ACCESSORY AFTER THE FACT
Cleaning Up in Lirpa's Wake
For some inexplicable reason, few manufacturers have produced accessories specifically designed for Lirpa products. Allsop, however, is a notable exception. Expanding their already broad range of audio and video cleaning systems, they've produced a cleaner fully compatible with the Lirpa Vehicular Compact Disc Reproduction System (VCDRS) CD player reviewed in (as usual) our April issue.
Allsop's prototype, on the left in the group photo, was modeled closely after the Lirpa player, and indeed could be made to cruise the disc just ahead of the VCDRS, ensuring a freshly cleaned surface at all times.
Its articulated design helped negotiate the tight bends where the CD's circumference narrows, towards the disc's center, and its blade could dislodge even the blobs of peanut butter used by misguided Lirpaphiles as a sound-enhancing disc treatment.
The articulated design proved a drawback, however, in radial cleaning (which, as designer Eivind Clausen pointed out, is the preferred mode for CDs); the scraper section was likely to go off at an angle when the system was backed up to the center for another pass along the next radius.
The final production version, on the right, is therefore an entirely different design. Its unarticulated (or "unhinged") design and shorter wheelbase permit its use in both cruise-ahead and radial modes, while its Caterpillar tread provides better traction on the disc's smooth surface.
In radial mode, the blade lifts automatically as the cleaner goes into reverse for its next pass, and differential tread drive repositions the unit at the precise angle required each time. The addition of the soft, absorbent "Lir-pad" to the blade, plus a reservoir of track-cleaning fluid in the unit, gently remove fingerprints which, research shows, are a more common problem than peanut butter in most homes. Removing the pad reveals a scraper blade which is capable of cleaning residue even from bubble-gum rock records.
---------- Lirpa's original Vehicular Disc Reproduction System (VCDRS)
CD player; Lirpa-compatibles at last: Allsop's prototype (left) and production
version.
Buy-Outs and Buy-Ins
While Clarion Shoji Co. Ltd. does make some home electronics, it's best known for car stereo, which comprises 83% of its business. That may be changing: In July, Clarion purchased McIntosh Laboratory for $28.6 million. Clarion has stated that it intends to retain McIntosh's product and production policies and its senior management. The sale, which was triggered by the death last year of McIntosh's co-founder and president Gordon Gow, will probably increase Clarion's prestige in Japan, where the McIntosh name is treated with respect bordering on reverence. The infusion of new capital may also lead to an expansion of McIntosh's product line-possibly even to car stereo. As McIntosh's longtime National Sales Manager, Dirk Roos, told Audio Week, a trade newsletter, "I think we're in a position to market something for Mercedes; they're not." Earlier this year, Philips purchased a 25% stake in Bang & Olufsen. This minority share is tied in with agreements between the two companies for cooperation on technology, purchasing, components, and subassemblies, extending a relationship that has existed since B & O's founding in 1925. Philips reports that it will not hold seats on B & O's board or participate in its daily management.
On the domestic front, International Jensen purchased Now Hear This (NHT). Unlike such previous Jensen acquisitions as Phase Linear, Advent, and Acoustic Research, NHT will continue to be headed by its co founders, Ken Kantor (author of several Audio articles) and Chris Byrne.
Perhaps the biggest news was the announcement that Sansui had been purchased by Polly Peck International, a British company involved in the food, textile, and leisure industries as well as in the manufacture of mass-market electronics. The resulting infusion of capital has already allowed Sansui to set up a new sales headquarters in Italy and strengthen its sales in other countries. It also allowed Sansui to purchase the audio interests of Mission Electronics a few months later. (Farad Azima, Mission's former principal owner, will continue to be the company's chief operating officer, however.) The least expected news was the announcement that Polk Audio has signed a letter of intent to purchase AGI, the British holding company that owns KEF and Boothroyd Stuart (makers of Meridian).
None of this activity belies the current wisdom that the rash of mergers and acquisitions that characterized the '80s won't continue into the '90s. After all, the '90s don't officially begin until 1991.
