Revox A-77 open-reel tape recorder

The Revox A-77 has extremely good speed regulation, vanishingly low wow and flutter, very low noise, superb tape handling, and the smoothest, widest-range frequency response of any recorder we have ever tested.

The portable version, with built-in monitor amps and speakers, is very compact for a machine with 10½ reel capacity, and is easily carried by one person. Now that the later version is equipped with a flutter-filtering tension arm, our only criticism of the A-77 is its use of three-circuit jacks for the micro phone inputs instead of the XLR-type receptacles that are considered to be "standard" in the US for on-location audio recording.

Incidentally, Revox claims that all A-77s are set up for Scotch low-noise tape. This may be true, but three samples of the unit were found to be rather imprecisely adjusted, exhibiting considerable high-end response deviations. As usual, we advise the buyer to do his own recorder setup (See "On Tape" in this issue) or have it done by some one he knows to be finicky.

Unlike the Revox G-36, the A-77 looks like a snap to service. All circuit subassemblies are on plug-in boards (footnote 1), and are readily accessible, and the service manual is clear and straightforward.

All indications are that this is by far the best tape recorder one can buy without going to a truly profession al machine. Only time will tell how well it can maintain its initially high standards of performance through months and years of use.

JGH wrote again about the A-77 in March 1971 (Vol.2 No.12):

In terms of performance, the Revox A-77 is unquestionably the best tape recorder we have ever tested, and we've tested some of the top professional machines.

It has a full complement of internal setup adjustments for matching it to the tape you're using, and although Revox states that A-77s are pre-adjusted for 3-M's 203 tape, we found that ours could be significantly improved (for use with that tape) by some further adjustment, after which it produced the smoothest, widest-range tapes (at a given speed) of any recorder we know of. The extended low- and high-frequency response limits are impressive enough (fig.1), but in fact it is the unusually smooth response between these limits that makes the A-77's playbacks sound virtually in distinguishable from the original signal.


Mechanically, the A-77 handles and performs superbly, with totally inaudible flutter (due in part to the flutter-filtering tension arm that was added shortly after the recorder was introduced), but there are indications that the deck may not be as trouble-free as the electronic sections evidently are.

We have never known a tape recorder that didn't have at least one "weakness" of some kind. The KLH Forty had tape-handling problems, the earlier Tandbergs had problems due to overheating, and even some of the big professional Ampexes have motor and solenoid problems. As for the A-77, a number of users have reported problems with the relay contacts and the reel-drum brakes. The fact that Revox's instructions recommend using reverse-wind torque (instead of the Stop button) to slow the tape after a high-speed wind suggests that the manufacturer, too, may be aware of a certain weakness in the braking system.

It is easy enough to get into the habit of doing this, and worth doing anyway because it stresses the tape less, but the need for doing it does make one feel just a little insecure about the deck.

Of 46 A-77 owners we have heard from, though, only 3 have had brake failures, 13 have had troubles that might have been attributable to relays, and 32 said they had had no problems that required professional service. Of the ones who did, all reported prompt and effective service from the Revox people, which may set some kind of a record. Our own A-77 (which we bought) has been used for perhaps 250 hours to date, and has worked flawlessly.

The A-77 is, by the way, available on special order in a 2-track version and/or a high-speed (15ips and 7½ips) version, for professional use, and no professional need apologize for using it. As for the home-type, 4-track, slower-speed one, this is going to be hard to beat. For sheer fidelity of recording, we doubt that it is beatable at the present state of the art. But we'll keep looking.

Manufacturer's Comment (1971)
Very early-production models of the A-77 used nylon brake shoes, which did on occasion "grab" during high-speed stops, but all A-77s made since over a year ago have cotton-pad brakes which have eliminated the problem. It is now entirely safe for the recorder to go from a high-speed shuttle direct ly to Stop braking, although it is still easier on the tape to slow it via reverse torque before stopping it.

The relay problems that some A-77 owners have experienced appear to be the result of air pollution, since the trouble can be effectively eliminated by a special contact-surface treatment that can be done by Revox in the US or by any of their dealers.

JGH returned to the Revox A-77 in December 1973 (Vol.3 No.5):

In the Stereophile issue dated Spring '71, our report on the original Revox A-77 concluded "For sheer fidelity of recording, we doubt that it is beatable at the present state of the art."

Well, the state of the art changes with time, and the A-77 has been surpassed by at least one other open-reel machine: The A-77-III Dolby B.

This contains four complete Dolby circuits, to allow simultaneous processing and deprocessing, so one can listen to the de-Dolbyed playback from a tape while it is being recorded. And since we all know by now just how effectively the Dolby noise reduction works, we won't linger to rhapsodize about it all over again. Just think of this as an ordinary A-77 with 10dB less audible hiss.

There are other differences between this and the earlier Revoxes, too. Because a Dolby requires careful adjustment of play and record levels, Revox has finally seen fit to provide metering of playback level (ahead of the play volume control). Aside from its value in Dolby setup, this greatly facilitates in-the-field checks of bias and signal levels, as well as making tape copying considerably easier. (Play any moderately loud passage, note the VU meter reading, and adjust record level on the second machine for the same reading.)

