VPI ADS Drive System

The 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 60/81Hz; analog logic controlled run/stop switching with the output RMS voltage @ 120VAC on startup, followed by a step down to 90VAC after an 8-second delay for quick starting of heavy platters.

The ADS is intended to remain powered on during listening sessions, allowing the analog oscillators to remain warmed up for lowest distortion. There is a separate run/stop switch to control the motor operation, which is used to control the starting and stopping of the motor. To operate the ADS apply power using the front panel power switch, power on is indicated by the illuminated blue bar included in the switch. Next turn on power switch on the motor and leave in the on position. The turntable is now started and stopped using the run stop switch in the middle of the ADS faceplate. Speed is chosen using the 33/45 RPM switch. When the run/stop switch is momentarily depressed the AC power is applied to the motor. The initial power applied is 120VAC, after 8 seconds the voltage level drops to 90VAC which is the run voltage. When 45 RPM is chosen and the start switch is momentarily pushed the platter starts up as just described at 33 RPM and after 6 seconds switches to 45 RPM which then lowers the output to the motor to the 90VAC run level. This sequence allows the ADS to quickly start heavier platters to 45 RPM. The ADS utilizes separate 60 Hz and 81 Hz oscillators to eliminate unnecessary switching circuitry in the oscillator circuits for long term speed stability and low oscillator distortion. LEDs indicate the Run/Stop condition and chosen speed. Speed adjustment controls provide a center detent position that is factory calibrated to 60 and 81Hz +/- .02 Hz in their center detented position. The controls also provide fine speed adjustment of approximately 3 Hz through continuously variable linear adjustment controls. 

Technical Specifications

• Line Voltage: 115/230 VAC Factory set
• Line Frequency: 50/60Hz
• Line Fuse: 1 amp (Slo-Blo)
• Output voltage: 115/230 VAC Factory set
• Start Voltage: 120/240 VAC
• Run Voltage: 90/180 VAC
• Output Frequency: 50Hz/60Hz Factory Set
• Output Frequency Range: 60 Hz Center Detent: 60Hz @33 RPM & 81Hz@ 45 RPM, 50 Hz Center Detent: 50Hz @33 RPM & 68Hz@ 45 RPM, Control Range +/- 3Hz
• Output Power: 15W
• Dimensions: 16” X 4” X 12” (W X H X D)
• Weight: 10lbs