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Burn-in: Real Or Imagined??? - Page 18

post #511 of 665
Quote:
Originally Posted by Alimentall View Post

I'm trying to figure out if 'decorrelation' in this context means 'stereo bass' or if it means varying the signal to each woofer with the sole intention of smoothing in room response or if it means 'independent of the associated speakers' and then what each person's 'side' of this is without wading through the entire thread!

My position, in short, is that it may be possible to record and reproduce some audible spatial effect at low frequencies, though the end result has not been convincingly demonstrated in my opinion. In doing so however, we must not reduce the timbral quality or the seat to seat consistancy of the bass. That's it!
post #512 of 665
Could be, but the thing is, if those frequencies have harmonic elements above 100Hz that we can localize (and it wouldn't be 'music' if they didn't), then our brain will 'correlate' them and the bass will appear to come from wherever we localize the rest of the music. Therefore, it's not really worth pursuing since our brain will handle it no matter what. I had a conversation with Bill Bush about this once and while he believed in 'stereo bass' in principle, he admitted that the conditions required to show any kind of bass 'imaging' are pretty unlikely in any kind of music. And again, even if you put the bass of an upright string bass on the other side of the room, your brain will merge the events with the spatially dominant high frequencies.

IOW, dual mono bass is essentially undifferentiated from stereo bass, except that the dual mono insures that you get some bass mode reduction assistance which may not happen if the bass all came from a single sub at times. The big issue is when the subwoofer is not terribly good, the crossover is not sufficiently steep and you have harmonic distortions coming from the sub, allowing you to cue into its position.
post #513 of 665
Quote:
Originally Posted by cap'n View Post

Your measurement technique is NOT simple, and not relevent unless your point ist hat we can create decorrelated recordings using directional microhones. Measuring at the blocked ears of a human or dummy head is simple and as relevent as you can get.

The dummy recording is only relevant for that dummy (and one that sits very still and is missing some parts of its body). JJ's miking configuration attempts to capture parts of the soundfield that are perceptually interesting. It may not be simple, but it is relevant.

There is a big difference between the goals of these two recording configurations. In theory, if the perceptual miking config does its job, any human can use their entire auditory system to sample the recreated soundfield to extract the perceptual cues that are unique to them. If done well, the recreated soundfield can be large enough to serve human head movements as well.

Dummy head recordings capture sound that has already been processed by the dummy's particular set of anatomical features, and therefore cannot capture perceptual cues that were not anticipated by the dummy's designers.

The first method attempts to recreate enough relevant bits of the original soundfield so that a large number of humans can get useful information out of it, while the second captures it for one very specific head and body configuration.

Quote:
Originally Posted by Alimentall View Post

IOW, dual mono bass is essentially undifferentiated from stereo bass, except that the dual mono insures that you get some bass mode reduction assistance which may not happen if the bass all came from a single sub at times.

The effects of stereo bass are spaciousness, envelopment, and externalization, not imaging. When you listen to mono bass recordings (most any pop music recording), the bass sounds like it comes from inside your head, assuming you're using good subs that have low distortion.

edit: just to repeat an important point that's been mentioned several times already: it's very hard to hear stereo bass with commercial recordings because the vast majority of them have mono bass, and those few that do have non-mono bass (ie. decorrelated bass) haven't necessarily recorded it correctly. So think about that before buying a second sub!

--Andre
post #514 of 665
Quote:
Originally Posted by AndreYew View Post

The effects of stereo bass are spaciousness, envelopment, and externalization, not imaging. When you listen to mono bass recordings (most any pop music recording), the bass sounds like it comes from inside your head, assuming you're using good subs that have low distortion.

Hey Andre,

Is this something that has been studied and verified by anyone? I have very high quality, low distortion subs and haven't ever heard bass inside my head, whether using single or dual subs, mono or stereo.
Quote:

edit: just to repeat an important point that's been mentioned several times already: it's very hard to hear stereo bass with commercial recordings because the vast majority of them have mono bass, and those few that do have non-mono bass (ie. decorrelated bass) haven't necessarily recorded it correctly. So think about that before buying a second sub!

What is the difference between 'decorrelated bass' and 'stereo bass'? The decorrelated bass is just randomly generated rather than recorded in stereo?
post #515 of 665
"Is this something that has been studied and verified by anyone? I have very high quality, low distortion subs and haven't ever heard bass inside my head, whether using single or dual subs, mono or stereo."

