The Hydraulic Reference Turntable employs a low-speed, recoil start synchronous motor on a double-deck spring mounting driving the platter via a rubber belt, thereby providing complete vibration insulation. The main bearing incorporates a silicone fluid filled well rotating at the same speed as the platter fine speed control being provided by a static vane immersed in the fluid. Platter speed in therefore determined by the a.c. mains frequency, which is effectively constant and the viscous fluid flow onto the vane, also effectively constant. Speed changing (45 r.p.m. and 33⅓ r.p.m.) is accomplished by moving the drive belt from one motor pulley to the other and a nech-lit stroboscope is provided for accurate speed setting.
In order to eliminate completely any mechanical shock to the equipment, on/off switching of the drive motor is accomplished by means of a magnetically-actuated vacuum switch. The sintered gold contacts on this switch guarantee an extremely long operational life
The Hydraulic Reference Turntable also has provision for the unique Transcriptor Sweep Arm representing a great advance in the field of record cleaning devices. This consists of a fine squirrel hair brush mounted on a balanced beam so that 1 gramme. Thus the use of the Sweep Arm ensures that the record is cleaned thoroughly whilst in use without producing any wear on the record or causing any noticeable amount of static.
A swinging squirrel hair brush is also available as an accessory for cleaning dust from the stylus assembly.
The Fluid Arm has been developed specifically for use with modern cartridges of not more than 16 grammes weight tracking at not more than 2 grammes.
The Fluid Arm employs a unipivot working in an oil-filled well, so that the arm beam assembly relies for its lateral support, stability and resonant damping on the fluid surrounding the pivot. This results in a substantially friction-free pivot of high stability.
An adjustable eccentric counterweight allows both lateral and longitudinal balancing of the arm. Fine control of longitudinal balancing to allow adjustment of the stylus tracking force within a fraction of a gramme is provided by a screwed counterweight.
Also provided is a bias compensating device so designed asto use a rolling motion. An adjustable bias weight operating through a pulley gives correct compensation as the stylus moves towards the centre of the record.
A lifting and positioning (or "cueing") device is provided incorporating a hydraulic lowerring handwheel which lowers the arm onto the record automatically, but which can be over-ridden when required for accurate manual positioning.
A plug-in headshell is fitted for mounting the cartridge no soldering is required and the signal outputs are taken via a pair of 3-feet (914 mm) long screened leads terminated in co-axial plugs.
Specifications turntable
Platter:
Diameter: 12 inches (305 mm) diameter cast and machined aluminium alloy disc fitted with six gold-plated brass wieghts.
Weight: 11 lbs (6 kg) statically balanced to within 3 grammes.
The record is supported on soft rubber pads thereby reducing rumble and induced static to an absolute minimum.
Main bearing:
Slim section ball-ended ground and polished steel spindle running onto a hardended steel thrust pad and into PTFE bushes (PTFE is a plastic material having a lower coefficient of friction than any other solid, and requires no lubricating)
Motor: Single phase synchronous recoil start
Power: 115 or 240 V, single phase 50/60 Hz
Speeds: 33⅓ and 45 r.p.m.
Speed control: ±2% of nominal
Speed indication: Neon-lit stroboscope geared up 6:1 to give a 6" reading for 1° variation in platter speed.
Wow and flutter: 0-01% at 33⅓ r.p.m.
Rumble: Not measurable
Dimensions (W x D x H):
Lid closed: 17¼ x 17 x 7 inches (438 x 432 x 178 mm)
Lid open: 17¼ x 21¼ x20 inches (438 x 540 x 508 mm)
Specifications Fluid Arm
Length: 9 or 10 inches, (229 or 254 mm)
Fixing: Single hole, 1 in (25 mm) diameter
Adjustment: Vertical - 2½ in. (64 mm); Horizontal - ½ in. (13 mm)
Counterweight overhang: 3 in. (76 mm) for 9 in arm; 3¼ in. (82 mm) for 10 in. arm
Overall length: 12 in. (305 mm) for 9 in. arm; 13 in.(330 mm) for 10 in. arm
Pivot to turntable centre: 8½ in. (216 mm) for 9 in . arm; 9½ in. (241 mm) for 10 in. arm
Lead capacitance: 65 pF/ft.
Cartridge type: Not greater then 16 grammes in weight, tracking at not more than 2 grammes, with ½ in. fixing centres. Compliance for 9 in. arms between 20 and 48 x 10⁻⁸ cm dyne and for 10 in. arms between 15 and 30 x 10⁻⁸ cm dyne.
Resonance of arm: This is a function of cartridge compliance and weight, but for cartridges of between 3 and 14 grammes weight it will e between 8 and 24 Hz
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