Imaging and SoundStage

fas42

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Excellent points, Art, it's good to see that there is not such a divergence in people's ideas and experiences as sometimes one is led to believe.

I'm particularly fascinated by your statements about early reflections and their importance: this is the first I've read about such and it makes complete sense to me. I have a feeling that this is the key ingredient in getting good, as in musical or "big" sound. If a system in its environment gets this wrong then all bets are off as far as being able to enjoy the sound. So one technique is to eliminate as much of the early reflections as possible: you then have a strongly imaging system at the expense of it sounding "real". To me, the alternative approach, of not interfering with these reflections is a harder road to take because perhaps then any harshness in the sound is more obvious, the system overall has to be in better shape for this to work.

So the people who are able to conjure up a huge image have got a system working closer to how natural, live sound works in the real world. And this is not so "unique": there is a small band of enthusiasts who pursue this avidly.

Am I correct in my thinking here?

Frank
 

terryj

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Jul 4, 2010
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I used to see the old timer audiophiles sketching out maps of their sound stage. Has anyone out there tracked image vs frequency, anyone out there ever sketched your sound stage. Anyone read about how to map sound stage? Where is an article or place in a book? I really want us to map our sound stages. It does take time and it’s fun. Just another way to get to know your system and talk about it.

You called??;)

Funnily enough art, this concept has been on my mind for a few months now.

cept I don't have that stereophile issue you mentioned.

Can I throw a spanner in the works and ask for your thoughts??

I have been asking myslef questions like this for a while. I am, however, approaching it from a slightly different tack. I don't see them as mutually exclusive either.

BTW, thanks for the hint to use the matt test, tho it is on my desktop it never occurred to me to use it.

So, where am I coming from? Well, as you mentioned, it has to do with the perceived image location (that also encompasses any and all other cues given us in the recording, at least those that convey the size, position, depth etc etc). But with the following twist.

You are attributing this imaging question to the room/speaker interface alone. Whilst I totally and completely agree and see how the image can be skewed by that, I (as is usual) have brought it back and wonder about it from a personal level.

I started from the following observation (and it HAS happened), I set up the image to be dead centre. Which we all agree is the right thing to do.

Then, along comes a friend and he says' Yeah, good, but WHY is the image six inches to the left??'. I think to myself, well that's interesting!!

Then harry comes along and says 'why is it ten inches to the right?'. Same set up, dead centre for me, off to the left for one and off to the right for the other. (ok, don't worry toooo much about the stated amounts, just illustrating a point)

In other words, the speakers are exactly the same, the speaker room interaction is exactly the same, yet to any given individual the results could vary.

Sorry for the long winded exposition.

So, I wonder to myself, WHY do *we* assume that even out own hearing has the same response in the left ear as it does in the right????

I mean, in the setup stages the image is five inches to the left (say), so I reduce the volume of the left speaker to swing the image to dead centre.

But WHY? A vol change is an even change of the volume across all frequencies.

(ignoring the room interaction which is the basis for this thread), my question has now become.."if I play the matt test, and notice the image shift left and right at different frequencies, could it be that my hearing is NOT exact left and right, and so any shift might have as a root that one ear is more or less sensitive at that frequency???"

Have I managed to make my point understandable???

I mean, I imagine many peoples left foot is physically different that the right, one eye may be less acute than the other, why have we assumed that our left and right ear tracks each other perfectly thruout the frequency range?

Anyway, as I said I don't see them as mutually exclusive, and the relative contribution of each (if my theorising has any merit at all) would vary from individual to individual.

THAT my room is well treated, I have begun to investigate this other idea, to find out for myself if it has any legs.

Would love any reactions to this idea.

Fully agree that often a 'big' soundstage equates with a mouth five feet wide.

You CAN have both, huge soundtsage with natural images within it.
 

MylesBAstor

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Apr 20, 2010
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OK, Musicality, from my perspective, is if a musical instrument sounds like the musical instrument. When I'm working on a room for an audiophile, they are very quick to point out that they are interested in musical accuracy, they want instruments and ensembles to sound great, real, somehow be lifelike. However, when someone is an image freak, they are mostly interested in the image of the sound, not the actual quality or accuracy of the sound.

I hope this simple effort clarifies my differentiation.

