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#281
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Howard Ferstler wrote:
John Atkinson wrote: Howard Ferstler wrote: The original reviews of the IC-20 systems by both High Fidelity Magazine and Stereo Review commented upon their ultra-wide dispersion. But what measurements did those magazines publish to support that contention? And how where those measurements performed? Perhaps I am mistaken, but I can't remember the late Julian Hirsch performing either polar plots[,] or the waterfall dispersion plots that I perform[,] in Stereo Review. And again if I remember correctly, High Fidelity only performed sound _power_ measurements. No response from Howard Ferstler. Where _are_ the measurements that support his comments about the Allison tweeter's dispersion? Even if the systems had only one forward-facing panel they would have those Allison drivers dispersing widely clear out to 90 degrees off axis. But without measured support for this statement, you have no basis to make it, unless you label it as being your _opinion_. Again, no substantiation for his statements from Howard Ferstler. However, they have dual panels, each angled out 45 degrees from dead ahead, meaning that they have extremely wide dispersion to each side and out to 135 degrees off axis. No, this results in _narrower_ dispersion on the primary frontal axis, with complex lobing apparent. Normally, I would not post a second reply to a message here (particularly one initially posted by Mr. Atkinson as a grandstanding move) and would wait for a counterpoint from my adversary. I am not "grandstanding," Mr. Ferstler, merely asking you to provide some measured substantiation for your comments about the objective performance of the Allison tweeter and the speakers that use it. Particularly as your _own_ in-room measurements reveal that even with the Allison speakers, the balance at your listening seat is dominated by the direct sound in the region covered by the tweeters. However, Mr. Atkinson's comments about the radiation pattern of the angled-panel Allison speakers gave me an incentive to contact Roy Allison, with a question regarding the difference between horizontally spaced tweeter and midrange driver pairs on a single, forward-facing panel and a situation where each of the units are on a separate panel, angled to either side of straight ahead. Okay. From Allison himself: "At frequencies above about a half wavelength a baffle effectively limits radiation to a maximum angle of 90 degrees around a driver mounted symmetrically in its smallest dimension - in other words, to 2 pi steradians. My own measurements indicate that this is too simplistic a view. If, for example, you look at fig.3 at http://www.stereophile.com/loudspeak...61/index6.html, which shows the 360-degree radiation pattern of a BBC LS3/5a, you can see that even with the recessed tweeter in this design, there is still significant radiation at some frequencies in the tweeter's passband more than 90 degrees to the side, even though the baffle is larger than a half wavelength at these frequencies. For the woofer in a Model One or IC-20 this doesn't apply, but the distance between the woofers isn't great enough for cancellation to occur within their range. If I remember correctly, the centers of the woofers and midrange units in these designs are separated by around 12", meaning that the cancellation will occur for frequencies where this difference results in a half-wavelength path difference. For someone listening on-axis to one of the drivers, there will be cancellation at 600Hz, which may be above the woofers' passband, but is certainly in the midrange units' passband. The tweeter radiation can't go around a right-angle corner at all... Not true, as I showed above with the BBC design. There will be diffraction at some frequencies but not others, meaning that it is not true that the drivers on each of the Allison speaker's baffles are not in each other's acoustic environments. Again, Mr. Ferstler where are your _own_ measurements that support what you say. and for the mids there is the slight beginning of interference at the bottom of their range. A half-wavelength path difference would result in significant, not "slight" interference. See for example, the horizontal dispersion of the popular center-channel speakers that use spaced midrange units or woofers. (A subject on which I agree with Tom Nousaine, BTW.) However, the crossover and the mid's inherent Q value are designed to compensate for that minor effect." I fail to grasp how adjusting the on-axis behavior compensates in any significant way for arbitrary and irregular dispersion effects. Please offer more detail, Mr. Ferstler. The ball is in your court, Mr. Atkinson. As I said, Mr. Ferstler, use of multiple, spaced drivers results in a less-wide, less-even dispersion pattern, owing to the interference between the spaced drivers producing a complex pattern of lobing. Yes, I will allow that by angling the baffles on which the spaced drivers are placed, you will reduce the interference, and there _will_ now be lobes aimed at wider off-axis angles than with a single drive-unit. But the price paid to achieve the existence of those lobes is a significant reduction in the smoothness of the radiation pattern, which Toole's and Olive's work has shown to be undesirable, subjectively. Your arguments have all been circular, Mr. Ferstler. That you like the sound of the Allison speakers goes without saying. But without measured data to support that opinion, your projection about the technical reasons for your preference are mere masturbation. John Atkinson Editor, Stereophile |
#282
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John Atkinson wrote: From Allison himself: "At frequencies above about a half wavelength a baffle effectively limits radiation to a maximum angle of 90 degrees around a driver mounted symmetrically in its smallest dimension - in other words, to 2 pi steradians. My own measurements indicate that this is too simplistic a view. If, for example, you look at fig.3 at http://www.stereophile.com/loudspeak...61/index6.html, which shows the 360-degree radiation pattern of a BBC LS3/5a, you can see that even with the recessed tweeter in this design, there is still significant radiation at some frequencies in the tweeter's passband more than 90 degrees to the side, even though the baffle is larger than a half wavelength at these frequencies. Fig 3 is an ugly beast of a 3-D plot to try and decipher... too much information, if you can't slide a cursor along to see values one loses ability to correctly interpret the amplitude value. At least my tired eyes do. In any case... I have a question. The fig3 plot says "Fig.3 Rogers LS3/5a, 1978 sample, horizontal response family at 50", normalized to response on tweeter axis, from back to front: differences in response 180 degrees-5 degrees off-axis; reference response; differences in response 5 degrees-180 degrees off-axis. " So the 0 degree plot should either agree with the on axis (fig 4 which is also at 50") or if truly normalized to on axis then I think the 0 degree plot should be flat. I can't see either situation in Fig 3. TIA for helping me understand, ScottW |
#283
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"Arny Krueger" wrote in message ... Clyde Slick wrote: "Arny Krueger" wrote in message ... Howard, I was very polite with you about your errors in those other posts. If you want to see vituperation, look at the corresponding posts from that well-known technical ignoramous, Scott Wheeler. If irony would wash your mouth with feces. Art, I prefer to watch your example rather than following it. Thanks for admitting that you solicit for scat fetish videos. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#284
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ScottW wrote: The fig3 plot says "Fig.3 Rogers LS3/5a, 1978 sample, horizontal response family at 50", normalized to response on tweeter axis, from back to front: differences in response 180 degrees-5 degrees off-axis; reference response; differences in response 5 degrees-180 degrees off-axis." Yes, the plot show the LS3/5a's output plotted in a complete circle at 5 degree intervals. So the 0 degree plot should either agree with the on axis (fig 4 which is also at 50") or if truly normalized to on axis then I think the 0 degree plot should be flat. I can't see either situation in Fig 3. The fig.4 response was subtracted from every response in fig.3. meaning that the 0-degree trace is indeed a flat, straight line. But the notable point is that the tweeter output doesn't stop dead at 90 degrees off-axis. Below 12kHz, there is still output apparent above -30dB floor of this graph, particularly at some frequencies. John Atkinson Editor, Stereophile |
#285
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MINe 109 wrote:
