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Gold Member Username: Edster922Abubala, Ababala The Occupation Post Number: 4152 Registered: Mar-05 | "Why bother with frequency response to 45KHz if humans can not hear frequencies higher than about 20KHz? Just because you can not hear 45KHz does not mean your brain does not process it. The tiny bones in your ear still vibrate and that information is still transmitted to your brain. In several studies, when an audience listened to a piece of music through a playback system capable of 45KHz reproduction, they reported a much more emotionally connected and involved feeling towards the music versus listening to the same piece of music on a system limited to 20KHz playback. In a sense, it was more "real" like a live performance is. There is good cause for this as acoustic instruments have overtones that greatly exceed 20KHz. Of course CD's have a shelf at 22KHz so it seems that this tweeter will be wasted unless playing SACD's or DVD-A's. Not true...the ERT is still going to add to the sense of spaciousness and dimensionality to the playback that most loudspeakers and even our Vifa equipped models can't reproduce - all with regular CD's." Just wondering what you all think of it: http://www.av123.com/products_product.php?section=speakers&product=74.1 |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 942 Registered: Dec-03 | 1. Referencing a Fletcher-Munson curve may explain a great deal. Human hearing is much less sensitive at the high and low ends of the scale than in the middle. 2. Many tweeters tend to roll off before 20kHz. 3. There are still many unanswered questions surrounding human hearing and perception because we have no way of tracing the pathways in the brain to see what happens. 4. Bringing in an addtional tweeter at 11 or 15kHz is going to have some effect whether or not there is material being reproduced above 22kHz. 5. Supertweeters can expand the horizontal dispersion of high frequencies which provides a more "live" feeling. |
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Gold Member Username: PetergalbraithRimouski, Quebec Canada Post Number: 1571 Registered: Feb-04 | Just because you can not hear 45KHz does not mean your brain does not process it. The tiny bones in your ear still vibrate and that information is still transmitted to your brain A vibration sensed by the ear and the information is sent to the brain. That sounds like a good definition of hearing. Of course CD's have a shelf at 22KHz so it seems that this tweeter will be wasted unless playing SACD's or DVD-A's. Not true...the ERT is still going to add to the sense of spaciousness and dimensionality to the playback that most loudspeakers and even our Vifa equipped models can't reproduce - all with regular CD's. By reproducing information that isn't there? That statement just discredited the whole page for me. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8637 Registered: May-04 | PG - You're not reading the sentence correctly. The original statement speaks of "tiny bones in your ear". To my knowledge "hearing" is done by the ear drum only. The other structures of the ear serve other purposes. In this case it's quite possible the "tiny bones" go back to something more primitive in our evolution and perform a function that isn't exactly "hearing" but more perception. While PG might find discredit in the statement regarding perception of extended response and its benefits from Redbook CD's, I have no particular problems with the idea as a general concept. If the tweeter is capable of extended response without distortion, dispersion anomalies or peaks and dips, it would seem likely the tweeter will perform "better" at lower frequencies. It should not take a genius to look at some of the measurements taken on various tweeters to see the assorted problems and response deviations which are typical as the driver nears its operational limits. By pushing those limits beyond the normally accepted "hearing" range of humans, the information we can hear, and stubtly perceive, is cleaner and faster and more similar to the live experience. Or, at least that's the typical explanation for such extended frequency response. Similarly, an amplifier with a power bandwidth four times the "normal range" sounds better than an amplifier which is limited to only 20-20kHz. This assumes both amplifiers are of similar design and construction and the only differences exist in the bandwidth of the amplifiers. But this has generally been accepted as a truth ever since the engineers at HK did the research for their wide-bandwidth Citation designs back in the 1950's. This is true no matter where the frequency response of the source stops - within reason. Getting signal response to a full 20kHz was quite a feat when HK did the research. 12-13kHz response from a phono source was typical in those days. At the low frequency extremes, pushing the limits of response down beyond the region of human hearing doesn't mean we don't perceive information that might exist beneath 20Hz. Why should it surprise anyone that the same effects exist at the highest frequencies? Even with a signal source which is bandwidth limited to 20-20kHz the driver (and the room) will add resonances and sounds which we hopefully take to belong with the original signal. If we hear those as adding more "air" and "spaciousness" to the sound, the broader the frequency extension of the driver, the more likely we will be to hear what we consider better sound reproduction. Consider a driver crossed at close to its physical limits with too shallow a roll off. The general consensus is that approach will add a "coarseness" and an "edge" and a discontinuity to the speaker's sound. Now take that same idea and apply it to the highest frequencies any driver is asked to reproduce and I would think you can see the real world benefits of very broad response. |
