The Authorised  ReVox Service Centre for the UK

the B77 is the industry standard...

Brian Reeves


mechanical concept

A well-designed tape transport mechanism will not distort mechanically. It is insensitive to shocks and vibrations and will retain these qualities over a wide range of temperatures. Therefore, REVOX B77 tape recorders use die cast parts for the motor chassis, the side bearers, the cross member and for the head block and the pinch roller arm. This ensures exceptional stability for the precision tape guiding system and the sound heads, as well as for the motors and the brake assembly. The motors are sturdy AC asynchronous types - unbeatable in simplicity and reliability - thus especially suited for heavy-duty use.

Direct drive capstan motor with tacho generator and servo electronics to ensure outstanding speed stability independent of variations in load or changes in the electrical supply voltage or frequency.

Magnetic tape recorders are an outstanding example of the perfect combination of precision mechanics and top performing electronics.  Even the best electronic circuitry would soon become worthless if the original precision in tape guiding is lost as a result of insufficient long-term stability. One of the basic requirements therefore, was to ensure stable performance for years, achieved with a rigid mechanical design, which disregards the possible advantages that may lie in such tempting advertising claims as "feather weight" and "slim line"!

Precision cannot be realized without ruggedness. This is the reason why all important parts of the B77 transport mechanism are made from solid die-castings.

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Speed control via servo electronics

In 1967 STUDER REVOX had already ushered in the age of electronic capstan speed control for domestic tape recorders. Ever since then many have tried to copy it, yet they have never been able to match its simplicity and effectiveness.

The principle of electronically regulating a sturdy asynchronous motor by means of a separate precision reference has stood the test so well that it has been adopted for the STUDER professional tape recorders years ago. The capstan motor and its precision reference combined with the inductive speed sensor and its control circuits form a regulating loop, which is highly insensitive to variations in power line voltage and frequency or changes in load. This system, which has proven its reliability in more than half a million tape drives, combined with ideal tape guiding results in outstanding motion stability (freedom from wow and flutter), which remains unchanged for years. The remarkable mechanical and electronic stability of the complete tape transport mechanism makes it well suited for mobile operation by powering it from car batteries in conjunction with an inverter. For pitch matching or to achieve special effects, motor speed can also be varied continuously over a wide range with the help of an external speed control.