In article , Howard Ferstler wrote: John Stone is a driver salesman. I replied at length to his commentary elsewhere. Go find it. You're quick to dismiss experts, aren't you? Wasn't Allison a speaker salesman? Allison designed both systems and drivers and published numerous articles on system design in the JAES. He even published articles in pop-audio magazines at one time. I doubt if Stone is a Fellow, or even a member, of the Audio Engineering Society. From The Encyclopedia of Recorded Sound: Allison became involved with electronic matters during U.S. Navy service and later at the University of Connecticut's school of Electrical Engineering. Early in his audio career, Allison was editor of Radio Communication, TV and Radio Engineering, and Communication Engineering magazines, Audio Editor of High Fidelity magazine and Editor of Audiocraft magazine. In 1959 he joined Acoustic Research, Inc. He became chief engineer in 1962 and became plant manager in 1964. In 1967, he became vice president in charge of research and development. In 1974, after leaving AR, he helped to found Allison Acoustics, RDL, and RA Labs. He has published numerous professional-level and hobby-related articles and wrote a book, High Fidelity Systems. He has been a Fellow of the Audio Engineering Society since 1973. His most important later articles, published in both technical and consumer-oriented journals, deal with speaker/room interactions. He is responsible for defining the "Allison Effect," which involves mid-bass cancellation artifacts between loudspeaker systems and room boundaries, and is also responsible for some highly regarded speaker driver and loudspeaker system designs. End of excerpt. PS: there is no entry for John Stone in The Encyclopedia. Howard Ferstler |
#286
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John Atkinson wrote:
Howard Ferstler wrote: John Atkinson wrote: Howard Ferstler wrote: The original reviews of the IC-20 systems by both High Fidelity Magazine and Stereo Review commented upon their ultra-wide dispersion. But what measurements did those magazines publish to support that contention? And how where those measurements performed? Perhaps I am mistaken, but I can't remember the late Julian Hirsch performing either polar plots[,] or the waterfall dispersion plots that I perform[,] in Stereo Review. And again if I remember correctly, High Fidelity only performed sound _power_ measurements. No response from Howard Ferstler. Where _are_ the measurements that support his comments about the Allison tweeter's dispersion? See pages 46 and 47 of my 1991 book, High Fidelity Audio/Video Systems (McFarland publishing). Hey, John, I believe that there was a review of it by Cory Greenberg in your magazine a long while back. Don't you remember those driver curves? Even if the systems had only one forward-facing panel they would have those Allison drivers dispersing widely clear out to 90 degrees off axis. But without measured support for this statement, you have no basis to make it, unless you label it as being your _opinion_. Again, no substantiation for his statements from Howard Ferstler. See the book. Also, see Allison's quote about how the angled-panel systems do not have problems with horizontal cancellation artifacts in another post I submitted in response to your earlier comments. Oops, I see up ahead that you managed to incorporate them right here. You then went on to do an amateur-hour analysis of them. However, they have dual panels, each angled out 45 degrees from dead ahead, meaning that they have extremely wide dispersion to each side and out to 135 degrees off axis. No, this results in _narrower_ dispersion on the primary frontal axis, with complex lobing apparent. Normally, I would not post a second reply to a message here (particularly one initially posted by Mr. Atkinson as a grandstanding move) and would wait for a counterpoint from my adversary. I am not "grandstanding," Mr. Ferstler, merely asking you to provide some measured substantiation for your comments about the objective performance of the Allison tweeter and the speakers that use it. Particularly as your _own_ in-room measurements reveal that even with the Allison speakers, the balance at your listening seat is dominated by the direct sound in the region covered by the tweeters. This is preposterous. At a listening distance of 15 feet (to each speaker, I would be well into the reverberant field even with fairly directional speakers. John, you have to remember that I am a "subjective" speaker reviewer. I am not quite as subjective as some other reviewers, but I am certainly more subjective than you are if we are talking about measurements. In any case, the best I can offer are Allison's own measurements on the drivers and systems. Of course, you may think that he is either fudging the facts or incompetent. However, Mr. Atkinson's comments about the radiation pattern of the angled-panel Allison speakers gave me an incentive to contact Roy Allison, with a question regarding the difference between horizontally spaced tweeter and midrange driver pairs on a single, forward-facing panel and a situation where each of the units are on a separate panel, angled to either side of straight ahead. Okay. From Allison himself: "At frequencies above about a half wavelength a baffle effectively limits radiation to a maximum angle of 90 degrees around a driver mounted symmetrically in its smallest dimension - in other words, to 2 pi steradians. My own measurements indicate that this is too simplistic a view. John Atkinson trumps Allison. John, you are indeed so complex and subtle an individual. If, for example, you look at fig.3 at http://www.stereophile.com/loudspeak...61/index6.html, which shows the 360-degree radiation pattern of a BBC LS3/5a, you can see that even with the recessed tweeter in this design, there is still significant radiation at some frequencies in the tweeter's passband more than 90 degrees to the side, even though the baffle is larger than a half wavelength at these frequencies. For the woofer in a Model One or IC-20 this doesn't apply, but the distance between the woofers isn't great enough for cancellation to occur within their range. If I remember correctly, the centers of the woofers and midrange units in these designs are separated by around 12", About 11 inches with the IC-20. About 9 inches with the Model One. meaning that the cancellation will occur for frequencies where this difference results in a half-wavelength path difference. For someone listening on-axis to one of the drivers, there will be cancellation at 600Hz, which may be above the woofers' passband, but is certainly in the midrange units' passband. Allison indicated that the crossover arrangement compensated for this in the reverberant field. In any case, I certainly have never measured an artifact at that frequency. Of course, all I measure is room response and not direct-field response. As you know, I do not put much stock in the direct-field response, anyway. The tweeter radiation can't go around a right-angle corner at all... Not true, as I showed above with the BBC design. John Atkinson has managed to disprove Roy Allison without really understanding what he was attempting to say. Remember, John, Allison's interest involved getting not only a smooth radiation pattern, but also involved having flat-power input to the listening room. An absolutely smooth first-arrival, direct-field signal was not high on his priority list. There will be diffraction at some frequencies but not others, meaning that it is not true that the drivers on each of the Allison speaker's baffles are not in each other's acoustic environments. Again, Mr. Ferstler where are your _own_ measurements that support what you say. John, unlike you I am not about to second guess Allison. And you very well know that the only measurements I do for my reviews are room curves. However, I also realize that guys like you often measure to death and still cannot correlate those measurements with what people hear. I certainly have seen this happen in the past with some of your amp measurements when they were contrasted with the subjective impressions of your reviewers. and for the mids there is the slight beginning of interference at the bottom of their range. A half-wavelength path difference would result in significant, not "slight" interference. See for example, the horizontal dispersion of the popular center-channel speakers that use spaced midrange units or woofers. (A subject on which I agree with Tom Nousaine, BTW.) You are on a roll, John. But the spaced-driver situation we have with typical center speakers involves interference effects over a broad frequency range. Even you admit that the interference effects with the Allison design limits the bandwidth covered by the artifacts. However, the crossover and the mid's inherent Q value are designed to compensate for that minor effect." I fail to grasp how adjusting the on-axis behavior compensates in any significant way for arbitrary and irregular dispersion effects. Please offer more detail, Mr. Ferstler. John, just for kicks I will send your comments to Roy to look over. I will get back to you. The ball is in your court, Mr. Atkinson. As I said, Mr. Ferstler, use of multiple, spaced drivers results in a less-wide, less-even dispersion pattern, owing to the interference between the spaced drivers producing a complex pattern of lobing. Yes, I will allow that by angling the baffles on which the spaced drivers are placed, you will reduce the interference, and there _will_ now be lobes aimed at wider off-axis angles than with a single drive-unit. But the price paid to achieve the existence of those lobes is a significant reduction in the smoothness of the radiation pattern, which Toole's and Olive's work has shown to be undesirable, subjectively. This is taste related, and involves imaging issues related to the impact of the first-arrival, direct-field signals. Yes, that can mean a lot to some individuals, but I have never felt that it was significant when auditioning speakers for realistic sound. Your arguments have all been circular, Mr. Ferstler. That you like the sound of the Allison speakers goes without saying. But without measured data to support that opinion, your projection about the technical reasons for your preference are mere masturbation. Well, I think you are a dirt bag, too, John. Unlike you, I really believe what I believe, whereas you are a turf-protecting (and probably job protecting) tweako journalist who grandstands. Howard Ferstler |