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Gold Member Username: PetergalbraithRimouski, Quebec Canada Post Number: 1575 Registered: Feb-04 | JV, you make a good point in the first paragraph and I conceed the bit about hearing. But I think that better performance at sub-20KHz frequencies because of extended frequency response is tenuous if only because frequency response bandwidth doesn't equate to driver quality. Otherwise we'd all be using Bose full-range speakers. Note that the statement discredited that web page for me, and not supertweeters as a whole. Another web page selling supertweeters might be more convincing than that one. |
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Gold Member Username: NuckPost Number: 2860 Registered: Dec-04 | Assuming that the amplification is capable of those'inaudible' frequencies, sure, I'll buy it. |
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Gold Member Username: ChitownPost Number: 1063 Registered: Apr-05 | "Why bother with frequency response to 45KHz" Isn't that the range that makes your dog howl? |
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Gold Member Username: NuckPost Number: 2864 Registered: Dec-04 | I think I hear the old dogs now! |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8640 Registered: May-04 | "But I think that better performance at sub-20KHz frequencies because of extended frequency response is tenuous if only because frequency response bandwidth doesn't equate to driver quality." We're veering off topic here, but do you assume driver quality has nothing to do with clean reproduction of the extreme low frequencies. I would certainly disagree with that idea. Restructure your sentence a bit and it reads like this, " ... I think that better performance at sub-20KHz frequencies ... doesn't equate to driver quality." With the extraneous material removed; is that what you actually meant to say? If so, how do you justify such an idea? |
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Bronze Member Username: BvgArvada, CO Post Number: 19 Registered: May-06 | Regarding hearing, you need those bones and a few other structures. The ear drum itself only converts sound waves into mechanical vibrations, which are indeed transmitted to the cochlea via "tiny bones". The cochlea is the organ responsible for translating mechanical vibrations into nerve signals, which are then converted in the brain into what we experience as "hearing". Some of these same bit are also involved in our sense of balance. For the record, mind you... |
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Bronze Member Username: BvgArvada, CO Post Number: 20 Registered: May-06 | Regarding the value of 45kHz tweeters, I suppose there may be some value in overbuilding them to run that high, from a mechanical standpoint. I'm not convinced of much value in the SQ though. Keep in mind that most people older than 30 can't even hear much of anything above 17kHz. So much so that there is a new product on the market aimed at driving loitering teens - who can generally hear those higher frequencies - away from storefronts. The teens, of course, have turned the tables, and built ring tones that their teachers can't hear, so that they can text message in class without getting caught! This from a recent story on NPR... |
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Gold Member Username: Edster922Abubala, Ababala The Occupation Post Number: 4167 Registered: Mar-05 | LOL I love NPR, even if the Republicans are trying to drive it into the ground even as we speak. |
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Gold Member Username: PetergalbraithRimouski, Quebec Canada Post Number: 1579 Registered: Feb-04 | Restructure your sentence a bit and it reads like this, " ... I think that better performance at sub-20KHz frequencies ... doesn't equate to driver quality." With the extraneous material removed; is that what you actually meant to say? If so, how do you justify such an idea? Quite the opposite, like my Bose comparison suggests. Output at some specified frequency does not equate to good performance at some other more useful frequency. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8646 Registered: May-04 | PG - Using Bose as your reference for "snake oil" proves nothing that isn't already known to anyone on this forum. Surely, no Bose subwoofer can respond with any quality to sub-20Hz signals no matter what the marketing folks at Bose feel looks good as a spec. Using Bose as your reference implies you assume all companies making such claims are as guilty as Bose of over-hyping their product. And, it's inclusion serves little purpose to the discussion at hand. Let's focus on companies such as B&W which can actually meet their specs. We'll leave the BoSe to the unwashed masses who wouldn't know additional "air" should they be standing in front of a fan nor "spaciousness" when they are in West Texas. Since we cannot go through each company's product line to measure for accuracy of such claims, the question to be examined should be, "Does real world ultra-wide frequency response mean anything of benefit to the "audiophile" when made available in a truly high end product?" It would seem to be beneficial to an amplifier. And, therefore, when assessing the performance of either a gain stage or a mechanical device such as a tweeter, I can see where the ability to go beyond what we can "hear" would be of benefit to the end consumer. Therefore, (actual) output at some specified frequency (above or below the human range of "hearing") does equate to good performance at some other more useful frequency. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 944 Registered: Dec-03 | In dealing with "standard" tweeters, those rated +/-3db to 20kHz, I find the majority will suffer from a dip somewhere around 15kHz then take off again as they approach 20kHz thereby meeting the "criteria". It's only in the very expensive tweeters this doesn't occur, or, in the case of most "super" tweeters. When dealing with tweeters that retain their flat response beyond 20kHz their low end response tends to be around 2500Hz or higher. A decision needs to be made to either use a low frequency driver that will play well to 2500Hz, use a mid-range driver (3-way system) or add a "super" tweeter to pick up where the "standard" tweeter leaves off. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8648 Registered: May-04 | I again will make an assumption that says most responsible manufacturers wouldn't use a driver with such limitations in a typical two way design where the drivers are crossed at less than 3kHz. Taking the additional crossover components of a three way design out of the equation, what then do "super tweeters" offer in terms of performance gains or limitations? |
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Gold Member Username: ChitownPost Number: 1065 Registered: Apr-05 | Tim how about the electrostatic type speakers? Do they have limitations producing in that upper range? |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 945 Registered: Dec-03 | "I again will make an assumption that says most responsible manufacturers wouldn't use a driver with such limitations in a typical two way design where the drivers are crossed at less than 3kHz." Responsible? The limitation is cost, not ethics. The choice is generally made to just live with the anomoly in the upper ranges where the average listener doesn't notice or may even equate it with "good" sound. "Super" tweeters are great if you can live with crossing them over at 5kHz. This means that you'll have to use a small mid or have some polar dispersion problems in the upper mid-range. Proper use of a "super" tweeter will, in most cases, still result in a 3-way system of some type. For example: using a 6" mid-woofer results in fairly uniform dispersion to about 2500Hz. Bring in your nice tweeter at 2500Hz using a very steep crossover slope and you're in pretty good shape the rest of the way. What if your price point doesn't allow for that? Say that your mid-woof won't behave well at 2500Hz. You'll need to use a tweeter that will reach even lower but chances are it's going to fizzle out around 16kHz. Your end result is something that sounds pretty good except it's lacking "air". Add a "super" tweeter and Viola! Stof: Not sure what you're refering to when you say "electrostatic". If you mean something like a Heil AMT you'll not experience the same situation as a low cost dome tweeter. But then, the Heil is a very expensive unit. If you mean something like the planar-magnetic in Emma, for example, they tend to be better behaved than domes as far as frequency response and often need to be padded at the upper end to keep them from increasing in sensitivity as the frequency rises. It's a good "problem" to have. |
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Gold Member Username: ChitownPost Number: 1069 Registered: Apr-05 | I was thinking of the higher Martin Logans, but that Heil looks cool. Heil Oskar |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8651 Registered: May-04 | Again I may be off base, but I would guess most manufacturers who utilize a tweeter capable of response anywhere from one-half to one-and-a-half octaves above that typical 20kHz limit aren't going be placing such a driver into a loudspeaker system where cost has become the driving force (no pun intended). I don't know the B&W line any longer, but I assume the fancy diamond tweeter with 50kHz response doesn't come in a $600@pair speaker. It would seem we're still back at a point where a manufacturer