Revox A77
Built from 1967 - 1977
The Revox A77 is still one of the
It is still one of the most widely used, semi-professional analog tape machines. Approximately 450,000 units in countless variations have been built worldwide.
The device is considered particularly robust and easy to service. The professional design, with three motors and three sound heads, was well-received not only for home use, but also by many small recording studios and broadcasting companies. The following versions of the A77 were produced:
MKI
The success story began in 1967 with the first version of the A77. Despite some initial teething issues, the MK II was quickly introduced.
Following the success of tube tape machines, the Revox A77 was the first fully transistorized tape machine and was a huge success. The robustness, ease of use, and powerful sound speak volumes for the A77!
MKII
Very quickly, in 1968 the MK II came onto the market.
The rigid deflection pin of the first version was replaced by a movable calming lever, loop catcher.
III
The biggest changes between the versions always concerned the appearance. The third version has a gray lower front panel, and the VU meters now have a silver scale and are illuminated.
The Revox A77 is often underestimated. The technology is very simple and therefore very robust. The A77 will outlast all other tape machines, and a well-serviced and adjusted A77 is the most powerful sounding Revox machine!
MKIV
The A77 MK IV, built from 1973 onwards, features silver buttons and a blue Revox logo. Technically, very little has changed in the 10 years of production. Nevertheless, the changes should not be ignored! This was and is true engineering masterpiece, the likes of which are unmatched today!
Technical data
Drive:
3 Papst outrunner motors
Electronically controlled capstan motor
Belt speeds:9.5 cm/s and 19 cm/sas a special version also with 19 cm/s and 38 cm/s
Pitch fluctuations:
at 19 cm/s better +/- 0.08%,
at 9.5 cm/s better +/- 0.1%
Frequency response across band:
30 Hz to 20 kHz + 2 dB to - 3 dB at 19 cm/s
30 Hz to 16 kHz + 2 dB to - 3 dB at 9.5 cm/s
Signal-to-noise ratio:
66 dB (2-track), 64 dB (4-track) at 19 cm/s
63 dB (2-track), 59 dB (4-track) at 9.5 cm/s
with Dolby:
67 dB (2-track), 65 dB (4-track) at 19 cm/s
64 dB (2-track), 62 dB (4-track) at 9.5 cm/s
Spooling speed: approx. 8 m/s
Electronics:(Portable device) 54 transistors, 32 diodes, 4 silicon rectifiers, 1 photoresistor, 4 relays
Even back then, the information was incomprehensible to most users!
Power consumption: approx. 70 - 100 VA
Weight: 15 kg
Mass: 41.5 x 35.9 x 18.0 cm
Accessories for Revox A77
Cleaning kit
In our experience, most recording or playback problems are caused by dirty tape heads and tape guides.
Wow and flutter and poor winding are also part of the error pattern!
Dust cover
The rectangular dust cover is more common than the second variant, which also encloses the coils.
The rectangular cover encloses the entire upper and lower front and thus also protects all control elements.
Dust cover
The second version (photo to follow) also encloses the large 26 cm reels. However, the NAB adapters with cups don't fit underneath. The tape machine's control panels are also exposed here. If you still want to use high-quality NAB adapters under the hood, we recommend NAB adapters with an aluminum grip ring.
NAB-Adapter mit Griffring
So that you can operate the Revox A77 with a dust cover and high-quality NAB adapter, darklab magnetics has developed a NAB adapter with a grip ring.
Of course, these adapters also fit any other Studer or Revox tape machine!
Wired remote control
The cable remote control may seem strange today, but it used to be a pure luxury.There were no other options! Ultrasound, infrared, or even smartphones—all that came later.
The remote control is extremely rare in its original packaging!
Band shears
A tape head cover with tape cutters was available as an accessory from Revox. This made gluing the tapes very easy.
Since it was rarely cut privately, ribbon scissors are also very rare to find.
Switch-on delay
from our development suitable for all Revox A77.Just plug in, no soldering (version 1), no screwing or anything else!
Does the loud popping noise when you turn on the Revox A77 bother you? Even worse are the loud pitches of the speakers. That's not good!
Spare parts for Revox A77
Tachosensor
Very often the speedometer sensors break apart.The case is very brittle and sticks to the rubber mat, which in turn sticks to the chassis.
These sensors with the bell of the tone motor cause the mechanical whistling at 800 Hz or 1.6 kHz.
Tonmotor
The sound motors have a shorter sound motor shaft than the sound motors of the B77.
The motors are precision parts and should be treated accordingly. The shafts are ground to 1/1000 mm (1 µm)!
counter
The first counters still had gears, which made a lot of noise. Counters with toothed belts were then introduced. We offer suitable digital counters for all Revox A77, B77, and PR99 MK I with LED displays. These are much easier to read!
VU meter
The Revox A77's VU meters are also highly sensitive precision components and should be handled with extreme care. The older VU meters, in particular, are falling apart. Sometimes the needle is off, sometimes the magnet is stuck.
Tone heads
Nowhere is there so much fraudulent activity as with clay heads! Lapped heads are sold as new or as good as new. Then elsewhere, it's claimed that a 5 mm diameter is desired, and so on.
If you need used brains, then only from trustworthy business partners!
Relay replacement
Many original components are no longer available or are ancient! If components are no longer available, we try to reproduce them. We always strive to be as close to the original as possible.In 2008, these relays were created in the highest quality, suitable for many Revox devices.
Counter 77
In 2003, the first counter for the Revox A77 and B77 was developed. Previously, a counter was developed for cutting cables up to 100 m long. By selecting the color filters, you can choose from seven colors. The display is four digits, just like the Revox counter. Leading zeros can be suppressed as desired..
Andruckrolle A77
The Revox A77's pinch rollers have an 11 mm shaft length. Many people use B77 pinch rollers with two 1 mm washers. This leads to significant wow and flutter. It's a shame for the recordings made this way.
We use only sintered bronze bearings and genuine rubber. The pressure rollers are ground round in the final step. This is the only way we can still meet Revox's specifications and requirements.
Sentences
WWe offer high-quality repair and capacitor kits for all Revox A77 circuit boards and many other Revox devices. All our kits include assembly plans and component lists.
circuit boards
We can also offer you parts from our repair stock for the Revox A77. All circuit boards are complete, serviced according to our high standards, and pre-adjusted in the test unit. Final calibration must be performed on the unit at your location. You receive a one-year warranty on the circuit boards we offer!
Transistor 2N3584
the advantages of original spare parts...
...nothing needs to be adapted, no adjustments! Simply swap, connect, and you're done! Where possible, we use the right original part.
Unfortunately, this transistor is no longer available. However, we do have replacements in TO220 packages!
other Revox tape recorders
