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#41
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Compensating for phase shift when bussing things out in digital?
On 06/09/2017 13:00, Scott Dorsey wrote:
James Price wrote: That said, comb filtering also applies to the reflection from the floor back into the mic(instant comb filtering), though I think it keeps stuff cleaner than multi mics. Yes, that's comb filtering caused by phase shift. The signal is delayed by the additional distance of the reflection. It takes about a millisecond for sound to travel a foot in free air. Move the mike five feet, you have a uniform phase shift of 5ms at all frequencies. A point of order. What you have is a uniform time delay of 5ms, which causes a different number of degrees of phase shift, depending on the frequency. The time delay will cause phase shift at all frequencies, but the angle of that shift will vary at different frequencies, so giving rise to comb filtering as some frequencies add and others subtract A phase shift of x degrees for multiple frequencies an be obtained at any frequency, but not by using a fixed delay in the signal path. Sloppy phrasing is what's causing a lot of the confusion in this thread. -- Tciao for Now! John. |
#42
Posted to rec.audio.pro
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Compensating for phase shift when bussing things out in digital?
On 9/5/2017 9:20 PM, James Price wrote:
You're assuming only harmonic overtones are present, which isn't the case, in my opinion. Your opinion? Oh. Overtones, by definition, are harmonically related. Of course you can mix a piano playing in C with a trumpet playing in B-flat and you'll have frequencies that aren't harmonically related. Then, you can have intermodulation distortion where two unrelated frequencies add or subtract to form another frequency that's not a harmonic of either frequency. -- For a good time, call http://mikeriversaudio.wordpress.com |
#43
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Compensating for phase shift when bussing things out in digital?
On Wednesday, September 6, 2017 at 7:00:39 AM UTC-5, Scott Dorsey wrote:
James Price wrote: That said, comb filtering also applies to the reflection from the floor back into the mic(instant comb filtering), though I think it keeps stuff cleaner than multi mics. Yes, that's comb filtering caused by phase shift. The signal is delayed by the additional distance of the reflection. It takes about a millisecond for sound to travel a foot in free air. Move the mike five feet, you have a uniform phase shift of 5ms at all frequencies. Same thing when you sum two microphones at different places in the room and leakage between them gets comb filtering. That is comb filtering caused by phase shift. I don't why you are getting so far afield talking about crazy unrelated stuff like beat notes. To paraphrase one of my earlier posts, delay a sound by .5 ms and 1K, 3K, 5K and 7K components will be 180 degrees out of phase and 2K, 4K, 6K and 8K components will be in phase. |
#44
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Compensating for phase shift when bussing things out in digital?
On Wednesday, September 6, 2017 at 8:03:26 AM UTC-5, Mike Rivers wrote:
On 9/5/2017 9:20 PM, James Price wrote: You're assuming only harmonic overtones are present, which isn't the case, in my opinion. Your opinion? Oh. Overtones, by definition, are harmonically related. Of course you can mix a piano playing in C with a trumpet playing in B-flat and you'll have frequencies that aren't harmonically related. Then, you can have intermodulation distortion where two unrelated frequencies add or subtract to form another frequency that's not a harmonic of either frequency. Incorrect. Harmonics are not just created the way we expect from pure sounds. Those are still created. I'm not going to go any further in this physics exercise but you're missing a step as to where and how partials are created and what makes them harmonic and inharmonic. Intermodulation distortion is nothing more than difference tones. |
#45
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Compensating for phase shift when bussing things out in digital?
James Price wrote:
On Wednesday, September 6, 2017 at 7:00:39 AM UTC-5, Scott Dorsey wrote: James Price wrote: That said, comb filtering also applies to the reflection from the floor back into the mic(instant comb filtering), though I think it keeps stuff cleaner than multi mics. Yes, that's comb filtering caused by phase shift. The signal is delayed by the additional distance of the reflection. It takes about a millisecond for sound to travel a foot in free air. Move the mike five feet, you have a uniform phase shift of 5ms at all frequencies. Same thing when you sum two microphones at different places in the room and leakage between them gets comb filtering. That is comb filtering caused by phase shift. I don't why you are getting so far afield talking about crazy unrelated stuff like beat notes. To paraphrase one of my earlier posts, delay a sound by .5 ms and 1K, 3K, 5K and 7K components will be 180 degrees out of phase and 2K, 4K, 6K and 8K components will be in phase. You can't be "in phase" or "out of phase." You can only be in phase _with_ something else, or out of phase _with_ something else. Yes, if you delay a sound by 0.5ms, then some components will be in phase with those of the original signal, and some will be out of phase with those of the original signal. This is why we get comb filtering when we mix that delayed signal with the original signal. But the phase relationship between the original components does not change. So if you had a 1K and 3K component that started out in phase with one another, they will remain in phase with one another after the delay. Phase shift is a relative thing, you have to specify what it's relative to. Still, this has absolutely nothing to do with beat notes or nonlinearity. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#46
Posted to rec.audio.pro
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Compensating for phase shift when bussing things out in digital?