who wants such response should be able to do a tweeter and a decent crossover and if the price changes by $200-500, so be it in a $5,000 package. The cost justifies the means and the advertising justifies both. Therefore, ruling out personal likes or dislikes regarding a multi-way speaker, or B&W in particular, I don't think we've really addressed whether a tweeter with response to 35-50kHz has any real world benefits to someone with a source which is bandwidth limited to an octave or so beneath that point. In one case, discounting whether we like the sound of an exotic metal or mineral based tweeter with extended frequency reponse, is the response itself worth the effort? Are there real world benefits? In another case, assuming such extended response is only the result of using such exotic materials, do the benefits outweigh the ofttimes hard sound of such drivers and the discontinuities that you can hear when they are crossed over to a slower, more massive, differently shaped mid frequency driver. I, for one, find anything past a soft dome almost always to be irritating and distracting over the long haul. Break up patterns or not, I'll generally prefer a Morel, Dynaudio or even KEF soft dome instead of a berylium such and such from any company I've heard. Ribbons and planar tweeters are the exception to that rule. But, they almost always introduce other issues to deal with. And, of course, at my age extended frequency response is a relative matter. I have to rely more on "perception" by those small bones than on "hearing" via the cochlea. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 946 Registered: Dec-03 | The Accuton 30mm Diamond tweeters go for about $2700 each when purchased in quantities of 20 or more and claim response to 100kHz with an Fs of 900Hz. I'm sure that price could be bettered if one were able to bypass the distributor. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8653 Registered: May-04 | That's helpful information, Tim, what with my birthday coming up. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 947 Registered: Dec-03 | Reminds me of a song by Camper Van Beethoven; "When I Win the Lottery" |
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Gold Member Username: John_aLondonU.K. Post Number: 4230 Registered: Dec-03 | Stof, Martin Logan quotes for its Vantage 34--23,000 Hz ± 3dB. I am inclined to think "snake oil". Well, the snake-oil vendor presumably knows what's really in the bottle. So let's say B&W and KEF supertweeters are well-intentioned, but the fact is we are all stone-deaf to sounds of frequency greater than 20 kHz, and we have to be very young and/or female to hear much beyond about 15 kHz. If there are benefits arising from reproduction of sound at frequencies above 20 kHz, they must be indirect, because the human ear just does not respond beyond that limit. Any textbook of physics or psychophysics of sound will say the same. I have a Denon test CD with a frequency sweep. I once got family members to raise their hands, and then lower them when they could no longer hear the test tone. I was first to put my hand down, at about 12 kHz. The teenagers and Mrs A could hear a bit beyond that, but even the 9 yr old put his hand down at about 16 kHz. That was with old plastic-dome-tweeter KEFs for which the -3 dB upper limit is quoted as 35 kHz. The CD drops out at 20 kHz, of course. Those speakers were made before CD was invented. Subjectively, I hear more detail, including extreme but obviously audible high frequencies, from my Quad ESL 63s than from those KEFs. Published frequency response specs for the Quad ESLs would probably elicit scorn from supertweeter fans. Australian HiFi says 30Hz--14kHz±3 dB for the newer ESL 988, and that is only if you ignore a bump at 100 Hz. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8656 Registered: May-04 | "If there are benefits arising from reproduction of sound at frequencies above 20 kHz, they must be indirect, because the human ear just does not respond beyond that limit." Gee, John, you did everything but answer the question being asked. Sorry to say, we are all fairly familiar with our hearing limitations. The question has become whether further extension has any benefits. In which case, it would be helpful if you laid out what "indirect" benefits you might surmise. And ... Super tweeters are often used by Quad owners due to the perceived lack of frequency extension coming from those panels. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 948 Registered: Dec-03 | "The question has become whether further extension has any benefits." I think what's needed is a comparison where the measured response of speaker A is 20 or 22kHz and speaker B is beyond that and at the same time keep all other parameters identical. I'm not aware of any such comparison ever being made. If anybody knows of one please share. Such a comparison wouldn't be done with CDs I suppose. |