As for Floyd Toole, I knew him when he was working off govt grants in Canada as the Canadian govt was investing heavily into bolstering Canadian audio manufacturing. Yes, they even wanted a TubeTrap factory up there. But….we already had one in Kaslo BC. Those guys didn’t want to move. Floyd got bigger and bigger in stature when he left Canada for a stint in the US with Harmon/JBL. I ran into him one day, fairly early in his career...and what happened left me feeling pretty cold towards him. I wanted to bring him up to speed on advancements in TubeTrap room acoustics, as best I knew….when he told me that he already knew all he needed to know about TubeTraps, they were bass traps, and he didn’t want to spend anymore time on the subject. Well, there is a huge difference between a product and what you do with it. But, he was on his own roll and was busy with his own ideas…. Since then I kinda tuned him out. Sorry about the divergence, I’ll get his book, and see what he says. Back to my world…

Acoustically, a musical room is typically a relatively bright room. Not reverberant but full of early reflections. Early reflections are those that arrive at the listener’s ears within say 35ms following the direct signal. Early reflections fuse with the direct signal. They make the direct more clear, easier to understand. This is the Hass Effect which is related to the precedence effect. It is called sound fusion. Our ear-brain listening system remains open for the first 35ms following any particular sound, open to reflections of that sound. These early reflections increase perceived loudness of signals without turning the volume up. The early reflections are off axis versions of the direct signal and may not have the same frequency content. Accordingly, high musicality speakers tend to be full range omni or semi omni speakers.

We don’t allow late reflections in musical spaces, which mean strong reflections say 40ms and beyond. Pre echo reflections, between 40 and 60 ms cause smearing of the top end of the frequency range, the upper partials. And for later arriving reflections we have of course echoes. Distinct echoes or flutter echoes are verboten because they mess up tempo and the ability to actually focus on quickly changing music dynamics. we don't mind some reverberation, but really we want to hear the reverberation in the recording.

However nice early reflections may be for musicality, early reflections simply wreck imaging. High imaging systems are fairly reflection free. They do not have strong early reflections. What they might have is a healthy backflash of late reflections. Echoes are either absorbed or diffused, either way, echoes are not to be heard. And reverberation? The less the better.

Most rooms are some blend of these two extremes and it’s a dialed in personal preference. And it doesn’t stop with the room. Hi imaging speaker tend to be directional. High musicality speakers tend to be more omni. The speaker choice and the room acoustics combine to provide the right balance of musicality and imaging for each person.

Well, that’s my version of the opening salvo about how rooms and speakers interact differently depending on musicality and/or imaging listening preferences. And also, it shows how these two aspects of listening tend to be mutually exclusive. …..Art Noxon

Art:

Slight off topic.

There's another area that you didn't touch upon--that is the interaction of the room and speakers and the resultant musical dynamics. The reason I raise that point is that in my experience, it's dynamics that tend to messed up by many room Rx products.
 

Art Noxon

WBF Technical Expert (Room Acoustics)
Mar 29, 2011
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Take photos of speaker and post them. How the speaker is laid out and built determines how it illuminate the room. I think wavefront shaping by the baffle board and the box is a big deal.
If the back side is any way tricky, let's see it. Don't worry about the mess in the room, everybody's is a mess most of the time.
Now, I'm not suggesting anything particular about anyone in particular, and I admit, I have seen some neat rooms posted here...

Oh, I'm not an amp person. But I think we all know that nothing sound better than a real, moderately (ouch) expensive audiophile preamp and amp
when it comes to getting great sound; musicality, imaging and soundstage. But I can't support a discussion on how important the amp is, but suffice to say....it's a prerequsite. How they do it, I don't know. I just know they do it.

art
 

Art Noxon

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Mar 29, 2011
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You are such a tease. And you are oh so right to bring it up. It is such a big deal I can't even begin to talk about it here. This part of our visiting is confined somewhat to imaging, soundstage, acoustics and now I see we've squeezed in speaker dispersion patterns.

Please visit the original thread I got talked into doing, a while back. "art noxon discussion corner on room acoustics" Note the "corner" part....I thought that was real funny becaues tubetraps are always put in the corners, at least. anyway, it's 15 some pages so far, but the wildness has slowed down, I think we all got tired going in just one direction. anyway go here for starters: http://www.whatsbestforum.com/showt...g-Room-Intelligibility-Test&p=56209#post56209 I think it is a good address.
Read the excitement and try some of the experiments yourself and let's see what some new blood brings. thanks for asking/mentioning Art Noxon
 

fas42

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Jan 8, 2011
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Art, my way of getting a huge soundstage, which a lot of people here seem to have trouble accepting, is taking a lot of care with all the little details, where the "devil" is, in other words. Pictures of the speakers would be irrelevant, over the years I have had classic boring boxes on concrete stands to my current silly little curved computer boombox style things, which are rather awkwardly placed in the room. One thing I am fussy about is locking the speaker to the room's structure as firmly as I can; if pushing on the side of the speaker feels like pushing on the side of a money safe, to some degree, then I know I'm close.