Until you have heard the differences in externalization from the decorrelated stereo bass you might not recognize that the bass is much more 'in your head' then the rest of the soundstage.

Shawn
post #516 of 665
Quote:
Originally Posted by cap'n View Post

You can introduce a resonance electronically of course, and you can optimize the response at the seats - but: you CANNOT create room modes! Those are strictly a function of the room, not the sources, and certainly not the electronics.

An interesting argument. Perhaps we need to have it in a space where we can measure the results, just to avoid the "theoretical" accusation again.
post #517 of 665
Quote:
Originally Posted by cap'n View Post

My position, in short, is that it may be possible to record and reproduce some audible spatial effect at low frequencies, though the end result has not been convincingly demonstrated in my opinion. In doing so however, we must not reduce the timbral quality or the seat to seat consistancy of the bass. That's it!

And "seat to seat consistancy" in a real, good concert hall, amounts to what?

Do we want to be able to sound like we are in a real, good, large venue, or not?
post #518 of 665
Quote:
Originally Posted by AndreYew View Post

The dummy recording is only relevant for that dummy (and one that sits very still and is missing some parts of its body). JJ's miking configuration attempts to capture parts of the soundfield that are perceptually interesting. It may not be simple, but it is relevant.

--Andre

I think i stated it before, but, this dummy is a full torso, even has fingers :-)

Still, at low frequencies there isn't much individualization. The dummy is pretty represenative. The point I object to to is saying that a soundfield is uncorrelated when you measure using an array of hyper-directional mics. In that case it would be more correct to say that the combination of soundfield and recording technique produces decorrelated signals. If i use two omni mics, and wire one out of polarity, would anyone agree that the correlation of the "room" is -1 ?!? how do we define uncorrelated? The most unambiguous way would be to sample the soundfield at two points using NON-directional mics. To make it more meaningful, lets measure at two points around 6" apart to match the human ears. We can add a sphere or even human shaped head and torso without loss of generality, since we all possess those. BUT IMHO when you add hypercardioid and shotgun mics in a specialized array, your definition of decorrelated has become very specific indeed.
post #519 of 665
Quote:
Originally Posted by jj_0001 View Post

And "seat to seat consistancy" in a real, good concert hall, amounts to what?

Do we want to be able to sound like we are in a real, good, large venue, or not?

Reproduction is the key word here. In order to "reproduce" a hall we must control the acoustic environment of a listening room to the degree that we acurrately reproduce all of the anomolies of the hall and the particular peculiarities acoustically at a defined listening ocation or area within that hall.
post #520 of 665
Quote:
Originally Posted by Alimentall View Post

Is this something that has been studied and verified by anyone? I have very high quality, low distortion subs and haven't ever heard bass inside my head, whether using single or dual subs, mono or stereo.

Well, if there were incontrovertible evidence, we wouldn't be having this discussion.

Quote:
What is the difference between 'decorrelated bass' and 'stereo bass'? The decorrelated bass is just randomly generated rather than recorded in stereo?

Decorrelated is just a 25-cent way of saying bass that is not mono. The kind of decorrelation obviously will affect how this stuff is perceived.

--Andre
post #521 of 665
Quote:
Originally Posted by sfogg View Post

"Is this something that has been studied and verified by anyone? I have very high quality, low distortion subs and haven't ever heard bass inside my head, whether using single or dual subs, mono or stereo."

Until you have heard the differences in externalization from the decorrelated stereo bass you might not recognize that the bass is much more 'in your head' then the rest of the soundstage.

Well, it depends on how it's being 'decorrelated' wouldn't it? I mean, when I flip a speaker out of phase, it sounds like the sound is going in one ear and out the other, push pull fashion. This is why I'm confused about what is being called 'decorrelated bass'. If you mean pure stereo bass, that's one thing. If you mean processed bass, that could mean a lot of things, not always positive.
post #522 of 665
Quote:
Originally Posted by cap'n View Post

I think i stated it before, but, this dummy is a full torso, even has fingers :-)

Very useful for simulating Internet armchair experts like me! I was thinking more about the legs, so that we have some of the soundfield interaction JJ was talking about.

Quote:
To make it more meaningful, lets measure at two points around 6" apart to match the human ears. We can add a sphere or even human shaped head and torso without loss of generality, since we all possess those. BUT IMHO when you add hypercardioid and shotgun mics in a specialized array, your definition of decorrelated has become very specific indeed.

