Revox A 77
|
Revox A 77
By Bruno Fazzini
Revox A 77 . La sorgente analogica per eccellenza non è, come si potrebbe subito pensare, il giradischi, ma è quel meraviglioso strumento a cavallo fra il mondo amatoriale e professionale che ha fatto sognare schiere di appassionati della mia generazione: il registratore a nastro magnetico.
Il registratore a nastro, inizialmente chiamato “magnetofono”, è uno strumento usato per registrare e riprodurre suoni utilizzando supporti magnetici a bobina aperta. Col tempo questo termine è stato sostituito dal più appropriato “registratore magnetico”.
Io ho avuto la fortuna di avere per le mani diverse macchine ben funzionanti di qualche anno fa, un Revox, uno Studer, e qualche altro buon prodotto giapponese (Teac, marchio creato nel 1953), e vi posso assicurare che a confronto con un giradischi di ottimo livello, il registratore a bobine vince in musicalità, dettaglio, precisione e, soprattutto, in dinamica. La Revox inoltre è un’azienda svizzera “storica”, fondata da Willi Studer (che già produceva apparecchiature di registrazioni professionali con marchio Studer). Il nome deriva dal primo prodotto dell’azienda, risalente al 1948, un registratore a bobine da 1/4 di pollice, rimasto celebre per il caratteristico calore del suono, il cui nome era inizialmente Dynavox.
Infine ricordiamo, nell’immediato dopoguerra, la realizzazione del primo registratore a bobine ad opera del suddetto Willy Studer, che divise la produzione delle sue macchine professionali con il marchio Studer, e amatoriali, con il marchio Revox.
Mitico fu il modello Revox A77, prodotto dall’agosto 1967 all’ottobre 1977, un registratore analogico a nastro a bobina aperta, pietra miliare nel suo genere per qualità sonore, raffinatezza ed affidabilità della meccanica.
Bruno Fazzini
This recorder is a masterpiece of electronic and mechanical engineering. The electronic function and motor control system certainly sets a new standard in deck design and performance which, coupled with the really high fidelity electronic performance, puts this new range of REVOX recorders in the connoisseur class.
(From HI-FI Sound Magazine, February 1968)
The REVOX A77 is an open reel tape recorder designed to fill the needs of the serious audiophile and the professional industry. It is a maximum performance machine that offers everything we believe to be value for use in the living room and for on-location recording, most importantly, uninterrupted recording time with convenience and ease of use, and maximum electronic and mechanical performance.
Detailed below are performance and convenience characteristics being offered for the first time in a tape recorder of this price.
(From a Revox brochure – 1972)
 |
Willi Studer and his Revox tape recorder have gained an en enthusiast following reminiscent of the veteran car era and such names as Bugatti, Bentley and Duisenberg. His machines have been characterised by their advanced design, precision engineering and by their clean dynamic sound; the result of low distortion and wide frequency response.
The first machines, designated T26 ware made in 1949. Many still operate today and are already valued as collector’s items – a distinction that few electronic products can claim. The T26 continued until 1955 when the 36 series was introduced, and with it the international recognition of Revox as the tape recordist’s recorder….See more
This recorder is a masterpiece of electronic and mechanical engineering. The electronic function and motor control system certainly sets a new standard in deck design and performance which, coupled with the really high fidelity electronic performance, puts this new range of REVOX recorders in the connoisseur class.