Off with the Cough
Coughs and concerts have the same season, alas, but lately concert halls are fighting back. At one performance in Ann Arbor, Mich., last winter, I noted bowls of cough drops at the entrance doors, individually wrapped in relatively noise-free waxed paper instead of crackly cellophane. According to Rich Warren of the Chicago Tribune, this is common in Michigan. This live-music noise-reduction technique may be spreading further: My wife just noted a similar bowl in the women's room at Avery Fisher Hall in Lincoln Center. (I didn't see any in the men's room, though.) According to Warren, the audience's cough rate is a good indication of how well they like the concert. The fewer coughs per minute, the greater the audience's approval.
dB mystery Resolved
Some mysteries don't last long, especially when you put Audio readers to solving them. I mentioned in our February issue that the audio manufacturers who listed "dBm" in the specs for their CD players' fiber optic outputs couldn't tell me what it meant, but readers from several companies have replied since then.
As in electronics, the dBm is a measure of power, re: 1 milliwatt (0 dBm = 1 mW). It is not, however, referenced to any particular impedance, says transmission technician Ed Lippman of New Jersey Bell (like most phone companies, a major user of fiber optics).
The power levels involved in fiber optics are quite low. Output levels of typical emitters are-10 to-20 dBm (0.1 to 0.01 mW); to allow for losses in long fiber runs, typical optical receivers have a sensitivity rating of -35 to -40 dBm (0.32 to 0.1 uW), according to engineer Dan Brown and president Michael Coppola, of Meson Design and Development (who make fiber-optic test equipment).
Further elaboration came from Randy Yates, an R & D engineer at Digital Sound Labs, which is involved in digital audio signal processing.
According to Mr. Yates:
A complete answer to the definition of dBm would bring up Maxwell's equations for electromagnetic wave propagation, so I hope a greatly abbreviated explanation will do.
Just as in audio, dBm is a means of specifying optical power, and is given by the following equation:
P dBm = 10 log
0.001 watt
where P is the total optical power launched by the fiber-optic transmitter or received by the fiber-optic detector (receiver). More generally, optical power is a function of the aperture area and therefore has units of watts/m^2, but in many cases fiber-optic systems use launched power since most of the power is coupled into or out of the cable. . . .
The basic goal is to ensure that the power launched by the transmitter, minus cable and interface losses, is greater than or equal to the power required by the receiver.
As to the levels found in home equipment, David Birch-Jones of Philips adds:
The de facto standard optical connector/transmission system for digital audio is the Toslink system, adopted by every body by mutual consent, since there is no apparent alternative at affordable cost. The system is specified by Toshiba as having a bandwidth from d.c. to 6 megabits per second (6 Mb/S). The transmitter output range (at the source component) is specified at between -21 and -15 dBm, and the receiver sensitivity (at the destination component) is specified at between -24 and -14.5 dBm. Apparently, 19 dBm is the typical value of the output level of a digital audio component that uses the Toslink system.
Directory Follies
We can't personally verify the thousands of items of data that manufacturers provide for our Annual Equipment Directory (and our May Car Stereo Directory), but we do check them for obvious errors, such as preamps rated at 50 watts per channel or crossovers with three bands separated by a single crossover frequency. And while some questionnaires are completed by people who know too little about the product, at least one was filled in by The Man Who Knew Too Much. Under "Notes: he commented: "Hideous board layout." We won't name the guy or the product, though; why lose an honest man his job?
Here's the Pitch
Since 1938, an international standard has set the pitch of the musical tone A at 440 Hz. For music written before then, this pitch is actually a bit sharp: Handel used an A of 422 Hz in 1740, Mozart used 421.6 Hz in 1780, and Verdi used 432 Hz. (About 1880, he even got the Italian Parliament to pass a bill mandating that pitch.) To the distress of opera singers, orchestras are ignoring the standard and tuning sharper still, in order to sound more brilliant and exciting.
Many major U.S. orchestras use 442 Hz, von Karajan used 448 Hz with the Berlin Philharmonic, and some orchestras have tuned as high as 452 Hz. That's almost a semitone higher than Verdi's pitch and more than a semitone above Mozart's. As a result, arias written in the key of C, for example, are now sometimes sung in the key of C sharp.