#287
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John Atkinson wrote:
ScottW wrote: The fig3 plot says "Fig.3 Rogers LS3/5a, 1978 sample, horizontal response family at 50", normalized to response on tweeter axis, from back to front: differences in response 180 degrees-5 degrees off-axis; reference response; differences in response 5 degrees-180 degrees off-axis." Yes, the plot show the LS3/5a's output plotted in a complete circle at 5 degree intervals. So the 0 degree plot should either agree with the on axis (fig 4 which is also at 50") or if truly normalized to on axis then I think the 0 degree plot should be flat. I can't see either situation in Fig 3. The fig.4 response was subtracted from every response in fig.3. meaning that the 0-degree trace is indeed a flat, straight line. But the notable point is that the tweeter output doesn't stop dead at 90 degrees off-axis. Below 12kHz, there is still output apparent above -30dB floor of this graph, particularly at some frequencies. John Atkinson Editor, Stereophile I have a comment, too. As best I can tell, this horizontal radiation pattern readout was done at just one height above the ground plane. Looks like measuring from a slightly different height would result in a different set of curves, given the interference effects and different radiation patterns from each driver in the vertical plane. How can one set of multiple polar curves be worth anything if a slight measurement-height change will change the shape of most of them? In order to make direct-field measurements like this meaningful (if we want to see the energy smoothness of the system into a total room space), not only would you have to do a full series at one height, you would also have to do a multiple series of horizontal RP readouts at a lot of other heights. So, as comprehensive as this information looks, it does have serious information gaps. Well, I suppose you could measure at the seated ear height and then the info would be good for the direct-field impact. However, I continue to believe that the direct field, which is only a small fraction of the total sound output from a speaker, does not tell us much about how a speaker sounds in a real-world listening room, at least if that real-world room is not padded and the listener is not sitting almost up against the speakers. Ironically, a room curve that stresses sound power would give us a better idea of the total power input to a room than even many fixed-height measurements in the direct field. Howard Ferstler |
#288
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MINe 109 wrote:
In article , Howard Ferstler wrote: Pal, you would have to use a LOT of wire to effect a proper delay line for that concentric-ring design. You would practically have to make it several miles long. At last! Yes, Quad use a LOT of wire, plus some phase tricks. http://www.stereophile.com/loudspeak...16/index6.html "These rings were fed by delay lines (employing some 11 miles of wire!) Holy cow. And you guys split hairs and get into a sound-quality twist about a few feet of speaker cable between an amp and some speakers! Howard Ferstler |
#289
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Arny Krueger wrote:
MINe 109 wrote: In article , "Arny Krueger" wrote: Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: I have only mentioned what another rather influential and knowledgeable individual wrote about it (well, said about it during a lecture). For all I know, the damned thing hung the moon. But in principle the system has characteristics that should make some purists a bit apprehensive. You haven't said what those are. The esoteric circuitry that allows for broad-bandwidth delays between each concentric ring. It's called 'wire'. You don't think it changes the sound. Wrong. It's a delay line composed of inductors and capacitors, and they are each well-known to change the sound. Finally, some support from you instead of vituperation. It helps when you are correct about things, Howard. Howard figured it out. Prove it. Yeah. Frankly, if I "figured it out" the result still went over my head. Howard Ferstler |
#290
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dave weil wrote:
On Sun, 17 Apr 2005 19:54:14 -0400, Howard Ferstler wrote: I think that laser interferometer analysis of cone or dome behavior probably begins to become a bit obsessive Cue irony loop... I'm still chuckling about the charge of serious comb-filtering on the Quad. There would have to be on the 57 version. On the one that uses concentric delays with the rings there would not be. However, the broad-bandwidth delay line that has to work with those rings has to be causing its own problems. Howard Ferstler |
#291
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Howard Ferstler wrote:
Yeah. Frankly, if I "figured it out" the result still went over my head. Stephen was just trying to be cute. Instead, he exposed his ignorance. |
#292
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On Tue, 19 Apr 2005 13:42:40 -0400, Howard Ferstler
wrote: dave weil wrote: On Sun, 17 Apr 2005 19:54:14 -0400, Howard Ferstler wrote: I think that laser interferometer analysis of cone or dome behavior probably begins to become a bit obsessive Cue irony loop... I'm still chuckling about the charge of serious comb-filtering on the Quad. There would have to be on the 57 version. No more than any other multi-driver speaker of any reasonable size. On the one that uses concentric delays with the rings there would not be. However, the broad-bandwidth delay line that has to work with those rings has to be causing its own problems. No more than most crossovers with their miles of wires (since you want to compare apples and zebras). |
#293
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In article ,
Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , "Arny Krueger" wrote: Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: I have only mentioned what another rather influential and knowledgeable individual wrote about it (well, said about it during a lecture). For all I know, the damned thing hung the moon. But in principle the system has characteristics that should make some purists a bit apprehensive. You haven't said what those are. The esoteric circuitry that allows for broad-bandwidth delays between each concentric ring. It's called 'wire'. You don't think it changes the sound. Wrong. It's a delay line composed of inductors and capacitors, and they are each well-known to change the sound. Finally, some support from you instead of vituperation. It helps when you are correct about things, Howard. Howard figured it out. Prove it. Yeah. Frankly, if I "figured it out" the result still went over my head. You figured out that the delay depends on lots of sonically benign wire. Stephen |
#294
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In article ,
"Arny Krueger" wrote: Howard Ferstler wrote: Yeah. Frankly, if I "figured it out" the result still went over my head. Stephen was just trying to be cute. Instead, he exposed his ignorance. Says the man who was willing to bet there wasn't a mile of wire in a Quad... Stephen |
#295
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In article ,
Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: Pal, you would have to use a LOT of wire to effect a proper delay line for that concentric-ring design. You would practically have to make it several miles long. At last! Yes, Quad use a LOT of wire, plus some phase tricks. http://www.stereophile.com/loudspeak...16/index6.html "These rings were fed by delay lines (employing some 11 miles of wire!) Holy cow. And you guys split hairs and get into a sound-quality twist about a few feet of speaker cable between an amp and some speakers! Isn't the point that I *don't* get into a twist about wire? Stephen |
#296
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In article ,
Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: John Stone is a driver salesman. I replied at length to his commentary elsewhere. Go find it. You're quick to dismiss experts, aren't you? Wasn't Allison a speaker salesman? Allison designed both systems and drivers and published numerous articles on system design in the JAES. He even published articles in pop-audio magazines at one time. I doubt if Stone is a Fellow, or even a member, of the Audio Engineering Society. Didn't he manufacture and sell speakers at one point? From The Encyclopedia of Recorded Sound: snip "In 1974, after leaving AR, he helped to found Allison Acoustics, RDL, and RA Labs..." Thought so. Someone may have mentioned it. End of excerpt. PS: there is no entry for John Stone in The Encyclopedia. So what? Stephen |