Since 1949 the Willi Studer Company have distinguished themselves by their dynamic advances in magnetic recording equipment for the broadcast and recording industries. The all-new REVOX A77 is therefore unique in processing studio breeding. Significant mechanical and electronic advantages resulting from this experience are clearly evident throughout the machine. Featured here is the wood surround version, available in the suitcase model which the optional plug-in 8 Watt per channel audio power amplifiers….. See more
MANUFACTURER’S SPECIFICATIONS,
Tape speeds: 71/2 (19 cm/sec) and 33/4 (9.5 cm/sec). Motors: three, incl. electronically governed capstan motor. Reel size-. 10 1/2 in. (27 cm) max. Tape heads: three. Wow & flutter- 0.08% max. at 71/2 ips; 0.1% max. at 33/4 ips. Frequency response: 50 – 15,000 Hz ±1.5 dB at 71/2 ips; 30 – 20,000 Hz, +2, -3 dB at 71/2 ips; 50 – 10,000 Hz ±1.5 dB at 33/4 ips; 30 – 16,000 Hz +2, -3 dB at 33/4 ips. Distortion: 2% max. at 71/2 ips, 3% max. at 33/4 ips. Crosstalk: better than 45 dB (stereo) and 60 dB (mono). Equalization: record: NAB, playback, NAB and IEC (switchable). S/N: 58 dB at 71/2 ips;. 56 dB at 33/4 ips. Oscillator frequency: 120 Hz. Inputs: low- and high-Z microphone; radio, aux. Outputs: 2.5 V across 600 ohms; 200 – 600 ohm phones. Output amplifiers: optional plug-in, 8 W/chan. rms. Remote control: optional; plug-in prov, on chassis. Weight: 34 lbs. (15 kg).
When the predecessor of the current ReVox A77 was reviewed in these pages (Feb. 1966) it was readily apparent that the reviewer could find little fault with the machine. The same could be said of the A77, which boasts complete transistorisation, electronic speed control, remote-control facility, and a quality of construction which puts it in the deluxe class….. See more
EQUIPMENT TEST REPORTS
By Hirsch-Houck Laboratories
It is a pleasure to report that the widely acclaimed, but no longer available, Revox G36 Mk III tape recorder has actually been surpassed in performance by Revox’s new Model A77. The A77 has fully solid-state electronics, a bias-oscillator frequency of 120 kHz (as opposed to 70 kHz for the G-36), and a new electronic motor-speed control. The A77 model we tested is a three-motor, four-track, two-speed recorder; however, it is substantially lighter and smaller than its predecessor. , The Revox A77 has its operating controls grouped into separate recording and playback areas. On the playback side are two rotary switches with concentric knobs. One switch establishes the playback mode stereo, either channel through both outputs, on both channels combined for mono…. See more
For technical sound
recording everything
points to Revox
1 Separate spooling motors of original high torque, low weight construction. 2 Sealed mains input selection and cabinet safety links socket. 3 Fully electronically stabilized power supply circuit. 4 Capstan motor servo control panel maintaining speed accuracy to better than 0,2% and incorporating electronic speed change from 71/2 to 33/4 ips. 5 Read head of capstan motor. 6 Tape transport logic control circuit panel. 7 Plug-in relays controlling all functions and eliminating damages from inadvertent mishandling. 8 Plug-in audio input/output amplifiers. 9 Plug in 120 Kc/s bias oscillator obviates multiplex interference. 10 plug-in record relay. 11 Unique multi-bank micro switch unit providing on-off, speed and spool size/tension variations on one control. 12 Professional practice glass-fibre panel with integral gold plated switch contacts. 13 Capstan motor of patented construction, cool running, low current consumption and wow and flutter better than international broadcast requirements….. See more
REVOX HS77 NAB AND IEC PROFESSIONAL
(Revox A77HS [high speed])
MANUFACTURER’S SPECIFICATION (Agfa PE36 at 38 cm/s). Professional mains transportable stereo recorders with Tachometer capstan motor .speed control. Tape Transport: Direct capstan drive, separate motors for fast forward and reverse wind. Wow and flutter: 0.04% maximum. Tape slip: less than 0.2%. Spool capacity: 26.5 cm, NAB hubs. Frequency response: 30 Hz – 20 kHz ± 1.5dB. Distortion: 2%. Equalization: NAB or IEC to order. Signal-to-noise ratio: 60 dB. Crosstalk: (1 kHz): 45 dB stereo, 60 dB mono. Tape speed, 38 and 19 cm/s. Bias frequency: 120 kHz. Inputs: 0.15 mV at 50 ohms to 6 K or 2 mV at 100 K (microphone, switchable); 2 mV at 33 K (radio); 40 mV at 1 M (auxiliary). Outputs: 2.5 V at 600 ohms (line); 1.2 V at 2.5 K (radio). Weight: 15 kg. Dimensions: 359 x 215 x 413 mm (plus spool overhang). Prices: On application. Manufacturer: Willi Studer, CH-8105 Regensdorf, Zurich, Switzerland……See more
An improved version of the critically acclaimed A77.
