Sherwood ST-905 Turntable Review

Sherwood’s ST-905 is a fully automatic record player with a two-speed, quartz-locked direct-drive turntable and a servo-driven linear-tracking (tangential) tone arm that takes a P-mount plug-in cartridge. All the operating controls are on the front of the turntable base so that they are accessible with the plastic dust cover lowered.

The full-size cast-aluminum platter (2-1/4 pounds with its rubber mat) is turned at 33-1/3 or 45 rpm by a frequency-generator-controlled direct-drive motor. Stroboscope dots cast into the underside of the platter and illuminated from below are visible through a window on the front of the base; they show a stationary pattern when the turntable is rotating exactly at the selected speed.

The straight, low-mass tone arm is mounted on a carriage that is moved along a rail by its own d.c. servomotor. The arm is also horizontally pivoted and free to move through a small angle in the plane of the record surface. Slight deviations from perfect tangency to the groove cause an interruption between an infrared light source and its sensors. This sends a corrective signal to the servomotor, which moves the arm so as to reduce the error. The arm servo can operate in either direction, permitting it to follow eccentric records. The arm is statically balanced by a counterweight that is factory set for the standardized 6-gram weight of a P-mount cartridge.

All the operations of the Sherwood ST-905 are controlled by pushbuttons for the thumbwheel-vernier pitch control. Pressing the quartz button engages a quartz-lock circuit that maintains the turntable speed at exactly 33-1/3 or 45 rpm. Releasing the button allows the speed to be adjusted over a nominal ± 4 per cent range with the vernier wheel. Momentary-contact buttons, with lights to identify their settings, select turntable speed and record-size indexing for 7-or 12-inch discs. Setting record size automatically sets the speed to either 45 rpm (7-inch) or 33-1/3 rpm (12-inch), but the speed can be changed after the turntable starts to accommodate 12-inch 45’s or 7-inch 33’s.

The turntable’s servo-driven tone arm cannot be moved manually, so two pushbuttons (labeled with horizontal arrowheads) are provided to move the arm in either direction through its motor system. Pressing either of these buttons lifts the pickup from the record. A light pressure causes the arm to move slowly; increasing the pressure causes it to move faster. When the desired arm position is reached, the cue button (labeled with vertical arrowheads) must be touched to lower it. At any time during play, the cue button can be used to raise or lower the pickup. The repeat button causes a record to be replayed indefinitely until it is pressed again. Finally, the start/reject button initiates the automatic operating cycles of the ST-905. One touch starts the motor, indexes the arm to the lead-in groove, and lowers it to play the record. A second touch raises the pickup, returns it to its rest, and shuts off the motor. (This sequence occurs automatically at the end of a record side even during manual operation.)

The Sherwood ST-905 has a silver-colored plastic base and a clear plastic dust cover. It measures about 15 inches wide, 13-3/4 inches deep, and 4-1/2 inches high, and it weighs 17-5/8 pounds. Price: $249.95.

Laboratory Measurements

For our tests, we plugged a high-quality P-mount cartridge into the arm of the ST-905. It was not possible to measure the vertical tracking force since the arm will not descend on a stationary turntable, but the cartridge operated properly throughout our use of the player. The operating speeds were exact when we used the quartz lock and could be varied over a range of about + 10 to —7.5 per cent using the vernier control. The weighted-rms flutter was 0.08 per cent, the weighted-peak flutter ±0.13 per cent; the flutter spectrum was confined to the range below 10 Hz. The unweighted rumble was a low —37 dB; with ARLL weighting the rumble was —60 dB, most of it occurring between 8 and 16 Hz.

The tone arm and cartridge resonated at about 11 Hz, and their combined effective mass was 11.5 grams. Subtracting the 6-gram weight of the cartridge showed that the arm mass was a very low 5.5 grams (this is one of the major advantages of most linear-tracking tone arms). The ST-905 was excellent at tracking warped records, the most direct benefit of a low-mass arm system. The rubber mounting feet isolated the turntable from conducted vibration quite well, with transmission through the base largely in the 25- to 50-Hz range.

The automatic-cycle times of the ST-905 were considerably shorter than those of most record players we have tested. The stylus reached the lead-in groove only 4.5 seconds after the start/reject button was pressed, and about the same time was required for the motor to shut off after the pickup reached the locked groove at the end of the record. Pressing the button again while the arm was closer to the outer edge of the record reduced the shut-off time to as little as 2 seconds. The manual slewing rates, using the two horizontal-cueing buttons. were about 5.5 seconds per inch in the slow mode and 1.1 seconds per inch in the fast mode.

The cueing system worked very rapidly (less than 0.5 second for either lifting or lowering the arm), but the arm shifted outward slightly each time it was raised, causing about 7 seconds of the record to be repeated in each up/down cueing cycle.

Comment

The record-playing performance of the Sherwood ST-905 was excellent. Once a record is placed on the turntable and the cover is lowered, there is no need to raise the cover except to change records. The control operations are easy and free of quirks (unless one requires absolutely exact up/down arm motion during cueing). Although its control buttons require very little pressure, the ST-905 is so light in overall weight that on a slippery surface it tends to slide backward when some of the controls are operated. If necessary one can restrain the unit’s base with one or more fingers while pressing the control buttons.

The ease of setting up a turntable that uses a P-mount cartridge is a very desirable feature, especially since one can choose from a wide variety of cartridge makes in all price and performance ranges. The essential performance of this record player should be much the same whichever P-mount cartridge one selects. The ST-905 is attractively styled and priced just above the least expensive linear-tracking turntables. It is an excellent value, and it would be hard to name any worthwhile feature that it lacks.

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