It depends more on the directivity of the matched pair than how well they are matched.
Sorry, no. Don't believe it. Does not fit with my experience at all.
Pano - I agree with you, not my experience. With a toed-in set of CD speakers there is almost no image shift across a wide seating area in my room. It takes some special design and setup, but it is doable.
You'd think so, yes. But in many cases it does not seem to be so. I don't know why.
The center image on musical recordings is usually correct, tonally. Which is why I don't really want to brighten the mid, but darken the sides. Or maybe split the difference.
Hey Pooh. I did some testing on the movement of the phantom image last night and the night before. Down in the cave with my crude caveman speakers.
The image stays put, with just the slightest shift. Wherever a sound is located from left to right, it stays there as I move. Because of space limitations, it's difficult to move outside the range of the speakers, so basically the range is from directly in front of each speaker across to in front of the other.
There was one weird exception. Listening to the album Come Fly With Me, Frank's voice seemed to move opposite of my movement. If I moved left, Frank moved right. I moved right, Frank moved left. I have no idea why that would be, unless Sinatra's ghost was just pranking me.
The image stays put, with just the slightest shift. Wherever a sound is located from left to right, it stays there as I move. Because of space limitations, it's difficult to move outside the range of the speakers, so basically the range is from directly in front of each speaker across to in front of the other.
There was one weird exception. Listening to the album Come Fly With Me, Frank's voice seemed to move opposite of my movement. If I moved left, Frank moved right. I moved right, Frank moved left. I have no idea why that would be, unless Sinatra's ghost was just pranking me.
There was one weird exception. Listening to the album Come Fly With Me, Frank's voice seemed to move opposite of my movement. If I moved left, Frank moved right. I moved right, Frank moved left. I have no idea why that would be, unless Sinatra's ghost was just pranking me.
You were probably moving in and out of nulls at a dominant frequency. As far as why the phantom center image quality varies, I think it's largely dependent on how the performers were mic'd - the recording process. Actual stereo vs multi mono-mics, maybe with some isolation. How recordings are made seems all over the place. Rarely consistent in any way. Acoustic reflections in the recording environment can create additional phases of direct signals, which will add/subtract differently anywhere in 3-D space with the direct signal. Comb filtering is often part of the deal. Then different comb filtering is likely to happen at the playback end. It will change with frequency and location of the listener. Perhaps this is why many recording engineers prefer the multi mono-mic approach. It probably gives a more solid phantom center image.
Aloha Pano,
Speaking as a former recording/mixing engineer, there are many ways to create the stereo illusion: Processing Stereo Audio Files
and http://www.cim.mcgill.ca/~clark/nordmodularbook/nm_spatialization.html
Not only can this be done during the mixing stage, but also after the fact in mastering as well. Plus many more techniques not mentioned in those articles - unlimited in fact by one's imagination.
However, reading the SOS article closely, the clue as to why the tone changes from the center phantom image to a bit brighter when panned to one speaker appears to be from the ears high frequency response changes based on the angle (i.e. location) of where the sound is coming from...
Thoughts?
Btw, I do hear what you are hearing. I have not tried your shuffler as I am going for accuracy (of reproduction). So my setup is "by the specs", equilateral triangle and all that.
With respect to phantom center image. The more the speakers frequency response match between each other the more stable the center image. One of the many reasons I use DSP is to ensure that each speakers frequency response is matched to within 1 dB of each other (the smallest change I can hear) which yields a rock solid center image over the speakers operating frequency range.
Ideally, not only does one want to match each speakers frequency response to a tight tolerance, but over time as well. Uli's Acourate software uses a measure called Interaural Coherence Coefficient (IACC) which is a measure of channel and room reflection equality for the first 10, 20, 80 milliseconds of sound travel:
That's a measure of my system. Again, like minimizing early reflections, the more the two channels are alike, over time, the more one can extract/hear off the music recording without channel imbalances messing with the imaging. 65 to 75% overall IACC is typical of a HiFi system, with very few systems reaching over 90%. But perhaps that is a different topic of discussion.
Hope some of that is useful.
Cheers, Mitch
Speaking as a former recording/mixing engineer, there are many ways to create the stereo illusion: Processing Stereo Audio Files
and http://www.cim.mcgill.ca/~clark/nordmodularbook/nm_spatialization.html
Not only can this be done during the mixing stage, but also after the fact in mastering as well. Plus many more techniques not mentioned in those articles - unlimited in fact by one's imagination.
However, reading the SOS article closely, the clue as to why the tone changes from the center phantom image to a bit brighter when panned to one speaker appears to be from the ears high frequency response changes based on the angle (i.e. location) of where the sound is coming from...
