Some Insight into the Design of the Merrill-Scillia Transcription Table

A record playing system consists of a record and four mechanical parts: the turntable, tone arm, cartridge and mat. Any alteration or change of any part comprising the system will change the sound characteristics of the whole.

Two elements are brought together when playing a recording: the recording and the stylus. The stylus is controlled by the cartridge, and in turn the cartridge is controlled by the tone arm. The record and the tone arm/cartridge are controlled by the turntable and the mat. We have found, through experimentation, the four key ingredients in an excellent turntable design. These key ingredients are the ability to absorb and dissipate:

(1) arm release energy
(2) record resonance energy
(3) airborne acoustic energy
(4) low self generation of noise

If all of these criteria are met, the turntable design is excellent. Turntable design can vary drastically from one manufacturer to the next. This does not mean that one design is better than the other. The only true definitive of the design is the sonic product. Most good turntable designers have addressed themselves to the problems of record resonance damping*, mechanical and airborne acoustic breakthrough damping, and internal noise generation. However, we have found that most turntables fall short on the ability to absorb and dissipate arm release energy (a term coined by us). In other words, the cartridge transfers its energy to the tone arm and this energy must be absorbed and dissipated by the tone arm mounting system or it will wind up as a standing wave. The MS turntable alleviates this problem.

*Damping - the ability to stop vibration. Damping is a product of mass, material density, and material type. These factors will determine the amount and frequency band of energy that will be absorbed.

The design criteria of a turntable should be such that the turntable becomes an entity within itself - thus being non-sensitive to tone arm, cartridge, and mat.

The Major Parts of the Turntable - An Explanation of Design

The Sub Chassis - The Heart of the Turntable

The sub chassis is the support system for the tone arm and the platter. The overall design envelope must start with one major objective in mind to absorb release energy from the tone arm. Sheer bulk of the sub chassis or platter for that matter is not the answer. (See paragraph on sub chassis weight.) We have found that tone arm release energy can only be absorbed by rigidly coupling the arm mounting, in other words, making it a non-removable part of the sub chassis. This rigid coupling eliminates any possibility of an energy transfer barrier and provides a consistent molecular media for dissipation of energy. When two types of materials are used in the sub chassis construction there inevitably is a molecular barrier formed which will not allow smooth transition of energy from one type of material to the other, such as hardboard or a plastic arm mounting platform attached to a metal sub chassis or visa versa. The MS sub chassis and bearing housing is manufactured from only one type of material, a compound which we first determined through written research and specifications then through our own experimentation. This material will absorb energy in the audio band whereas other materials were lacking this ability. This material is also known to be stable across the entire HZ frequency range. Energy that enters into the sub chassis can be dissipated by the sub chassis. The type of Ter polymer compound used, as well as the size and density of the sub chassis was determined by implementing further experimentation on our part. Another important design criteria is the fewer the spring suspension points the less energy inlets into the sub chassis. We are the originator and only manufacturer to make a true one-piece sub-chassis which consists of the sub-Chassis itself, the bearing body and the tonearm mounting boss. The MS uses a three point equal tension spring suspension sub chassis. To have the least amount of energy inlet, a suspension design utilizing one spring would be ideal, but design and manufacturing complications hamper this type suspension. Finally, three spring points will give a tripod effect allowing even weight distribution.

A Comment Regarding Sub Chassis Weight and Energy Absorption Capability

The neophyte tends to think that the heavier the sub chassis is, the better the turntable. If this were true, then our suggestion would be to buy a heavy unsuspended turntable and mount it on three springs. However, what makes a sub chassis good or bad is not the weight but its capability to absorb and dissipate energy in the audio band. This energy will enter from three main sources; arm release energy, spring inlet energy, and airborne energy. Ability to absorb tone arm energy is controlled by the quality of coupling between the arm and the design dimensions of the sub chassis, as well as with the type of material used in the sub chassis construction. We have found that a coupling of ultra high integrity from the sub chassis to the arm is of absolute importance; therefore the MS turntable does not employ a removable arm mounting board. The MS sub chassis is designed to absorb "release energy" (a term coined by us) emitted from the tone arm.

