The Monaco is unequivocally a work of art. It must be understood that record grooves contain only amplitude information and no frequency information. The frequency information of the record is generated by the speed turned by the playback device. Any deviations, changes or errors in the speed accuracy during playback will change the pitch of the signal retrieved by altering its recorded frequency. Simple fact, the more accurately you turn the record the more accurate the frequency/pitch is reproduced and hence the lower the level of distortion and the greater the level of realism. This is why Grand Prix Audio viewed superior speed control essential to assuring superior playback performance. I have always touted this concept with regard to my KAB Modified Technics SL-1210 MKII. The most acclaimed designs in both cutting lathe and playback turntables have one thing in common; they feature direct drive.
The industry has so maligned direct drive that a person would be led to believe that it is impossible to produce good sound without a belt drive and big, bulky, heavy, and complicated contraptions. With careful study of the problem one quickly learns a very different lesson. In fact, belt drive is a hopelessly flawed method of turning a platter, because it cannot maintain a constant and perfect speed. This may be the reason the state-of-the-art in turntables has remained underdeveloped and far from its zenith even after more than 50 years. The designers keep trying to make a fundamentally flawed design do something it simply cannot, which is to deliver a highly consistent and accurate platter speed. The current turntable designs simply do not maintain a consistent speed when measured at the platter.The Monaco's drive system uses a Digital Signal Processing (DSP) controller coupled to an optically encoded feed back loop to monitor and control the motor. It features an encoder disc with over 4,700 individual lines. The DSP system makes individual speed measurements and speed adjustments (if required) over 4,000 times a second. The system makes extremely sensitive adjustments to the energy being feed to the motor in a way that will maintain unparalleled speed accuracy. The system operates on a nominal 5 volts DC.
Grand Prix Audio found a suitable motor configuration in the high tech world of computer chip manufacturing where motion control on the order of tenths of thousandths of an inch is an every day reality. Their motors were derived from these applications and are manufactured and hand wound to their specification and are made in the USA. The DC motor has 12 poles with a high tech ceramic magnet rotor and incorporates Hall sensors. Because the DSP controller knows the position of the rotor relative to the stator at any point in its rotation (via the Hall sensors) it can commutate the motor in a manner that eliminates any torque variation as the magnets pass from pole to pole. The result is a running motor that is dead smooth; all ‘notching’ has been eliminated.
The heart of the Monaco Turntable is the unique drive system. Its soul is the computer control module. It is the DSP processing which occurs inside this module that makes this extraordinary speed control possible. The DSP controller runs at 40 million instructions per second (40 MIPS) and is specifically optimized for precision motor control applications. The control module receives and processes the encoder signal and adjusts platter speed, as needed, over 4,000 times per second. The control module interface features the power on/off button, the speed select switches for 33 1/3 and 45 rpm, and the speed trim and display that allow for adjustment of the set speed in increments of .2% in 5 steps above or below the nominal speed setting. The power cord is installed into a socket on the control module. An umbilical cable leads from the control module to a 16 pin Lemo connector termination. This is plugged directly into the female Lemo connector in the turntable plinth. The control system is factory upgradeable by laptop computer enabling future potential performance updates.
To ensure the drive system is adequately isolated from the platter stylus interface, requires a different approach to the bearing design. There are two loads to consider; the vertical thrust load required to support the mass of the platter (including the stylus load) and also and more critical the horizontal rotational loads of the platter and drive system. The common platter bearing design is high tolerance bushings and shaft type bearings. Unfortunately, even the most carefully manufactured version of this bearing will have mechanical contact and thus noise and friction.
Grand Prix Audio decided that the best way to solve this problem was to immerse the entire platter spindle/bearing assembly in an oil bath. This allows a film of high pressure oil to develop that eliminates any mechanical contact. This design uses the motion of the platter itself to create the pressure required to support the spindle. The motion of the platter spindle in the bearing creates adequate oil pressure in the close tolerance assembly to separate the platter from the spindle bearing with a cushion of oil. This also offers extraordinary damping. The oil volume is constantly in circulation from the base of the spindle bearing up the shaft and out the top to fall by gravity back to the sump below. This is an elegant solution to the bearing problem. Simple, elegant, and absolutely optimal, it ensures NO MECHANICAL CONTACT in the horizontal plane whatsoever by any components. Further, it is maintenance free and requires no special set up. It is simplicity itself. Nothing can be quieter than no mechanical contact, nothing. It also offers extremely favorable damping and energy management compared to more complicated approaches.
The platter spindle is a high alloy stainless steel shaft that rides in the solid single piece phosphor bronze bearing / mount structure. The vertical thrust load is carried on a coaxially located high precision silicon nitride ceramic ball bearing that rides on a bearing pad made of a proprietary hybrid alloy. A damped support rod,
independent from the platter bearing and spindle, provides vertical support for this assembly. The thrust bearing assembly and support shaft are also fully immersed in oil.
The drive system of the Monaco design does not require a large mass because the drive system is inherently stable and accurate by itself. Thus large amounts of inertia and mass are not needed to manage speed stability. Speed accuracy is ensured by means other than flywheel effect. It is also true that a large mass is not required to
manage the energy of the stylus upon the record. Adding more mass will not improve speed accuracy; it
simply makes no difference beyond a certain point with this type of drive system.
The Monaco Turntable plinth is constructed from solid laminate of carbon fiber cloth pre-impregnated with toughened epoxy resins. This carbon “pre-preg” material is the same type used in Formula One cars and jet fighters. The carbon pre-preg cloth is as many as 20 layers thick and is applied in various directions, to best take
advantage of its properties. It is laminated into a highly polished, high precision solid aluminum mold. This is then cured at 250 degrees Fahrenheit and 250psi while under vacuum. Each individual plinth structure takes several days to construct. It is comprised of separate upper and lower sections that are bonded together with internal hard point features. It is filled with a proprietary polymer combination to improve its energy attenuation. The completed structural assembly is then CNC machined to exacting tolerances in excess of +/- .001”. This plinth is unrivaled in its unique combination of strength, stiffness and damping properties.
Summing up some of the Monaco’s key features:
• Direct drive with no mechanical contact in the horizontal plane. The lowest noise drive and bearing
design architecture possible.
• DSP controller with an active feedback loop measures and controls the speed of the platter directly to
yield the most consistent and accurate playback possible.
• The DSP control system is checking speed 4,000 times per second (7,200 times each revolution at 33-
1/3 and 5,333 times each revolution at 45 RPM) and making corrections as required.
• Speed accuracy of better than .002% from absolute when measured with 3 sigma protocol.
• No Mechanical Contact platter bearing. It is a passive oil immersion hydrodynamic non-mechanical
contact bearing. It has absolutely no mechanical contact in the horizontal plane thus, providing the most
noise free bearing possible.
• A vertical thrust bearing that is separate and isolated from the spindle bearing and drive system. This
ensures rock solid platter control under all conditions. It uses a high tolerance high sphericity silicon
nitride ceramic ball riding on a hybrid alloy bearing pad.
• An enormously rigid plinth made of carbon fiber composite coupled with Grand Prix Audio exclusive
internal damping. It is truly a 21st Century plinth, high rigidity combined with extraordinary damping in a
single structure.
My friend was using a Triplanar Tonearm and an Airtight PC-1 Supreme Cartridge and the sound was "Superb". Of all the tables available today, if I had the financial wherewithal, this would be my choice. There is an old adage that says: "A thing of beauty is a joy forever"............The Grand Prix Monaco Turntable.