The first was of the D6 in Vol. 7 No. 6, which puts it at autumn, 1984, just as the D6C was coming out. The author, George W. Graves, listed it as the WDM-6! He was new at reviewing, actually, as the editors described him as “a reader who submitted this article just on speculation, and we printed it! His musical tastes range from occasional jazz to large scale symphonic and operatic works, and he works as a marketing engineer for a semiconductor manufacturer. Other readers who feel inspired to write up products that haven't already been reviewed by Stereophile should feel free to submit articles—but don't be too disappointed if we turn them down!”
One would think that, with all their enthusiastic promotion of digital audio, Sony might have forgotten about analog audio. Not so. For over a year now, Sony has had available a Model WDM-6, known as the Professional Walkman—a deluxe version of their original Walkman, which includes stereo recording capability. Not only is this the only Walkman-type cassette recorder that has high enough quality to satisfy audiophiles, it also has accessories available to make it into an amazingly good portable recording system. The $350 WDM-6 is just a little larger than a paperback copy of Gone With The Wind. The machine may be powered from an optional AC adaptor, from four AA cells, or from an optional rechargeable nicad pack sold by Sony. The nicads can be charged inside the unit while it is operating from its AC adaptor, and a fully charged pack will run the unit for two hours continuously. That makes it a good idea to carry a couple of spare fully charged packs if you're doing any serious recording. The unit has a crystal-stabilized servo-controlled capstan drive and Dolby B noise reduction, high-quality microphone inputs, and it will record on metal tape as well as conventional tape formulations. But it is the accessory microphone which makes this tiny recording system so unusual.
The ECM-929LT is a single-point stereo microphone about the size of a lady's pearl-handled automatic pistol, which is unusual enough in itself. But what makes this unique is that instead of being the usual -Y stereo microphone (using crossed cardioids or figure-8s), this is a true M-S microphone! M-S is an abbreviation for the German minel-seite, which means middle-side. An M-S mike consists of two pickup elements: a cardioid element (unidirectional, heart-shaped pattern) facing forward, and a figure-8 bidirectional element with its lobes facing to opposite sides. Neither element by itself is capable of yielding a proper stereo output, but when the signals are combined in a special way, they do. In fact, by adjusting the way the signals are combined, they can be made to produce an infinite variety of pickup patterns ranging from mono unidirectional (forward only) through every stereo angle to mono omnidirectional (all-around). The combining, or matrixing, can be done with transformers or with active devices and resistor networks. In the ECM-929LT, transformers are used and a switch on the mike itself selects transformer taps to provide unidirectional mono, 90° stereo angling, or 120° stereo angling.
The choice of three modes (rather than more) is inspired by economy, since each mode requires a different combination of taps from the transformer windings, and more taps would raise the cost.
If a greater variety is desired, Sony offers another accessory, the cigarette-pack-sized MRU-60 ($65), which uses resistors and solid-state circuitry, and connects between the microphone and the recorder to provide infinitely variable adjustment of the pickup pattern. It works beautifully, and in some instances its ability to control the size of the stereo "stage" is invaluable. But you do give up something in exchange. It adds some hiss, while the transformer matrixing does not. And the three patterns provided by the basic mike are adequate for most recordings. The same resistive matrixing is used in a smaller and more expensive Sony M-S mike, the ECM-939LT ($115), but it too is noisier than the larger, transformer-equipped one, so I do not recommend it.
With such an unobtrusive and portable recording system as this, there is a temptation to sneak it into live concerts and "cop a performance." This is not really a good idea. Not only is it unethical, illegal, and likely to get you in trouble, it won't even get you a very good recording. Hand-holding a microphone causes scrabbling noises, it can make one's arm painfully tired after a while, and the recording perspective from an audience seat is usually too distant for a good recording.
Getting permission to record a concert isn't impossible, particularly if the participants are amateurs, at which time you can think about proper placement of the mike. I won't get into the subject of microphone placement here because it could take up a whole book, but with the mike controller on the ECM-929 you can widen or narrow the pickup field after you've set up the microphone.