The Constant Resonant Tuning System

The MS turntable was designed to have approximately equal effective mass distribution above and below the spring suspension points. A unique Constant Resonant Tuning System allows the sub chassis to accommodate virtually all tone arms. The springs utilized at all 3 points on the sub chassis are of the exact same rate. The reason behind this design utilizing equal compression rate springs is to always have equal and consistent compression force. This allows the sub chassis to absorb spring inlet energy to a very high degree; because the band of frequency allowed to enter the sub chassis is always known. Also equal spring rates make set-up very easy. The tuning system is capable of shifting weight to any spring in order to achieve total equilibrium of the sub chassis and maintain a constant resonance. The sub chassis resonant frequency remains the same (constant) with the use of any tone arm up to 3 pounds.

The Motor

The MS uses a proprietary 24 pole synchronous motor with enough torque to pull the platter up to speed in less than 3 seconds. This motor is surrounded by a fluid bath to absorb impulse energy. Why a synchronous motor? There are over 120 power impulses per one platter revolution. These impulses are small and easily absorbed into constant torque. Speed accuracy is excellent. The power supply frequency becomes the speed regulator. Remember the wall clock in the kitchen that kept time within a minute or two a month? It used a type of synchronous motor.

Fluid Damped Motor

A fluid, with a high viscous index (325), surrounds the motor to damp resonance peaks created by impulse torque.

Impulse Damping Motor Pod

All motors produce a certain amount of vibration energy. This energy, if allowed to couple into the sub chassis will cause coloration. The motor pod helps to absorb and dissipate this induced vibration. The motor pod also functions as a magnetic energy trap to reduce the magnetic field surrounding the motor.

The Platter System

The platter system is responsible for helping to damp record resonances, and absorbing any energy transmitted through the spindle. The MS turntable uses a two piece platter system - the driven platter (inner platter) with bearing spindle and the record support platter (outer platter). The MS does not drive the outer record support platter directly with the belt.

Why a Two Piece platter System?

Reason One: The two pieces when placed together, damp each other. This is of great importance in order to help damp the record, the platter itself must be well damped.

Reason Two: Platter systems that are driven via the record support platter have an inherent problem. Impulse energy generated by the motor is transmitted through the belt and in turn transmitted directly into the platter carrying the mat and record. By driving an inner platter, a platter system can be designed to absorb and dissipate belt transmitted energy before it reaches the outer platter that supports the mat and record, thus giving a much lower intrusion of impulse energy noise into the musical signal. To further damp the platter system a lead coupling is used to couple inner and outer platter.

Reason Three: Many manufacturers are driving an acrylic record support platter directly. Turntables that drive this style of platter directly cannot have reliable speed accuracy. The speed accuracy varies because the acrylic expands and contracts many thousandths of an inch over normal room temperatures ranges. The MS however, employs a driven platter cast from a proprietary aluminum resin compound that is diametrically stable through a wide temperature range. Remember, the smaller the diameter, the less diametric change. Acrylic as well as other like materials are extremely diametrically sensitive to temperature changes and humidity and are thus unfit as a driven platter.

The record support platter, is manufactured from a Co polymer compound for optimum energy absorption. A double coating of lead is applied to the acrylic, acting to help absorb record energy. A thin coating is applied to the lead to enhance the coupling impedance efficiency. The periphery clamping ring is constructed from a metal alloy since it is handled a good deal by the operator and therefore needs to be strong and durable. The edge shape of the periphery clamp is designed to absorb energy.

The Spindle

A stainless steel spindle with a small hardened thrust ball is used. The spindle contacts a ball of almost five times the size which provides a very small contact area and results in extremely low friction. Since no sonic difference was found when the thrust ball was placed on the top or the bottom of the spindle, we placed it at the bottom so that an ultra quiet oil well type bearing could be used.

Sub Chassis Bearing

A bronze alloy oil well type bearing and a thrust ball are utilized. This type bearing allows the spindle to ride on a cushion of oil, proves to be ultra quiet, has an excellent life, and has the ability to handle hundreds of pounds of weight. The alloy used to manufacture the bearing sleeve is not an oil impregnated bronze or a general alloy but a special alloy used throughout the Aerospace industry in such applications as helicopter rotor shaft sleeves. This special alloy possesses a fine micro grain structure as well as high tensile strength and wear properties and is virtually indestructible.

