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#162
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Speakers Then and Now
On Fri, 09 Jan 2004 19:10:09 GMT, ow
(Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of total radiated power changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#163
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Speakers Then and Now
On Fri, 09 Jan 2004 19:10:09 GMT, ow
(Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of total radiated power changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#164
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Speakers Then and Now
On Fri, 09 Jan 2004 19:10:09 GMT, ow
(Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of total radiated power changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#165
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Speakers Then and Now
On Sat, 10 Jan 2004 08:44:25 +0000 (UTC),
(Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 19:10:09 GMT, ow (Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- So "total radiated power" is not foward power minus reflected power (neglecting any small resistive losses in the antenna)? This whole discussion has been about consevation of energy and coupling efficiency. If you do indeed get four times the power density over half a sphere surface compared to a whole sphere, conservation of energy says you have to double the (acoustic) power input. This can come from coupling efficiency changes or increased electrical input. If the transducer is 100% efficient it *must* come from increased electrical input but if it is only 1% efficient this is not a requirement. You all lose. |
#166
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Speakers Then and Now
On Sat, 10 Jan 2004 08:44:25 +0000 (UTC),
(Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 19:10:09 GMT, ow (Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- So "total radiated power" is not foward power minus reflected power (neglecting any small resistive losses in the antenna)? This whole discussion has been about consevation of energy and coupling efficiency. If you do indeed get four times the power density over half a sphere surface compared to a whole sphere, conservation of energy says you have to double the (acoustic) power input. This can come from coupling efficiency changes or increased electrical input. If the transducer is 100% efficient it *must* come from increased electrical input but if it is only 1% efficient this is not a requirement. You all lose. |
#167
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Speakers Then and Now
On Sat, 10 Jan 2004 08:44:25 +0000 (UTC),
(Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 19:10:09 GMT, ow (Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- So "total radiated power" is not foward power minus reflected power (neglecting any small resistive losses in the antenna)? This whole discussion has been about consevation of energy and coupling efficiency. If you do indeed get four times the power density over half a sphere surface compared to a whole sphere, conservation of energy says you have to double the (acoustic) power input. This can come from coupling efficiency changes or increased electrical input. If the transducer is 100% efficient it *must* come from increased electrical input but if it is only 1% efficient this is not a requirement. You all lose. |
#168
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Speakers Then and Now
On Sat, 10 Jan 2004 08:44:25 +0000 (UTC),
(Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 19:10:09 GMT, ow (Goofball_star_dot_etal) wrote: On Fri, 9 Jan 2004 18:12:59 +0000 (UTC), (Stewart Pinkerton) wrote: On Fri, 09 Jan 2004 16:20:14 GMT, henryf wrote: The point is: There exist examples of the power delivered by things depending on what the surroundings do with their output. (Contrast this with the original quote from Peter Larsen above.) No, there exist examples of local intensity levels varying with surroundings, there are *no* examples of changing. -- So if I pull the directors off a yagi I will see no increase in reflected power as measured by my directional coupler? Sure you will, but that's just a reflection (ahem!) of coupling efficiency, and note that you will indeed have altered the directivity of the array. -- So "total radiated power" is not foward power minus reflected power (neglecting any small resistive losses in the antenna)? This whole discussion has been about consevation of energy and coupling efficiency. If you do indeed get four times the power density over half a sphere surface compared to a whole sphere, conservation of energy says you have to double the (acoustic) power input. This can come from coupling efficiency changes or increased electrical input. If the transducer is 100% efficient it *must* come from increased electrical input but if it is only 1% efficient this is not a requirement. You all lose. |
#169
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Speakers Then and Now
On Tue, 06 Jan 2004 21:35:30 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: On Tue, 06 Jan 2004 13:18:10 +0100, Peter Larsen wrote: Metal is as poor as kevlar unless you are very good at making cross-overs. If you are very good at making cross-overs then something that is rigid in the pass band is attractive. The B&W Kevlar drivers are not rigid in the pass band, they are *designed* to move into bending mode. Yes, yes, yes, kevlar units (x) tend to have a nice smooth drastically rising response because of that well designed breakup, but eventually things do get to steep dips, the major issue is of course the rising response, they are possibly not heavy enough to remain linear when breaking up ... it would be great if somebody could explain this better. This is nonsense. *All* pistonic drivers have a 3dB/octave rising response due to directivity changes as the radiated wavelength approaches the diameter of the cone. This has *nothing* to do with movement into bending mode, which in fact corrects this rise by progressively reducing the radiating area with increasing frequency. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#170
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Speakers Then and Now
On Tue, 06 Jan 2004 21:35:30 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: On Tue, 06 Jan 2004 13:18:10 +0100, Peter Larsen wrote: Metal is as poor as kevlar unless you are very good at making cross-overs. If you are very good at making cross-overs then something that is rigid in the pass band is attractive. The B&W Kevlar drivers are not rigid in the pass band, they are *designed* to move into bending mode. Yes, yes, yes, kevlar units (x) tend to have a nice smooth drastically rising response because of that well designed breakup, but eventually things do get to steep dips, the major issue is of course the rising response, they are possibly not heavy enough to remain linear when breaking up ... it would be great if somebody could explain this better. This is nonsense. *All* pistonic drivers have a 3dB/octave rising response due to directivity changes as the radiated wavelength approaches the diameter of the cone. This has *nothing* to do with movement into bending mode, which in fact corrects this rise by progressively reducing the radiating area with increasing frequency. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#171
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Speakers Then and Now
On Tue, 06 Jan 2004 21:35:30 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: On Tue, 06 Jan 2004 13:18:10 +0100, Peter Larsen wrote: Metal is as poor as kevlar unless you are very good at making cross-overs. If you are very good at making cross-overs then something that is rigid in the pass band is attractive. The B&W Kevlar drivers are not rigid in the pass band, they are *designed* to move into bending mode. Yes, yes, yes, kevlar units (x) tend to have a nice smooth drastically rising response because of that well designed breakup, but eventually things do get to steep dips, the major issue is of course the rising response, they are possibly not heavy enough to remain linear when breaking up ... it would be great if somebody could explain this better. This is nonsense. *All* pistonic drivers have a 3dB/octave rising response due to directivity changes as the radiated wavelength approaches the diameter of the cone. This has *nothing* to do with movement into bending mode, which in fact corrects this rise by progressively reducing the radiating area with increasing frequency. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#172
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Speakers Then and Now
On Tue, 06 Jan 2004 21:35:30 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: On Tue, 06 Jan 2004 13:18:10 +0100, Peter Larsen wrote: Metal is as poor as kevlar unless you are very good at making cross-overs. If you are very good at making cross-overs then something that is rigid in the pass band is attractive. The B&W Kevlar drivers are not rigid in the pass band, they are *designed* to move into bending mode. Yes, yes, yes, kevlar units (x) tend to have a nice smooth drastically rising response because of that well designed breakup, but eventually things do get to steep dips, the major issue is of course the rising response, they are possibly not heavy enough to remain linear when breaking up ... it would be great if somebody could explain this better. This is nonsense. *All* pistonic drivers have a 3dB/octave rising response due to directivity changes as the radiated wavelength approaches the diameter of the cone. This has *nothing* to do with movement into bending mode, which in fact corrects this rise by progressively reducing the radiating area with increasing frequency. -- Stewart Pinkerton | Music is Art - Audio is Engineering |