Saturday, 12 April 2014

ReVox B77 MKII high speed

The Revox B77 Tape Deck
Proven Professional Design.

Precision Transport
Professional recordists know that for long-term stability and performance successful tape transport design must begin with the chassis frame itself. No matter how smooth-running the motors and highly-refined the heads, since both are referenced to the recorder's frame, any long-or-short-term flexing or imprecise machining in the chassis will inevitably degrade performance. To achieve the required stability - at a weight compatible with home use - the Revox B77 uses a sturdy aluminium die-casting for the chassis, headblock, pinch roller and mechanism, and each mounting point is painstakingly machined for extraordinary tolerances. The Nextel-coated case around the transport provides a similarly sturdy layer of protection for the mechanism.

Precision Three-Motors Drive
Studer-Revox manufactures its own drive and winding motors so their characteristics can be optimized for recorder use. For example, when heavy reels must be started up from rest they must be fed initially with a higher starting voltage, which is gradually reduced via a triac circuit to normal running voltage. The entire operation must be entirely smooth or the tape could snarl or stretch. Studer motors and controls are one reason why our decks are so widely acknowledged to be the gentlest-handling you can own.

The capstan motor employs a precision-machined set of teeth at the circumference of its motor. As the motor turns, these teeth create a series of pulses that are read by a tachometer head and whose rate is compared against the frequency of a stable internal oscillator. In this way, even very slightest speed variations are immediately detected through a fast-acting servo system. To reduce wow and flutter even further, the direct-drive capstan shaft is machined to an accuracy of one one-thousandth of a millimeter, is hard chrome-plated and is artificially aged during the manufacturing process to ensure long-term stability.
Precision Heads and Electronics
Studer tape heads - from 1 to 24 track models - are world-renowned and are designed and build in our own facilities. The head cores are made from a physically hard, magnetically soft metal allay called Revodur, which has nearly perfect electromagnetic qualities. Whether you purchase your B77 in a quarter- or half-track stereo format its heads will be built to the same standard of polish employed in our professional studio decks.

The head nest of the B77 also contains space (1) for the inclusion of a fourth head, to be used for slide-projector synchronization or other audio-video control purposes, in addition to the regular erase, record play units. An infrared sensor within the head area (2) actuates automatic shut-off in the event of tape run-out or breakage.
Three-Head Monitoring and Special Effects
Because the record and playback heads of the B77 are individual, separate units, each can be optimized for its specific function. A narrow gap is employed for playback to extend the frequency response, while a wider gap is employed during recording to ensure full penetration of the oxide layer on the tape. Since the record and playback electronics are also separate, this permits you to monitor the recorded result a split-second later, making direct comparison possible to avoid the possibility of an unsatisfactory recording. The sophisticated electronics and separate heads of the B77 also permit various special recording effects. Without external components or cables the Revox B77 can:

- Duoplay, where both recorded tracks are used simultaneously but for different, interspersed information, as in language laboratories.
- Simuplay, where a running commentary musical part, or translation is recorded on one track and a synchronized musical part or other accompanying material is recorded on the other.
- Sound-on-Sound, where a single individual, by playing various musical parts and successively mixing his live part with a previously recorded section, can build up an entire performance.
- Echo/Reverb, where tape-delayed echo or ambience can be added to a recorded track.
Precision Editing Facilities
An accurate splicing block and non-magnetic sheertype cutter are build right into the front panel of the B77, encouraging creative tape editing. Additionally, a lever switch is included that activates the playback amplifiers during the fast-winding modes, and shifts their operation to a pulse-type control. In this way you can quickly shuttle back and forth between fast forward and rewind to find the exact point at which an editing cut is to be made. For even finer-pin pointing of critical cuts the reels can be rotated manually while the tape remains against the playback head.

Fine Speed Adjustment
The Revox B77 MK II (not the MK I) contains a built-in vari-speed control with a range of ± 2 half-tones. for a larger range of ± 7 half-tones it is necessary to use the external vari-speed control.

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