James Price wrote:
On Wednesday, September 6, 2017 at 8:03:26 AM UTC-5, Mike Rivers wrote: On 9/5/2017 9:20 PM, James Price wrote: You're assuming only harmonic overtones are present, which isn't the ca= se, in my opinion. =20 Your opinion? Oh.=20 =20 Overtones, by definition, are harmonically related. Of course you can mix= a piano playing in C with a trumpet playing in B-flat and you'll have freq= uencies that aren't harmonically related. Then, you can have intermodulatio= n distortion where two unrelated frequencies add or subtract to form anothe= r frequency that's not a harmonic of either frequency.=20 Incorrect. Harmonics are not just created the way we expect from pure sounds. Those are still created. I'm not going to go any further in this physics exercise but you're missing a step as to where and how partials are created and what makes them harmonic and inharmonic. Inharmonic partials are not harmonics. That's why we call the inharmonic. Harmonics are integral multiples of the original signal caused by nonlinearity. Other partials are mixing products, not harmonics. Intermodulation distortion is nothing more than difference tones. Yes, and IMD products are not harmonics. You are seeming to want to use the word harmonics differently than physicists use it. In any event, none of this has the slightest connection with phase shift and group delay. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#47
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Compensating for phase shift when bussing things out in digital?
Incorrect. Harmonics are not just created the way we expect from pure sounds. Those are still created. I'm not going to go any further in this physics exercise..... well this is another semantics problem regarding the verb to "mix" in audio parlance, "mixing" is just adding and this is a linear process and no new frequencies, intermod or harmonics are created (ideally). in RF land "mixing" is multiplying and this is non-linear and new frequencies are creating including harmonics and sum and difference intermods. m |
#48
Posted to rec.audio.pro
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Compensating for phase shift when bussing things out in digital?
On Wednesday, 6 September 2017 11:43:40 UTC-4, James Price wrote:
Incorrect. Harmonics are not just created the way we expect from pure sounds. Those are still created. I'm not going to go any further in this physics exercise but you're missing a step as to where and how partials are created and what makes them harmonic and inharmonic. Harmonics are multiples of the fundamental frequency. Nothing else. Partials can be harmonic or inharmonic. It's OK if you want to call the harmonically related partials "harmonics," but the inharmonic ones are, er. . . , inharmonic and therefore are not harmonics. Intermodulation distortion is nothing more than difference tones. Music theorists don't use the term "intermodulation distortion" but often refer to "beats." Mix 440 Hz with 442 Hz and you get a 2 Hz component. When that 2 Hz component mixes with the 440 Hz and 442 Hz tones, that's when you get intermodulation distortion. |
#49
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Compensating for phase shift when bussing things out in digital?
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#50
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Compensating for phase shift when bussing things out in digital?
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#51
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Compensating for phase shift when bussing things out in digital?
"Mike Rivers" wrote in message
... On 9/5/2017 9:20 PM, James Price wrote: You're assuming only harmonic overtones are present, which isn't the case, in my opinion. Your opinion? Oh. Overtones, by definition, are harmonically related. Of course you can mix a piano playing in C with a trumpet playing in B-flat and you'll have frequencies that aren't harmonically related. Then, you can have intermodulation distortion where two unrelated frequencies add or subtract to form another frequency that's not a harmonic of either frequency. No, overtones are not necessarily harmonics, by definition. Overtones at frequencies that are integer multiples of the fundamental are harmonics. In the real world of musical instruments, overtone frequencies may be nearly exact integer multiples of the fundamental frequency; so close as to be, practically, harmonics. But in some instruments, the deviation from exact integer frequencies, or "inharmonicity" is significant, as any competent piano tuner knows. And in some cases, the overtones have no apparent relationship to the integer multiples, as in many percussion instruments. The overtones at integer multiples are harmonics, but many overtones are not harmonics. |
#52
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Compensating for phase shift when bussing things out in digital?