Amps are terribly, terribly important. This not working right completely destroys the soundstage, for me at least, especially if the volume is turned up. The imaging and soundstage should not vary, to the limits of the amp's clipping capability.

Frank
 

Art Noxon

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Mar 29, 2011
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terryj and crew,

Good points and they remind me of something. In the good ole days (pre home theater) I went to lots of CES shows and helped lots of rooms get set up. Great fun, great people working together in high stress situations. “The show starts in 6 hours and the room still sounds bad…” that show starts at 9am, which calculates to it being 3am when this sentence was said. And still we usually pulled the room together by show time. I sometimes wondered if being weary was better for hearing sound or not. Being weary under pressure means you don't have time to fool around, daydream, wonder, postulate etc.... It means try it, hear it, decide, do over and over till it gets close enough, quit and take a nap. the focus is intense and fast. On the other hand, are we so tired that our senses dull and our wishful thinking overlays our perceptions and we just talk ourselves into hearing what we think we want to hear. It is hard to only have your perceptions and feelings to go on. Especially for an "engineer". Now we have the MATT test which is a great way to keep track of what is going on.

After the show starts, the place fills up with people and not and then there would be a few audiophile whe came through the crowded halls and sit down into good rooms where I was as well. These guys were real troopers. They were blind. My heart went out to them. And I watch them listen to their favorite record they hauled in. Of all of us, they were by definition the real listeners, and the rest of us were at best, fair weather listeners. What they did while they were listening was to move their head. I began to study other recognized golden ears while they were listening intently and they too sowly but with intent, moved their heads. It seemed that they were grooving conservatively grooving with the music. And so, then I tried it. After all, what do I know? Monkey see, monkey do.

I was used to staring in a zoned out way, just seeing the image of the sound along with the sound. It seemed very natural. I had a hard time closing my eyes. It seemed to put to much pressure on my eyes, in some way a distracting effort.

One time I got a gift, 2 ping pong balls that had each been squished and sanded on a flat board until it had an elliptical opening 1” high and 1.5” wide. And was shown how to make it. You pop each one into the eye socket where is just seems to easily stay with zero effort. You can keep your eyes open and see nothing but a grey fog. Perfect for audio listening. Too bad it looks bug eyes. But if anyone in the room had them on, who cares….Anyway, the ping pong balls work great.

Back to bobbing and weaving. When I tried it I found I was assimilating the whole situation, not must some telescopic version of the situation. By moving back and forth, rotating my head, just slightly, I wasn’t seeing how every different microscopic position changed what I was hearing. I was spatially averaging the situation, and the spatial average was very unchanging.

Well, it's been a long trip from loading in and tuning TubeTraps in 30 bad motel demo rooms in 2 days and one long night to pingpong ball audiophile listening balls to the head moving spatial averaging style of listening. And it brings us to a new stage in our explorations. We all listen, otherwise we wouldn’t be hanging out here. So, how do we listen? Everybody will be different. We can try each other’s styles on too. I told my story, and now it’s your turns. I'm all ears..........


While I'm waiting, lets go on. Just what does happen when we manage to move our head and pan an image a few inches? Also, what do recording engineers do do pan an image a few inches? And then, do these two versions of panning an image have anything to do with each other? There are two image pan systems that work on our ear-brain. We have amplitude panning and phase panning. Phase panning is another way to say time delay panning. Both are inside the image part of the Haas effect.

Time delay panning is how the image shifts towards the speaker that delivers an earlier signal. Its range is 0 to maybe 2 ms. The other is amplitude panning where the image shifts towards the louder speaker. The dB range is maybe 0 to 20 dB sound level difference, one ear compared to the other. And naturally you could delay pan to the right 6” and amplitude pan it th the left back 6” and have a spot on center image.

Now you know why when you are setup on the sweet spot and then move to the right, you get a louder right signal and an earlier arriving right signal. The image is double panned to the right. No wonder the image position falls off center so easily.

