Michell Engineering’s flagship turntable, the Orbe, continues to receive acclaim the world over. The Michell Orbe turntable takes the established concept of the GyroDec to greater heights, adding to it an extra level of isolation, better structural damping, and an improved motor drive system. As of January 2004, the motor controller employs the revolutionary Never-Connected mains isolation circuit.
– Double chassis, suspended pendulum subchassis
– Damped subchassis
– 60 mm thick massive acrylic/vinyl platter of high inertia
– Screw-down record clamp, compatible with standard and 180g audiophile pressings
– Inverted oil-pumping bearing
– Custom arm boards available for most tonearms
– High-quality standalone DC motor with tacho feedback speed control
– Orbe Controller NC motor power supply with Never-Connected circuit
The task of a turntable seems to be simple. At audio frequencies, the tonearm should be kept locked above the groove, without any extraneous motion relative to the cartridge. And the groove should be dragged at a constant angular speed underneath the stylus. This means that over the whole frequency band of 10Hz up to 20kHz and beyond, the whole loop made by record, platter, bearing, (sub)chassis, arm board, tonearm, and cartridge body should behave in an utterly rigid and non-resonant fashion. Any flexing of the same dimensions as the microscopic undulations in the groove detracts from sonic fidelity.
At lower-than-audio frequencies, the tonearm should be made able to freely follow the groove’s warps and excentricities, so as not to damage LP or cartridge, and this without inducing any spurious signals into the cartridge’s generator. Only when these demands are fulfilled can the stylus trace the actual information embedded in the record’s groove walls.
LP records are warped. They vibrate along with the music as the stylus traces the groove and tend to move and bend under the pressure of the arm and cartridge when they are insufficiently supported. Michell turntables clamp the record to a hard platter. This flattens out warps, and it also couples the LP tightly to the platter so that internal resonances can be drained away from the stylus, as if the LP effectively is of a much higher thickness and rigidity.
The Gyro SE and GyroDec models use a simple clamp to press down the LP record; the Orbe and Orbe SE benefit from a more advanced screw-down clamp and a washer that raises the LP at its center: under action of the clamp the record’s playable area is then very tightly pressed down onto the flat platter, right to its edges.
Michell make the platter from a proprietary self-damping compound of carbon/vinyl-loaded acrylic. This material closely approaches the mechanical and acoustical properties of the vinyl record itself, enhancing the coupling between both. Indeed, at boundaries of materials with like acoustic impedances, transmission of vibrational energy occurs. Whereas at boundaries of dissimilar materials, be they LP versus felt, metal, glass, or just air, only part of the energy is transmitted, the remainder being reflected back into the album, towards the stylus.
Above measures not only result in a neutral and precise sound, but also in a very low susceptibility to record blemishes, ticks and pops. This is one of the reasons why a Michell Engineering turntable not only excels in the replay of good LP’s, but also pulls the same trick with less than pristine records.
The platter should be supported so that it can revolve smoothly, without any extraneous vibrations and motion. This is the job for the main bearing, the very heart of a turntable. Michell employ a unique inverted bearing that locates the point of rotation above the center of gravity of the platter, and exactly at the height where the drive belt invokes. This makes the platter/bearing a self-stabilising component that cannot be provoked into rocking modes.
The precision bearing has a case-hardened steel shaft that is secured upright in an oil well, threaded into the subchassis from below. A massive bronze housing, precision-machined as a pair with the shaft, is attached to the platter via the integral record spindle. A thrust ball sits on the flat top of the shaft centralized by an inverted cone in the top of the housing. This housing has a spiral machined into its inner bore to draw a high quality synthetic oil from the bath to the top of the bearing shaft as the housing rotates with the platter. A hole is drilled from the top of the shaft down to the oil well to allow the trapped oil to return to the bottom. This unique oil pumping mechanism results in low friction and wear, and in low rumble and noise year after year of operation.
The LP/cartridge/arm trio is to reside on its own ‘island’. The suspension decouples them from the outside world with its motor noise, footfall, acoustic vibrations, and other potential disturbances. All Michell turntables, except the TecnoDec, suspend the heavy subchassis and platter from three extension springs. This is an elegant and self-stabilising solution as the center of gravity of the floating mass is conveniently put below the suspension points.
Rocking and nodding modes of the subchassis are hence discouraged, while overall turntable setup is straightforward, and drift is virtually inexistent. In addition, the total suspended mass of about 11Kg ensures that any incoupled energy can not result in large displacements.
The spring towers double as the actual turntable supports, terminated in heavy aluminium cones. The towers are sectioned in two vertical parts, making a high-pressure point-contact with a bearing ball. This makes for a true three point support, which gives the springs and the suspended subchassis a firm reference to ground.
The floating chassis’ task is to keep the bearing and arm board rigidly in relation to each other. It is a heavy and rigid cast aluminium component, internally strengthened with beams and ribs. The Orbe and Orbe SE benefit from an additional layer of DensoDamp mastic which results in an acoustically inert subchassis with excellent self-damping properties.
Offering a wide range of custom-made arm boards, Michell can keep the mass, and the mass-distribution, of the subchassis, platter, and arm a known constant. This translates into a suspended chassis turntable that works optimally with almost any existing tonearm.
The most obvious task of a turntable is to keep the record at a constant and precise angular speed, without low-rate drift, without audible wow, and without high-frequency noise components which detract from the music’s delicacy.
The 3.5Kg heavy platter, precision balanced, acts as a large flywheel. The Orbe’s platter is made of three GyroDec platters bonded together to form one massive slab of acrylic. The GyroDec and Gyro SE employ a single-thickness acrylic platter, loaded with the gold-plated brass weights which over time have become Michell’s signature. Once up to speed, and aided by the low-friction bearing, the platter only wants to maintain its motion, and not much extra input from the motor is needed.
This motor is a very precise, reliable, and low-noise DC motor that has been selected only after extensive listening sessions and reliability tests. The Orbe models use a version of the same motor with a tacho speed control loop back to the supply. With all Michell turntables, the motor is a stand-alone unit, housed in a heavy base of metal (almost 3Kg for the Orbe), to elimate vibrational breakthrough to the turntable. The HR and Orbe Controller NC supplies effectively isolate the motor from the potentially poluted mains network.
Drive is relayed to the platter via a precision-ground soft round-section neoprene belt, which runs around the platter’s circumference. This results in a very high reduction of noise transfer from the motor.