Revox A700

The Revox A700 is a sophisticated, professional-grade reel-to-reel tape recorder introduced in 1973 as a successor to the popular A77. It combines advanced servo-controlled mechanics with integrated circuit-based electronics, designed for high fidelity, reliability, and ease of use in demanding applications.

Mechanical and Transport Features

• Tape Transport:
  Three servo-controlled AC motors: one electronically regulated capstan motor and two spool motors controlled via tape tension sensors.
  Quartz clock generating a 1.6384 MHz reference signal ensures precise capstan motor speed control.
  Speed sensor ring detects total motor motion using frequency and phase comparison with the reference clock.
  Electronic regulation maintains constant tape tension during all modes, including winding and braking.
  ‘Fail Safe’ auto-stop logic monitors tape motion, tension, and photoelectric end-of-tape sensors to prevent damage.
  Supports three tape speeds: 3¾ ips (9.5 cm/s), 7½ ips (19 cm/s), and 15 ips (38 cm/s).
  Tape speed can be externally varied via an optional unit, allowing a range from 2.5 to 21.5 ips for pitch control or special effects.
  Maximum reel size: 10½ inches (26.5 cm), with no tension change required for reels from 1.5" to 10.5".

Audio and Electronic Features

• Track System: 4-track, 2-channel stereo (half or quarter track configurations).

• Heads: Three heads (erase, record, playback), with provision for an optional fourth head.

• Inputs:
  4 balanced microphone inputs with selectable high/low impedance.
  1 stereo phono input with built-in RIAA preamplifier for magnetic cartridges.
  1 stereo radio input.
  2 auxiliary stereo inputs.

• Mixing and Controls:
  Four individual linear faders for input mixing and one stereo master fader for recording volume.
  Two linear faders for output volume and balance control.
  Stepped tone controls for bass and treble (±8 dB in 2 dB steps).

• Outputs:
  Fixed line outputs (Line A and B) at 1.55 V.
  DIN radio output at 0.775 V.
  Two headphone outputs with volume and tone control.
  Power amplifier output with volume and tone control.

• Meters: Jewel-bearing VU meters with optical overload warning lights, switching between record and playback monitoring modes.

• Stereo Echo and Dubbing: Built-in stereo echo facility for recording and multi-play for dubbing.

• Sound Head Assembly: Plug-in design allowing half or quarter track operation; optional mounting for additional heads.