A professional recorder for the discriminating enthusiast.
The new REVOX A77 MK lll is the best recorder that REVOX has ever made. A unique synthesis of reliable electronics and precision mechanics. It sets a new standard in tape recorder design and performance. While fully capable of meeting the most rigorous studio demands, its ease of operation also makes it the perfect choice for the serious enthusiast.
Ergonomic design for (instinctive) operation
Operating elements systematically laid out and functionally grouped
– Feathertouch push buttons (relay controlled) for all Transport functions
– All functions can be remote controlled (optional) o Accurately calibrated VU meters with special lights to indicate record mode…...See more
Special version REVOX Dolby A 77 Tape Recorder containing entirely new Dolby B circuits to achieve the ultimate in noise reduction: even the softest pianissimo can be free of tape noise.
Even the best professional tape ,recorders have their dynamic range limited by tape hiss. This hiss may take on a high nuisance value during quiet passages or when low level sounds are present, especially if slower tape speeds are employed with quarter track tape width. Furthermore, this hiss level increases in tape dubbing with each subsequent copy of the tape. However, by applying a new electronic process developed by Ray Dolby, the inherent tape hiss can be rendered inaudible. In conjunction with the excellent recording and playback….See more
REVOX A77 with Dolby Noise Reduction System, Additional Technical Data
All mesurements taken with Revox 601 tape. Dolby electronics switched on.
2-Track Version (values for the 4-Track Version are shown in parenthesis)
| Signal to Noise Ratio off tape, weighted as per CCIT |
At 7 1/2 ips. better than 67 dB (65 dB) At 3 3/4 ips. better than 64 dB (62 dB) |
| Signal to Noise Ratio weighted as per ASA A |
At 7 1/2 ips. better than 70 dB (67 dB) At 3 3/4 ips. better than 67 dB (65 dB) |
| Distortion measured off tape, 500 Hz peak Level (assumed to be +6 VU) |
At 7 1/2 ips. better than 1% (1.5%) At 3 3/4 ips. better than 1.5% (2%) |
| Distortion Operating Levekl 0 dB (100%) |
At 7 1/2 ips. better than 0.5% (0.5%) At 3 3/4 ips. better than 0.5% (1.5%) |
Copyright, 1972
by North American Publishing Co.
Reprinted by permission from the November 1972 AUDIO MAGAZINE
Whatever we said about the original Revox A77 in October, 1968, could well be repeated here, except that this model is better-being Dolby equipped. There are a few minor differences in appearance and a few in the mechanism itself. The upper portion of the unit-behind the tape reels-now has a stainless steel front over the plastic main panel, whereas the original was dark gray plastic. The lower portion of the first model was brushed stainless steel, while the, current model has a dark gray plastic panel.…..See more
Copyright, 1972
by Billboard Publications, Inc.
Reprinted by permission from the November 1972 HIGH FIDELITY
Comment: Some readers, accustomed to associating the Dolby circuit with cassette equipment and a price in the $300 range, may be taken aback by this unit. Since they have been told that cassettes are inherently noisier than open reel because of the slow Transport speed, they may think that only the cassette can profit from Dolby noise reduction. Not so. While Dolby processing offers demonstrably more dramatic improvements in the cassette format, Revox has traditionally designed its recorders for those who want the best that tape has to offer and, indeed, for professional as well as home use. In such a context the Dolby B offers an improvement that is both measurable and audible – and therefore significant….See more
Copyright, 1972
by Ziff-Davis Publishing Co.