The Bearing Oil

We have developed a special (black) oil for use in the turntable bearing. With a shear strength of over 100,000 pounds per square inch, this high viscosity oil gives the platter some viscous damping effect, and helps in maintaining low impulse transmission of input torque.

The Springs

After extensive experimentation with extension springs and compression springs, we chose the compression type for two reasons:

(1) Unlike the extension type, the compression spring's rate of progression is much higher. This fact helps our design to damp unwanted oscillations of the sub chassis. And,
(2) access to the sub chassis and complete set-up are all easier.

This being said, there are still many inherent problems that plague spring suspended turntables throughout the industry.

These problems include:

(1) The need to rotate the spring to find the level spot when leveling the suspension.
(2) Side deflection due to uneven loads.
(3) Coil bind due to excessive loading of the suspension.
(4) Uneven and non repeatable compression rate.

We have chosen to solve these problems. And with further experimentation using 3 D modeling and spring geometry software, we have devised a new concept in spring design termed - a "Machined Spring".

These springs are manufactured from solid round stock. The coil thickness and diameter are calculated to support a certain amount of weight and compress evenly and repeatably which translates into a spring that emits a consistent HZ frequency. The springs are guaranteed not to experience coil bind at full compression with a min. gap of .015" between coils. Side deflection is eliminated by utilizing dual start coil geometry. The ends are flat and parallel to each other as they are a machined surface so this in effect eliminates rotating the spring to find it's flat spot in relation to leveling the suspension.

The classic suspended turntable has just been made extremely easy and reliable to set up. There is also a great improvement and stability in sound reproduction.

Periphery Record Clamping System

The MS has a unique record clamping system unlike any turntable on the market. The MS has a large, oversize platter that the record rest's upon. An outer periphery, gravity clamping ring is placed over the record and holds the outer edge of the record firm against the mat - something no inner clamp can achieve by itself.

The periphery clamping ring is constructed from a metal alloy since it is handled a good deal by the operator and therefore needs to be strong and durable. The edge shape of the periphery clamp is designed to absorb Energy.

An inner clamp is used in conjunction with the outer periphery clamp. The combination of inner and outer clamps allows for equal distribution of force across the entire record. This unique clamping system makes an astonishing difference in sonic quality.

Record Mat

The MS comes with a built in lead mat with an impedance matching coating, and a recess for the record label.

Tone Arm Cable Mounting System

The MS comes equipped with a system designed to accommodate most all tone arm cable routing. We are at this time the only manufacturer in the industry doing so.

The cable strain mounting system mounts on center with the tone arm mounting boss on the back of the plinth (base). It is important with all turntables that vibrational energy collected on the cable is terminated before it reaches the tone arm. And on a suspended deck, that the tone arm cable not affect the travel or bounce of the sub chassis.

If a tone arm is used with wiring exiting out of the arm and over the back of the table, the cable or individual wiring can be held taunt and positioned correctly with one or two of 5 different diameter holes. The dust cover is equipped with an access hole on center with the mounting boss to facilitate the through put of tone arm cabling. If there is a case of wiring that has to be routed down through and out the rear of the plinth (base), a blank off access plate can be removed, which is also located on center with the tone arm mounting boss at the rear of the plinth (base). The cable strain then can be relocated to the lower position to hold the wiring. If there is a case of an SME type arm used with RCA cables running directly into the arm, this system will accommodate this type of wiring. If there are single wires that need to be soldered to RCA connectors, the blank off plate has provisions for a set of Cardas GRFAL thin female RCA bulkhead jacks. There are counter bores located on the back side of the plate to fit a socket for securing the nuts. If the tone arm uses a conventional DIN connector and cable, then the cable can be routed and secured with a p-clip supplied and attached to the inside of the plinth (base) and routed out of an access hole located at the bottom center of the plinth (base).

Screw Down Center Clamp

The reason for not using a screw down center clamp in the past is energy that is transmitted from the motor via the belt into the platter system is also transmitted into the spindle. With a clamp that attaches tightly to the spindle this constantly present energy is drawn from the spindle, fed through the clamp and dumped into the record. After a long period of research we have designed an inner drive platter that utilizes a material having a resonance bandwidth that will compliment our center clamping system. Using the screw down center clamp, the chain of energy transmitted events will be as follows; Portions of the bandwidth of energy that is fed from the motor through the belt into the inner drive platter will be damped by the platter material. The remaining energy will be fed into the spindle. This energy, in turn is fed into the clamp. The clamp itself is designed in a manner that the remaining bandwidth of energy that is dumped into this clamp will be absorbed completely before it radiates into the record. Therefore, what we have achieved is a system that absorbs and dissipates impulse and noise energy generated by the motor before it is fed into the record via the inner platter, spindle, and center clamp. The center clamp can then do its primary job of holding the record in firm contact with the mat. If your vinyl is warped, we have supplied an industry first lead washer which functions as does the driven platter and vinyl support platter lead, aiding in dampening resonance.

