The well-known reliability of the Revox A77 is a result of a
professional design concept, a concept which successfully combines
the advantages of a solidly constructed tape transport mechanism
with the advantages of an advanced electronic circuit design.
A 3-motor transport mechanism with electronically regulated
capstan motor and solenoid operated servo-brakes possesses few
parts which are subject to mechanical wear. The use of a diecast
motor chassis and head support ensures that a high degree of
mechanical precision and long term stability are maintained,
even under excessively heavy use. The mechanical and electronic
properties thus complement each other in a most successful way.
Rugged 3-Motor Tape Drive
with its 3 motors on a solid die-cast chassis, the A77 possesses
the basic design features of a professional tape recorder. Due
to the direct drive principle, there are no friction wheels,
clutches or belts needed. This makes for a mechanically simple
drive system with only a few movable parts. Thus, wear is reduced
to a minimum, a point of vital importance for the long life
of a tape recorder.
|By using this 3-motor principle, each function
has been optimized. The spooling motors are designed to cope
with normal tape tension and high speed winding, which can be
made very fast even with 10.5 inch reels, while the capstan
motor is solely responsible for the linear forward motion of
the magnetic tape.
Electronically Regulated Capstan Motor
Uniform motor speed - and with it even tape motion - does not
rely on utilizing the power line frequency, but is controlled
instead by an internal electronic regulating system. Tape speed
is thus stable and to a high degree independent of any variation
in power line voltage or frequency. Therefore, the A77 may also
be used by driving it from batteries (via an inverter with sine
wave output) and nothing whatsoever has to be changed when moving
from a 50 Hz to a 60 Hz electric supply area or vice versa.
The change of tape speed is also achieved electronically, free
of any mechanically wearing parts, and free of any influence
on the characteristics of the tape drive mechanism.
Electronic Control of Tape Drive Functions
All functions of the tape drive mechanism are controlled by
a simple relay logic. This makes possible soft "finger
touch" switching, as well as remote control of all operating
modes. Solenoid activated servo-brakes ensure safe and positive
stopping of the tape even from the highest winding speed.
Modular Amplifier Circuitry
The audio electronics of the A77 offer the following typical
characteristics: extremely low distortion; high signal to noise
ratio; linear response and exact equalization characteristics.
All amplifier boards plug in for easy servicing. Only the combination
of these properties makes for a recorder of outstanding quality.
Two input channels may be switched separately to work from either
low or high impedance microphones or from other sound sources
as well. Two microphones may be connected directly to the front
panel or to the socket strip on the rear. Separate input controls
for each channel permit the mixing of two monophonic signals,
or the exact balancing of stereophonic recordings and two precisely
calibrated ASA VU-meters ensure accurate modulation of the recording
REVODUR Sound Heads
The REVODUR sound heads have improved magnetic characteristics
and a much higher life expectancy. Consistent quality is thus
assured since STUDER REVOX designs and builds their own magnetic
Separate calibration controls for each speed and channel permit
precise bias and equalization adjustments of the A77. This forms
the basis for the excellent recording characteristics of all
A77 recorders, because our published specifications are minimum
values, which must be met by each and every recorder.
The A77 professional recorder is available in 7 ½/15
IPS half & full track configuration and is fitted with Cannon
XLR connectors on inputs and outputs. Inputs are balanced, line
level and require +8dBM for full tape modulation. The input
levels are preset and no front panel adjustments are provided.
|The outputs have independent line amplifiers providing
a balanced +8dBM preset line level. In addition an adjustable
output is provided to feed headphones or unbalanced equipment.
Optional plug in 8 watt amplifiers are available for the half
track machine to drive external speakers or the 4 internal speakers
included in the suitcase version.
Line: balanced; sensitivity +8dBM (preset for full modulation;
Cannon XLR3 connectors.
S. L. S.
The A77 is available ina super low speed of 15/16 & 1-7/8
IPS. With the A77 super low speed 15/16 IPS version Revox reliability
is now available for all logging applications. Over 12 hours
can be recorded in one pass on two tracks, with 3,600 feet of
tape. With a modification to the end of tape lamp circuits,
two machines can be linked to provide automatic logging for
|The S. L. S. model combines mechanical simplicity
and proven reliability with a very reasonable cost. A true alternative
to complex and costly loggers. The A77 S. L. S. is available
in half and quarter track formats.
||60-5000 Hz +2 -3dB
|Wow and Flutter
|Recorded Peak Level
140NWB/Revox 601 Tape
|Less than 3%
|S /N ratio, unweighted
||Greater than 46dB
||Greater than 68dB
|The A77 Autostart machine automatically goes into
the record mode in the presence of a signal. It will continue
to record for up to 7 seconds (variable) after the signal has
been removed and then stops. (Trigger sensitivity is variable
for each channel).
| The A77 Autostart is ideal for any operator unattended
monitoring application where
good recording quality (7½ IPS) is required. For example
Radio stations can use this Revox machine to receive network
news feeds automatically. Security firms who must record telephone
calls can do so backed up by Revox dependability.
