Revox B77
The Revox B77 is a 1/4 inch tape recorder from the Swiss company Revox . As the successor to the Revox A77 and Revox A700, the new Revox tape recorder was launched on the market in 1977. Together with an amplifier B750, an FM tuner B760 and a turntable B790 B77 which formed a complete HiFi system. The B77 was supplemented from 1989 to 1993 by the C270 series with Dolby HX Pro , XLR connections and an RS-232 interface (thus controllable by computer).
Versions
The B77 was manufactured in the versions MK I (1977–1980) and MK II (1980–1998). In total, there were 61 different models and variants of the B77 with all special versions.
In addition to the standard version with speeds of 9.5 / 19 cm / s, there was also a B77-HS (high speed) with 19/38 cm / s and a B77-LS (low speed) with 4.75 / 9.5 cm / s and also a B77-SLS (Super Low Speed for monitoring tasks) with 2.38 / 4.75 cm / s tape speed.
There was also a B77-Auto with automatic recording start and three variants with an additional pilot head for simple to sophisticated slide projector controls. Finally, the B77-DOL offered separate Dolby B processors for recording and playback for maximum signal-to- noise ratios .
technology
Tape heads
The B77 has a total of 3 heads ; a separate one for playback, recording and deletion. Studer Revox has many years of experience in the manufacture of tape heads and has optimized them for the various tape machines. In line with the company's philosophy, all tape heads in the Studer Revox company were manufactured using a proprietary process with the proven quality. The precision sound heads in all-metal technology are developed and manufactured for Revox devices as well as for the professional tape recorders from Studer. The special alloy REVODUR guarantees high-quality magnetic properties and a long service life, the shape of the head mirror is designed for very smooth frequency responses down to the lowest frequency . The core package carrier was milled from the solid with the highest precision in order to achieve optimal evenness of the individual track positions. The gap of the playback sound head measures only 2 µm (0.002 mm). The core packages are made of high-quality magnetic material with high permeability for minimal losses. In this way Revox achieved low noise levels and low distortion . Long pole shoes guaranteed a straight frequency response down to the lowest frequencies .
Sound motor control
The Revox B77 is an example of the close interaction between precision mechanics and electronics. The high precision in production and the great stability in the construction guarantee the original accuracy of the tape guidance even after years. Studer Revox had already begun the age of electronic tone motor control for amateur devices back in 1967. This precision in control was the measure in tape technology for years. The principle of electrodynamic control of a robust asynchronous motor with a separate precision reference has proven itself so well that it was also used in the professional Studer studio tape machines. The precision reference and the tone motor form a servo circuit with contactless speed sensing and control electronics , which is largely independent of mains voltage , mains frequency and load fluctuations. This drive principle, which has been tried and tested in half a million drives, together with the tape guide, enables optimum synchronization properties that hardly change even after years of operation. For pitch corrections and effects, the tone motor drive can also be varied continuously over a wide speed range. In the MKII version of the B77, up to 2 semitones could be corrected.
casing
The tape recorders of type B77 all have a drive chassis, side and rear wall supports, a tape head support and a pressure arm made of die-cast parts . This construction offers a high level of stability for the precision tape heads, the tape guide, for the motors and also the brake unit. The motors are simple, thereby also robust AC - Asynchronläufer and thus continuous operation even under harsh conditions.
Tape cutting
The integrated REVOX tape cutter makes tape cutting a simple matter. A useful cutter device for easy motorized maneuvering and searching for the exact interface by hand is built in. When a cut button is pressed, the tape is placed on the tape heads, the playback amplifiers are switched on, and the rewind buttons act as impulse buttons. This enables a cutting point or a starting position to be found by motorized maneuvering and set by hand in the most precise manner.
equipment
There were numerous accessories for the B77 tape machine. Wired remote controls such as the 10 m cable remote control, the external tone motor control and a hand or foot repeater remote control. The B77 could also be controlled via some infrared remote controls such as the B205. For this, however, an external infrared receiver of the type B202 had to be connected. Tape material, reels, NAB adapters or a dust cover rounded off the comprehensive range.