"Mike Rivers" wrote in message
... Incorrect. Harmonics are not just created the way we expect from pure sounds. Those are still created. I'm not going to go any further in this physics exercise but you're missing a step as to where and how partials are created and what makes them harmonic and inharmonic. Harmonics are multiples of the fundamental frequency. Nothing else. Partials can be harmonic or inharmonic. It's OK if you want to call the harmonically related partials "harmonics," but the inharmonic ones are, er. . . , inharmonic and therefore are not harmonics. But that wasn't your claim. You didn't say that all harmonics are harmonics, you claimed that all overtones are harmonics. Big difference. Not all overtones are harmonics, and he didnt say that inharmonic overtones were harmonics. Your statement above is correct, but it doesn't prove your previous, different, claim. |
#54
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Compensating for phase shift when bussing things out in digital?
wrote:
in RF "mixing" means multiplying or modulating in RF "combining" means adding which is what audio folks call mixing yeah its confusing Which is why the only safe way of describing what is going on is to show the sin(ft+theta)+.... math.... --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#55
Posted to rec.audio.pro
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Compensating for phase shift when bussing things out in digital?
On Wednesday, 6 September 2017 20:01:18 UTC-4, None wrote:
No, overtones are not necessarily harmonics, by definition. Overtones at frequencies that are integer multiples of the fundamental are harmonics. In the real world of musical instruments, overtone frequencies may be nearly exact integer multiples of the fundamental frequency; so close as to be, practically, harmonics. But in some instruments, the deviation from exact integer frequencies, or "inharmonicity" is significant, as any competent piano tuner knows. And in some cases, the overtones have no apparent relationship to the integer multiples, as in many percussion instruments. The overtones at integer multiples are harmonics, but many overtones are not harmonics. Quit being an asshole, will you? Musicicians deal in overtones. Scientists deal in harmonics. Musicial instruments are physical things, and they aren't perfect. That's why some overtones are slightly off being integer multiples of the fundamental. It's what makes musical instruments more interesting than sine wave generators. When it comes to percussion instruments, they make noise, and noise can be composed of many unrelated frequencies. If a musician chooses to call them overtones, so be it. |
#56
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Compensating for phase shift when bussing things out in digital?
"Mike Rivers" wrote in message
... Quit being an asshole, will you? Musicicians deal in overtones. Scientists deal in harmonics. Plenty of scientists deal with overtones which are not harmonics, especially in the science of acoustics, even in non-musical contexts. Plenty of musicians as well. The two words usually mean two different (but obviously related) things. Are you continuing to deny that, as you apparently did in a recent post? Gee, anyone who reads this group knows that I actually can be a real asshole when I feel like it, but in this case, I was simply disputing your claim: "Overtones, by definition, are harmonically related." That's an unnecessarily narrow definition. Most of the scientists and engineers that I've worked with over the last 45 years, in the fields of acoustics, audio, and music, have used a definition of "overtone" that includes overtones that are not harmonics, such as the definition in the first dictionary that comes to hand, Merriam-Webster. Yes, I've seen your definition as well (I think Tremaine uses it), but there is whole wide world outside that limited definition. |
#57
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Compensating for phase shift when bussing things out in digital?
On 9/6/2017 10:23 PM, None wrote:
your claim: "Overtones, by definition, are harmonically related." That's an unnecessarily narrow definition. It's good enough for me. I'm done arguing with you about this. If you want to argue about something significant and related to the subject at hand (see above "Subject"), then bring it on. -- For a good time, call http://mikeriversaudio.wordpress.com |
#58
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Compensating for phase shift when bussing things out in digital?
"Mike Rivers" wrote in message news
It's good enough for me. I'm done arguing with you about this. If you want to argue about something significant and related to the subject at hand (see above "Subject"), then bring it on. Quit being an asshole, will you? If someone's using their own personal definition, rather than the one that most everyone else uses (just to be an asshole, apparently), it's useful to point that out, as it's significant and related to the subject at hand. Sure, you can use your own definition, but when you try (and fail) to foist your narrow definition on everyone else with a self-important condescending edict, it's worth calling you out. |
#59
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Compensating for phase shift when bussing things out in digital?
On Wednesday, September 6, 2017 at 11:09:59 PM UTC-4, None wrote:
"Mike Rivers" wrote in message news It's good enough for me. I'm done arguing with you about this. If you want to argue about something significant and related to the subject at hand (see above "Subject"), then bring it on. Quit being an asshole, will you? If someone's using their own personal definition, rather than the one that most everyone else uses (just to be an asshole, apparently), it's useful to point that out, as it's significant and related to the subject at hand. Sure, you can use your own definition, but when you try (and fail) to foist your narrow definition on everyone else with a self-important condescending edict, it's worth calling you out. DAW = No! DAS = Yes! Jack |
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