REFERENCE TURNTABLE / Nagra



REFERENCE TURNTABLE

DRIVE UNIT

The heart of the Reference turntable is its motor drive system. For some time, it has been recognized that multi-motor drive systems enhance the speed stability of a turntable's rotating platter. The Reference turntable employs dual high precision, Swiss made, decoupled, brushless DC motors. This arrangement optimizes both torque and speed accuracy. This massive motor drive system weighs 11.2 kg/24.6 lb. Expect additional details once the patent process is underway.

SPEED STABILITY

In addition to the innovative two motor system, the turntable features a well thought out technology for absolute speed calibration. An accelerometer monitors the floating chassis to ensure that it is absolutely stable otherwise calibration does not take place. Calibration is done over a 20 second window during which time the platter's speed is precisely calibrated during actual playback (stylus in groove). During this 20 second cycle the platter's speed is compared with a high precision quartz reference. Any deviation from this absolute speed reference is corrected accordingly. An easy to read, distinctly Nagra Modulometer on the turntable's front control panel makes calibration (and pitch control) simple. During listening no active speed control is employed. While listening, the motors are only running in a closed loop mode. By eliminating active speed control the "cogging" and associated ill effects on image stability generated by such active systems is avoided.

REEL TO REEL INSPIRED BELT SYSTEM

Attention to detail even extended to the belt used in the motor drive. For this essential part we took inspiration from the iconic Nagra IV-S tape machine. Because the original supplier of these belts is no longer in existence, we undertook a chemical analysis of the belt composition and have faithfully reproduced this high performance part. We have decided to pay tribute to Nagra's analog recorder legacy by calling Nagra's LP drive "Nagra IV – LXX caliber".

AEROSPACE MATERIAL PLATTER

The Reference turntable/tonearm system employs a heavy, phenolic damped, CNC machined, aerospace grade aluminium platter featuring an Alcantara surface providing an ideal platter-vinyl interface.

PRECISION MECHANICS BEARING

Beneath the platter is a sub-platter and shaft/bearing system whose most notable features include a subplatter machined from high strength aluminium. A phenolic interlayer is applied atop the sub-platter for resonance decoupling. The transition from sub-platter to the shaft/bearing system is accomplished via a machined brass adapter which is re-machined in mounted form for tightest tolerances. The shaft/bearing housing is machined from spheroidal graphite iron. The ultra precision shaft is fabricated from induction hardened steel which is subjected to a centuries old watchmaker's super finishing procedure. The shaft bushing is machined of sintered bronze and high temperature/pressure impregnated with oil for maintenance-free operation. The bearing is comprised of stacked carbide balls which have been subjected to the highest polish grade possible.

CHASSIS AND SUB-CHASSIS

Non resonant chassis - The backbone of the Reference turntable can be considered the chassis and sub-chassis. In this case, massive plates of aircraft grade aluminium and phenolic have been precisely CNC machined to form a low resonance, high rigidity, layered structure of aluminum/phenolic/aluminum preventing sound coloration from the system's mechanical parts.

Floating suspension - Integral to the performance of any ambitious turntable system is its suspension. In this case, Nagra engineers devised a unique solution which outwardly mimics the suspension systems of both our HD PREAMP and HD DAC X. Internally, however, is found an ingenious system combining both mechanical and hydraulic principals. The substantial suspension pillars employ both a spring mechanism and a highly viscous fluid contained in a "diver/chamber" configuration which, when combined, provide suspension and displacement in three dimensions.

This innovative system provides unparalleled resistance to both self-generated and room/airborne vibrations and resonances. To ensure stability of the floating suspension, the plane on which the suspension functions is as close as possible to the plane of the LP playing surface thus, the "form follows function" height of the suspension pillars. Proof of this concept and its implementation included testing with a high performance, deep bass capable loudspeaker played loudly within centimetres of the turntable as it played an LP. The result was absolutely no breakthrough of vibration or resonance transmission to the highly sensitive cartridge/tonearm interface. Lab measurements confirm a self-resonance of the suspended chassis of less than 3Hz thus guaranteeing freedom from coloration or feedback even at significant listening levels. Overall levelling of the Reference turntable is easily accurately accomplished by rotating the massive threaded feet of the suspension pillars.

POWER SUPPLY

Nagra has always paid obsessive attention to the power supplies of all of our products. The Reference turntable's power supply is clear evidence of the significance that our designers place on this critical contributor to performance. An external, HD sized chassis houses a linear power supply featuring an oversized medical grade transformer and ultra low noise regulators providing a quiet, stable supply to the massive super-cap drive unit.

REFERENCE TONEARM

The Reference turntable was designed as a system. This means that the turntable and its tonearm were designed to work from the "ground up" as a unified playback system. Careful consideration was given to the development of a tonearm with performance capabilities commensurate with the turntable itself.

Dual concentric carbon fiber tube

The Reference turntable's tonearm wand is a dual concentric carbon fiber including an intermediary layer of wood. The wood is used to form shape as well as to eliminate potential vibration. The result is an ultra rigid, extremely low resonance platform for both the cartridge connection and bearing mounting. The arm is a single 10.5" piece, meaning that there is no separate head shell (and concomitant deleterious joint). This eliminates the additional electrical and mechanical connections and resonance point that necessarily accompany a two part headshell/arm wand. The tonearm's bearing is a simple, extremely precise, CNC machined, hardened steel cone captured in a resonance isolating, silicone damped, ultra high density polyethylene receiving cup. The tonearm's traditional counterweight is supplemented by a low hung, saddle shaped weight providing stability while minimising the tonearm's effective mass.

Leonardo da Vinci is oft quoted as saying that simplicity is the ultimate sophistication. No truer proof of this axiom is demonstrated than by that fact that the Reference turntable's tonearm is comprised of only eight parts. But for the arm wand itself, all other components in the tonearm were designed by the Nagra team and manufactured and assembled in Switzerland in accordance with the highest standards of Swiss precision.

Watchmaker precision adjustment

Precise alignment of stylus geometry in an LP's grooves is critical. A sophisticated magnetic antiskating mechanism was designed to achieve this goal. Unique in its design and execution, a patent will be pursued for this masterpiece of engineering. Extensive listening tests of multiple geometries and materials led the Nagra design team to an OCC copper cable for the tonearm's internal wiring.

Vertical tracking angle of the cartridge is an extremely important alignment parameter. Users of the reference turntable/tonearm will enjoy the ability to easily and repeatably adjust VTA "on the fly". An oversized, high precision, rotary collar facilitates smooth, exactingly fine adjustments, as with a precision camera lens. This system permits up to 10 mm/.4 in. of vertical travel.

Cartridge azimuth adjustment is facilitated by a simple yet ingenious eccentric portion of the tonearm which, via an accompanying dial, permits precise adjustment of this critical parameter.

For those who wish the option to employ a different tonearm, the Reference turntable can be ordered without a tonearm. Custom armboards for a variety of tonearms can be manufactured in-house.

PURE COPPER WEIGHT

The record weight included with the turntable was also the focus of intensive research and listening tests. Numerous permutations of materials and shapes were studied before a final combination of material and shape were settled upon. The result is a compact but heavy copper weight in a distinct form factor.

The Reference turntable is an analog product governed by immutable laws of physics and mechanics, very much like Nagra legendary reel to reel recorders. As such, it is not subject to the rapidly progressing and ever-changing developments of the digital domain. This means that the turntable will remain technologically relevant for generations. For many it will be a last turntable purchase and a product which is proudly passed down from generation to generation. Just like many Nagra III recorders from the 50's, which are still in active use today, the Nagra Reference turntable is a product for life.

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