#297
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John Stone wrote:
On 4/17/05 6:54 PM, in article , "Howard Ferstler" wrote: Hey Howard, this will be my last post for at least a week. I'm with an engineer from Norway and we'll be seeing some of those engineer jerks I mentioned before. Anything you want me to ask Toole? How about Linkwitz? If this thread is still alive when I get back, I'll post the curves of the Allison tweeter so others can see what we're talking about. Good enough. Remember, those guys are a whole lot more interested in having the direct-field signal be flat and coherent than they are in sound power. However, the direct-field signal is only a small fraction of what we hear from any speaker, and in my opinion its only salient feature is its ability to deliver precise imaging. Well, let's look at the power curves that Consumer Reports has run for years. Their reviews consistently put Allison's lower-priced speakers ahead of most of the competition. Yes, I know there is more to performance than power curves, but the fact is that Allison's "dated" tweeter design, not to mention his work with integrating that tweeter with the woofer (often an upward-facing unit that helped to keep the horizontal dispersion uniform over a wide area) allowed him to keep up with and usually surpass all of those more modern units you automatically lionize. Irrelevant. Nobody has argued about the dispersion. Nothing in all this drivel you have posted so proves anything about the "pulsating hemisphere theory" Except the design of the driver. And don't say it has to work that way because that's the way he designed it. That's a circular argument. Baloney. It worked, and continues to work as good as even the best current designs (when the integral crossover work is figured in) and better than most. Hey, John, I know you have a business to protect, so I forgive you. Against Allison? He's been out of business for years, and never made raw drivers for anyone else. Actually, Mark Davis asked Allison to build drivers for the original dbx Soundfield One system. Davis (Phd from MIT and the guy who later on helped give us Dolby AC-3) felt that the Allison drivers were the best available. Roy toyed with the idea and then decided that being an OEM supplier was not his cup of tea. When soft dome tweeters were first introduced the white papers at the time said they had better dispersion than cone diaphragms because the convex shape pushed the high frequencies outward. But when concave dome tweeters came out, it was discovered that they had exactly the same dispersion as convex domes. So much for that theory. I am not aware that Allison had anything to do with this at all. Certainly, his driver is different from most other domes. In any case, Allison has told me that driver shape does not automatically make a difference, so he is in agreement with your latest research. Indeed, he once showed me a curve of a 1-inch cone tweeter (used in the old AR-6 decades ago) that he said radiated as widely and smoothly as typical dome one inchers. I printed that curve in a book way back in 1991, by the way. Finally. Now put that together with the coaxial cone being driven off the edge of a 1/2" dome and you get the picture But the Allison driver, being convex instead of concave like the small cone tweeter, had way better dispersion. The reason involves the nature of the shape of the driver and the radial flexing surround. The tweeters still worked. The explanation was all wrong. What was discovered through physical observation(laser interferometer) is that the diaphragm completely decouples from the voice coil at high frequencies, and the tweeters act like ring radiators. Concave or convex, it made no difference. The dome was contributing virtually nothing outside a very narrow ring on either side of the voice coil. OK, but what we are discussing is the impact of the flexing surround around that dome. Because it moves radially and is far larger in relation to dome size than typical other surrounds, it has an impact on the dispersion. You may speculate about how it really behaves, but as best I can tell that is all it is: speculation. That's right Howard, speculation. On your part and on ours. Many thanks for stating that your team is also speculating. But ours is informed and yours isn't. Informed speculation? Well, I assume that Allison's "informed speculation" is as precise as yours, particularly considering that he designed the tweeter. You are speculating based on no knowledge of what paper does at high frequencies. We are speculating based on what we've seen paper do at high frequencies in laser tests. On drivers other than the Allison unit. Hey, John, even he would admit that. So would I. However, you also do not know everything he knows about drivers. If you're talking about me, you're right. If you're talking about SEAS, our body of knowledge on drivers far outstrips his. We've been at it much longer and have far better tools at our disposal. Our head engineer has studied all Allison's papers and we have measured that tweeter. So we know what he knows and a bunch more. Actually, I reviewed a system that used SEAS Millennium drivers a while back. It performed admirably, but not exceptionally. The tweeter's output into the top octave was not a power-response match for the Allison tweeter or even a number of conventional tweeters I have measured, such as the one in an NHT unit I also reviewed. There was the usual midrange-driver efficiency rolloff up near the crossover point to the tweeter. Still a nice system, however. Just not world beating. As explained above there are plenty of complex mechanical systems out there that work, but whose behavior is not fully understood. And radiating diaphragms exhibit VERY complex vibrational behavior, much of which is not fully understood-even today. And in some important ways all of this work with analysis is overkill. There is a point where going the current state of the art one better has no meaningful impact. Ah yes, that famous Howard Ferstler "frozen in time" point of view. There is a lot to say for the good old days. Certainly that would apply to both overkill engineering and the way audio buffs behave these days. I think that laser interferometer analysis of cone or dome behavior probably begins to become a bit obsessive, given what is possible from even a perfect one-inch standard dome. You think? What is the relevance of that given that you're operating totally out of the dark? Well, that system I mentioned, with its SEAS drivers did not perform any better than my Dunlavy Cantatas when it comes to direct-field detail, and against my Allison IC-20 systems it was a no-contest situation when it comes to a sense of soundstaging spaciousness and frontal depth. I mean, speakers were able to do live-vs-recording work that was fantastic way back in the AR-3 era. Yes, that system is dated in many ways (particularly concerning its rather high woofer/midrange crossover frequency), but given its success during those demos (where seasoned audio buffs and journalists were even impressed) it is hard to believe that world-shaking improvements have happened since that era. Better systems, yes, but not as eye opening as you "we make super-duper driver" freaks might believe. Are your scared of the dark? Well, those AR-3 systems sure impressed those audio journalists. This is why driver design remains part science and part art. The behavior of that Allison surround will be very complex because it isn't just a paper cone, its a paper cone that's rigidly fixed at one end. Actually, it is not rigidly fixed. There is a very thin foam ring between the surround edge and the mounting plate. According to Allison, without the ring the driver will ring somewhat. Good try, though, John. Doesn't change anything. The paper surround is far less rigid than the foam ring so the ring will do very little. Not according to Allison. Heck, he obviously tested the thing with and without the ring. Your guys were certainly not in a position to do that. If the foam is only there to "somewhat stop ringing" it isn't a key part of the moving system. Good try Howard. Bunk. It is obviously a key part. And you better hope the effects of that foam gasket are subtle, because that 25 year old foam is gonna be hard and brittle. Depends upon the kind of material. Some such stuff holds up for a long time. The foam he used with the tweeter, as well as the foam surround he used with the midrange, was not the same as the foam he used with the woofers. Admittedly, woofer-surround of foam does deteriorate. In any case, I have Allison tweeters here 27 years old that measure the same on axis as others also on hand that are 15 years old. And those 15-year old jobs managed to deliver sound-power output to a higher frequency than the Millennium tweeter in that system I mentioned. Indeed, in terms of flat power to the microphone in my listening room, virtually no other tweeters I have measured were as flat between 4 kHz and 16 kHz as the Allison units. "Greater" how? Its no greater than