Jazz in Its Natural Juices
At the JVC Jazz Festival in New York this past summer, Stan Getz made it clear that the microphone pickup attached to his sax with Velcro was no friend of his.
During his first set, Getz did the finger-across-the-throat gesture twice to the man on the huge mixing console at the back of Carnegie Hall. Then he played unamplified, with obvious relish.
Toward the end of the set, the pickup eluded the Velcro and dangled, like a dead mouse, from its cord. Getz seemed to ignore it, and played on gloriously, the rich sound of his horn only a little softer, with Kenny Barron's piano-playing a little gentler underneath. Getz's expression, though, was pure boyish mischief, and he moved around the stage more vigorously so the audience could see the microphone, humbled. As the last note faded, a soundman in a jacket and tie appeared on stage and firmly replaced the device in its Velcro trap.
As the second half drew to a close, the equipment became balky again. The same soundman appeared at pianist Kenny Barron's elbow to discreetly whisper that the batteries in the sax microphone had begun to give out. Barron told Getz loudly at the first opportunity, and Getz told the audience: "This thing's dead. But then, so am I!" And then, having vanquished the microphone, he played on much longer, the sound rich and unamplified, the boyish grin intact. And we never saw the soundman on stage again.
-Roberta Thumim
Out of Your Head
Sounds that sit between the speakers in stereo listening sit between our ears when we listen to stereo recordings via headphones. The reasons were known as far back as the 1970s: Headphone listening bypasses the normal interactions between the pinna of the ear and sound waves arriving from different points in space. But the solution then available was to record the sound of speakers in a room by using mikes placed in a listener's ear canals and then to play those recordings to the listener via headphones.
With digital signal processing, it's now possible to synthesize these pinna effects. So far, according to F. L. Wightman of the University of Wisconsin (Journal of the Acoustical Society of America, January 1990), this technique is being used for auditory and perceptual research, and it is being studied for the use of pilots and crew in space stations and aircraft-which probably means that the technique is not yet cheap.
"Not yet" does not mean "never." Home and car stereo equipment that uses DSP for other purposes is already on the market. It should not be terribly difficult to come up with a digital algorithm to simulate the effects of average pinnae and to use that algorithm in processing signals directed to the headphone outputs. In the future, it might even be possible to measure an individual listener's pinna effects and generate custom algorithms to be incorporated into the listener's audio equipment.
Ironies in the Fire
After nearly three years of legal maneuvering, DAT is here. Once the electronics and recording industries agreed on the Serial Copy Management System (SCMS) and bills had been introduced to mandate SCMS in all home DAT recorders, Japan's Ministry of International Trade and Industry (MITI) gave the go ahead for their export. The first to actually export DAT was Sony, and they were slapped with a lawsuit from a group of songwriters and music publishers. The suit seeks to halt the sales of DAT on grounds that it contributes to copyright infringement; the people behind the suit favor levying royalty fees on recorders and blank tapes.
This is the second time Sony has taken the heat for the industry in a copyright-infringement suit. When the Betamax VCR was introduced, the company was sued on grounds that taping TV programs off the air would infringe copyright; the Supreme Court ruled in Sony's favor in 1984. When the Betamax case was filed, however, Sony was defending its own proprietary technology, which had been brought out without consensus by the Japanese electronics industry.
With DAT, the manufacturing consensus is already in place. This time, the EIA is expected to aid Sony's defense fund. And both Sony and its competitors vow to continue selling DAT.
The upshot of the Betamax case was a dual irony. The movie industry, which had tried to block home VCRs, now makes a substantial portion of its income from home video sales and rentals. But Sony's Betamax, which cleared the legal ground for all home VCRs, in great part lost out to the newer format, VHS, whose proponents had developed enough of a consensus to make it a virtual industry standard (and whose dominance is now threatened by 8-mm video, which Sony developed).
Similar ironies could come of the DAT suit. After all, the music and recording industries make a substantial portion of their income from sales of prerecorded cassettes and would stand to make still more from prerecorded DAT releases.
(adapted from Audio magazine, Dec. 1990)
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