SME - SME Model 20/3A Turntable with Series V Arm

Includes Series V tonearm

Turntable

The finely engineered Model 20/3 is built to the same exacting standard and incorporated many design features originated for the Model 20/12. Massive construction, extensional damping of major surfaces and lack of vibration from moving parts ensures exceptional detail, resolution and uncolored performance.

A turntable should address the problems of extraneous vibrations. These emanate from numerous sources including air and structural vibration from loudspeakers, groove modulation, stray electrical fields and mechanical imperfections in moving parts. In the Model 20/3, superb instrument quality machining is allied with fundamental physics. The higher the mass and stiffness of a body the less it will flex and vibrate; the duration of a vibration can be shortened by suitable damping.

Model 20/3 weighs approximately 63 lbs (28.6 kg), significant in relationship to its size because it is density that matters. For example, the same weight of metal spread over a large enough area would be aluminum foil! The sub-chassis measures only 17-5/16 in (440 mm) by 13-3/4 in (350 mm) but weighs 24 lbs (11 kg). Its thickness 5/8 in (16 mm), resists flexing at low frequencies while high-frequency resonance is attenuated by efficient extensional damping.

The Model 20/3 has no “sonic signature” of its own. The sub-chassis is suspended on forty ‘O’ rings that ensure freedom from feedback. The method of attachment allows the rings to be removed or replaced easily, even while a record is playing! A large centrally placed damper controls sub-chassis movement.

In addition to a cartridge’s electrical output, mirror image acoustic signals reacted in the arm and record, will pass into the sub-chassis in the course of dissipation. However the usual closed loop design does not address the problem of their differing phase so in the Model 20/3 the structural interfaces concerned have received special attention to provide paths of the required impedance. This control of vibration is fundamental to the design of the turntable and goes much of the way in explaining the stunning tonal dynamic neutrality and “quietness” that it exhibits.

The turntable is driven by a 3-phase, brushless out runner inductance motor with 8-pole Neodymium magnets and 3 integrated Hall position sensors. The electronic controller uses a high performance microprocessor, optimized for motor control. Closed loop speed control is implemented using a proportional plus integral (PI) algorithm. Fine pitch speed adjustment allows increments/decrements of ±0.01% of selected speed.

Features

• Four point suspension for stability.
• Sub-chassis suspended on eighty strands of rubber in the form of forty purpose moulded ‘O rings.
• Suspension adjustable through trimmers used in conjunction with a gauge to give recommended settingsor varied to suit individual conditions.
• Central fluid damper controls sub-chassis motion and offers resistive ground-path for acoustic signals.
• Two screws lock down the sub-chassis and seal the damper for transport.
• 19mm diameter main spindle machined from high - chrome steel, hardened, ground and super finished runs in a sealed oil bath for lifetime lubrication.
• Screw down reflex record clamping system minimises record resonance.
• 6.5Kg (14lb) platter with unique Isodamp face machined with a fine scroll for optimum record interface.
• Generous use of extensional damping and resistive loop construction ensure sonic neutrality.
• Optional mounting on steel ball feet or compliant inserts, both affording levelling adjustment.
• Four jacking screws built into the sub-platter allow the thrust bearing to be off loaded for transit.
• The Power Supply design incorporates a 4-layer surface mount technology pcb with on-board user adjustable speed variation control.
• Large diameter strobe disc supplied allows precise adjustment of standard speeds.
• Speed range: 33 1/3, 45 & 78 rpm.
• Fully shielded in-line control unit.  LED's indicate themain functions
  

Technical Specifications

• Dimensions: 17.32"W x 13.78"D x 6.77"H
• Dimensions PSU: 5"W x 10-3/4"D x 3-1/4"H
• Packing: Substantial case.
• Net weight with power supply: 31Kg (68lb)
• Shipping weight approximately: 45Kg (100lb)