other 1/2incher above 5khz, so I'm assuming you're referring to its output below 5K. Yes, that's explained by the large surround. But at those frequencies, dispersion is not an issue. But output is. The surround allows the driver to disperse like a 1/2 incher and still have considerably more output capability below 5 kHz. Frankly, given what Hirsch measured with that budget Allison speaker I mentioned in another post, it has greater output above 5 kHz, as well. You're speculating again. Well, one thing for su the 15-year-old tweeters in my Allison IC-20 systems generated flatter and more extended power over the treble range than those new SEAS tweeters in the system I reviewed. I will admit, however, that the tweeter (and the midrange drivers, too) were sure pretty looking items. Whatever the design results when it comes to sound, SEAS does know how to make good-looking drivers. Of course, looks are not what we listen to. Why should it be magic? One look at the surround design and one has to see that it is going to have an effect that is related to the radial movement. There's that precision again. "It is going to have an effect" How is the effect achieved. That's been the question since day one. And you still haven't answered it. Neither have you. Your guys never did an analysis that substantiates your opinion of the tweeter's diaphragm behavior. You just assume that the radial movement of the surround does not contribute to its top-octave behavior. I'm the one saying that the simple explanation is that above 5khz the radiation is off the dome. Conjecture. Did your people do a laser interferometer measurement? If not, then you are speculating. Incidentally, the dome is not just hanging out there. Behind it is a fiber damping material. If its conjecture, then what is the dome there for? Part of the overall design. The thing was designed to simulate a pulsating hemisphere without actually being a pulsating hemisphere. Baloney. You are speculating about a tweeter design that you have not even analyzed with the laser device. You just assume that the driver must have problems or anomalies. We know it has problems and anomalies from the measurements. And you just said laser devices are obsessive. Which is it? Well, they are obsessive to you. I have done room-curve measurements of the tweeter (installed in the IC-20 systems) and it had a response that was both more extended and smoother than what I measured with the system that employed your SEAS Millennium tweeter. You are basically saying that if I do not know the physics involved I am unqualified to say anything about the concept. Exactly. Because if you understood even a little, you wouldn't be making the claims you are making. Ditto, for you. So, you are basically saying that a pulsating hemisphere movement will not disperse any better than a moving diaphragm of the same diameter? Not mounted the way the tweeters are in your speakers, no. OK, now are we discussing the mounting of the tweeters in the IC-20 systems, or are we discussing the design of the tweeter itself? You are speculating. You have no solid proof that this theory of your works. You just assume that the driver behaves this way. You speculate even more than I do, John. I understand how drivers work. Turn the Allison diaphragm around and it is a cone tweeter with a rigid (mostly) termination. Those drivers are well understood. Yes, and on pages 46 and 47 of my book, High Fidelity Audio/Video Systems there are on and off-axis curves from the Allison convex dome and a one-inch cone tweeter. They are almost mirror images of each other, reversed, and yet the Allison tweeter has way, way better dispersion than the one-inch cone. Heck, Thiel did exactly the same thing-though far more refined-with the coaxial mid/tweet in his 2.3 and 2.4 systems. Far more refined? Looks like we are speculating again, John. I've discussed it at length with Jim Thiel. He's had many years and much better tools to refine the concept. That's what happens in the real world. Well, I suppose any designer would consider his designs to be more refined than what is produced by the competition. This gave him much better low end output (the cone could move). He uses this driver between 400 and 20khz And guess what? He got the output and dispersion of a 1" dome with the low frequency extension of a 3.5" cone. Surprise,Surprise!! Good for him. Given that the Allison tweeter (and similar Allison midrange) were designed back in 1975, I think that Allison gets the prize for the first idea. Actually, the tweeter in the old Kloss Advent speaker was also kind of this way, although the shape of the thing was quite different from the Allison tweeter. As best I can tell, the Thiel tweeter is also shaped quite differently, and maybe somewhat like the Kloss design. Nope. It's just a dome. Don't you have any curiosity at all? It's all there with a click of your mouse. I thought you said that it had a special, oversized surround. Make up your mind. and all your other measurements are referenced to these on axis measurements. Like it or not, that's how its done. Well, given your take on this and my comments above, it looks like they need to widen their horizons a bit. Bull****. The effect of wider dispersion will show up in the polar plots, which are done on all tweeters. Give me a break. In many cases, the spec sheets for tweeters stop measuring at 45 degrees off axis. And there is a whole lot more room area covered from 45 to 90 degrees off than there is from zero to 45 degrees off. Almost 2.5 times as much, actually. This means that the response beyond 45 degrees has a huge impact on the spectral balance of the driver in a real-world listening room. One that does not have padded walls, at least. First off, your Allison tweeters are no different in dispersion capability at 6kHz and below than a 1" dome. I certainly hope so. So what? So it means that the power response is the same between the 2 at those frequencies. And those are the frequencies where crossover occurs. To splice the mid or woof to the tweeter, the sensitivities in that range will have to match. The radiation patterns also have to match. Typically (as with the speaker I reviewed that had SEAS drivers) the midrange is so much larger than the tweeter that the wide-off-axis response begins to sag as the midrange reaches up towards the tweeter and then it flares outward in power as the tweeter cuts in. This results in a choppy wide off-axis response (the same thing may happen with the woofer as it reaches up towards the midrange crossover point) that I think is very detrimental to proper sound reproduction in normal listening rooms. Of course, many guys (ones that some consider to be knowledgeable) do not consider that wide off-axis response all that important, provided that the direct-field, first-arrival signal is flat. Well, I disagree. The direct-field signal is only a pint-sized fraction of what we hear with speakers. and this is where the low sensitivity of the Allison comes into play-and why he has to double or quadruple them to get reasonable overall output. Baloney. The sensitivity may be low on axis, but the overall efficiency is enhanced by the wide dispersion. Look at it this way (again): if we have two drivers, one wide dispersing and one narrow dispersing and measure both on axis and both are equal, which will play louder with the same input signal in a typical room? You probably believe that they would be equal. However, they are not, because the wide-dispersion job is putting more reflected, power-response energy into the room. Only in a padded or anechoic room would the other tweeter be equally loud. Nobody will accept a tweeter with this sensitivity level today. Again, the tweeter's wide dispersion makes its power-response efficiency rather good. And when it comes to response levels at the listening position it is the power-response efficiency that counts and not the direct-field, on-axis efficiency. Put those tweeters on angled panels, like what we have with the more upscale Allison models, and at 90 degrees off the systems are as flat as they are on axis. Of course, I am being unfair here, because we are discussing drivers and not systems. Put our tweeters on angled baffles and the gain is the same. Really Howard, isn't the angled panel the main contributor to the Allison dispersion? How audible is a few dB more or less above 10kHz, mostly bounced off the wall, above 10kHz? You probably couldn't tell the difference given the state of your hearing. My hearing "limitations" notwithstanding, the Allison IC-20 sounds more spacious and realistic than systems with tweeters that disperse in a more conventional manner. Both types existed when Allison was in business and customers freely chose Yep. This means that the critical distance between the direct and reverberant fields is not stabilized with such designs (changes back and forth in distance from the speakers as the frequency climbs up the scale), and to my way of thinking this is a much bigger problem than a lack of tight imaging and imprecise focus. To YOUR way of thinking? From someone who doesn't even understand the basic mechanisms of driver diameter and dispersion? What validity does your view of "critical distance" bring to this discussion? If the system disperses evenly at all frequencies, the critical distance will be stabilized. If the drivers disperse differently at different frequencies, the critical distance will move back and forth between the speaker and the listener. The listener will sometimes be in a direct-field dominated location and at other times will be in a reverberant-field dominated location. This ain't no good, John. You know, jerks like Heyser, Toole, D'Appolito, Linkwitz, Barton. What you'll never understand is that if even if these guys had an Allison tweeter available today, they'd reject it out of hand, for all the reasons I stated before. Well, what these guys like or liked involves taste. Remember, it was you who said that speaker design is as much an art as a science, and my contention is that speaker performance is as much a product of taste as of science. Okay, so these guys are just know nothings with an opinion, but you are the master? No. I am not alone in considering imaging and tight soundstage focus to be an overrated requirement for good loudspeaker performance in typical listening rooms. 