Thoughts?
Btw, I do hear what you are hearing. I have not tried your shuffler as I am going for accuracy (of reproduction). So my setup is "by the specs", equilateral triangle and all that.
With respect to phantom center image. The more the speakers frequency response match between each other the more stable the center image. One of the many reasons I use DSP is to ensure that each speakers frequency response is matched to within 1 dB of each other (the smallest change I can hear) which yields a rock solid center image over the speakers operating frequency range.
Ideally, not only does one want to match each speakers frequency response to a tight tolerance, but over time as well. Uli's Acourate software uses a measure called Interaural Coherence Coefficient (IACC) which is a measure of channel and room reflection equality for the first 10, 20, 80 milliseconds of sound travel:
That's a measure of my system. Again, like minimizing early reflections, the more the two channels are alike, over time, the more one can extract/hear off the music recording without channel imbalances messing with the imaging. 65 to 75% overall IACC is typical of a HiFi system, with very few systems reaching over 90%. But perhaps that is a different topic of discussion.
Hope some of that is useful.
Cheers, Mitch
Mitch, please see my earlier post(s) with this theory, and graphs of hrtf explaining it.
Agree. Doesn't seem to be a "staple" technique of the recording craft.
Circle of confusion again.
My current SPS system "Stargate Point Source" has virtually no problem with tone changes when moving around the room. it's based on a Tannoy Dual Concentric front loaded in big (14 square foot mouth lol) horn down to 150 cycles. I have it toed in quite a bit where the axis crosses in front of me YET as I move either direction the center phantom and the entire soundscape moves with me. So if I sit on the end of the sofa to the left the illusion is virtually the same as (and tone) as if I am in the sweet spot - the differences is the soundscape moves with me a couple of feet. I wonder what speaker/room mechanism keeps it anchored in other systems?
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See
http://www.diyaudio.com/forums/mult...t-vs-accurate-hi-fidelity-15.html#post4482884
"Either this gets "fixed in the mix" or speakers designs should modify their responses away from flat to try and strike a balance between correct tonal balance for the center image vs that for panned full left or right by applying "HRTFEQ". Given so much of the image clusters in the center, I think best bet is provide about 2/3 equalization"
Unless of course you're lucky enough to have one of of Mitch's recordings
Mitch;
IACC usually means Inter-Aural Cross-Correlation, which is a well defined measure of the correlation of the two ear signals. One might be able to define an Inter-Aural Coherence Coefficient - a normalized version of the IACC, but it would be improper to use the acronym IACC as this has been used for decades in room acoustics to mean Cross-Correlation.
Earl, agreed. I come to it from using Griesinger's algorithms in Lexicon's digital reverb when I was still working in studios: DAVID GRIESINGER (LEXICON): Creating Reverb Algorithms For Surround Sound
However, Inter-Aural Coherence Coefficient is used in the acoustics industry if ones does a search.
Uli's definition: www.audiovero.de/acourate-wiki/doku.php?id=wiki:funktionen:td-functions:iacc_interaural_coherence - Translator
Uli does credit Blauert, Braasch, and Griesinger in the screenshot I posted.
Based on my experience, it is an objective measure I can use to determine the quality of a stereo image.
Fixing the link to Uli's IACC definition: https://translate.googleusercontent...erence&usg=ALkJrhhZ9cwwCPZbaxyBlTmT5VMhh6jyRg
That could be it, yes. I wonder how I could test that?
As you've seen DDF has proposed the same thing earlier in the thread. I seems logical, but I'm not sure it's the major cause. Comb filtering seems to be, and shuffling the phase above about 900Hz certainly removed the effect on my system. Perhaps it's a combination of the two.
Ditto here with my Troglodyte speakers. Not much tonal shift across the listening space. As to why the image does not shift on my system, when it clearly does on other - I just don't know. Perhaps room acoustics? I can't think the speakers themselves are anything special.
I dunno. Maybe because it sounds better? It is a real, documented effect that is not always fixed in the mix. And as you already know, I have no slavish devotion to someone else's ideas. I've been present at too many recording sessions to know that those involved agree about as often as guys on diyAudio do.
It's art, not science. If it can sound better a my house, why not?I hear sounds that move across the speakers change tonality and think "that's not right". I doubt the mix or mastering engineers really meant it to sound that way. If I can fix that, I will. If you don't hear it or it doesn't bother you - why even be concerned?
A parallel in the TV world is all the awful looking monitors I would see in editing suites and television control rooms - especially guys shooting sports. I made a good little side income calibrating those monitors. No way did I want my TV at home to look like the junk I saw in the field. I don't care if that's what they are mastering on - it's not right.