Technical specifications
All B77 tape machines have a 3-motor drive with 2 AC winding motors and 1 AC capstan motor . The level meters is vu-meters for ASA norm with LED -Übersteuerungsanzeigen.
| B77 standard ST | B77 High Speed HS | B77 Low Speed LS | ||||
|---|---|---|---|---|---|---|
| Belt speeds 1 | 9.5 cm / s (= 3¾ inches / s) |
19 cm / s (= 7½ inches / s) |
19 cm / s (= 7½ inches / s) |
38 cm / s (= 15 in / s) |
4.75 cm / s (= 1⅞ inch / s) |
9.5 cm / s (= 3¾ inches / s) |
| Target speed tolerance | +/- 0.2% | +/- 0.2% | +/- 0.2% | |||
| Variable internally 2 | +/- 10% | +/- 10% | +/- 10% | |||
| with external addition | 6.5-28 cm / s | 13-56 cm / s | 3.25-14 cm / s | |||
| Fluctuations in pitch 3 | 0.09% | 0.07% | 0.07% | 0.05% | 0.18% | 0.09% |
| Slip | Max. 0.2% | Max. 0.2% | Max. 0.2% | |||
| Coil size | up to max. 26.5 cm | up to max. 26.5 cm | up to max. 26.5 cm | |||
| Rewinding time 1100 m | approx. 135 s | approx. 135 s | approx. 135 s | |||
| Equalization | NAB 90-3180 µs | NAB 50-3180 µs | NAB 50-3180 µs IEC 70 µs |
NAB 50-3180 µs IEC 35 µs |
NAB 120-3180 µs | NAB 90-3180 µs |
| Frequency response 4 | 30 Hz ... 16 kHz + 2 / −3 dB |
30 Hz ... 20 kHz + 2 / −3 dB |
30 Hz ... 20 kHz + 2 / −3 dB |
30 Hz ... 22 kHz + 2 / −3 dB |
40 Hz ... 10 kHz + 2 / −3 dB |
30 Hz ... 16 kHz + 2 / −3 dB |
| Distortion factor (1 kHz) | 2.5% (NAB) | 1.5% (NAB) | <2% (NAB) | <1% (NAB) | 3.0% (NAB) | 2.5% (NAB) |
| S / N ratio 5 | 2-track:> 64 dB 4-track:> 60 dB |
2-track:> 67 dB 4-track:> 63 dB |
2-track:> 67 dB | 2-track:> 68 dB | 2-track:> 62 dB 4-track:> 58 dB |
2-track:> 64 dB 4-track:> 60 dB |
| Crosstalk attenuation at 1000 Hz | Stereo:> 45 dB Mono:> 60 dB |
Stereo:> 45 dB Mono:> 60 dB |
Stereo:> 45 dB Mono:> 60 dB |
|||
| Extinguishing damping at 1000 Hz | > 75 dB | > 75 dB | > 75 dB | |||
| Inputs per channel 6 | MIC asymmetrical LO position: 0.15 mV / 2.2 k ohm for microphones from 50 to 600 ohms HI position: 2.8 mV / 110 kOhm for microphones from 50 to 20 kOhm Radio: 2.8 mV / 20 kOhm AUX: 40 mV / 220 kOhm |
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| Overdrive resistance | 40 dB (1: 100) | |||||
| Outputs per channel 6 | Output: max. 1.55 V / RL min. 20 kOhm, adjustable with level control, max. −26 dB radio: max. 1.55 V / RL min. 20 kOhm, adjustable with level control, max. −26 dB Phones: (2 ×) max. 5.6 V, short-circuit proof, ideal for headphones from 200 to 600 ohms |
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| Capstan diameter | 4.51 mm | 9.06 mm | 3.00 mm | |||
| Engine type | default | High speed | Low speed | |||
| Rated speed | 400 and 800 min -1 | 300 and 600 min -1 | ||||
1 electronically switched , 2 from the setpoint , 3 according to DIN 45507 , 4 over tape measured at -20 VU , 5 according to ASA-A, re. 514 nWb / m measured over tape , 6 re . 514 nWb / m
literature
- Peter Holenstein : The talking machines. Studer-Revox. The life's work of audio pioneer Willi Studer . Oesch Verlag, Zurich 1998, ISBN 3-7263-6713-6 .
Web links
Individual evidence
- ↑ reeltoreel.de, ReVox C270 series , accessed on April 26, 2020 (the page is based on the C270 catalog from 1989).
- ↑ Test reel tape recorders Revox B77 Dolby and ASC AS 6002/38. (PDF; 4.8 MB) (No longer available online.) In: HiFiStereophonie. May 1, 1979, pp. 682-699 , archived from the original on September 20, 2009 ; Retrieved January 9, 2013 .
- ↑ Peter Holenstein : The speaking machines. Studer-Revox. The life's work of audio pioneer Willi Studer . Oesch Verlag, Zurich 1998, ISBN 3-7263-6713-6 .
- ↑ Revox B77 - The most important versions. Retrieved January 9, 2013 .
- ↑ Brochure B77 - Revox documents
- ↑ B77 accessories - http://www.reeltoreel.de/Revox/B77Z.htm
- ↑ Technical data B77 - Revox documents
- ↑ ReVox B77 - The most important versions on www.studerundrevox.de