2) Some people like speakers to sound like speakers, rather than like live ensembles. Oh please, there's no mistaking your Allisons for a live ensemble. Says you. How many top-tier Allison models have you listened to? Enough of the model 1 to know what it is and to not like it. Yep, you are a tight imaging guy. I'll just bet that you are also a pop- or rock-music freak. But rock-music people do not even need super-quality audio systems. Heck, remember those live-vs-recorded concerts Villchur held decades ago with AR-3 speakers? And he was doing that with speakers that are not in the same class as the Allison models, although Villchur was, like Allison, more interested in flat power response and wide dispersion than in tight-imaging and precise instrumental focus. Looks like Villchur knew what really mattered way back in the 1960s. Those live vs recorded things were parlor tricks. Everyone knows in a large reverberant space, the acoustics of the space will dominate the sound character. It worked. And with speakers that had rather erratic direct-field performance, loads of diffraction effects, and drivers designed four decades ago. Sure, some systems these days are superior, but my point is that the AR-3 was still good enough in that era to come pretty damned close to duplicating the sound of live ensembles. If all of that laser interferometer work and other design tricks that your team and other driver-design teams are doing is such a big deal, there would be a huge advance over what the AR-3 could do. However, even if the newest designs are somewhat better, they are not all that much better. Actually, the main advance since the AR-3 involves maybe better midrange dispersion (with the AR-3a and AR-LST) and then later on flatter mid-bass reproduction due to the boundary-analysis work done by Allison. They sound like speakers, diffuse radiating speakers. Anyway, aren't you the one that keeps harping on the fact that 2 speakers can't possibly reproduce the experience of live music in a room? Sure, but for reasons unrelated to what we are discussing. Right. So tell me again how a pair of IC 20's sounds like a live ensemble? Close, though, or at least better than anything else I have auditioned for magazine reports. If I add in my center speaker and throw in a bit of good DSP surround ambiance I am doing even better. Howard Ferstler |
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dave weil wrote:
I'll say this about the CD8 - at levels that one would usually consider medium loud, the speaker as a system starts to distort, so it isn't a system that one would use to achieve "realistic" levels of high output music. This wouldn't hold true with the IC-20, which I have heard stay relatively "clean" at pretty impressive output levels. Still, the CD-8 stays coherent at levels that satisfies me about 95% of the time. It is a good system. Measures about as flat in my big room as the IC-20, too. Howard Ferstler |
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Arny Krueger wrote:
Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: I have only mentioned what another rather influential and knowledgeable individual wrote about it (well, said about it during a lecture). For all I know, the damned thing hung the moon. But in principle the system has characteristics that should make some purists a bit apprehensive. You haven't said what those are. The esoteric circuitry that allows for broad-bandwidth delays between each concentric ring. It's called 'wire'. You don't think it changes the sound. Wrong. It's a delay line composed of inductors and capacitors, and they are each well-known to change the sound. Finally, some support from you instead of vituperation. It helps when you are correct about things, Howard. See my response to those comments of yours. I am going to add a few more if I can find the thread again. Howard, I was very polite with you about your errors in those other posts. If you want to see vituperation, look at the corresponding posts from that well-known technical ignoramous, Scott Wheeler. Yeah, he is a bit of a tweap, isn't he. Howard Ferstler |
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Howard Ferstler wrote:
Arny Krueger wrote: Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: I have only mentioned what another rather influential and knowledgeable individual wrote about it (well, said about it during a lecture). For all I know, the damned thing hung the moon. But in principle the system has characteristics that should make some purists a bit apprehensive. You haven't said what those are. The esoteric circuitry that allows for broad-bandwidth delays between each concentric ring. It's called 'wire'. You don't think it changes the sound. Wrong. It's a delay line composed of inductors and capacitors, and they are each well-known to change the sound. Finally, some support from you instead of vituperation. It helps when you are correct about things, Howard. See my response to those comments of yours. I am going to add a few more if I can find the thread again. Howard, I was very polite with you about your errors in those other posts. If you want to see vituperation, look at the corresponding posts from that well-known technical ignoramous, Scott Wheeler. Yeah, he is a bit of a tweap, isn't he. Howard Ferstler I meant twerp. Howard Ferstler |
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Arny Krueger wrote:
Dome tweeters have broad dispersion, especially if they are small - that's what they do. Furthermore, who's to say that braod, nearly hemispherical dispersion is even a good thing? In another response, I mentioned several factors that prove that wide and uniform dispersion over a system's operating range is a good thing. I'll list the five of them again and then add one more that may be the most important of all: 1) It allows the designer to keep the critical distance (the point between the direct and reverberant fields) between the listener and speaker stabilized. With directional speakers, this critical distance moves back and forth between the speakers and listener. Depending upon the frequency, the sound is sometimes direct-field dominated and sometimes reverberant-field dominated. With wide-dispersion drivers the critical distance does not move so much. If a speaker is going to be directional, it should stay that way over the midrange and treble frequencies, and keep directionality under control. 2) It allows the treble frequencies to be as spacious sounding as the midrange frequencies. With treble beaming, this characteristic is not there. 3) It allows a speaker to soundstage more effectively in typical listening rooms. Placement is also not as critical, as the speaker does not have to be aimed at the listener. 4) Following number three, above, it allows anyone listening from off-axis locations to get the same spectral balance from the speaker as those sitting closer to the speaker's axis. 5) With the midrange being wide dispersing (particularly in comparison with systems that have largish midrange drivers) it reduces the radiation-efficiency sag common at and near the crossover frequency. Yes, certain horn designs overcome this, but the result is a speaker that spotlights sound instead of spreading it out along the soundstage. OK, here is number six and it is a bit longer than the others and basically serves as an explanation for number five: At wide off-axis angles a typical woofer will be omnidirectional at lower frequencies and then (because wavelengths are more directional as they get smaller in relation to driver diameter) get more directional as the frequencies it handles work their way upward towards the midrange crossover point. When the signals go high enough for the midrange to begin to take over the dispersion of the whole system flares outward and so we have a flat/dip/flat situation at wide off-axis angles over the operating range of the woofer and midrange. However, as the midrange handles still higher frequencies, its dispersion also narrows (just like with the woofer), and so there is a dip at wide off-axis angles as the crossover point is approached. The tweeter cuts in as the frequencies continue to climb, and again, the wide off-axis response flares outward again. So, we again get a flat/dip/flat situation with the midrange and tweeter interface. So, while the system may be flat on axis and even fairly flat at moderately wide angles off axis, at extremely wide off-axis angles (beyond 45 degrees and out to past 60 or 70 degrees) the response of the system will be choppy. This choppiness contributes to the power response (and therefore the room response) and therefore colors the spectral balance of the system. Yes, directional horns can keep the response rather narrow and controlled at wide off-axis angles and can keep those woofer/mid and mid/tweeter slumps under fair control. (My Dunlavy Cantatas actually work this way, while still being rather narrow dispersing.) However, most conventional systems, even some well-regarded ones, do not enjoy that feature. Howard Ferstler |
