Revox A77 MK IV 2-track *half track), High Speed - 1977

The Revox A77 Mk IV is the final version of the legendary A77 series and is generally considered the most refined model. It was produced from 1974 to 1977, just before the A77 was succeeded by the B77. 

Key features

• Solid-state (transistorized) electronics, unlike the earlier tube-based G36.
• Three-motor direct-drive transport with electronically regulated capstan.
• Supports reels up to 10.5 inches (26.5 cm).
• High-speed (7½ & 15 ips / 19 & 38 cm/s) version.

Mk IV improvements

Compared with the Mk III, the Mk IV introduced:

• Updated styling with silver transport buttons and a blue Revox logo.
• Lower-noise transistors and incremental electronic refinements.
• Improved switches and controls for greater reliability.
• Most changes were evolutionary rather than a complete redesign; the transport remained the proven A77 mechanism. 

Typical specifications include:

• Frequency response up to 20 kHz (depending on tape speed).
• Signal-to-noise ratio up to about 66 dB for the 2-track version.
• Wow and flutter around 0.08%