Revox A700

Revox A700 – 2-Track / Half-Track Reel-to-Reel – 9.5 / 19 / 38 cm/s – Fully Restored & Calibrated Using Reference Tapes

The Revox A700 is one of the most technically ambitious tape machines of the classic Revox era. With its sophisticated three-motor transport, electronically controlled tape handling, three-head design and three tape speeds up to 38 cm/s (15 ips), it combines excellent usability with an engineering philosophy approaching professional tape technology.

Our machine is the particularly desirable 2-track stereo / half-track version. Combined with its maximum tape speed of 38 cm/s (15 ips), this configuration is particularly well suited to high-quality analogue recording and reproduction.

Our A700 has been fully restored in our specialised workshop. As part of the restoration, almost all electrolytic capacitors were replaced.

The machine was subsequently completely readjusted mechanically and electrically and calibrated using reference tapes.

The result is particularly impressive at 38 cm/s / 15 ips. At this speed, our A700 performs at an exceptionally high sonic level and demonstrates the potential of a carefully restored and correctly calibrated 2-track tape machine.

Cosmetically, the machine also presents very well. The front panel remains in very good condition. The wooden side panels show some age-related scratches, but no serious damage. Overall, this is a very attractive and well-preserved example.

2-Track / Half-Track Stereo – Designed for Quality

An important feature of our A700 is its 2-track stereo, or half-track, configuration.

In this format, the tape width is used for two stereo channels. Unlike a quarter-track stereo recorder, the tape is not turned over after one pass to record a second stereo programme in the opposite direction.

The advantage is the greater usable track width available for each channel.

Half-track recording therefore provides particularly favourable conditions for a high signal-to-noise ratio, wide dynamic range and high-quality magnetic recording.

The trade-off is increased tape consumption. The tape cannot simply be turned over and used again in the opposite direction as with a quarter-track stereo machine.

For a machine of the A700's calibre, however, this more uncompromising approach is particularly attractive – especially in combination with 38 cm/s / 15 ips.

Three Tape Speeds: 9.5 / 19 / 38 cm/s

The A700 offers three selectable tape speeds:

• 9.5 cm/s – 3¾ ips
• 19 cm/s – 7½ ips
• 38 cm/s – 15 ips

This gives the machine considerable flexibility.

9.5 cm/s provides long playing times with relatively economical tape consumption. 19 cm/s represents the classic compromise between tape consumption and high reproduction quality.

The A700's most exciting operating mode, however, is 38 cm/s / 15 ips.

At this speed, twice as much tape is used for the same recording time as at 19 cm/s. Combined with the 2-track / half-track format, this provides excellent conditions for serious analogue recording.

38 cm/s and Half-Track – A Special Combination

The combination of 2-track recording and 38 cm/s is one of the defining features of this A700.

At 38 cm/s, Revox specified an overall record/replay frequency response of 30 Hz to 22 kHz (+2/−3 dB) or 50 Hz to 18 kHz within ±1.5 dB.

Specified wow and flutter at this speed is better than ±0.06%.

Technical figures, however, tell only part of the story.

Our freshly restored and calibrated machine demonstrates particularly clearly at 38 cm/s / 15 ips why high-quality analogue tape recording remains so fascinating.

At this speed, the A700 sounds superb – confident, dynamic and remarkably natural.

Three Heads and True Off-Tape Monitoring

The A700 uses separate heads for erase, record and playback.

This three-head arrangement provides genuine off-tape monitoring.

During recording, the source signal can be compared directly with the signal that has just been recorded onto the tape and reproduced by the playback head.

The user can therefore monitor the actual recording while it is being made.

This is a major advantage for serious recording and is also an important prerequisite for precise professional calibration.

Mechanically and Electrically Calibrated Using Reference Tapes

A high-quality reel-to-reel recorder is an electromechanical precision instrument.

The fact that the motors run and both channels record and reproduce a signal says relatively little about whether a machine is actually operating to its intended standard.

Tape path, tape tension, head geometry, replay parameters and recording electronics must all work together correctly.

Following restoration, our A700 was therefore completely readjusted mechanically and electrically.

Calibration was carried out professionally using reference tapes.

The essential playback parameters can therefore be aligned against a defined magnetic reference rather than adjusted by ear or against an arbitrary prerecorded tape. The recording electronics can subsequently be correctly aligned on this basis.

For a 2-track A700 intended to demonstrate its full potential at 38 cm/s, this careful adjustment is particularly important.

Fully Restored

Our Revox A700 has not merely been inspected or checked for basic operation. It has been fully restored.