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Gold Member Username: ChitownPost Number: 1071 Registered: Apr-05 | There is also a difference between a snakeoil salesman that claims music produced beyond 20 KHZ is actually a better experience even though it can't be heard then a manufacturer that says our product is capable of producing beyone 20 KHZ. The second, while arguably not useful, can have their claims be measured and in that I won't put them in the snakeoil salesman category. A Tag Heuer watch claims it can work in 3 atmospheric pressure. How useful that is to anybody is very debatable, but I suppose they are not lying. |
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Gold Member Username: John_aLondonU.K. Post Number: 4232 Registered: Dec-03 | That's right, Stof; that's what I meant. Jan; which question? I was responding to Stof's "...how about the electrostatic type speakers? Do they have limitations producing in that upper range?" The short answer to that is "Yes". Then the original question, in Post 1, from Edster, is ""Why bother with frequency response to 45KHz if humans can not hear frequencies higher than about 20KHz?". Edster suggests some "indirect effects". In vision, we don't seem to bother with frequencies of light we can't see. Invisible, ultraviolet, light will give you a sun tan. A "superdisplay" that gives the ultraviolet will therefore have "indirect effects". But I don't think it would enhance the viewing experience when watching a movie. If people want it, that's OK. Apologies if I misunderstood your original response, but, yes, if speaker manufacturers go to the trouble of making speakers that reproduce ultrasound, then they may also include other factors that will make the speakers good speakers. Ultrasound is not harmful. The question seems to me to be whether there is any benefit to sound quality in a response extending to 45 kHz, and whether reproducing it is, therefore, a sensible way of spending money. I understand that bees can see ultraviolet light, invisible to us, just as bats can hear ultrasound, inaudible to us. People have checked these things out. There are always new things to discover, admittedly. If bones in our ears vibrate, as Edster suggests, in response to 45 kHz, and we respond, it ought to be possible to demonstrate that. |
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Gold Member Username: NuckPost Number: 2868 Registered: Dec-04 | How should one respond to such ultra high frequency stimulation, though? Salivate above 30kHz?(my dog Pavlov) Curl like a cat around my legs at the sound of the canopener? As well, when I asked about piezo tweeter a while back, Tim questioned the ability to produce the frequency to the speaker. If we don't produce it, does anybody hear? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8660 Registered: May-04 | "The question seems to me to be whether there is any benefit to sound quality in a response extending to 45 kHz, and whether reproducing it is, therefore, a sensible way of spending money." Yes, exactly, that is the question. Except we have limited the discussion to companies which might actually achieve their stated goal. We have excluded those who only want us to believe what we read. Are there beenifts to such extended response? One of the arguments for analog is the infinite frequency repsonse of the medium as opposed to the intentionally bandwidth limited CD format. No one has, to my knowledge, measured infinite, or even much of anything beyond 24kHz, response from an LP source, but the argument persists. So, what sort of propoganda are audiophiles buying into? |
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Gold Member Username: Edster922Abubala, Ababala The Occupation Post Number: 4184 Registered: Mar-05 | > So, what sort of propaganda are audiophiles buying into? Good Lord, methinks one could start a whole separate thread on that theme and it would continue well into the next century! |
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Gold Member Username: John_aLondonU.K. Post Number: 4234 Registered: Dec-03 | In any design, one has to weight costs and benefits. The CD was made on the assumption that there was no benefit, only cost, in reproducing sound outside the range of human hearing. There are always things that can be measured but not experienced, at least not directly. People buy hifi systems because they sound good, not because they produce effects that can only be distinguished with test equipment. "Trust your ears" still seems a good, common-sense point of view. By the way, a correction; ultrasound can be harmful. It is used for loosening dirt and cleaning laboratory apparatus, also for smashing up very small things like cells. It is then used at much higher energies than those produced by natural sound sources. One dangerous feature of high energy ultrasound is precisely that people can't hear it - the damage to the ear can be done without the person being aware of it. |
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Bronze Member Username: HammondrckrPost Number: 19 Registered: May-05 | keep in mind, 20khz is only average human ear, there are people who can hear higher than 20khz and lower than 20hz, I knew that phisics class would come in handy |