Needless to say, all current-model Revoxes (including non-Dolby ones) incorporate design modifications that were prompted by some problems in early models. The reel brakes no longer tear themselves apart if actuated during a high speed wind, relays are much more reliable, and the motors now run cool. And Revox's astounding warranty policy still applies: One year for the capstan, pinchwheel and heads, and a lifetime warranty on everything else. (This means your lifetime, as long as you own the recorder—not the the recorder.)

The machine is still as much of a pain in the neck to thread as it always was, and the service manual is a horror. The only real glitches we found in our samole, though, were: 1) a tendency for the Input/Tape monitor switch to imprint audible clicks on the tape; and 2) a rather pronounced boost of low-end frequencies when playing back tapes that were recorded to conform to the NARTB equalization curve that is standard for all tapes, including pre-recorded ones, made in the US.

We contacted Revox, USA about the clicks, and were told that they had not encountered the problem. It struck us as highly unlikely that we would receive for testing the only clicky A-77-III that had been manufactured, so we conducted a telephone poll of local Revox dealers whom we know well enough to get the straight poop from. Not one had encountered the clicky switching, and neither had any of their customers. So we were forced to conclude that the problem, if not unique to our sample, is quite rare. If you do encounter it, though, don't despair. It is not supposed to happen, and Revox will willingly if not joyfully undertake to eliminate it.

The low-end rise was more difficult to pin down. Playing its own tapes, the A-77-III's low end was almost perfectly flat down to around 25Hz. Yet when playing tapes made on other good recorders (and this included commercially produced music tapes), there was a low-end rise amounting to what sounded like about 3dB of boost at 40–50Hz. To date, Revox has not acknowledged the existence of this, and neither were we able to find anything in their playback circuitry that would account for it, but there it is. And we did not find it in their 2-track model or in any of their previous 4-track models. It is not related to the Dolby, for the rise is there whether the Dolby is in or out of circuit. It is easily corrected with any variable-turnover tone control, but there is really no excuse for its being there at all.

Revox prices keep going up. When we bought ours in 1971, the basic 4-track model (we got a 2-track one) was priced at $569, which was a good price for a recorder of such performance capability. How the price for the same model (but incorporating the improvements we mentioned before) is $799 without the Dolby, which is likely to make a prospec tive buyer take a long, thoughtful look at the competition. Even at their inflated prices, though, the ReVox units are going to be hard to beat on overall performance. And no-one else is offering a warranty like Revox's. That's worth something.

Manufacturer's Comment (1973)
On return of the sample A-77-III Dolby that Stereophile tested, we checked the low-end response with a l/4-track STL alignment tape and found a 1dB rise at 40Hz—well within our published specifications. A 4-track, non-Dolby machine and a 2-track Dolby machine checked at the same time showed a similar response.

With regard to pricing, in the high-fidelity industry it is unusual for a piece of equipment to be in production for long enough for price increases to become apparent. The Revox A-77, because of its superior design, has been in production for some five years without its performance being surpassed. During this time, costs of raw materials have risen worldwide, production costs have increased, improvements in components and materials have been incorporated into the A-77, and the dollar has suffered an unusually severe decline in purchasing power. To put it simply, quality, like gold, has retained its intrinsic value. The dollar unfortunately has not.

The value-for-money of the A-77 is still extremely good though, and this is reinforced by your comments about the original A-77 and the A-77-Dolby B: "For sheer fidelity of recording, we doubt that it is beatable at the present state of the art."

Footnote 1: I bought a secondhand Revox A-77-III in the late 1970s and used it for many live recordings over the next decade or so. I replaced it with a Revox PR99 and while I still have the A-77, some of the original paper-epoxy plug-in boards have crumbled into dust.—John Atkinson

jmsent's picture

...have crumbled into dust." Really? I've never seen that happen to a circuit board, and I'm a restorer of vintage electronic items. The only exception would be due to long term heat exposure from e.g. a tube socket. I wonder if Revox got ahold of a bad batch of pcb material? Even the old paper phenolic stuff in cheap '50s transistor radios still holds up reasonably well. I recall that later versions of the A77 were using the green colored glass epoxy boards. Those should hold up very well. I'm sure replacements boards would be available, as a lot of these decks have been parted out.

mcleanra's picture

Revox CEO Christoph Frey, after reading my messages, on April 18, 2020, wrote, "However we are willing to support you with a free repair. However you will have to send the product to the factory in Germany:

Revox Deutschland GmbH
Am Krebsgraben 15
78048 Villingen-Schwenningen
Tel.: + 49 7721 8704 0"

As of this date, my machine is in Germany and has not been returned to me.

Does anyone at Stereophile have J. Gordon Holt's notes for the revision he posted Nov 6, 2019, stating in his 2019 article the lifetime warranty still exists for the original owners?

John Mclean

Jim Austin's picture

Does anyone at Stereophile have J. Gordon Holt's notes for the revision he posted Nov 6, 2019, stating in his 2019 article the lifetime warranty still exists for the original owners?

No, sorry. Best of luck with the Revox.

Jim Austin, Editor