The B77 is a reel-to-reel tape machine launched in 1967 under the ReVox brand. The machine is built like a tank using quality components assembled inside a simple design which made the B77 a very reliable recorder.

The B77 was designed to be incredibly robust, using diecast parts for the motor chassis, the side bearers, the crossmember and for the head block and the pinch roller arm. This ensured exceptional stability for the precision tape guiding system and the sound heads, as well as for the motors and the brake assembly. The motors were sturdy AC asynchronous types – unbeatable in simplicity and reliability.

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

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.

 

Tape transport mechanism:

3-motor tape drive, 2 AC driven spooling motors; 1 AC driven capstan motor, electronically regulated

Tape speeds:

3.75 and 7.5 ips or 7.5 and 15 ips, electronic change-over

Tolerance from nominal:
With external accessory, speed variable:

± 0.2%
from: 2.5 ... 11 ips (3.75/7.5 ips machines)
5 ... 22 ips (7.5/15 ips machines)

Wow and flutter
(as per DIN 45507/ consistent with EEE standard 193-1971):

at 3.75 ips less than 0.1%
at 7.5 ips less than 0.08%
at 15 ips less than 0,06%

Tape slip:

Max 0.2%

Reel size:

Up to 10.5 inch diameter
(min. hub diameter 2.36 inches)
tape tension switchable (for small hub diameters)

Winding time:

Approx. 135 sec for 3600 ft of tape

Tape transport control

Integrated control logic with tape motion sensor provides for any desired transition between different operating modes. Contactless electronic switching all motors. Remote control of all functions and electronic timer operation are possible.

Equalization
(as per NAB):

3.75 ips: 90 µsec / 3180 µsec
7.5 ips: 50 µsec / 3180 µsec
15 ips: 50 µsec / 3180 µsec

Frequency response
(measured via tape, at -20 VU):

At 3.75 ips:
30 Hz ... 16 kHz +2 / -3 dB
50 Hz ... 10 kHz ± 1.5 dB

At 7.5 ips:
30 Hz ... 20 kHz +2 / -3 dB
50 Hz ... 15 kHz ± 1.5 dB

At 15 ips:
30 Hz ... 22 kHz +2 / -3 dB
50 Hz ... 18 kHz ± 1.5 dB

Peak recording level:

514 nWb/m corresponds to 6 dB above 0 VU

Level metering:

VU meter as per ASA standard with LED peak level indicators

Distortion

 

At 0 VU
(257 nWb/m)

At 0 VU + 6 dB
(257 nWb/m)

 

At 3.75 ips:

< 1%

< 2.5%

 

At 7.5 ips:

< 0.6%

< 1.5%

 

At 15 ips:

< 0.6%

> 1.5%

Signal to noise ratio
(weighted as per ASA-A, measured with tape)

Half track

At 3.75 ips better than 64 dB
at 7.5 ips better than 67 dB
at 15 ips better than 65 dB

 

Quarter track

At 3.75 ips better than 60 dB
at 7.5 ips better than 63 dB

Crosstalk
(1000 Hz):

Stereophonic
Monophonic

Better than 45 dB
Better than 60 dB

Erase depth:

At 7.5 ips better than 75 dB

Inputs per channel

   

MIC (unbalanced)

Position LO:

0.15 mV / 2.2 kOhms
for 50 ... 600 Ohms microphones

 

Position HI:

2.8 mV / 110 kOhms
for microphones impedances up to 20 kOhms

 

Radio:

2.8 mV / 20 kOhms

 

AUX:

40 mV / 220 kOhms

 

Overload margin on all inputs:

40 dB (1:100)

Outputs per channel
(level at 6 dB above 0 VU / 514 nWb/m):

OUTPUT

1.55 V, internal resistance 390 Ohms adjustable with preset control, max. attenuation -26 dB (Rj max. 1.5 kOhms)

 

RADIO:

1.55 V, internal resistance 4.7 kOhms adjustable with preset control, max. attenuation -26 dB

 

PHONES:

(2 x) max 5.6 V, internal resistance 220 Ohms, short-circuit proof, optimum matching impedance 200 ... 600 Ohms

Connectors for:

Remote control of tape transport functions
Remote control of variable tape speed
Slide projector or crossfade unit
(electronics optional)

Semi-conductor complement:

11 IC, 1 opto-coupler, 4 Triac, 60 transistors, 33 diodes, 5 LED, 2 full wave rectifiers, 3 relays

Electric current supply
(voltage sector):

100,120,140,200, 220,240 V
50 ... 60 Hz, max 80 W

Main fuse:

100 ... 140 V: 1 A slow-blowing
200 ... 240 V: 0,5 A slow-blowing

Weight:

Approx. 37 lbs. 7 ozs (17 kg)

Dimensions (W x H x D):

17.8 x 16.3 x 8.14 inches
(452 x 414 x 207 mm )

Required clearance for 10.5 inch reels:

Max width: 21.2 inches (538mm)
Max height: 18.25 inches (463.5 mm)

The Gear Rack

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