I think some of those things make sense at first glance, but a miking technique has to consider the playback system as well --- they should be complementary, so miking with a human-sized sphere may not necessarily be correct for a particular kind of playback system. If a playback system's speaker configuration requires a signal to be recorded on a sphere much bigger than a human head to get the soundfield info it needs, than that's what needs to be done. Which parts of a soundfield do we need to sample, so that the playback system can recreate the right conditions around a human head?

--Andre
post #523 of 665
So what is the setup that supposedly causes this 'in the head' bass? Are we back to the 'reversal'/bigfoot/loch ness monster days of 'only in a lab under these precise conditions'? I don't recall ever hearing bass inside my head. But i can tell if a single subwoofer is placed to one side of me rather than in front or behind me.
post #524 of 665
Quote:
Originally Posted by Alimentall View Post

But i can tell if a single subwoofer is placed to one side of me rather than in front or behind me.

I used to have my subs (in another home theater in another home) to my sides and I could "hear" them as well. I think I was feeling the air compression rather than actually hearing the sub. The driver was only about 6 feet from the listening position. But the FR was ruler flat in that position.
post #525 of 665
Quote:
Originally Posted by AndreYew View Post

Very useful for simulating Internet armchair experts like me! I was thinking more about the legs, so that we have some of the soundfield interaction JJ was talking about.



I think some of those things make sense at first glance, but a miking technique has to consider the playback system as well --- they should be complementary, so miking with a human-sized sphere may not necessarily be correct for a particular kind of playback system. If a playback system's speaker configuration requires a signal to be recorded on a sphere much bigger than a human head to get the soundfield info it needs, than that's what needs to be done. Which parts of a soundfield do we need to sample, so that the playback system can recreate the right conditions around a human head?

--Andre

I dont dissagree with that. And BTW, the dummy has legs. In our case we use it for measurements in a car so you can imagine that legs are needed.
post #526 of 665
Quote:
Originally Posted by audioguy View Post

I used to have my subs (in another home theater in another home) to my sides and I could "hear" them as well. I think I was feeling the air compression rather than actually hearing the sub. The driver was only about 6 feet from the listening position. But the FR was ruler flat in that position.

That's what I was wondering - if we are hearing it or feeling a pressure differential. I also think it is a feeling and was wondering if that is how the body got dragged into the discussion.
post #527 of 665
Quote:
Originally Posted by jaxter View Post

Reproduction is the key word here. In order to "reproduce" a hall we must control the acoustic environment of a listening room to the degree that we acurrately reproduce all of the anomolies of the hall and the particular peculiarities acoustically at a defined listening ocation or area within that hall.

Agreed. Now, can you do that with mono bass? No.
post #528 of 665
Quote:
Originally Posted by AndreYew View Post

I think some of those things make sense at first glance, but a miking technique has to consider the playback system as well --- they should be complementary, so miking with a human-sized sphere may not necessarily be correct for a particular kind of playback system.


Well, the mike technique that lead to the measurements in this thread is on a .9 millisecond radius, which is very near the ear-to-ear (around the head) distance.
post #529 of 665
Quote:
Originally Posted by Alimentall View Post

That's what I was wondering - if we are hearing it or feeling a pressure differential. I also think it is a feeling and was wondering if that is how the body got dragged into the discussion.

The body got dragged in because its size is in the right ballpark to interact with the lowest end of the frequency range that people believe stereo bass works in (40 Hz). It's not so much feeling it but that the body becomes an object large enough to convert soundfield velocity into soundfield pressure which is then sensed by the ears.

According to theory, the best place to hear that mono bass-in-head sound is with the speakers right in front of you. It can be hard to isolate this from other effects, because as you mentioned, sub filters have a finite slope, among other things.

--Andre
post #530 of 665
This is outstanding entertainment, this venue is generally prone to sensitive "feelings" being rubbed the wrong way, likely due to misalignment of perceptions. The concept of posting ideas is to create and sustain discussions. I have observed, digressions are the norm. We all have a place in these forums and need to be mindful, take the time to read and learn before replying with emotional clouded eyes. Take the classic example when jj_0001 claims insults were posted; I scratch my head and ask myself, how old is this contributor? Bring them some warm milk, fresh cookies, rub their belly and help them settle down :-)

With regards to digressions, I get the impression jj_0001 has good intentions but in my view, has not effectively provided tangible insightful neutral data to work from, simply a philosophical point of view. For example, I am still waiting for something to sink my teeth in, as an Audio Grasshopper, I have not generally speaking, acquired useful knowledge from philosophers such as jj_0001. Again, I do not doubt they have good intentions,simply left wanting for more helpful insight and I am feeling depleted at the moment.

