Thorens New Reference is the result of our effort to achieve the perfect interpretation of musical recordings. The electrical signals in a record player are created by mechanical vibrations of the cartridge’s stylus as it moves along the grooves of a vinyl record. These vibrations are converted into sound.
In exactly the same way, all other mechanical vibrations in the turntable are processed and cause distortion and other unwanted effects. The sources of these vibrations are, for example, the vibrations of buildings, people walking, sound waves from music and the self-generated vibrations of the turntable itself. Since it is not possible to distinguish between actual musical vibrations and parasitic disturbances, they should be avoided as far as possible.
The Thorens design team consisting of Helmut Thiele, responsible for the construction and design of the new Reference, has taken up this challenge.
With Thorens New References, for the first time a turntable is designed and optimized from the ground up together with a fully active vibration isolation system. Thorens partnered with German company Seismion, internationally recognized for its class-leading active vibration isolators, to create a turntable designed around the vibration isolation system as an integral part of the system. Seismion took full advantage of its experience in active isolation systems used for the semiconductor industry, nanotechnology, and scientific laboratories, to create vibration isolation never before seen and experienced in turntables.
Active vibration isolation relies on extremely high-sensitivity piezoelectric acceleration sensors and fully linear electronic control circuitry to generate unrivaled low-noise, distortion-free control forces. This sophisticated mechatronic system is based on so-called Sky-Hook-Damping and isolates disturbances already below 1 Hz and reduces them to less than 1% (-40 dB) at frequencies of 10 Hz and higher. This performance is far superior to any other insulation (figure 1). This figure shows the comparison of the active isolation system – Sky-Hook-Damper – and a high performance Air Spring. Especially at critical frequencies around resonance, active isolation performs up to 100 times better. At 10 Hz, it is still about 17 times stronger in isolation than with an Air Spring. Other shocks, such as rubber mounts, have a much lower level of performance and are not shown in this comparison.
The overall system is designed so that the center of gravity, COG, is close to the isolation plane. In this way, the coupling of horizontal vibrations and tilting movements is considerably reduced (figure 2). Furthermore, the chassis itself is made non-resonant by its layered structure of highly damped materials.
The result of vibration isolation is simply pure music as hardly experienced. The effect goes far beyond simply eliminating footfall vibrations. In fact, even the smallest vibrations in the nanometer to picometer range are still efficiently isolated, due to non-contact actuators. The system also follows music with high dynamics between quiet and loud sequences extremely quickly, as the active control forces stabilize the system and lead to an instantaneous settling time of the isolation system. An adaptive leveling system, which keeps the turntable precisely level to within 20 micrometers, completes the active isolation system.
Drive unit with Seismion’s innovative absolute velocity damping platter
The other fundamental part of any turntable is the drive unit. The ultimate goal is to achieve the perfect and constant rotation speed of the platter. This refers to both the absolute speed and the modulations of the speed around the average value, also called wow and flutter. Thorens New Reference features a high-quality German-made three-phase synchronous motor, which is driven by three fully linear power amplifiers with 120° offset sinusoidal signals. The engine torque is transmitted to the platter by a belt. The hydrodynamic bearing is optimized through the use of theoretical lubrication equations. In this context, the Sommerfeld number is used, which describes the thickness of the lubrication film and the diameter of the bearing. This number is named after the German physicist Arnold Sommerfeld, who conducted several fundamental investigations in the field of hydrodynamics. A small Sommerfeld number means that the bearing is already centered at very low rotational speeds, which minimizes wear and ensures minimal off-center errors such as runout and spin. The hydrodynamic bearing is manufactured and finished by hand in Germany.
The overall system is designed so that the center of gravity, COG, is close to the isolation plane. In this way, the coupling of horizontal vibrations and tilting movements is considerably reduced. Furthermore, the chassis itself is made non-resonant by its layered structure of highly damped materials.