Now remember, we are talking if a fairly “reflection free zone, a place where side wall reflections and other early reflections are not very strong, or downright non-existing. If we have lots of early reflections, we just get a huge non focused image hanging between the speakers and no matter where we sit in the room, the image just sits there hanging between the speakers. Heck, you can go to the next room and there behind the wall you sell see the imaging hanging between the speakers. At least that happened to me, and it was at a manufacturer’s home/party in LA but we weren’t loaded. It was the fantastic, full-range omni Walcott, something that looked like a moon-lander.

I guess I can track the hypothetical, different strokes for different folks. I know that the size of the sweet spot means something. What of the speaker setup is so awful that the sweetspot is the size of a grapefruit while your head is the size of a cantaloupe? I’d guess it would be pretty hard for anyone to agree what was where. This leads us to a test. Just how stable is your center image? or how big is your sweetspot?

That’s right. Dial your center image in and then sway to the left and then to the right. How big of a sway can you do and still have a center image. If it moves as soon as your head moves, the sweetspot is too small, or your head is too big. I’d say good sweetspots seem to be about 18” wide, maybe 2’ tall and 3 to 4’ long, and in a banana shape. Flat down front and tapered up towards the back.

If you are desperate to share a single sonic event, all at once, you put one guy (guy includes gals) slumped down in the first chair, the second sitting behind on a stool and hunched over while the third stands behind. Adjust heights so each head has a clean view of the speakers. We called this listening position "bobsled listening". Haven’t the slightest idea what it’s called today, or if it is even done. Maybe it gets easier after 2 beers and people loosen up, especially in a show room filled with stranger. Really, all 3 can witness the same thing at one time.


Back to the different center position theme. I will look that up in a Psychoacoustics manual. I’m just sure plenty of people have been tested for this effect. Let’s see what statistical double blind testing has to say…if anything.... Zwicker/Faustl (reference manual on psychoacoustics) says that the just audible side to side position shift corresponds to a shift in inter ear sound level by 1 to 2 dB.

But what is the point of minimizing sonic image alignment because somebody might hear something different than we do? It could mean your sweet spot is too small. Even if it is huge, and the difference is still perceived, then where does it lead us? At least it means don’t be surprised if you don’t agree within a few inches about where an image is located.

Echolocation is a natural 2 ear process of knowing where a sound comes from. If you hear a Psst coming from 2:30 in the horizontal, your eyes and neck muscules automatically rotate towards that sound. I’m sure that one person would say it’s at 2:33 and someone else would say it’s at 2:24 and so on. I can look that up too. Humans have a statistical range of reaction. We aren’t clones. Ok, have I hammered on that enough?

I guess not.....Our ear-brain is constantly recalibrating itself. If we hear a certain frequency range go Tssssst off at some angle and we autonomically react and turn towards it. We think it came from point A but see that it came from point B. We retrain ourselves to hear that particular sound as coming from point B, not A.

I’m not so concerned that someone else can hear exactly what I hear. I’m first interested in that I can hear what I think I’m supposed to hear. If I do a frequency sweep and the image sits in one spot, nice and bright and tight for part most of the low end of the sweep, and then at some midrange frequency the image flies off 3’ to the right, then rises up another 4’ and then turns into a dim, huge fuzz ball throughout the high frequency part of the sweep, I get mad. I’m not worried about what someone else thinks, I’m worried about what I think.

When that happens I, and I speak from experience, I just look around, trying to find the bad boy, the trouble maker in the room. Sometimes, heck, usually, it’s a dumb lamp shade. If I can’t find it I get a long stick and tie a lightweight feather pillow or acoustical foam to the end and like a giant Q tip, waive it around, listening to the distorted image. Sooner or later I will block the goofy signal path and the image snaps back together. I start fairly close to the speaker so I minimize the risk I’ll be blocking the errant signal path on its way off the wall or something towards me. I want to know what direction the problem is from which speaker. That way it’s easier to sight in on. And it’s usually quite a joke when you find out what was messing with your listening mind.

Here’s something else. When I work for the audiophile, and demo a defect to them, they always smile and pull out some album, knowing which track and seconds into it they are looking for and they demo the same distorted musical passage back to me, but this time it's inside a musical setting, but it does the same thing. I love it when the artist and the engineer agree in an instant on something, each in their own way, each using their own set of tools and their own way of explaining it. Clarifying mysteries is much more rewarding than demonstrating mysteries that no one ever knew about. If you didn’t know about it, and weren’t mad about it, you probably don’t need it fixed.