Reprinted by permission from the August 1972 STEREO REVIEW
When we tested the Revox A77 tape recorder several years ago (January 1969) we found it to be an outstanding machine in every important respect. The Revox A77 is still with us – a few minor bugs have been eliminated, but it is essentially unchanged – and it has earned itself a solid reputation as one of the top home or “semi-professional” tape recorders. Revox has now added Dolby B circuits to the already very quiet A77 and has released it as the A77/Dolby B. The standard machine without the Dolby circuits is still being manufactured.
A careful external examination is required to reveal the presence of the Dolby system. When the hinged cover plate is lowered to expose the tape-loading path, the two pushbuttons to the left of the heads (SPEAKERS OFF and REEL MOTORS OFF) have been replaced by two Dolby recording calibration knobs. The playback power amplifiers of the A77 have been eliminated from this version, probably to make room for the Dolby circuits…. See more
Copyright, 1972
by Straight Arrow Publishers
Reprinted by permission from the October 12, 1972
ROLLING STONE MAGAZINE
The Top “Semi-Pro” Tape Deck
If you get turned on by big bridges, German cars, Swiss watches, Leica cameras, and Computers if you had three Erector sets at the same time as a kid; if you shadowed the TV repairman and the plumber when they worked in your house; if you just know they’re going to bury you with a screwdriver tucked into your shroud, a Revox tape deck would make you very, very happy.
And if you are a music maker or music listener besides, a Revox would make you ecstatic!
The Revox A77 Dolbyized deck sells for $999, and can make recordings with sound equal to million-dollar studios. It is compact enough to strap on the back of a motorcycle, and rugged enough to survive a crash. It either contains or may be combined with every imaginable feature and accessory, and is as fool-proof and easy to operate as any recorder I know of….See more
Copyright, 1972
by Davis Publications, Inc.
Reprinted by permission from the Fall 1972 HI-FI STEREO BUYERS’ GUIDE
How do you improve upon an already superb tape deck? If you are Revox you simply avoid gimmicks that would only complicate what is probably the easiest-to-operate mechanism – whether professional or amateur – and concentrate on squashing the tape noise through use of a Dolby B noisereduction system. The fact is, the only apparent difference between the old A77 and the Dolby A77 is the Dolby system. Well, it’s the Dolby, but with a big difference. You don’t get a calibration tape with the Revox because the machine is supplied so precisely adjusted you don’t have to match tapes, make any corrections, or do anything other than record as you normally would…. See more
REVOX A77
Professional
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….See more
The A77 S. L. S. is available in half and quarter track formats.
| SPECIFICATIONS | 15/16 IPS |
| Frequency Response | 60-5000 Hz +2 -3dB |
| Wow and Flutter | . 3% |
| Recorded Peak Level | 140 NWB |
| Distortion at 140NWB/Revox 601 Tape |
Less than 3% |
| S /N ratio, unweighted | Greater than 46dB |
| Erase Efficiency | Greater than 68dB |
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 ips
Operating positions: horizontal, vertical or inclined. Remote control: momentary contact switching for all functions
Electronics
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 IEC (switchable)
•(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 k ohms
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
Technical Specifications (General)
| Dimensions: | Standard | Carrying case |
| Width | 415 mm (16.33) | 514 mm (20.23) |
| Height | 359 mm (14.13) | 380 mm (15.00) |
| Depth | 180 mm ( 7.08) | 224 mm ( 8.81) incl. cover |
With 26.5 cm (10.5 inch) reels (all models), max. width 539 (21.22), max. height 442 (17.40).