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dave weil wrote:
On Tue, 19 Apr 2005 13:42:40 -0400, Howard Ferstler wrote: dave weil wrote: On Sun, 17 Apr 2005 19:54:14 -0400, Howard Ferstler wrote: I think that laser interferometer analysis of cone or dome behavior probably begins to become a bit obsessive Cue irony loop... I'm still chuckling about the charge of serious comb-filtering on the Quad. There would have to be on the 57 version. No more than any other multi-driver speaker of any reasonable size. With multi-driver systems the spacing occurs only at and near the crossover points, and will vary depending upon how far apart the drivers are located. With the 57, the spacing exists at all frequencies. Howard Ferstler |
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MINe 109 wrote:
In article , Howard Ferstler wrote: Yeah. Frankly, if I "figured it out" the result still went over my head. You figured out that the delay depends on lots of sonically benign wire. Sonically benign? You guys debate the merits of upscale speaker wire leads that are six feet long and you are telling me that 11 miles of wire is no big deal? Give me a break. In any case, Arny showed that 11 miles is still not enough. Howard Ferstler |
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MINe 109 wrote:
In article , Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: Pal, you would have to use a LOT of wire to effect a proper delay line for that concentric-ring design. You would practically have to make it several miles long. At last! Yes, Quad use a LOT of wire, plus some phase tricks. http://www.stereophile.com/loudspeak...16/index6.html "These rings were fed by delay lines (employing some 11 miles of wire!) Holy cow. And you guys split hairs and get into a sound-quality twist about a few feet of speaker cable between an amp and some speakers! Isn't the point that I *don't* get into a twist about wire? Stephen Well, if 11 miles of wire is sonically benign, then it looks as if a good speaker hookup involving maybe a dozen feet of the copper would not require upscale wire to do the job. Lamp cord would do just fine. Howard Ferstler |
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MINe 109 wrote:
In article , "Arny Krueger" wrote: Howard Ferstler wrote: Yeah. Frankly, if I "figured it out" the result still went over my head. Stephen was just trying to be cute. Instead, he exposed his ignorance. Says the man who was willing to bet there wasn't a mile of wire in a Quad... Says the man who has zero evidence that there is a mile of wire in a Quad. |
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MINe 109 wrote:
In article , Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , "Arny Krueger" wrote: Howard Ferstler wrote: Arny Krueger wrote: MINe 109 wrote: In article , Howard Ferstler wrote: MINe 109 wrote: In article , Howard Ferstler wrote: I have only mentioned what another rather influential and knowledgeable individual wrote about it (well, said about it during a lecture). For all I know, the damned thing hung the moon. But in principle the system has characteristics that should make some purists a bit apprehensive. You haven't said what those are. The esoteric circuitry that allows for broad-bandwidth delays between each concentric ring. It's called 'wire'. You don't think it changes the sound. Wrong. It's a delay line composed of inductors and capacitors, and they are each well-known to change the sound. Finally, some support from you instead of vituperation. It helps when you are correct about things, Howard. Howard figured it out. Prove it. Yeah. Frankly, if I "figured it out" the result still went over my head. You figured out that the delay depends on lots of sonically benign wire. Please define "lots" in terms of miles of wire, and show an independent source that supports your claim. |
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Howard Ferstler wrote:
MINe 109 wrote: In article , Howard Ferstler wrote: Yeah. Frankly, if I "figured it out" the result still went over my head. You figured out that the delay depends on lots of sonically benign wire. Sonically benign? You guys debate the merits of upscale speaker wire leads that are six feet long and you are telling me that 11 miles of wire is no big deal? Give me a break. In any case, Arny showed that 11 miles is still not enough. Just to clarify - if this kind of delay is implemented with a delay line (which includes other electronic parts), then 11 miles is way more than enough. If it is implemented by depending on just the delay due to the length of the wire, then it isn't. |
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Correction:
Arny Krueger wrote: MINe 109 wrote: In article , "Arny Krueger" wrote: Howard Ferstler wrote: Yeah. Frankly, if I "figured it out" the result still went over my head. Stephen was just trying to be cute. Instead, he exposed his ignorance. Says the man who was willing to bet there wasn't a mile of wire in a Quad... Hyperbole? My well-supported claim was that it would take something like 166 miles of wire to make the Quad ESL 63 work the way you said it does. I speculated that there might not be a mile of wire in the Quad, but instead SP says that there was 11 miles of wire. Well, 11 miles of wire is still a lot less than the 166 miles of wire it would take to implement a useful delay based purely on the delay due to a signal passing through a wire. Schematics of the Quad ESL 63 clearly show a delay line composed of inductors and capacitors, not delay due to the length of the wire. Of course Stephen, they obviously didn't teach you how to recognize a delay line on a schematic in your music classes, so how would you know? I don't know which is worse -being pecked to death by ducks or being pecked to death by a music teacher, a waiters, and a makeup artist, each with his own delusions of grandeur. |
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Arny Krueger wrote:
Just to clarify - if this kind of delay is implemented with a delay line (which includes other electronic parts), then 11 miles is way more than enough. If it is implemented by depending on just the delay due to the length of the wire, then it isn't. Just how much space would 11 miles of wire occupy? If this wire is anything but micro-thread size the speaker would have to be huge - and damned heavy. The same people who ignore the problems with having 11 miles of skinny wire inside of a speaker probably use wire between their speakers and amp as big around as garden hose. So goes the lunatic world of high-end audio. Howard Ferstler |
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Arny Krueger wrote:
Hyperbole? My well-supported claim was that it would take something like 166 miles of wire to make the Quad ESL 63 work the way you said it does. I speculated that there might not be a mile of wire in the Quad, but instead SP says that there was 11 miles of wire. Well, 11 miles of wire is still a lot less than the 166 miles of wire it would take to implement a useful delay based purely on the delay due to a signal passing through a wire. Schematics of the Quad ESL 63 clearly show a delay line composed of inductors and capacitors, not delay due to the length of the wire. Of course Stephen, they obviously didn't teach you how to recognize a delay line on a schematic in your music classes, so how would you know? I don't know which is worse - being pecked to death by ducks or being pecked to death by a music teacher, a waiter, and a makeup artist, each with his own delusions of grandeur. This is a very funny post that hits the mark. Howard Ferstler |
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Here is a brief, additional reply to Mr. Atkinson, and I
will leave it at that: There is some diffracted output at more than 90 degrees, but it is NOT significant compared with the output of the driver radiating on the right-angle panel. The crossover frequency between woofers and mids is 350 Hz, well below Mr. Atkinson's postulated 600 Hz. As for mids, reinforcement from the front wall can be expected to increase below 600 Hz by the same reasoning that some cancellation is to be expected from the other mid. All you need do is put the Model Ones or IC-20s in the recommended position with respect to the front wall. Wrapping it up, it has been suggested to me that it is pointless to argue with a magazine editor. I should have realized that at the outset. Howard Ferstler |
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John Atkinson wrote:
ScottW wrote: The fig3 plot says "Fig.3 Rogers LS3/5a, 1978 sample, horizontal response family at 50", normalized to response on tweeter axis, from back to front: differences in response 180 degrees-5 degrees off-axis; reference response; differences in response 5 degrees-180 degrees off-axis." Yes, the plot show the LS3/5a's output plotted in a complete circle at 5 degree intervals. So the 0 degree plot should either agree with the on axis (fig 4 which is also at 50") or if truly normalized to on axis then I think the 0 degree plot should be flat. I can't see either situation in Fig 3. The fig.4 response was subtracted from every response in fig.3. meaning that the 0-degree trace is indeed a flat, straight line. OK, I see it now.... jeez I hate 3-d plots. But the notable point is that the tweeter output doesn't stop dead at 90 degrees off-axis. Below 12kHz, there is still output apparent above -30dB floor of this graph, particularly at some frequencies. You sure this tweeter doesn't have a magic surround as well? Some tweeko-freeko types are claiming surrounds can have an effect on high frequency radiation patterns and dispersion . ScottW |
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"Arny Krueger" wrote in message ... I don't know which is worse -being pecked to death by ducks or being pecked to death by a music teacher, a waiters, and a makeup artist, each with his own delusions of grandeur. It's hard to tell what might annoy a disabled ashtray enginer. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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Clyde Slick said: It's hard to tell what might annoy a disabled ashtray enginer. Getting tossed out of the Promise Breakers, his pisant little Baptist church, and RAH-E certainly took their toll. |
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"Howard Ferstler" wrote in message ... Wrapping it up, it has been suggested to me that it is pointless to argue with a magazine editor. I should have realized that at the outset. You should have learned that when you submitted plagiarized material. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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In article ,
"Arny Krueger" wrote: Please define "lots" in terms of miles of wire, and show an independent source that supports your claim. It's part 'L63CO1A'. Order one and unwind it. Stephen |
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Howard Ferstler wrote:
John Atkinson wrote: the plot show the LS3/5a's output plotted in a complete circle at 5 degree intervals...the notable point is that the tweeter output doesn't stop dead at 90 degrees off-axis. Below 12kHz, there is still output apparent above -30dB floor of this graph, particularly at some frequencies. As best I can tell, this horizontal radiation pattern readout was done at just one height above the ground plane. That's correct. It's the horizontal dispersion measured on the tweeter axis with the speaker several feet _above_ the "ground plane." (Why don't you just say "ground" or is that not sufficiently technical-sounding?) Looks like measuring from a slightly different height would result in a different set of curves, given the interference effects and different radiation patterns from each driver in the vertical plane. How can one set of multiple polar curves be worth anything if a slight measurement-height change will change the shape of most of them? Spew!!! Now I've got my milk coming out of my nose! Mr. Ferstler, did you ever read even _one_ book on loudspeaker engineering? This graph shows that, contrary to what you claimed Roy Allison had told you, the tweeter's output doesn't stop 90 degrees off-axis. End of story, I would have thought. but no, I expect you will go running to Roy for _another_ explanation only to have it garbled by the filter of your lack of understanding. :-) In order to make direct-field measurements like this meaningful (if we want to see the energy smoothness of the system into a total room space), not only would you have to do a full series at one height, you would also have to do a multiple series of horizontal RP readouts at a lot of other heights. No. All you need do is do what I did in the review to which you and I have been referring: perform radiation pattern measurements in two orthogonal planes. The speaker's overall radiation can be inferred from the two sets of measurements. If you had studied mathematics instead of philosophy at school, Mr. Ferstler, you wouldn't embarrass yourself in this manner. :-) John Atkinson Editor, Stereophile |
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Clyde Slick wrote:
"Howard Ferstler" wrote in message ... Wrapping it up, it has been suggested to me that it is pointless to argue with a magazine editor. I should have realized that at the outset. You should have learned that when you submitted plagiarized material. I assume that you are a very influential individual within the industry. In that case, if my "plagiarism" is all that big a deal for you, I suggest that you contact somebody who can fix my ass and put me in my place. If I am a real problem for you as a published writer, grow some gonads and do something about it. If you cannot do that, you loutish, forked-tongue, sockpuppet misfit, I suggest that you just give it a rest. Howard Ferstler |
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John Atkinson wrote:
Howard Ferstler wrote: John Atkinson wrote: the plot show the LS3/5a's output plotted in a complete circle at 5 degree intervals...the notable point is that the tweeter output doesn't stop dead at 90 degrees off-axis. Below 12kHz, there is still output apparent above -30dB floor of this graph, particularly at some frequencies. As best I can tell, this horizontal radiation pattern readout was done at just one height above the ground plane. That's correct. It's the horizontal dispersion measured on the tweeter axis with the speaker several feet _above_ the "ground plane." (Why don't you just say "ground" or is that not sufficiently technical-sounding?) Maybe you are measuring above a concrete patio out in your back yard. That would not be the ground. I used ground plane to make sure you knew what I meant. Actually, I was just being cute. In any case, so what we have is one measurement in the horizontal plane, with no reference to horizontal measurements at other heights. One slice through the sphere and nothing more. Looks like measuring from a slightly different height would result in a different set of curves, given the interference effects and different radiation patterns from each driver in the vertical plane. How can one set of multiple polar curves be worth anything if a slight measurement-height change will change the shape of most of them? Spew!!! Now I've got my milk coming out of my nose! Mr. Ferstler, did you ever read even _one_ book on loudspeaker engineering? This graph shows that, contrary to what you claimed Roy Allison had told you, the tweeter's output doesn't stop 90 degrees off-axis. Well, this is a subject change, given what I said in the previous paragraph. I was referring to how the horizontal readout will change if you move the microphone up or down even a small distance from your initial location. End of story, I would have thought. but no, I expect you will go running to Roy for _another_ explanation only to have it garbled by the filter of your lack of understanding. :-) No, he is as tired of you as I am. Whatever I do, I will not mislead readers by spouting the kind of claptrap you do - and even more to the point, that your magazine's contributors do with your editorial blessing. Yes, John, I realize (even Dave Rich says this) that you certainly do know how to measure speakers better than most other reviewers. And as I have said before, you certainly do know how to make good recordings. The paradox here is that in spite of this you edit a magazine that is mostly mumbo jumbo. I suppose it could be said that you are just stuck with the job. Say, have you visited Floyd Toole and Sean Olive yet? I am curious about how your discussion of Ferstler went. Big, bad Ferstler, picking on all the tweako freakos. In order to make direct-field measurements like this meaningful (if we want to see the energy smoothness of the system into a total room space), not only would you have to do a full series at one height, you would also have to do a multiple series of horizontal RP readouts at a lot of other heights. No. All you need do is do what I did in the review to which you and I have been referring: perform radiation pattern measurements in two orthogonal planes. The speaker's overall radiation can be inferred from the two sets of measurements. Inferred? And your readers will understand this? I do not think that two measurements in two planes will deliver meaningful data, if what you are aiming for is a useful (to readers) indication of the overall radiation pattern and spectral balance. If you had studied mathematics instead of philosophy at school, Mr. Ferstler, you wouldn't embarrass yourself in this manner. :-) Well, one thing that the study of philosophy taught me, John, is how to tell the ethical difference between right and wrong. Howard Ferstler |
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