The result of vibration isolation is simply pure music as hardly experienced. The effect goes far beyond simply eliminating footfall vibrations. In fact, even the smallest vibrations in the nanometer to picometer range are still efficiently isolated, due to non-contact actuators. The system also follows music with high dynamics between quiet and loud sequences extremely quickly, as the active control forces stabilize the system and lead to an instantaneous settling time of the isolation system. An adaptive leveling system, which keeps the turntable precisely level to within 20 micrometers, completes the active isolation system.
Together with the innovative active damping technique, the belt-driven approach has several significant advantages:
- Unlike Direct Drive systems, the turntable is isolated from the drive motor due to the elastic belt. Therefore, the high inertia of the platter is used efficiently and helps to passively maintain a constant speed of the platter. In addition, any motor jitter is strongly suppressed by the second order low-pass characteristics of the platter/belt.
- A common disadvantage of belt-driven systems is the potential resonance of the platter, seen as wow and flutter. The rotational inertia of the platter forms together with the elasticity of the belt an oscillatory system. The resonant frequency is usually about 4 Hz, but it depends on the actual values of the system parameters. The orange plot shows a peak around 4 Hz, where all disturbances are strongly amplified. This means that the rotation speed of the platter is no longer constant, but modulated with 4 Hz around the average speed. This effect is known as wow and is highly undesirable, especially since the human ear is more sensitive to this frequency range. Platter vibrations are mainly caused by friction in the platter bearing, a non-perfectly circular platter, belt irregularities, and slippage between the belt and the platter, which is necessary to transmit engine torque. The orange graph drops sharply for higher frequencies. This is the desired effect of the inertia of the platter.
The Thorens New Reference features an innovative and highly effective active cushioning system from Seismion. The deep knowledge and experience with sky-hook damping systems featured in the “Reactio” active vibration isolator is used for the platter’s new approach to active damping.
The platter rotation speed calculation is based on two ultra-high-precision quartz oscillators with a long-term stability of max. 3 ppm for 20 years, allowing for safe cross-checking and reliable speed control for the life of the New Reference. In fact, it means that the absolute speed remains within a range of 33.3332 to 33.3334 rotations per minute for 20 years.
The signal from the high-precision rotation encoder, which is mounted on the platter shaft, is fed to the control electronics, which performs absolute velocity damping of the platter. The effect could be likened to highly viscous platter bearings, commonly used in belt-driven turntables. However, the active damping system designed for Thorens New Reference has several advantages compared to passive damping techniques performed by viscous disc bearings:
- Active damping reduces resonance amplification at 4 Hz and maintains the sharp decay at higher frequencies, while a highly viscous platter bearing has a negative effect at higher frequencies, as the graph does not decay as sharply and the effect of inertia of the platter is not used in the best way.
- The active damping effect can even be increased much more than by passive means.
- The platter bearing can be designed to have as little friction as possible, since damping is actively generated. As a result, this bearing only generates a minimal constant braking moment, in contrast to a viscous damped bearing.
Due to the low braking moment, the stresses on the motor and the belt are significantly lower. Therefore, all disturbances are minimized and the service life is also improved. Active damping does not create any constant braking torque, but only dynamic moments to eliminate modulation frequencies.
As a result, the absolute velocity damping system in the Thorens New Reference efficiently absorbs any frequency modulation to the highest possible level.
Finally, also the active isolation system explained in the previous section also contributes to a better performance of Wow and Flutter, since it stabilizes the entire subframe on which the platter is placed.
The Thorens New Reference can be fitted with up to 3 tonearm bases and can accommodate 9″, 10″, and 12″ tonearms. In addition to the newly developed TP160 cutaway tonearm with a length of 12″ inches and continuous silver wiring, the Thiele TA01 tonearm is also used.
The complex kinematics of the Thiele TA01 combines the precise and rigid guidance of a rotary arm with the advantages of a tangential arm. This design guides the capsule with a maximum tracking error angle of 0.036 degrees along the length of the disc. The tonearm tube is double-walled and filled with a 2-component gel for optimal damping. The result of this design is unique spatial resolution, extreme detail, and perfect tonality.
We are very proud to present this world innovation for the 140th anniversary of Thorens during the High-End Show in Munich, says Thorens owner and CEO Gunter Kürten.