After having worked in audio for many moons, doing my best to learn from colleagues and apply knowledge gained, I have yet to find an industry to densely populated by opinions and philosophy. When taken for what it is, audio is intuitive. I would add that their is always something new to learn and we need to be receptive to what others have gathered, take what's useful and grow.
post #531 of 665
Maybe AudioGrasshopper should learn more about the careers of the participants in this thread's little symposium, before making a second vacuous post to AVSForum.
post #532 of 665
Quote:
Originally Posted by krabapple View Post

Maybe AudioGrasshopper should learn more about the careers of the participants in this thread's little symposium, before making a second vacuous post to AVSForum.

I realize that you idolize jj, but isn't that going too far?
post #533 of 665
Count on more touchy/feely alternative science from the hordes on the left coast.
post #534 of 665
Quote:
Originally Posted by AndreYew View Post

According to theory, the best place to hear that mono bass-in-head sound is with the speakers right in front of you. It can be hard to isolate this from other effects, because as you mentioned, sub filters have a finite slope, among other things.


Single source bass or mono multi-source bass? And when you say right in front, do you mean perpendicular to your ear axis? Does the effect only happen when there are no high frequencies?
post #535 of 665
Quote:
Originally Posted by jj_0001 View Post

Agreed. Now, can you do that with mono bass? No.

Are we talking about electronically controlling the output of the subwoofers to better merge into the room or are we simply saying that there needs to be more musical differentiation in the low frequencies?
post #536 of 665
Quote:
Originally Posted by krabapple View Post

Maybe AudioGrasshopper should learn more about the careers of the participants in this thread's little symposium, before making a second vacuous post to AVSForum.

Yes, of course we should consider the history, body of work and careers of the individulas before we disrespect such great wisdom. They couldn't possibly be wrong- could they?
post #537 of 665
Quote:
Originally Posted by QueueCumber View Post

I realize that you idolize jj, but isn't that going too far?


JJ, Sean, Todd, Earl, Alimentall and Andre are signal in this recent discussion; you and AudioGrasshopper, from the evidence presented so far, are noise. Clear now?

Quote:
Originally Posted by jaxter View Post

Yes, of course we should consider the history, body of work and careers of the individulas before we disrespect such great wisdom.

Yes, of course we should...and of course, the logic and evidence behind their arguments. Grasshopper doesn't seem to have considered either.

Quote:


They couldn't possibly be wrong- could they?

Nice strawman.
post #538 of 665
Quote:
Originally Posted by jj_0001 View Post

Agreed. Now, can you do that with mono bass? No.

Actually there is no substantiated research that clearly indicates that you cannot achieve reasonably accurate reproduction with mono-bass sources that I am aware of.

Your rhetoric assumes that you must have stereo bass to maintain accurate representation subjectively in a listening room. In a concert hall the acoustic instruments are all individual mono sources. The spaciousness comes from the reflections of the room or the reverberation time. The source is still mono.

I also do not know of very many stereo recordings that actually utilize stereo bass in the final mix, including multi-channel recordings which usually sum the bass into a single channel. Stereo is simply a psychoacoustic way of achieving multiple sources of sound with only two speakers.

Admittedly this is a difficult area of acoustics to define clearly with the given research at this time. But I do believe that the possible benefits of stereo bass (if any are proven) would be overridden if any sacrifice was made to the timbre. Our sensitivity to tone (frequency response) is well researched and documented. The idea that we lose much detail in spaciousness from frequencies below say 100 Hz in small listening room belies the fundamental physics of acoustics and hthe crrent level of knowledge about human perception of sound.
post #539 of 665
Quote:
Originally Posted by jaxter View Post

Actually there is no substantiated research that clearly indicates that you cannot achieve reasonably accurate reproduction with mono-bass sources that I am aware of.

Just as I said to JJ, there's a WHOLE lotta qualification in that statement, enough so to make it useless.
post #540 of 665
Quote:
Originally Posted by krabapple View Post

JJ, Sean, Todd, Earl, Alimentall and Andrew are signal in this recent discussion; you and AudioGrasshopper, from the evidence presented so far, are noise. Clear now?

Don't forget to include yourself under noise. Unless of course you consider your juvenile idolatry meaningful to this discussion?
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