Guest matty g Posted February 3, 2007 Report Share Posted February 3, 2007 I have a what may seem like a dumb question, but I can't seem to get a straight answer from anyone. Who was responsible for the first dome tweeter? Was it Fisher Radio Corp., Accoustic Research or neither? I can think of no better place to ask this question than The CSP.ThanksMatt Link to comment Share on other sites More sharing options...
Pete B Posted February 3, 2007 Report Share Posted February 3, 2007 From my post #26 here:http://www.classicspeakerpages.net/dc/dcbo..._id=&page=#9410Credit for the development of direct radiating loudspeakers (speakers without horn loading) is generally given to Rice and Kellogg of General Electric Co. Research Labs, around 1925, as was documented in their paper: "Notes on the Development of a New Type of Hornless Loudspeaker" The point here is that they tried several drivers with flat diaphragms that otherwise are very similar to modern dome drivers. Finally, in their Figure 7 is a dome driver of "aluminum spinning" with a "thin rubber edge" suspension. I estimate the dome at about 1", and across the full suspension is shown as 2". They also speak of the "inertia diaphragm loudspeaker" which is what we call today the mass controlled region of flat response.There is mention of the authors here:http://72.14.203.104/search?q=cache:UeB5TA...s&ct=clnk&cd=14 Link to comment Share on other sites More sharing options...
Guest matty g Posted February 3, 2007 Report Share Posted February 3, 2007 Thanks, PeteA very interesting read - lots of good posts, too. I guess what I really meant was who was first responsible for the use of a dome tweeter in a hi-fi loudspeaker system. After reading the posts attached, it appears that it probably was AR in '58. Does that sound right?Matt Link to comment Share on other sites More sharing options...
tysontom Posted February 3, 2007 Report Share Posted February 3, 2007 >Thanks, Pete>>A very interesting read - lots of good posts, too. I guess>what I really meant was who was first responsible for the use>of a dome tweeter in a hi-fi loudspeaker system. After reading>the posts attached, it appears that it probably was AR in '58.>Does that sound right?>>MattThis is correct, Matt. The earlier Rice and Kellogg patents do not show a rim-driven, direct-radiator device designed for high frequencies. Most all authorities in the field consider the AR-3 dome tweeters, introduced in 1958, to be the first commercial dome tweeters. Dome diahprams of several descriptions had been around for many years, but were primarily used as compression drivers for horn-loaded devices.http://www.classicspeakerpages.net/dc/user_files/1912.pdfhttp://www.classicspeakerpages.net/dc/user_files/1913.pdf--Tom Tyson Link to comment Share on other sites More sharing options...
Guest matty g Posted February 3, 2007 Report Share Posted February 3, 2007 Thanks, TomUpon further research, it looks like Fisher claims to have come up with the first peripherally driven cotton soft dome tweeter in '64 - but it may be an advertising gimmick. Anyway, thanks for clearing that up.Matt Link to comment Share on other sites More sharing options...
Pete B Posted February 3, 2007 Report Share Posted February 3, 2007 The subject of this question is "Dome Tweeter History", and my reference was to the technical paper, not the patent:Rice, Chester W. and Edward W. Kellogg, "Notes on the Development of a New Type of Hornless Loudspeaker," Transactions of the American Institute of Electrical Engineers 44, 1925, p. 461-475. Note that this was also reprinted in the AES Journal.The patent does cover a rim driven, direct radiator dome and it is not specific about operating frequency range. It simply states that the fundamental resonance should be below the lowest frequency to be reproduced. It clearly covers the required conditions for flat response with direct radiator drivers.This is prior art. Spin it however you want, AR did not invent the dome driver. Just one authority who would not agree is Wadsworth, a professor at the WPI Acoustics Laboratory:http://www.auditory.org/asamtgs/asa94mit/3pNS/3pNS3.htmlI will drop out of this discussion since, you need to really read the history and realize that a patent is simply a legal document, it does not make the history.Matt, I was not referring to commercial application so much as the inventor of the basic idea. Link to comment Share on other sites More sharing options...
