pass characteristics.
2. Belt-driven systems may resonate, causing wow and flutter. The platter’s rotational inertia and belt elasticity act as an oscillatory system. The resonance often occurs around 4 Hz but varies based on system parameters. Resonance amplification is observed around 4 Hz, resulting in non-constant platter rotation, known as wow, a highly undesirable effect.
Figure 5 showcases the weighty DIN 45507 or IEC 386 curve, where maximum weighing aligns with the platter/bearing system’s typical resonance. Platter vibrations are induced by bearing friction, non-circular platters, belt irregularities, and slippage necessary for torque transmission. The curve drastically drops for higher frequencies, representing desired platter inertia effects.
The Thorens New Reference leverages Seismion’s advanced active damping system expertise. Dual ultra-high precision quartz oscillators provide platter rotation speed calculation stability of 3 ppm over 20 years, ensuring reliable, long-term speed control.
The platter’s rotation encoder signal is processed by control electronics for absolute velocity damping. This damping resembles highly viscous platter bearings but offers superior advantages:
Active damping diminishes resonance amplification at 4 Hz, maintaining high-frequency drops effectively compared to passive viscous damping methods.
Thorens Latest EditionAn actively damped platter bearing can strive for minimal friction, generating minimal constant braking torque compared to viscous damped bearings.
The low braking moment reduces motor and belt stresses, minimizes disturbances, and extends service life. Active damping doesn’t produce continuous braking torque but dynamic moments eliminating modulation frequencies.
Consequently, the absolute velocity damping system in the Thorens New Reference effectively dampens any frequency modulations to the maximum extent.
The Thorens New Reference supports up to 3 tonearm bases for 9”, 10”, and 12” tonearms, including the TP160 cutting bearing tonearm and the Thiele TA01 tonearm.
The Thiele TA01’s intricate kinematics blends pivoted tonearm precision with tangential tonearm advantages, ensuring minimum tracking error angles across records. The double-walled, gel-filled tonearm tube provides optimal damping for unmatched spatial resolution, extreme detailing, and perfect tonality.
