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B77 Specification





Tape transport mechanism:

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


Tape speeds:

3.75 ips and 7.5 ips, electronic change-over, tolerance from nominal +-0.2%

With optional vari-speed speed variable from 2.5.....11 ips


Wow and flutter:

(as per DIN 45507)

At 3.75 ips <0.1%, at 7.5 ips <0.08%


Tape slip:

Maximum 0.2%


Reel size:

Up to 10.5 diameter (minimum hub diameter 2.36)

Tape tension switchable for small hub diameters


Winding time:

Approximately 135 seconds for 3,600 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 of all motors. Remote control of all transport functions and electronic timer operation are possible



(as per NAB)

3.75 ips: 90 microsec/3180 microsec

7.5 ips: 50 microsec/3180 microsec


Frequency response:

(measured via tape at -20 VU)

3.75 ips 30Hz.....16kHz +2/-3dB

50Hz.....10kHz +-1.5dB

7.5 ips 30Hz.....20kHz +2/-3dB

50Hz.....15kHz +-1.5dB


Peak recording level:

514 nWb/m corresponds to 6dB above 0VU


Level metering:

VU meter as per ASA standard, with LED peak level indicators



3.75 ips at 0VU <1%, at 0VU+6dB <2.5%

7.5 ips at 0VU <0.6%, at 0VU+6dB <1.5%


Signal to noise ratio:

(weighted as per ASA-A)

Half track

3.75 ips >64dB

7.5 ips >67dB

 Quarter track

3.75 ips >60dB

7.5 ips >63dB



At 1kHz stereo >45dB, mono >60dB


Erase depth:

At 7.5 ips >75dB


Inputs per channel:

MIC LO 0.15mV/2k2ohms for low impedance microphones

MIC HI 2.8mV/110kohms for high impedance microphones

RADIO 2.8mV/20kohms

AUX 40mV/220kohms


Outputs per channel:

(Level at 6dB above 0VU)

OUTPUT 1.55V/390ohms adjustable with preset

RADIO 1.55V/4k7ohms adjustable with preset

PHONES 5.6V/220ohms adjustable with control


Connectors for:

Remote control of tape transport

Remote control of variable tape speed

Slide projector or crossfade unit (electronics optional)



11 ICs, 1 opto-coupler, 4 triacs, 60 transistors, 33 diodes, 5 LEDs, 2 full wave rectifiers, 3 relays


Electric current supply:

100.....240V ~ +-10%

Voltage selector for 100V, 120V, 140V, 200V, 220V, 240V

50.....60Hz without conversion, maximum power 80 watts

Main fuse 120V 1A slow-blow, 240V 0.5A slow-blow



Approximately 17kg



452 x 414 x 207 mm (W x H x D)

Clearance required for 10.5 reels height 464mm, width 538mm


The B77 head block