MS Outboard Power Supply Speed Control (33-45rpm)

The MS turntable uses an AC driven synchronous motor. The AC synchronous motor was chosen because the speed is fixed by the frequency input; therefore no speed control is necessary. A DC motor must have the speed regulated by a servo system. Speed control servo systems work on the principle of error correction. The motor speeds up; the servo control slows it down. Brushless type DC motors can have (depending on design) low noise output but will have varying degrees of flutter problems due to the hunting characteristics of the servo control.

The AC synchronous motor will have long-term speed stability and will rotate at exact speed without servo hunting problems. A synchronous type AC motor powered directly from the AC power line will inherently, due to the design of the motor, suffer from some degree of low-level AC line noise input into the platter system. A good analogy of this noise transmission is if you consider a piston type speaker which is a linear drive motor (it utilizes a magnet and a coil). The motion of the cone follows the motion of the input electrical signal. If the speaker is fed a very pure low distortion sine wave, the cone moves in a pure sinusoidal motion with only the distortion component of the speaker itself added to the output. A synchronous motor is very similar to a speaker in that it has a coil of wire and a magnet. Rather than being a linear motion motor it is a rotational motion motor. If the motor is driven by a pure sine wave, the input is turned into rotational forces of a pure nature and only the impulse component of the motor itself will be added. But, when a synchronous motor is driven by an electrical voltage source that is less than pure its output will contain all of the electrical anomalies. In all turntables that are powering the synchronous motor directly form the AC line, the belt and platter system is responsible for filtering any AC line anomalies. If the available power in your area is very trashy, this input can be noticed as sonic degradation when compared with a synchronous motor that is driven by pure, clean, sine wave.

The MS outboard power supply and speed control system, physically consists of a control box with power - speed switching (33-45 rpm) and a separate AC transformer. The power supply and speed control electrically consists of a regulated power supply, a low distortion oscillator, phase shift network, and Class A motor drive circuitry. When using the power supply, the motor receives a pure low distortion sine wave and can produce only clean impulse torque. This clean impulse torque is very easy to smooth into constant motion.

Some features of the MS Outboard Power Supply Speed Control include:

• Temperature stabilized crystal oscillator ensures constant motor speed without drift from power up to an extended length audio session.
• Digital counter circuitry offers both 33 and 45rpm operation with the same oscillator at the touch of a button.
• Digital to Analogue conversion uses frequency compensation components for perfect sine wave generation at both speeds.
• Dual complementary symmetry outputs for each winding produce the cleanest sine wave possible without harmonics as found with square wave generators.
• All resistors are 1% metal film to minimize the effects of temperature drift and noise. All capacitors are 200% rated for extended life with minimal component degradation.
• All semiconductors are 200% rated for power
• Power supply is fused and short circuit protected.
• Fully shielded toroidal transformer is 10x overrated for cleanest possible input voltage. Transformer is specifically manufactured for us by Plithron - a company well known for their audio and medical transformers
• Large heat sinks used on output transistors insures cool operation and long component life.
• Water based flux is used for all component connections on circuit board. Once board is assembled it is thoroughly cleaned. This ensures corrosion free connections for life.
• Circuit board is conformal coated to military specifications to ensure the integrity of all connections.
• Connectors are used on circuit board VS. Direct soldering to board. This ensures no contamination from flux residuals or breakdown in conformal coating.
• Gold plated sockets are used for all integrated circuits to minimize the effects of heat on sensitive components.
• Positive connections made with insulated stake on type terminal are inline with military standards of component building.
• Minimal use of shrink wrap. Nothing to hide.
• Components used are Mil. Spec. wherever feasible.
• Power supply can be configured (by manufacturer) for world wide voltage operation.
• SMI/RFI protected.