The first principle of recording is Put The Mike On A Stand. This is easy to do with the 929 because it has both a standard mike-stand fitting and one for a photo tripod. I use a Vivitar collapsible camera tripod, which measures a mere 12 inches in length when folded and extends to about 48 inches when set up. My tripod, recorder, microphone, headphones, extra battery packs, and several cassettes all fit easily into an inexpensive brief case fitted with a foam lining. As the mike has only a 6-foot cable, you will need an extension for it in order to do musical recording. The microphone's output plug is a miniature phone plug, like those used on headphones for Walkman-type units, so I investigated the possibility of using a Walkman headphone extension cable for the microphone. Its cable turned out to be shielded, which made it ideal for the purpose. Most such extensions are suitably shielded but some are not; check by unscrewing the plug cover at one end before buying. (If the cover isn't removable, don't buy it; consider another brand instead.) The mike's output impedance is low enough to allow the use of up to 100 feet of cable, but since the output is not balanced, hum may be a problem with runs of more than 50 feet.
So, what kind of tapes can you expect from this diminutive system? Well, it has always been difficult for me to assess the sound of a tape recorder, perhaps because a live recording is so close to the source (as opposed to a disc recording, which is several generations removed) that my perceptions are a mixture of what I hear and what I remember of the actual event. All I can say is that the Walkman Professional is capable of sound rivaling that from most nonprofessional reel-to-reel recorders. The M-S recording technique has long been acknowledged as one of the most accurate ways of recording stereo, and the Sony M-S system for the Walkman can deliver uncannily accurate stereo imaging. The reproduced soundstage stretches laterally to beyond the sides of the speakers, and each instrument is placed in its own space. Front-to-back depth is excellent, and rendered with rocklike solidity. The mike sounds very smooth, and even though it is rated 3 dB down at 70 Hz, its low end sounds very good. In fact, my only complaint about the 929 mike has nothing to do with its sound: Instead of using a penlight cell or the ubiquitous 9-volt transistor-radio battery, it uses one of the expensive and hard-to-find silver-oxide button batteries. (Just try and find one of those on a Sunday afternoon!) In short, this is a recording system for which few apologies must be made. The fact that it is so portable, and costs under $500 for a complete recording system capable of sound that would have cost several thousand just ten years ago, makes it all the more remarkable. Pretty good for a device that I bought simply to enjoy flutter-free music on airliners.
This is from the September 1987 issue (Vol. 10 No. 6), from a piece about tape decks by Alvin Gold. (Incidentally, George Graves II, as he was now known, was still around and reviewed the NAD 6300 in this issue).
Excerpt about the Sony:
…I cannot resist telling you that one of the best-sounding of the lot outside the predictable top Nakamichis is a little delectation from Sony called the WM-D6C, also known as the Walkman Professional. I had actually tried this deck once before, but hadn't really come to grips with it. Now, I discover, this slightly outsize and almost geriatric battery-powered recording Dolby B/C portable is on a par, measurement-wise, with almost any mains-driven machinery, including some at very much higher prices, and that sonically it just about betters them all. It sounds sweet, lucid, clear, and altogether easy on the ear, works as to the manner born with Type IV metal tapes, and doesn't even cost all that much. It urinates (in the best possible taste, of course) all over any of the current CD Discpeople on all counts up to and including practicality on the move, and excluding background hiss—though Discpeople often sound noisy too.
The other rather shocking realization at the end of the project was to discover how poor most of the decks sounded when Dolby was used, especially Dolby-C. Some decks managed to incorporate Dolby processing without the sound becoming grossly flattened and synthetic, but most didn't, which points to low-grade chips and/or low-grade installations. To add insult to injury, Dolby has been responsible historically, through no fault of its own, for almost total stagnation in the development of cassette-deck technology over the past decade or more. On the one hand, all the old, and now largely discredited, measurement guys were feeding the makers with the "fact" that hi-fi meant 60dB signal/noise; on the other there is Dolby offering 10dB on a chip (20dB with Dolby-C, which predictably sounds worse), and as most machines are already good for 50dB, they didn't need to try any more.