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Gold Member Username: ChitownPost Number: 1073 Registered: Apr-05 | Well if you really wanted an experience I suppose you can extend the range enough to have it blow air in your face and hair like the old Maxell (or was it Memorex) commercials. I suppose there may be a benefit to some people who can hear an extended range, but I would argue in this day of Ipod and loud concerts, even a majority our youth can't hear beyond a certain range due to ear damage. |
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Gold Member Username: John_aLondonU.K. Post Number: 4236 Registered: Dec-03 | Thanks, alan. I thought 20 kHz was the best case, not the average. Google gave me this nice link. Must get some headphones and give it a try. The max frequency I could hear was 8 kHz but my computer speakers probably do not go to 12 kHz, the next step. I could hear 12 kHz OK on the speakers. But not 16 kHz. That could well be me. Low frequencies: 30 Hz, just about, on speakers; 45 Hz fine. Nothing below 125 Hz on the computer. Equal loudness contours and audiometry - Test your own hearing. Many thanks, Joe Wolfe, University of New South Wales. |
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Gold Member Username: Stu_pittIrvington, New York USA Post Number: 1379 Registered: May-05 | John A. - "By the way, a correction; ultrasound can be harmful..." The term "Ultrasound" simply means any soundwave above what humans can hear. Similar to infrared meaning electromagnetic energy that has a frequency below red light (the lowest people can see). Being an Athletic Trainer (similar to what's known as a physiotherapist in your neck of the woods), I have a lot of experience and knowledge of therapeutic ultrasound. It's a mechanical destructive waveform. The soundwaves cause things to vibrate at a cellular level. Depending on intensity and parameters (constant or pulsed), it has varying effects. It may be used to locally heat small areas, which has a number of physiological effects. It may also be used to break up scar tissue and bruising/blood clotting. The effects can be negative if used the wrong way. The N azis (I had to edit that word) did extensive medical tests proving that it can burn and sever nerves and arteries/veins. It can also make an eye exploed in the same manner a microwave oven will make a raw whole egg explode. Ultrasound in the US is fixed at a couple of points, mainly being either 1 megaHertz or 3 megaHertz. Surprisingly, the lower frequency has a much greater depth of penetration. Either of these frequencies will not effect the person using them, nor anyone else in the vicinity. They only effect the area which is being directly treated. Ultrasonic energy is very localized due to the wavelength being extremely small. Also, these frequencies cannot pass through air alone. They need a coupling medium (having a significant percentage of water) in order to be transmitted, hence the gel when someone is getting treated. As far as I know, "Ultrasound" below these levels have little to no significant physiological effects. In relation to our conversation, "Low frequency" sounds have a very low frequency, and therefore a very large wavelength. This is why we can feel very deep bass, and it seems to come from everywhere. "High frequency" sounds have a very high frequency, and therefore a very small wavelength. Unless reflected, we can pinpoint where high pitched sounds are coming from, because they are very localized. Sound coming from a speaker will never reach anywhere near that level. If fact, I don't think their's anything in everyday life that will reach that frequency. Sorry to go off on a tangent. |
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Gold Member Username: John_aLondonU.K. Post Number: 4237 Registered: Dec-03 | Stu, In my opinion, that is not at all off topic, and very interesting. Thanks! Yes, "ultrasound" means any sound of frequency higher than that which humans can hear. I imagine we are discussing whether 45 kHz qualifies for the term. I saw pre-natal ultrasound scans of some of our children. That's also off topic. But amazing technology. The resolution on the last one was amazing - shape of nose, length of hair. But I digress... I was thinking of devices like these Ultrasonic homogenizers which operate at 20 kHz and there are real safety issues, increased by the fact that the operator cannot hear them. MegaHertz ultrasound; well, don't tell the speaker manufacturers....! |
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Gold Member Username: Stu_pittIrvington, New York USA Post Number: 1380 Registered: May-05 | John - Thanks for the link. Very interesting. I haven't any experience with the equipment listed, but from what I gather from the literature, it works in the same fashion as Therapeutic Ultrasound. In regards to a 45Hz speaker, my knowledge of how soundwaves work lead me to believe you'd have to be pretty close to it for sustained amounts of time to have any damage. How close is too close? How long is too long? I have no idea. I'd imagine that few pople would listen close enough for long enough. Then again, I'd be very concerned if headphones or ear buds produced that frequency. Is their an Audiologist in the house? |
