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Thomas J. Norton Posted: Aug 06, 2015 Published: Jun 01, 1992 0 comments
If anyone can be said to be the guru of the transmission line, that would have to be Irving M. "Bud" Fried. He has been promoting the design for years now, first with the made-in-England IMF designs, later with the designs of Fried Products, made right here in the US of A. He has long been convinced of the basic superiority of the design, and still uses it in his top-of-the-line systems. But true transmission lines are invariably big, heavy, hard to build, and, for all of those reasons, expensive. Essentially, they involve a long, convoluted, heavily damped tunnel behind the bass driver which channels the back wave to the outside world. The length and cross-sectional area of the tunnel are of some importance, although the technical basis for the transmission line, as applied to a loudspeaker enclosure, has never been firmly nailed down. Certainly there is no mathematical model for the transmission line as complete as that developed over the past two decades for the sealed or ported box (footnote 1).

But Bud Fried has clung to the transmission line, for all of its complexities. In order to bring at least some of its touted advantages to a lower price point, he had to come up with a variation which would work in a smaller enclosure. That variation was the "line tunnel," which, according to Fried, originated in an early-1970s Ferrograph (a British company specializing in tape recorders) monitor which was later adapted by IMF. Basically it consists of a short (compared with a transmission line) duct from the inside to the outside of the heavily damped enclosure. The duct is designed with approximately the same cross-sectional area as the loudspeaker cone.

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Thomas J. Norton Posted: Oct 18, 1994 0 comments
The future is rarely what anyone expects it to be. I still remember reading, as a child, predictions in Popular Science that everyone would have a personal helicopter by 1980. It never happened, though it sure seemed like a reasonable projection of events. Events, however, have their own agenda.
Thomas J. Norton Posted: Aug 04, 2016 Published: Apr 01, 1993 4 comments
Boy, do we ever get letters. From readers angry that we review too many expensive products. From readers depressed that we review too many affordable products. From readers bemoaning our digital coverage. From readers asking when we're going to get with the 21st century and stop gushing over analog. From readers wanting more coverage of tube products. From readers wanting more coverage of MOSFET amplifiers designed for high voltage gain on the output stage.
Thomas J. Norton Posted: Mar 05, 2009 Published: Jan 05, 1995 0 comments
Like all companies that have been in business long enough to become fixtures in the marketplace, Infinity has seen its share of changes. It has long been that audio rarity—a company with one foot in the High End and one in the mass market. For the past few years, however, and despite continuing production of the now-classic IRS in its Series V incarnation, Infinity's mass-market foot has been the more firmly planted. Infinity, now a large company, is part of an even larger conglomerate, Harman International.
Thomas J. Norton Posted: Aug 13, 2014 Published: Feb 01, 1991 0 comments
jbl160.250.jpgA visiting manufacturer recently told us here at Stereophile of an ongoing informal "survey" he was conducting. He would ask strangers to name three brands of loudspeakers. Their responses were not what I would have expected. They almost invariably named Japanese companies—two of the most commonly mentioned were Hitachi and Panasonic. Other than my spell-checker insisting that I change "Hitachi" to "hibachi," I have nothing in particular against these two manufacturers; they are well-recognized in many product categories. But loudspeakers? I can only guess that the respondents were dredging up the only consumer electronics companies that came readily to mind.

My list for most recognized loudspeaker brands would most certainly have included JBL. How could it not? They have been involved in home high-fidelity since 1954. And for years before that in professional audio—primarily motion picture theater sound, a field in which they are still active. In short, they were around before there was such a thing as "hi-fi."

Thomas J. Norton Posted: May 14, 2016 Published: Mar 01, 1991 0 comments
As I write these words in January 1991, we're right in the midst of an annual media feeding frenzy: the "Best of the Year" follies. This usually takes the form of lists compiled in groups of ten for reasons that must hearken back to some obscure Druidic practice. You know the routine: "Ten Best Books of the Year," "Ten Best Films of the Year," "Ten Top Personalities of the Year," "Ten Best Sports Plays of the Year." Every corner of the media seems eager to get into the act. Special-interest magazines are hardly immune. Car enthusiasts can get their fill of "Cars of the Year." Computer literates find their favorite rags full of the "Ten Best Computers/Computer Accessories/Computer Programs." And music magazines regale us with the "Ten Best Recordings of the Year." Everyone with access to a transmitter or printing press has got, it seems, a little list.
Thomas J. Norton Posted: Oct 27, 2003 Published: Jan 01, 1992 0 comments
Stardate: 3087.6. Location: somewhere in the 4th quadrant. In response to Captain Kirk's orders, Mr. Sulu throws a few well-chosen levers and sliders—not much different in design and function from those used by Flash Gordon and Captain Video—to redirect the Good Ship Enterprise where no man has boldly gone before. New adventures begin immediately after the bridge crew pick themselves up off the deck and nonchalantly resume their stations.
Thomas J. Norton Posted: May 14, 2016 Published: Apr 01, 1991 0 comments
Michael, who might be termed our typical audiophile (if anything in Santa Fe can be termed "typical"), may have found his digital processor, but he's still in a quandary about choosing the right power amp to drive his new loudspeakers. He has listened to a number of them over the past few months, and has been unable to find one which satisfies him in every way. I suspect he has a lot of company. The thorny problems of room acoustics and placement aside, loudspeakers are easier. Their signatures are pronounced and generate strong feelings one way or another; it's usually no problem to narrow down one's choices in this category.
Thomas J. Norton Posted: Aug 28, 2014 10 comments
In the late 1980s, KEF, then as now a leader in bringing new technology to loudspeaker design, developed a unique coincident driver that positioned the tweeter in the throat of the midrange/woofer cone. In a flash of inspiration, they dubbed it the Uni-Q, and the driver immediately not only found its way into the company's more upscale speaker designs, but also became a key element in a major European research project on room acoustics. That study's results appear to have been inconclusive, but the Uni-Q lives on as the defining element of KEF loudspeakers.
Thomas J. Norton Posted: Jun 18, 2015 Published: Jun 01, 1992 1 comments
By now most readers will be familiar with the relatively new tuned-cavity method of low-frequency loading. Such designs have popped up all over the place of late, especially in those little satellite/woofer systems, but KEF can rightly lay claim to generating the design's theoretical basis, as JA described in his review of the KEF R107/2 loudspeaker in Vol.14 No.5 (May 1991). Essentially, the technique consists of loading the rear of a woofer in a conventional fashion—usually a sealed box—but also loading the front of the driver into another enclosure, ducted to the outside. Basically, the design acts as a bandpass filter with its response centered on the port-tuning frequency. The rolloff is smooth and rapid on either side of this frequency, providing a natural low-pass characteristic but thereby virtually mandating a three-way system. If properly designed, this configuration offers a number of theoretical advantages. The radiating element is actually the air in the port, which is low in mass. Low distortion is possible, as is relatively high sensitivity.

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