REVOX PERFORMANCE SPECIFICATIONS
FOR REVOX A77 MK I / REVOX A77 MK II / REVOX A77 MK III / REVOX A77 MK IV
| Mechanical | |
| Tape Transport | Three Studer eddy current motors. Electronically governed capstan motor. Electronic speed change. Solenoid operated via 3 relays. |
| Tape Speeds: | 3.75 and 7.5 ips (9,5 cm and 19 cm/sec.) ± 0.2% High speed Version: 7.5 and 15 ips (19 cm and 38 cm/sec.) ± 0.2% |
| Wow and Flutter: | max. ± 0.04% at 15 ips max. ± 0.08% at 7.5 ips max. ± 0.1% at 3.75 ips (Weighted at DIN Standard 45507) |
| Tape Slip: | Less than 0.2% |
| Reel Diameter | Maximum 10.5″ (26,5cm) (Minimum hub diameter 23/8 inches) |
| Forward / Rewind | Fast winding time for 1800′ (1100m) is 92 seconds |
| Tape Heads | Three (Separate precision erase, record and playback heads.) Patented ‘True Radius’ design ensures excellent S/N ratio and head wrap |
| Guide System: | The Heads, the capstan drive, and the machines tape guides are mounted to a one-piece casting to maintain precise alignment. |
| Operating position: | horizontal or vertical |
| Electrical | |
| Monitoring | Individual stereo record and playback heads with separate preamps, plus separate record and play circuits permit full source-tape monitoring. |
| Equalization: | NAB Standard on both record and playback at all speeds.IEC Standard switchable on playback only. |
| Record Playback Frequency Response:(Based on Revox 601) |
15 ips – 30 Hz – 20 kHz ± 1.5 dB 7.5 ips – 30 Hz – 20 kHz + 2 / – 3 dB 3.75 ips – 30 Hz – 16 kHz + 2 / – 3 dB |
| Signal to noise: | 2-Track: 15 ips – better than 66 dB 7.5 ips – better than 66 dB 3.75 ips – better than 63 dB4-Track: 15 ips – better than 62 dB 7.5 ips – better than 62 dB 3.75 ips – better than 59 dBAdd 4 dB to the above figures with Dolby on, referenced to less than 2% THD (Reference with Scotch 203 or Revox 601 or equivalent. Weighted as per CCITT C-curve to exclude supersonic bias noise.) |
| Distortion at full modulation at 1 kHz: |
Max. 2% at 15 ips and 7.5 ips. Max 3% at 3.75 ips. |
| Crosstalk at 1 kHz: | Stereo, better than 45 dB Mono, better than 60 dB |
| Bias frequency: | 120 kHz, push-pull oscillator. Designed for low noise, high output tapes |
| Input sensitivity per channel | Microphone, switchable LOW/HIGH LOW: 50 – 600 ohms (unbalanced) 15mV HIGH: up to 100 K ohms 2.5 mV RADIO: 33 K ohms 2.5 mV AUX: 1 M ohms 33 mV |
| Output per channel | OUTPUT: max 2.5 rms @ 600 ohms RADIO: max 1.2 rms @ 2.5 K ohms PHONES: 200 – 600 ohms (no electrostatic) |
| Semiconductor complement: | 54 Transistors; 32 diodes, 4 silicon rectifiers, 1 CdS-cell |
| Remote control: | Fully electric for all operation functions. |
| Output Amplifiers: | Plug-in optional. 2 x8 watts continuous rms power, 2 x10 watts music power as per IHFM, 4-16 ohms, less than 1% distortion. |
| Power Supply: | Electronically stabilized. |
| Mains voltages: | 110, 130, 150, 220,240, 250V / 50-60 Hz. |
| Power consumption: | 70 … 100 watts |
| Dimensions: (Wooden Cabinet) |
161/4” W x 141/8” H x 81/2” D. (Measurements include knobs but not reels.) |
| Weight: | Approximately 34 pounds (» 15 kg) |
| All figures quoted are minimum performance values as measured with REVOX 601 tape normally exceeded by all units. | |
VIDEO