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Gold Member Username: NuckPost Number: 2882 Registered: Dec-04 | Brings to mind PB,s listening test, with ear to speaker, LOL! Where is he when we need proof! |
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Bronze Member Username: StefanomSilver Spring, MD United States Post Number: 64 Registered: Apr-06 | Keep in mind that the ultrasonic homogenizer focuses 150+ watts of ultrasonic energy into an extremely localized area over a period of time. On the other hand, the amount of sonic energy we receive in every day life is much, much, much, much, much less than this. IIRC, a 120dB sound intensity level is equivalent to one watt/meter^2. Now think what 150 watts over say, 1cm squared would be as far as intensity... I wouldn't worry too much about it in any event. |
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Gold Member Username: John_aLondonU.K. Post Number: 4240 Registered: Dec-03 | Stephen, Thanks. Yes. But my point is that people cannot hear even the collateral damage from 150 Watts at 20 kHz, apparently. Those things come with ear muffs which you are advised to wear even when they operate in a closed chamber. I would not worry about the sound pressure level coming from speakers at those frequencies. But can anyone hear them at all, that seems to me to be the question. |
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Gold Member Username: John_aLondonU.K. Post Number: 4241 Registered: Dec-03 | Let me repeat this link http://www.phys.unsw.edu.au/~jw/hearing.html Very nice. I can hear 60 Hz to 12 kHz on an iMac's built-in speakers. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8666 Registered: May-04 | "In regards to a 45Hz speaker ... " In regards to a 45kHz speaker, the question is not whether we can actually hear the frequency nor whether it can destroy cellular activity. The original question, and its amendment to disqualify Bose from the issue, deals with whether the high frequency response capability of the tweeter has any direct benefits to the listener at the lower frequencies we admit to hearing. |
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Gold Member Username: NuckPost Number: 2893 Registered: Dec-04 | Well then, no. I cannot imagine the capability of reproducing an inaudable frequency having any direct benefits upon frequencies up to about 20kHz. However, after hearing the B&W,last week(803,s) I doubt that the frequency claims are bogus, but how would I know if the qualities of the tweets are beneficial if I can only hear one third of the range? Sounded good to me with Bryston. Are the Bryston 7SSTs capable of 22+KHZ?. Dunno. If the source and amp are not capable, what the better? The diamond tweets are fabulous, BTW. |
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Bronze Member Username: StefanomSilver Spring, MD United States Post Number: 65 Registered: Apr-06 | Fun link their John. I guess my hearing isn't too bad as 16kHz comes in well for me. Just reminds me of one time when I was at my ex-wifes aunts house. She had these old RCA wireless speakers, and whenever they were on, they had a fairly loud, high pitched hum to them. Did she notice? Nope. Did she care when we pointed it out to her? Nope. |
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Gold Member Username: John_aLondonU.K. Post Number: 4246 Registered: Dec-03 | "whether the high frequency response capability of the tweeter has any direct benefits to the listener at the lower frequencies we admit to hearing". I am with Nuck, and cannot think how this would work. There is nothing below the fundamental frequency of a tone or note. If the fundamental is ultrasonic, I can't see how that sound can be heard at all. It could set up an audible resonance in something, I suppose. But that would make a sound you could record, and hear, just as well, directly. Jan, why "admit to hearing"....? Why not just "hear" or "or aware of"....? You know I like a good conspiracy theory as much as the next man, but..... |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8671 Registered: May-04 | "Admit to hearing" only reflects the variability in each person's ability. Gentlemen, if you read my previous comments, you'll see that hearing 45kHz isn't the real issue with extended response. We all understand that none of us are going to lower their hand at 55kHz. Please read my comment posted here, Monday, June 05, 2006 - 03:27 P.M. It surmises the ability to reproduce higher and lower frequencies than required enable the driver to better respond to those frequencies it is required to reproduce properly. This could be thought of as analogous to the benefits of a high powered automobile with plenty of torque at street speeds. While the driver might never cruise at 195 m.p.h., the additional performance which enables that speed will be beneficial should the need arise to use the power in an acccident avoidance situation. While the comparison to a car, where many factors can determine its usable performance, might not be perfect, I think the analogy still holds true in a broad sense when compared to a loudspeaker driver. If the performance at the very extremes is good, that should translate into better than average performance under average conditions. |