=======================

And as for the “huge mouth” phenomena, I have a story to tell. I was saving it, but now that you brought it up……..No, not now.... Soon, but not tonight….Art Noxon
 

microstrip

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Art,
Off-topic, but I think that it can be of interest for other people. Can we hide ASC tube traps and other acoustic panels placed against the speaker wall behind a loose drapery placed one feet away from them? What types of cloth can be used for this purpose?
 

Art Noxon

WBF Technical Expert (Room Acoustics)
Mar 29, 2011
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Art:

Slight off topic.

There's another area that you didn't touch upon--that is the interaction of the room and speakers and the resultant musical dynamics. The reason I raise that point is that in my experience, it's dynamics that tend to messed up by many room Rx products.

Just noticed "off topic" and I was curious what was off topic. I know I diverge once in a while maybe all too often, and I could stop with the side bars, but I aked about that some time ago and the crew said, keep telling the mini stories so I do.

The off topic could be because this thread is dedicated to "imaging and soundstage". And we are deep into the different topic of musicality. I'm afraid I started this off topic by noting that the audiophile community, or at least my perception of it, seems divided into two camps; music nuts and image freaks. I know I'm being a little dramatic or taking things to extremes but I'm just trying to make a point, clearly enough that everyone gets it. The point is that it seems that imaging and musicality seem to not necessairly be mutially inclusive. Brighter, more reflective rooms tend to be the more musical and a less imaging version of room setup, while conversly; darker, less reflective rooms tend to be more about imaging and less about musicality. Although making generalities is dangerous, that's the general trend I see.

However, when you keep going with the room setup everything starts to come back together. The "ultimate audiophole listening room" pioneered bynJ Peter Moncrieth in his IAR reviews of TubeTraps, breaking the ice with the first one and a year later putting the icing on the cake in the second one. He created a whole room setup with tubeTraps, with every stack of tubes and every reflector in assigned poition within 1/4". A few years later, a group of high end audio manufacturers realized they all had set up the same room. It was pretty much the Moncrieth room except using even newer Traps. It was coined the 2C3D room and ran with ASC, Spectral, MIT and Avalon. Dozens of this room have been buildt I can tell you, they are very musical and very good at imaging and a holographic sound stage. It's a once in a lifetime experience to sit and listen in one of these full on rooms.

So you are right I hope to have patched things back together......Art
 

Ron Party

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Art, great posts. Thanks for taking the time to put forth all of your thoughts, knowledge and experience.
 

Art Noxon

WBF Technical Expert (Room Acoustics)
Mar 29, 2011
38
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Eugene, OR
www.acousticsciences.com
Art,
Off-topic, but I think that it can be of interest for other people. Can we hide ASC tube traps and other acoustic panels placed against the speaker wall behind a loose drapery placed one feet away from them? What types of cloth can be used for this purpose?

Guilford "701" is the old designation. It's called Regatta and Vertical Surfaces now. Another Guilford fabric is even more breathable and lighter weight, called Cirrus. Choose light color so you can't see through so easily. If you want mail me a piece of what you are thinking about, I'll check it out. I also like open mesh screens like Awntex.

What ever it is, you want to be able to put it tight against your lips and breath in and out right through the fabric without much annoying effort. .......Art Noxon
 

terryj

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Jul 4, 2010
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Thanks very much Art.

AND, as it is often ME with the reputation for long boring posts, it's good to see a long post from someone else and NOT boring!;)

You want stories? I got STORIES haha.

terryj and crew,
I began to study other recognized golden ears while they were listening intently and they too sowly but with intent, moved their heads. It seemed that they were grooving conservatively grooving with the music. And so, then I tried it. After all, what do I know? Monkey see, monkey do.

(not ignoring the blind fellas, just making the quotes a manageable size).

Whaddya know, I too have wondered whether or not gentle movements of the head helps us as a species to locate objects! TBH I don't expressly recall trying to knowingly move my head to test the theory...I think I talked myself into believing that it might not apply to an artificial construct like stereo. Hmm, maybe I should have followed my instincts?

You seemed to be asking a survey type question? Well, I always listen with my eyes close. Well, when listening if you follow. And yes!, for whatever reason at times it seems that the eyes just don't want to shut comfortably. That is an odd one, so I can fully understand the use of a blind fold or ping pong balls.

Haha, sometimes I have a different but related phenomenon..after a few beers it is dangerous to close the eyes cause the room starts to spin!!;) Now that I hardly drink anymore (we all gotta grow up and mature some day eh?) that effect comes more easily, and after way less beers. It's a problem I tells ya.