As part of this work, almost all electrolytic capacitors were replaced.

This represents substantial work on an A700, as the machine contains sophisticated electronics not only for recording and playback but also for transport control, motor regulation and tape handling.

Following restoration, the machine was completely readjusted mechanically and electrically and calibrated using reference tapes.

We are therefore offering not simply a functioning vintage tape recorder, but a comprehensively restored and carefully readjusted example.

Sophisticated Three-Motor Transport

A major part of the A700's technical fascination lies in its transport.

The machine uses three motors. Two motors drive the reel tables directly, while a separate motor is responsible for the capstan drive.

Tape tension is electronically regulated, while the capstan drive also employs sophisticated electronic control.

Revox specified nominal tape-speed tolerance at just ±0.1%.

The A700 accepts reels up to 26.5 cm / 10.5 inches in diameter and is therefore ideally suited to the classic large NAB reels.

Large reels are particularly useful at 38 cm/s, where tape consumption is naturally considerably higher.

Exceptionally Comprehensive Facilities

The A700 is considerably more than a simple tape transport.

Revox equipped it with an unusually comprehensive recording and control section.

Alongside line-level inputs, microphone inputs are provided. Remarkably, the A700 even incorporates an integrated RIAA phono input for magnetic cartridges.

A suitable turntable can therefore be connected directly to the machine – an unusual feature today and a fascinating indication of the central role Revox envisaged for the A700 within a sophisticated analogue system.

Large VU meters are provided for level setting and are supplemented by optical peak indication.

Two headphone outputs are also available.

Electronic Tape Counter

Even the tape counter demonstrates the engineering ambition behind the A700.

Instead of a simple mechanical counter, the machine uses an electronic counter displaying minutes and seconds.

The display is calibrated for 19 cm/s. At 38 cm/s the displayed value is divided by two, while at 9.5 cm/s it is doubled.

For a machine of this era, this was a remarkably advanced solution.

Cosmetic Condition

Our A700 is in good overall cosmetic condition.

The front panel is particularly well preserved, with the controls, markings and characteristic Revox appearance remaining very attractive.

The wooden side panels show some age-related scratches. These are visible and we do not wish to conceal them, but there is no serious cosmetic damage.

Overall, the machine presents very well for its age, with the excellent condition of the front panel being particularly noteworthy.

Technical Data

• Manufacturer: Revox
• Model: A700
• 2-track stereo / half-track
• three-head reel-to-reel tape recorder
• three-motor transport
• separate erase, record and playback heads
• true off-tape monitoring
• tape speeds: 9.5 / 19 / 38 cm/s
• corresponding to 3¾ / 7½ / 15 ips
• maximum reel diameter: 26.5 cm / 10.5 inches
• electronically controlled tape tension
• regulated capstan drive
• nominal speed tolerance according to Revox: ±0.1%
• wow and flutter at 38 cm/s according to Revox: better than ±0.06%
• record/replay frequency response at 38 cm/s according to Revox: 30 Hz – 22 kHz (+2/−3 dB)
• VU meters
• optical peak indication
• electronic tape counter
• microphone inputs
• line/auxiliary inputs
• integrated phono input for magnetic cartridges
• two headphone outputs
• remote-control facilities

Condition and Restoration of Our Machine

• 2-track / half-track version
• good overall cosmetic condition
• front panel in very good condition
• wooden side panels with some age-related scratches
• no serious cosmetic damage
• fully restored
• almost all electrolytic capacitors replaced
• completely readjusted mechanically
• completely readjusted electrically
• calibrated using reference tapes

Our Conclusion

The Revox A700 is one of the most fascinating tape machines of the classic Revox era, and our example combines the particularly attractive 2-track / half-track configuration with three tape speeds of 9.5 / 19 / 38 cm/s.

The combination of half-track recording and 38 cm/s / 15 ips is particularly appealing. Here, maximum playing time and economical tape consumption take second place to creating the best possible conditions for high-quality magnetic recording.

With a tape machine more than five decades old, however, its present technical condition is crucial.

Our A700 has therefore been fully restored. Almost all electrolytic capacitors were replaced before the machine was completely readjusted mechanically and electrically and calibrated using reference tapes.

The result is particularly impressive at 38 cm/s / 15 ips, where this A700 performs at an exceptionally high sonic level and demonstrates why a properly aligned 2-track reel-to-reel recorder can still be such a remarkable analogue source.

A great Revox for the serious tape enthusiast – 2-track, three speeds up to 38 cm/s, comprehensively restored and carefully calibrated using reference tapes.