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Multi-Way Conventional loudspeakers with crossovers

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Old 24th March 2013, 07:25 PM   #8491
ra7 is offline ra7  United States
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Quote:
Originally Posted by myhrrhleine View Post
No they are not. It doesn't matter what the frequency is.
Time is the same for propagation. Regardless of the frequency.
Sound propagates as waves. A 100 Hz wave is much longer than a 10 kHz wave. To get information at 100 Hz will take longer.
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Old 24th March 2013, 07:53 PM   #8492
nuconz is offline nuconz  United States
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Originally Posted by ra7 View Post
Sound propagates as waves. A 100 Hz wave is much longer than a 10 kHz wave. To get information at 100 Hz will take longer.
ok, so the orchestra needs to play the sub-C (on piano) sooner than the middle-C in order for the orchestra to hear them 'time aligned'? wow, dude!
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Old 24th March 2013, 08:06 PM   #8493
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It's simple math, dude. You don't have to argue with me. Do it yourself and find out.

We are discussing reproduction of sound. The reproduction should ideally be linear to perfectly reproduce how it was played. Research has shown that phase does not matter outside the crossover region. Of course, this has been debated here and elsewhere and in theory it looks like it should matter. But experimental evidence points otherwise.
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Old 24th March 2013, 08:16 PM   #8494
nuconz is offline nuconz  United States
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Originally Posted by ra7 View Post
It's simple math, dude. You don't have to argue with me. Do it yourself and find out.

We are discussing reproduction of sound. The reproduction should ideally be linear to perfectly reproduce how it was played. Research has shown that phase does not matter outside the crossover region. Of course, this has been debated here and elsewhere and in theory it looks like it should matter. But experimental evidence points otherwise.
i'm not going to argue with you. above you said, "Sound propagates as waves. A 100 Hz wave is much longer than a 10 kHz wave. To get information at 100 Hz will take longer."

this statement doesn't have anything to do with phase and it's wrong.

if you play the lowest (sub-C) on the piano simultaneously with the middle-C, you will hear them at the same time (simultaneously)! if the drivers on a speaker are 'time aligned' the same holds true.

BTW the wavelength of a 10kc wave is 1.356" and the wavelength of the 100hz wave is 135.6". start time of waveform is the same; so is the end time, if sounded simultaneously for the same period of time (in some measurement). i'm done.

Last edited by nuconz; 24th March 2013 at 08:18 PM. Reason: needed to add time component
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Old 24th March 2013, 08:49 PM   #8495
ra7 is offline ra7  United States
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ok, so now you found that the wavelengths of a 100 Hz and 10 kHz wave are different. To recognize that it is a 100 Hz wave, you need at least one complete cycle. One complete cycle of a 100 Hz wave is 135 inches long or 11.3 feet. Speed of sound is 1126 ft/s. So, it takes 10 ms for that wave to pass through a plane (the plane of your ears, say). A 10 kHz wave takes 0.1 ms to pass through the same plane. If you start them both at the same time from the same point, the 10 kHz wave will have conveyed all its information much before the 100 Hz wave.

If you have ever done measurements, you will recognize this issue in gating. To get information down to 100 Hz, the gated time needs to be much longer. Indoors, long gate times lead to reflections creeping in. Therefore, you need to do a nearfield measurement when measuring low frequencies.
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Old 24th March 2013, 09:40 PM   #8496
nuconz is offline nuconz  United States
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Originally Posted by ra7 View Post
ok, so now you found that the wavelengths of a 100 Hz and 10 kHz wave are different. To recognize that it is a 100 Hz wave, you need at least one complete cycle. One complete cycle of a 100 Hz wave is 135 inches long or 11.3 feet. Speed of sound is 1126 ft/s. So, it takes 10 ms for that wave to pass through a plane (the plane of your ears, say). A 10 kHz wave takes 0.1 ms to pass through the same plane. If you start them both at the same time from the same point, the 10 kHz wave will have conveyed all its information much before the 100 Hz wave.

If you have ever done measurements, you will recognize this issue in gating. To get information down to 100 Hz, the gated time needs to be much longer. Indoors, long gate times lead to reflections creeping in. Therefore, you need to do a nearfield measurement when measuring low frequencies.
couldn't resist responding to this one!

i wonder what percentage of all music ever played suffered the indignity of having certain notes cut short so that only a fractional wavelength reached the listeners?

and since we are striving for perfection here at a sub-sanity granular level, shouldn't we ban all recordings made on wax cylinders? after all, only Caruso was (about) first recorded on these!
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Old 24th March 2013, 10:22 PM   #8497
ra7 is offline ra7  United States
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By the time notes are stopped, several cycles have already been launched. You know what frequency it is. If you stop it before even one cycle is completed, something that I bet never happens in music, it is nothing. It does not carry enough information to reveal what it is. At least, that is my understanding.

This is beside the point anyway. The point was about 1/4 inch making a difference in getting the horn to mesh with the woofer. My answer was that it would make a small difference in the phase overlap between the woofer and horn, and that might be perceptible due to the ripple in frequency response in the crossover region.
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Old 25th March 2013, 12:05 AM   #8498
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I think that there is some real misunderstanding going on here. You do not need to hear a completed wave for that to excite your ear. To say that you have to wait for the entire wave to pass is just not so. Your ears will pick up the rising pressure wave and the speed that it is passing long before the entire wave has to pass. Our ear brain feedback loop is better than that.

As has been stated all sound at a given temperature and pressure travels at a fixed speed. The length of the wave has nothing to do with the speed of sound in air. You do hear the different beat frequencies as a complex waveform and that is how we hear music, otherwise you could only listen to one frequency at a time which I think we all know is not realistic. So the same thing goes for time misalignment, it isn't slower for longer waves, the launch time is still the same if the phase of the signal is starting from the same 0 degree reference point. The real difference is in the decay time, a higher frequency wave will have a much shorter decay time than a longer wave. I think that it is an inverse square rule with distance but could be wrong on the math there.
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Old 25th March 2013, 01:59 AM   #8499
nuconz is offline nuconz  United States
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Originally Posted by Kindhornman View Post
I think that there is some real misunderstanding going on here. You do not need to hear a completed wave for that to excite your ear. To say that you have to wait for the entire wave to pass is just not so. Your ears will pick up the rising pressure wave and the speed that it is passing long before the entire wave has to pass. Our ear brain feedback loop is better than that.
i do apologize, but i was joking about the 'indignity' thing.

this is why i jumped to the 'music model' instead of the 'test tone' model that has been discussed - in order to bring about some reality.

while i don't have an O-scope, i can put some test tones through the old pipes with the audio generator, and verify the frequency with the counter.
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Old 25th March 2013, 02:04 AM   #8500
nuconz is offline nuconz  United States
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Originally Posted by ra7 View Post
The point was about 1/4 inch making a difference in getting the horn to mesh with the woofer. My answer was that it would make a small difference in the phase overlap between the woofer and horn, and that might be perceptible due to the ripple in frequency response in the crossover region.
this has not always been the point in this discussion - that is why i jumped in about speed of sound, etc. i don't think that anyone has disputed this point, except to correct phase alignment with time alignment.

there is a 'setup procedure' on the WWW somewhere on just how to do this with i believe an old A7 VOT system. if i can find it, i'll post here.
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