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#1
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panning question
hello everyone,
let's say you have a mono-recorded snare track. then you put it dead center in a mix. now let's say you are listening to the whole track on a set of speakers, and you are not in the ideal apex-of-the-isocoles-triangle listening position. would this mean that the snare track is sort of out of phase with itself now? the two speakers are not hitting your ears at the same time, so their must be some selective frequency cancellation going at this point. i've just been pondering the idea that absolute phase-accuracy to the listener on a pair of speakers can be a fleeting proposition. |
#2
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On Thu, 23 Jun 2005 18:36:41 -0700, genericaudioperson wrote:
hello everyone, let's say you have a mono-recorded snare track. then you put it dead center in a mix. now let's say you are listening to the whole track on a set of speakers, and you are not in the ideal apex-of-the-isocoles-triangle listening position. would this mean that the snare track is sort of out of phase with itself now? the two speakers are not hitting your ears at the same time, so their must be some selective frequency cancellation going at this point. i've just been pondering the idea that absolute phase-accuracy to the listener on a pair of speakers can be a fleeting proposition. You worry too much. Relax, have a homebrew... |
#3
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wrote in message ... i've just been pondering the idea that absolute phase-accuracy to the listener on a pair of speakers can be a fleeting proposition. No doubt about it. Just think of those poor dogs listening to 5.1 surround while sitting in one corner of the room... no go have that beer. ;-) |
#4
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wrote:
hello everyone, let's say you have a mono-recorded snare track. then you put it dead center in a mix. now let's say you are listening to the whole track on a set of speakers, and you are not in the ideal apex-of-the-isocoles-triangle listening position. would this mean that the snare track is sort of out of phase with itself now? the two speakers are not hitting your ears at the same time, so their must be some selective frequency cancellation going at this point. Right, but it's different on your two different ears. And you can tell because the image shifts to the side. The effect is more pronounced at lower frequencies, because we use relative phase between channels to image only lower frequencies, while the ears mostly use amplitude effects at higher frequencies. i've just been pondering the idea that absolute phase-accuracy to the listener on a pair of speakers can be a fleeting proposition. It is. If you get out of the sweet spot, you don't get a complete stereo image. If you have wide-dispersion speakers, moving around within the sweet spot will still cause the image to shift. That's why control rooms are usually set up for monitoring in a narrow area. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
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thanks, Mr. Dorsey.
I didn't know about the differences in high/low pitch localization like you described. I knew bass was more omni-directional, but the stuff you described is definitely a new one for me. Is there a ballpark frequency range above where it becomes mostly amplitude? |
#6
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Every book I've ever seen gives a different number. According to a
href="http://whistlepig.cs.indiana.edu:31415/q700/node2.html"this/a paper at Indiana University, it's 1500 Hz. As memory serves from acoustics a few years back, that is more or less correct. Somebody correct me if I'm mistaken... More on localization for anyone who's interested: http://en.wikipedia.org/wiki/Sound_localization Mike |
#7
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wrote:
I didn't know about the differences in high/low pitch localization like you described. I knew bass was more omni-directional, but the stuff you described is definitely a new one for me. Bass _production_ and _reproduction_ is more omnidirectional, only because the wavelength is longer. You can make a bass horn that is just as directional as a PA horn at 1 KC, it just has to be a few hundred times larger. The bass directionality issue is only due to size of the sources and microphones. But imaging is a different matter altogether. Now, remember that most recordings today are just panpotted stereo and have only amplitude differences between channels, no phase differences. This isn't real stereo at all, and the low end imaging suffers very badly. Some systems out there, like Q-Sound have tried to add real phase differences between channels without stereo miking, but they tended to get overused and got a bad name. Is there a ballpark frequency range above where it becomes mostly amplitude? I think by 1 KHz or so, interchannel phase differences aren't much of an issue any more. At 1 KHz, your head is about half a wavelength wide and that's about the point at which the differences start to become useless. The actual point, of course, varies with your exact head size and shape. But down at 50 Hz, there is _no_ perceived amplitude difference at all because the distance between your ears is so much shorter than a wavelength. There is a nice discussion of some of this stuff on http://www-engr.sjsu.edu/~duda/Duda.Research.html somewhere, I think. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#8
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Unless your head is 10' wide, of course.
Dave |
#9
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#10
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For what it's worth, I've recently heard some pretty believable
phase-panning software demoed. One downside is that once you introduce that axis, the image size is much more noticable; distance "behind" the speakers is also affected by their separation, so closely-spaced speakers (eg a desktop pair) scale down the whole "soundstage" and you wind up with a band of deep-voiced rabbits or something about that size. Admittedly that should be no weirder than the fact that a TV image is smaller than life-size, but we're less used to hearing it and it may take a bit of getting used to. |
#11
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Joe Kesselman wrote:
For what it's worth, I've recently heard some pretty believable phase-panning software demoed. Even Q-Sound worked pretty well in the original demos. But when it came out, people figured out that they could do all kinds of radical things with it, placing sounds outside of the speakers and making exaggerated depth effects. So they did, and then they wound up with albums that had poor mono compatibility and couldn't be played on and radio. And one of them was Madonna, and that was pretty much the end of Q-Sound. One downside is that once you introduce that axis, the image size is much more noticable; distance "behind" the speakers is also affected by their separation, so closely-spaced speakers (eg a desktop pair) scale down the whole "soundstage" and you wind up with a band of deep-voiced rabbits or something about that size. Admittedly that should be no weirder than the fact that a TV image is smaller than life-size, but we're less used to hearing it and it may take a bit of getting used to. I dunno, this is exactly what I am used to hearing, but then I mostly listen to classical music. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#12
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#13
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thank you very much, Mr. Dorsey. that completely helped my
understanding. |
#14
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thanks for the wikipedia link. i wouldn't have thought to look there!
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#15
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"DaveDaveDave" wrote:
Unless your head is 10' wide, of course. I've actually worked with a few egos like that... -- "It CAN'T be too loud... some of the red lights aren't even on yet!" - Lorin David Schultz in the control room making even bad news sound good (Remove spamblock to reply) |
#16
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"Mike Rivers" wrote:
For what it's worth, a delay makes a pretty good panpot if you're careful. By sending the direct signal to one channel and a delayed version to the other channel at equal levels, you can move it from one side to the other without affecting the balance of the channels. ....which works until it's played back in mono, and then you have a phasey, comb-filtered poopy pile stuck to your aural shoe. On the drive home last night I noticed how easily the stock radio in my car collapses to mono. It kept fading back and forth between mono and stereo depending on which way the car was heading. -- "It CAN'T be too loud... some of the red lights aren't even on yet!" - Lorin David Schultz in the control room making even bad news sound good (Remove spamblock to reply) |
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