Stephens Electronics Reel to Reel Tape Recorders

Stephens Electronics, Inc. after an auspicious start in eight track tape recorders, John Stephens began around 1970, producing excellent studio tape recorders. He pioneered a unique tape drive system that did not use controllers or a capstan motor. Just the supply and take-up motors were required as he had a unique
rotating idler that compared the output of an LED and pulses that were compared to a crystal-locked time base for servo transport motor control. The Stephens machines were all half track with tape widths between half-inch and 2 inch. It is estimated that about 200 or so were manufactured.

Source

Tape Op Interview