Dual motor tape recorder system

A high performance magnetic tape transport and tape cartridge. The cartridge includes coplanar hubs carrying tape rolls rotatable about fixed axes. The transport includes a pair of capstans, each mounted on its own carriage assembly with its own drive motor. The capstans have a high friction surface. The carriage assemblies are spring biased with equal force toward the front of the cartridge. When the cartridge is inserted in the transport, the capstans drivingly engage the peripheries of the tape rolls, and magnetic transducer heads in the transport engage the front face of a span of tape between the rolls. The capstan motors are driven by a servo control system. The servo system provides fully bi-directional operation, highly accurate speed control, and unprecedented tension control, both across the transducer head and in the takeup roll. In one embodiment, the servo system is a dual DC tachometer system which includes dynamic speed correction for both capstans and a constant hold-back force component for the capstan driving the periphery of the supply roll. In another embodiment, both the motor driving the periphery of the supply tape roll and the motor driving the periphery of the takeup tape roll carry high resolution digital tachometers and are phase locked to reference frequencies which differ by an amount which maintains desired tension. Circuitry is provided for safe shut-down upon loss of power.