Getting back to basics
For all its seeming complexity, there are really only three basic requirements of any well designed turntable:
That the turntable platter rotate at a constant unvarying speed
The the tone arm enable the cartridge to trace the microscopic undulations in the record groove freely and accurately
That it be extremely reliable and trouble free.
The turntable proper
Let us examine the turntable mechanism first. In addition to rotating at an exact speed, a well designed turntable should be able to play a record with:
Minimum rumble - that is, it should not contribute any mechanical noise of its own to the music.
It should have undetectable wow and flutter. That means it must be free of slow and fast variations in pitch caused by momentary variations in speed.
Belt drive plus.
The primary cause of turntable rumble is the transmission of vibrations from the drive motor to the tone arm as it tracks the record.
Over the years, various methods have been devised to reduce rumble. Perhaps the simplest, most affective and reliable is the use of a belt drive system. By connecting an elastic belt from the drive shaft of the motor to the rim of the turntable platter, while the belt acts as a very effective mechanical filter damping out motor vibrations.
However, there is one drawback to this otherwise admirable system. It lacks sufficient torque or start up power to actuate the arm lifting and cycling functions quickly and efficiently.
To remedy this problem, Elac has designed an ingenious drive system with an idler assist called Belt Drive Plus, which is incorporated in the new Elac PC 830.
An idle wheel driven directly by the motor brings the platter up to speed quickly and indexes the arm over the lead-in groove of the record. As soon as the tone arm descends and the stylus touches the record, the idler is disengaged end the turntable operates in the belt drive mode only.
To reduce wow and flutter, the Elac PC 830 couples the motor to a heavy (4:4 pounds), dynamically balanced turntable platter. The mass of the platter in rotation creates a flywheel effect and very effectively smoothes out any momentary speed variations.
It's worth noting that the flat, precision ground rubber drive belt used in the Elac PC 830 is resistant to heat and humidity. Moreover, long term dimensional stability is insured through the use of an automatic belt release that reduces tension on the drive belt when the turntable is not in use.
Precise and continous speed monitoring is provided for via an illuminated strobe and a pitch control that is adjustable over a range of ±3% of nominal speed.
In addition, the Elac PC 830 satisfies another vital, but often overlooked, requirement of a well designed turntable. It incorporates a dual element, tuned suspension system that provides maximum isolation from external vibrations, thus rendering it virtually immune to acoustic feedback as well as other sound bluring sources.
The well behaved tone arm
Just as a well designed turntable should do nothing more than rotate silently at a precise, unvarying speed, so should the tone arm assume a completely bening role. Its only function, to present the cartridge to the record without let or hindrance.
But this is more easily said than done. For today's better cartridges play at such very low tracking forces, often 1 gram or less, that many tone arms are hard pressed to cope with them. As a result performance can be seriously degraded.
To operate properly at these very low tracking forces, a tone arm must be very light and rigid. In addition, it should have a very low moment of inertia, so as not to impede the movement of the stylus in the groove. But that's only the begining, a well designed tone arm should also have:
Very low mass, especially at the head where it counts most.
Very low tracking error. That is, its design geometry should permit it to remain as nearly tangent to the groove as possible, at any point on the record.
Skating or side thrust compensation to keep the stylus centered in the groove.
The ability to function properly with a wide veriety of cartridges
A cueing control for simple and precise manual operation
To successfully meet all these requirements. Elac has designed a superb new tone arm for the PC 830.
Special alloy, tubular construction makes it very light and rigid while significantly reducing mass. Freedom of movement has been optimized through the use of microprecision ball bearing races in both the vertical and horizontal pivos enabling the tone arm to perform faultlessly with most lightweight, high compliance cartridges.
To provide greater stability and further improve tracking, the tone arm is dynamically balanced which has the added advantage of making turntable leveling non-critical. The offset angle (geometry) of the head minimizes tracking error and a positive contact, slide-in cartridge mount permits precise adjustment of stylus overhang to further reduce distortion.
To insure perfect centering of the stylus, in the groove at any point on the record, a highly effective antiskating adjustment is provide for conical elliptical and CD-4 styli. Thus uneven groove wear and distortion are materially reduced. A viscous damped cueing control sets the tone arm down gently anywhere on the record. And the same gentle lowering action also comes into play during automatic operation.
The finishing touch
In the final analysis, however, any first rank turntable is more than a collection of features. It is a study in human engineering. It should respond instantly and effortlessly. It should enable you to play a single record or a batch of records whit a minimum of fuss and bother. In short, it should never get between you and the music .
Drive System: Precision ground belt plus idler assist
Operational Mode: Single and multiple play
Speeds: 33-⅓ and 45 rpm
Speed Adjustment: ±3%
Wow and Flutter (DIN) ±0,6%
Unweighted ; better than 44 dB
Weighted : 64 dB
Tone arm: 205 mm tubular alloy
Tracking Error: less than ±1,4 degrees
Tracking Force Adjustment: 0,5 - 4 grams
Platter: 285 mm diameter zink diecast
Platter Weigth: 4,4 pounds
Power Consumption: 15 watts
Dimensions (W x H x D): 435 x 175 x 350 mm