Category:Super High Fidelity
Country of Manufacture:Switzerland
Release dates:1973 - 1978
Original Price: $1800
Speeds: 3 3/4, 7 1/2, 15
Max Reel Size("): 10.5"
Number of heads: 3
Dimension: 19 x 18¼ x 8¾ " (483 x 460 x 225 mm)
Head Composition: Permalloy
Head Configuration: Stereo
# Motors: 3
Voltage(s): 110-120v, 220-240v, Multi
Frequency Response:30Hz to 22kHz at15 ips
Wow and Flutter:.06% at 15 ips - .08% at 7½ ips - .1% at 3¾ ips
Signal-to-Noise Ratio:65 dB at 15 ips - 66 dB at 7½ - 63 dB 3¾ ips
Sound quality rating:7 / 10
Long-term reliability rating: 7/ 10
Weight: 24 kg.
Billed as a ‘totally professional machine, the Revox A700 stereo tape recorder was a servo controlled, three motor, three speed (3¾ , 7½ , 15 ips) machine with a 10½ inch maximum reel capacity. It was the follow-up to the fabulously successful A77 but it never really achieved the same heights of popularity, being almost 2½ times the price of its predecessor.
Extensive use was made of integrated circuits in both control logic and audio circuitry. The tape transport mechanism employed three servo controlled AC motors with a quartz clock generating a reference signal for control of capstan motor speed at 3¾ , 7½ , and 15 ips. A speed sensor ring operated simultaneously over the entire circumference of the capstan motor to detect total motor motion.
Servo control of spooling motors was via two independent tape tension sensors and constant tape tension was maintained in all operating modes (including wind and braking procedures).
‘Fail Safe’ auto stop logic operated in all the modes. Logic control monitored tape via tape motion; tape tension; and photo electric ‘end of tape’ sensors. Auto stop activated at the end of the reel, if the reel jammed externally prior to the tape tension exceeding permissible level or in the event of tape breakages.
A ‘repeat’ program mode was provided for instant replay. Regardless of operating mode, when the button was pushed, the tape transport re-wound. Releasing the button automatically stopped the transport and engaged ‘play’ mode.
Tape speed could be varied externally via an auxiliary unit for variation of tape speed over 7 half tones at any of the three tape speeds or with an external variable frequency oscillator, with a range from 1 to 10 kHz, making it possible to vary tape speed from 2½ to 21½ ips.
Four individual linear faders were provided for input mixing with one stereo master fader for record volume. Other features included jewel bearing VU meters with over modulation warning lights, stereo echo facility for recording and multiplay for dubbing, two individual linear faders for control of output volume and balance, stepped tone controls (bass and treble), 5 separate outputs, ‘plug in’ sound head assembly in half or quarter track configurations, provision for mounting a 4th head in the head block and a switched power outlet for tuner, amplifier, etc.
Price when new USA $1,800.00 UK £647.90
Track System Half or Quarter Track Stereo Versions
Motors Three servo controlled AC motors with a quartz clock generating a 1.6MHz ref. signal for control of capstan motor speed at all speeds.
Maximum Reel Size 10½ ”
Tape Speeds 3¾ , 7½ and 15 ips
Frequency Response (from tape at – 20 VU)
3¾ ips: 30Hz to 16kHz +2/-3dB; 50Hz to 10kHz 1.5dB
7½ ips: 30Hz to 20kHz +2/-3dB; 50Hz to 15kHz 1.5dB
15 ips: 30Hz to 22kHz +2/-3dB; 50Hz to 18kHz 1.5dB
Wow & flutter
15 ips: better than ± 0,06%
7½ ips: better than ± 0,08%
3¾ ips: better than ± 0,1%
Signal to Noise Ratio weighted as per ASA A, measured via tape
15 ips better than 65 dB
7½ ips better than 66 dB
3¾ ips better than 63 dB
Peak recording level 6 dB over 0 VU for a tape flux of 514 nWb/m
Level metering VU-meter as per ASA-standard, with optical overload indication-Overload threshold: +6 dB, 514 nWb/m
Response Time 10 msec Delayed Decay approx. 0.5 sec.
Crosstalk (1000Hz) mono better than 60 dB; stereo better than 45 dB
Distortion Peak Level or 0 VU respectively (1000 Hz)
at 15 ips and 7½ ips better than 2% or 0.6 % respectively
at 3¾ ips better than 3% or 1% respectively
Equalization NAB Standard
Semi-conductors 19 Integrated Circuits, 2 large scale Integrated Circuits, 93 Transistors, 92 Diodes, 7 Full Wave Rectifiers
mic lo 0.15 mV 6 kOhm
mic hi 1.8 mV 6 kOhm
radio 1 stereo input, Sensitivity 3 mV /33 kOhm
phono 1 stereo input, equalized as per RIAA Sensitivity: 2.5 mV 50 kOhm
aux (2) Sensitivity 40 mV 100 kOhm
line A: 1.55 V. Ri = 5 kOhm
line B: 1.55 V. Ri = 5 kOhm
radio (DIN): 0.775 V. Ri = 10 kOhm
adjustable level (volume, tone):
headphone: 4.9 V. Ri = 100 Ohm per output
power stage: 3.1 V. Ri = 100 Ohm
bass, ± 8 dB at 80 Hz in 2 dB steps; treble, ± 8 dB at 8 kHz in 2 dB steps
19 x 18¼ x 8¾ ” (483 x 460 x 225 mm)
Half or quarter-track stereo versions / Optional Remote control – A700 tape drive control