Revox B77 MKII

The Revox B77 MKII is a professional-grade reel-to-reel tape recorder known for its precision mechanics, high-fidelity audio performance, and robust build quality. It is an evolution of the original B77, featuring improved drive electronics and built-in vari-speed control.

Mechanical and Transport System

• Drive:
  Three-motor system: two AC coil motors for reel spooling and one electronically controlled AC sound motor for the capstan.

• Capstan Motor:
  Features a precision-machined toothed circumference read by a tachometer head for fast servo feedback, ensuring minimal wow and flutter. The capstan shaft is hard chrome-plated and machined to an accuracy of one-thousandth of a millimeter for long-term stability.

• Tape Speeds:
  Electronic speed change-over with standard speeds of 3.75 ips (9.5 cm/s) and 7.5 ips (19 cm/s), with variants supporting 15 ips (38 cm/s) and lower speeds (down to 2.38 ips) for specialized applications.

• Tape Slip:
  Maximum slip is 0.2%.

• Reel Size:
  Supports reels up to 10.5 inches (26.5 cm) diameter.

• Winding Time:
  Approximately 135 seconds for 3600 feet of tape.

Audio Performance

• Frequency Response:
  30 Hz to 20 kHz (+2 dB / -3 dB) at 7.5 ips
  30 Hz to 16 kHz (+2 dB / -3 dB) at 3.75 ips

• Signal-to-Noise Ratio:
  Greater than 64 dB at 9.5 cm/s and greater than 67 dB at 19 cm/s (ASA-A weighted).

• Wow and Flutter:
  Less than 0.1% at 3.75 ips, approximately 0.08% at 7.5 ips.

• Total Harmonic Distortion:
  Approximately 0.5%.

• Crosstalk:
  Greater than 45 dB at 1 kHz.

Electronics and Controls

• Vari-Speed Control:
  Built-in tone motor control allows fine adjustment of tape speed.

• Inputs and Outputs:
  Line input sensitivity around 40 mV; microphone input 0.15 mV; line output approximately 1.55 V.

• Power Consumption:
  Maximum of 80 VA.

• Synchronization Fluctuation:
  <0.06% at 38 cm/s
  <0.08% at 19 cm/s
  <0.10% at 9.5 cm/s.

Physical Dimensions and Weight

• Dimensions (W x H x D): 452 x 414 x 207 mm

• Weight: Approximately 17 kg (37.5 lbs)

Variants and Additional Features

• Multiple versions available including:
  B77-HS (High Speed: 19/38 cm/s)
  B77-LS (Low Speed: 4.75/9.5 cm/s)
  B77-SLS (Super Low Speed: 2.38/4.75 cm/s)
  B77-AUTO (automatic recording start)
  Versions with additional pilot head for slide projector control

• Dolby noise reduction options available in some models for improved noise performance.