VPI offers their Analogue Drive System unit to really lock in the speed of your VPI turntable, with speed adjustments available via the front dial, and push-button speed switching (33.3 to 45rpm).
The VPI ADS design includes two pure analog frequency generators featuring low distortion and noise; a high current Class-A/B amplifier that is transformer-coupled to the turntable output; analog control logic for low noise operation; 33/45 RPM analog speed adjustment controls with center detent positions that are factory calibrated for 50Hz; analog logic controlled run/stop switching with the output RMS voltage @ 230VAC on startup, followed by a step down after an 8 second delay for quick starting of heavy platters.
The ADS includes a lighted power on/off switch allowing it to remain powered up during listening sessions for the oscillators to remain warmed up for lowest distortion. There is a separate run/stop switch to control the motor operation. The ADS also utilises separate oscillators to eliminate unnecessary switching circuitry in the oscillator circuits for long term speed stability and low oscillator distortion. Turntable speed is chosen using a switch located between the 33 RPM and 45 RPM speed adjustment controls; LEDs indicate the Run/Stop condition and chosen speed. Speed adjustment controls provide a center detent position that is factory calibrated to 50Hz +/- .02 Hz in the center detented position. The controls also provide fine speed adjustment of approximately 3 Hz through continuously variable linear adjustment controls.
Speed Control and adjustment:
The front panel contains a two-position push button switch for selecting either 33 RPM or 45 RPM operation. Pressing the switch either latches it in or releases the switch to its outward position for 33 RPM operation. There are separate speed adjustment controls for 33 and 45 RPM. The controls have a detented center position that is factory calibrated for 50 Hz (33 RPM). The speed is also continuously adjustable +/- 3 Hz for fine tuning of the platter speed using a stroboscopic disk and 50 HZ light source. Blue LED indicators adjacent to the controls indicate which speed is set at a glance.
Motor Stop and Run:
The ADS is meant to be left powered on during the listening session. The platter is started and stopped by the front panel Run/Stop momentary push button switch. There is an LED indicator the glows red when stopped and green when the platter is turning.
There is an IEC power module on the rear panel to supply AC power to the ADS. The IEC module contains a fuse drawer that holds a 1-amp slow blow fuse protecting the ADS from electrical system malfunctions. AC power to the ADS is controlled by the power switch located on the left-hand side of the front panel. When the ADS is powered up, the indicator in the switch glows blue indicating the internal power supplies are functioning properly.
Line Voltage: 230 VAC Factory set
Line frequency: 50Hz
Current maximum (fuse): 1amp (Slo-Blo)
Output fuse: .25 amp (Fast Blo)
Output Frequency Range: 33 RPM 45 RPM
Output current: 200ma AC RMS
Dimensions: 16” X 3” X 12” (W X H X D)