The A77 Autostart has the same fine specifications as the regular
model 11102 (a push for Manual button disables the auto start
circuitry for normal operation) and is available in quarter
and half track formats at 3¾ and 7½ IPS.
|All figures quoted are
minimum performance values as measured with REVOX 601 professional
tape. They are valid for two and four-track recorders, except
where otherwise stated.
Tape Drive Mechanism
Design principle: 3-motor tape drive mechanism, electronically
regulated servo capstan motor
Tape speeds: 3¾ and 7½ ips, selected by electronic
switching. Deviation from nominal ±0.2%
Wow and flutter: weighted,
at 7½ ips, less than ±0.08%
at 3¾ ips. less than ±0.1%
Measured in accordance with IEEE standard 193-1971 (consistent
with DIN 45507)
Tape slip: not exceeding 0.2%
Tape reel dimension: up to 10½" outside diameter
(minimum hub diameter 2 3/8 ")
Uninterrupted playing time: with long playing tape 3600 feet,
3 hours 12 mins. at 3¾ ips. 1 hour 36 mins. at 7½
Operating positions: horizontal, vertical or inclined. Remote
control: momentary contact switching for all functions
Semi Conductor Complement: 54 transistors, 32 diodes. 4 silicon
rectifiers, 1 light dependent resistor. 4 relays
Amplifier: plug-in printed circuit boards
Frequency response: measured via tape at 7½ ips.
30-20,000 Hz ±2/-3dB
50-15,000 Hz ±1.5 dB
at 3¾ ips.
30-16.000 Hz +2/-3dB
50-10.000 Hz ±1.5 dB
Equalization: recording as per NAB*, playback as per NAB* or
(consistent with DIN 45513/H)
Distortion: measured via tape at 1 kHz peak level and 0 VU respectively
at 7½ ips, less than 2% or 0.6% respectively
at 3¾ ips, less than 3% or 1% respectively
Signal to noise ratio: measured via tape,
weighted as per ASA - A:
at 7½ ips, better than 66 dB
4-track better than 62 dB
at 3¾ ips, better than 63 dB
4-track better than 59 dB
Crosstalk: at 1000 Hz for monophonic operation, better than
60 dB, stereophonic operation, better than 45 dB
Oscillator frequency: 120 kHz (push-pull oscillator)
Overload margin for each input: 40 dB
Inputs per channel
Microphone (switchable for high and low impedance microphones):
Sensitivity for 50-600 ohms low impedance microphones: 0. 15
mV. maximum 15 mV
Input impedance 2. 2 k ohms
Sensitivity for high impedance microphones up to 100 k ohms:
2. 5 mV. maximum 250 mV. Input impedance: 220 k ohms
Input connectors RCA-phono sockets and phone jacks
Radio: sensitivity 2.5 mV. maximum 250 mV, input impedance 33
Input connector 5-pin DIN socket
Auxiliary input: sensitivity 35 mV, maximum 3. 5 V,
input impedance 1 M ohm
Input connectors RCA-Phono sockets
Outputs per channel
Output for amplifier: maximum output voltage 2. 5 V. source
impedance 600 ohms
Output connector RCA-phono socket
Output for radio: maximum output voltage 1.2 V, internal impedance
2. 5 k ohms
Output connector 5-pin DIN socket
Output for headphones: recommended load impedance 200 ohms or
higher, volume adjustable
Output connector phone jack
Power output stages: optional plug-in amplifiers, all performance
characteristics conform to DIN 45500
8 watts continuous average power per channel, measured with
a load impedance of 8 ohms at a maximum total harmonic distortion
of 1%. Loudspeakers having a nominal impedance of 4 to 16 ohms
may be connected.
Loudspeakers (2 per channel in the suitcase model) will be automatically
disconnected when plugging external loudspeakers into the respective
DIN output sockets.
Power requirement: electronically regulated power supply.
Operation on 50 to 60 Hz power line without the need for change-over.
Power consumption without power stages 70 W approximately, with
power stages 70 to 100 W. fuse rating.
110 to 150V: 1 amp, slo-blo
Weight: approximately 33 pounds
Model variations: walnut cabinet or metal case with or without
power amplifiers, suitcase model with built-in loudspeakers,
2-track or 4-track version
With 26.5 cm (10.5 inch) reels (all models),
max. width 539 (21.22), max. height 442 (17.40).
||415 mm (16.33)
||514 mm (20.23)
||359 mm (14.13)
||380 mm (15.00)
||180 mm ( 7.08)
||224 mm ( 8.81)
STUDER INTERNATIONAL AG
CH-8105 Regensdorf, Switzerland
Phone 01 8402960