tysontom Posted February 3, 2007 Report Share Posted February 3, 2007 >Thanks, Tom>>Upon further research, it looks like Fisher claims to have>come up with the first peripherally driven cotton soft dome>tweeter in '64 - but it may be an advertising gimmick. Anyway,>thanks for clearing that up.>>MattMatt,Yes, I believe that what you state above is true (see my comments below). What I am saying, however, and what most historians conclude, is that Ed Villchur introduced the *first* commercial application of the direct-radiator dome tweeter with the 1958 AR-3. Villchur certainly did not invent the dome-shaped, rim-driven diaphragm; these devices had been around for many years, but used primarily with acoustical-coupling devices such as horns. As far back as 1937 L.B. Cornwell (patent 2084945) described a dome-like driver with a hemispherical diaphragm and rim-driven voice coil. This dome almost resembles modern-day plastic domes, but the device was designed to be used with a horn appendage. Villchur's patent attorneys knew that these devices could be considered "prior art," and although no one had described a rim-driven dome tweeter to be used for direct-radiator applications, the AR patent (patent #3033945) described the suspension-system and operating characteristics of the dome.I have often questioned if a dome driver had been used commercially before 1958, but I have been unable to find such an example. One may certainly exist! Perhaps other readers could come forth with examples, and this would help clarify this matter. I have questioned several loudspeaker designers and historians here and in Europe, but everyone seems to conclude that they know of no other commercial loudspeaker introduced before the AR-3 that used dome tweeters.Matt, to confirm what you asked above, the first soft-dome tweeter was indeed the 2-inch Fisher device, designed by Bill Hecht, founder of United Speaker Systems, and patented in 1967. I'm not sure when it appeared on the Fisher speaker, but Avery Fisher contracted with USS to build their speaker systems for them, including the XP-4A system (see Fig. 2 that included the soft-dome tweeter. Note, too, the use of the Carbonneau 5-inch midrange drivers, similar to the AR-2. This reflected Avery Fisher's desire to challenge the AR dominance in the speaker industry, but he was not completely successful). The fabric dome was coated with a rubber-like material, and the dome also had a rubber "octopus-like" suspension as a part of the patent (patent #3328537). McIntosh also contracted under license with Bill Hecht's firm, and for several years used the Hecht driver. McIntosh later refined the Hecht tweeter by improving the suspension and magnet assembly, and although it was designed by Roger Russell, the patent was awarded to Frank McIntosh!http://www.classicspeakerpages.net/dc/user_files/1926.jpgFig. 1. AR-3 2-inch Phenolic-Dome Midrange Tweeter (1958)http://www.classicspeakerpages.net/dc/user_files/1925.jpgFig. 2. Fisher XP-4A Speaker System with Hecht 2-inch Dome Tweeter http://www.classicspeakerpages.net/dc/user_files/1927.jpgFig. 3. McIntosh 2-inch Dome Tweeter Patented by Frank McIntoshhttp://www.classicspeakerpages.net/dc/user_files/1928.jpgFig. 4. AR-3a 1.5-inch Soft-Dome Midrange Driver (1967) It is interesting that the patent for the soft dome was issued in June, 1967, but the October 1967 AR-3a, which also used a soft-dome midrange (more or less co-invented but not patented), never resulted in any court challenges. Soon after Hecht received his patent, Philips of the Netherlands began supplying a 1-inch soft-dome tweeter to McIntosh and more or less blatantly ignored the Hecht patent, deciding that it was not strong enough to defend in court. The patent remained, but Hecht challenged neither Philips nor McIntosh -- or anyone else after that to my knowledge. No question, though, that Hecht was responsible for the first soft-dome tweeter, and he deserves credit for it.--Tom Tyson (03Feb07) Link to comment Share on other sites More sharing options...
Steve F Posted February 3, 2007 Report Share Posted February 3, 2007 <>In fact, Hecht did bring suit against Boston Acoustics in the '80's. Early BA A-series speakers used a 1" Vifa dome, but later A's and all subsequent models used BA-designed domes manufactured at BA's MA facility. BA has a proprietary several-million dollar robotic tweeter line that produces some of the world's best--and most uniform and consistent-- dome tweeters anywhere. The machine self-analyzes and auto-QC's, adjusting for adhesive dispensing, VC alignment/centering in the gap, all kinds of things. The mfg tolerance is +/- 1 dB to the ref tweeter, and it's not some idle advt slogan.Perhaps Hecht was jealous of BA's incredible success and profitability that started in the 80's, while his own company--Phase Technology-- languished (and continues to languish) in near obscurity. Perhaps he felt that BA would be an "easier" mark, legally, than giant Phillips. It's all conjecture.Who knows. I don't believe the suit ever went anywhere. Certainly BA has continued to this day to produce their superb domes, without any "Mfg'd under license from Phase Technology" attributions.See my recent entry under the Boston Acoustics section for a surprising nugget about who they manufactured woofers for!Steve F. Link to comment Share on other sites More sharing options...
kkantor Posted February 4, 2007 Report Share Posted February 4, 2007 Tom,Did you ever hook up with Knud Thorborg at Peerless in Denmark to pick his brain about European work on domes in the late 50's and early 60's?-kkkantor.spaces.live.com Link to comment Share on other sites More sharing options...
tysontom Posted February 4, 2007 Report Share Posted February 4, 2007 >Tom,>>Did you ever hook up with Knud Thorborg at Peerless in Denmark>to pick his brain about European work on domes in the late>50's and early 60's?>>-k>>kkantor.spaces.live.com>Ken,I did communicate with Knud Thorborg, and he pretty much concurred with what we've been saying here regarding the beginning of the dome tweeter. He thought that the AR dome was the first used in a loudspeaker, and he said he knew of no other dome that preceded it, but he did not elaborate on European designs. Unfortunately, I have misplaced or mis-filed his reply to my e-mail; when I locate it I will post it on this forum.--Tom Link to comment Share on other sites More sharing options...
rl1856 Posted February 20, 2007 Report Share Posted February 20, 2007 But wasn't there a law suit concerning the dome driver, filed by Fisher Radio against AR, and ultimately decided in favor of Fisher ?Best,Ross Link to comment Share on other sites More sharing options...
tysontom Posted February 21, 2007 Report Share Posted February 21, 2007 >But wasn't there a law suit concerning the dome driver, filed>by Fisher Radio against AR, and ultimately decided in favor of>Fisher ?>>Best,>>RossRoss,I have no knowledge of such a lawsuit -- which could only be on the soft-dome tweeter -- which is not to say that it didn't occur. I did read somewhere or heard someone mention such a lawsuit, but I don't remember any details by whom or against whom. Besides, the patent for the soft-dome tweeter was held by William Hecht, not Avery Fisher. Do you have the complaint file number or location of the suit? I know that AR continued, unabated, to produce their soft-dome tweeter well after the fuss during the late 1960s. I also know that AR paid no royalties to Fisher or Hecht; so insofar as no monies were paid and production never changed, I doubt that Fisher won any lawsuit.--Tom Tyson Link to comment Share on other sites More sharing options...
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