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Gold Member Username: ChitownPost Number: 1078 Registered: Apr-05 | Jan I see where you are going as reference to the topic, but then again in your analogy the top speed a car can achieve may or may not have anything to do with acceleration which can help you avoid accidents. i.e. cars with very large engine can go to very high speeds, but have tough time accelerating from say 40 - 70 MPH which may help you change lanes in an expressway to avoid accident. Smaller, lighter engines with tighter gear rations tuned for acceleration tend to do better in those circumstances. Now you mentioned torque. Higher torque capacity can help a big engine tow heavy loads when it has to whereas, as you mention, the top speed is not really that important since we can't drive that fast here. Is that a more useful analogy of the abilities of a speaker to go very high and very low to do better in between when it has to? |
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Gold Member Username: John_aLondonU.K. Post Number: 4248 Registered: Dec-03 | Point taken. Perhaps the word is "headroom". I see B&W specifies - 3 dB at 28 kHz for some of the 800 series. So, yes, maybe the much higher frequencies the tweeter will go to are just a result of trying to get the audible ones as good as possible - and well within the speaker's capabilities. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8672 Registered: May-04 | "While the comparison to a car, where many factors can determine its usable performance, might not be perfect ... " |
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Gold Member Username: NuckPost Number: 2897 Registered: Dec-04 | vroom |
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Gold Member Username: John_aLondonU.K. Post Number: 4250 Registered: Dec-03 | Somewhere there is surely an automotive forum where people agonise about problems such as the limited ground clearance of a Lambourgini. |
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Gold Member Username: PetergalbraithRimouski, Quebec Canada Post Number: 1588 Registered: Feb-04 | As Tim has already said, most super-tweeters are not optimized for lower frequencies. There seems to be a design issue here, and designing for 25KHz may imply a sacrifice at lower frequncies instead of a gain. A driver designed to reach 25KHz doesn't make a good subwoofer either. So a supertweeter designed for 25KHz might behave a bit better at 20 KHz than a tweeter designed up to 20KHz, but that might not even be relevant at 16KHz. |
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Gold Member Username: NuckPost Number: 2906 Registered: Dec-04 | The B&W tube loaded tweeter was designed for the flexibility in question, I think. As it was explained to me, loosely, the tube smooths out the midbass/low tweet transition over a 1Khz band(@3.5), then allows the various higher frequencies to be controlled naturally by the tube shape and volume, and using no tube effect above around 10Khz. The diamond tweeter is then able to extend to the very high ranges we are discussing. Of course, this is the 800 series and they ain't cheap. |
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Gold Member Username: John_aLondonU.K. Post Number: 4252 Registered: Dec-03 | Supertweeters and the effect of coherence by Jim Lesurf. |
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Gold Member Username: PetergalbraithRimouski, Quebec Canada Post Number: 1590 Registered: Feb-04 | If that turns out to be the reason that people like supertweeters, that would certainly debunk them... |
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Gold Member Username: NuckPost Number: 2970 Registered: Dec-04 | I think that the 'supertweeter' and the designed diamond tweeter from B&W are different beasts. A simple piezo for 6 bucks from Radio Shack has been around for a while. As well, the RS 'supertweeter' that we used in speakers as a kid. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 8680 Registered: May-04 | John - An interesting, if sometimes difficult to wade through, article. But, it doesn't really address the quality of the driver. Assuming a perfect speaker in both instances and assuming both drivers sum equally at all frequencies is, to begin with, a bit of a fantasy. Certainly at anything more than about 1 meter away from the drivers. However, rather than merely additional output obtained by adding an additional driver, what we appear to be more interested in would be the quality benefits of designing a driver capable of extended frequency response. I don't see any comments which address this matter in your linked article. |
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Gold Member Username: NuckPost Number: 2972 Registered: Dec-04 | Interesting to note. The 802D (the D denotes the diamond tweeter),is rated to 32Khz. The 702, 703 and 705 are arated to 50 Khz, without the diamond designation. I would like to defer to B&W's diamond specs as golden(being a fan), but how does the standard metal tweet achieve a higher response than the diamond? Off to the B&W site yet again. |