So at night, by far the best compromise for me is a darkened room at least. If you want to close your eyes you are not trying to shut out light as in daytime say.

Just for completeness, here is what I took to be a 'survey'
So, how do we listen? Everybody will be different. We can try each other’s styles on too. I told my story, and now it’s your turns. I'm all ears..........


While I'm waiting, lets go on. Just what does happen when we manage to move our head and pan an image a few inches? Also, what do recording engineers do do pan an image a few inches? And then, do these two versions of panning an image have anything to do with each other? There are two image pan systems that work on our ear-brain. We have amplitude panning and phase panning. Phase panning is another way to say time delay panning. Both are inside the image part of the Haas effect.

Interesting...I have been led to believe that time (or phase) panning is not normally done??? It seems to be jneutrons area of interest. Of course, I could have completely misunderstood the argument!

Time delay panning is how the image shifts towards the speaker that delivers an earlier signal. Its range is 0 to maybe 2 ms. The other is amplitude panning where the image shifts towards the louder speaker. The dB range is maybe 0 to 20 dB sound level difference, one ear compared to the other. And naturally you could delay pan to the right 6” and amplitude pan it th the left back 6” and have a spot on center image.

Yes, hence it is an essential part of the speaker setup process. Not only equal amplitude from each speaker, but the impulse arriving at the same time left and right. Either will skew the image as you have just stated.

Now you know why when you are setup on the sweet spot and then move to the right, you get a louder right signal and an earlier arriving right signal. The image is double panned to the right. No wonder the image position falls off center so easily.

Ok, you wanted a story? Well, yours don't make you look like an idiot where mine does, but it is still a story right?

BTW, this will prob address a few later points of yours, so I won't specifically go and quote them ok?

Man, this is so embaressing, but boy I am STILL getting hearty belly chuckles at my stupidity!

I have been chasing this image phenomenon for not some little time now, so much so that unfortunately I have been obsessed with it and any and all flaws I think I see. (chasing down a bug in the system..oh it is active four way DIY, so plenty of room for ME to make silly mistakes, so all of this hardly applies to anyone else I suspect).

I have recently rebuilt the baffle, hence a re-wire of all the amps blah blah. It sounded TERRIBLE, for the life of me I could not work out why that should be. After a month or so I suddenly got this heretical thought...'maybe it is (a particular) amp?'

Sure enough, the amp was faulty. Horrible horrible distortion, and strangely enough that distortion somehow went thru the entire system and was also distorting the tweeters. Replaced it, all was good again (for that stage of the setup process)

WHY is that an interesting story?? Because I am NOT an amp guy, personally if the amp works, does not clip etc in use, then I am happy.

So, the reason it took me so long was my own preconceived 'absolutes and certainties' in audio. We are at times our own worst enemy eh? It just reinforced my already held thoughts on life..."always check your own assumptions". That is where you get whomped, every time. Your OWN assumptions.



Well sorry, that was NOT the story I started to tell! I just get on forums and like to gab. Apologies. Here is the story that addresses your later points.

So I have rebuilt the speakers, fixed the amp issue, now on to the later refinements. The imaging is driving me INSANE. It shifts at different times, sometimes to the left, other times to the right. Arrggh

Aware of my own theory, I start double guessing myself, 'maybe at night I am tired and the right ear relaxes' tada yada...all an attempt to understand this happening.

It is off to one side, so I play a test track..little girl with guitar on centre stage type thing...image dead centre!

Ok, pink noise thru the system...image dead centre. (if I'd played the MATT test..apart from your latest point it would have been ..image dead centre.

Go back to music...image off to one side!

Ok, I'm prob getting boring so move to the end of the story...somehow I had hooked up the left ten to the right speaker, and the right ten to the left speaker.

No WONDER every test track I payed to test the centre image position showed the image at dead centre!! The speakers were playing the exact same signal!!

AND, I had tried to shift the image during listening to centre by adjusting the relative volumes. So, by making the left louder (say) to shift it to the left, it made the ten in the right louder hence weakening the effect! I was pulling my hair out, I was putting in 'insane' level differences in, yet the image hardly shifted!

And every test showed a correct centre image.

Remember what I said about checking your own assumptions eh? So there ya go, a funny story of one persons stupidity yet related to the topic of the thread.








Back to the different center position theme. I will look that up in a Psychoacoustics manual. I’m just sure plenty of people have been tested for this effect. Let’s see what statistical double blind testing has to say…if anything.... Zwicker/Faustl (reference manual on psychoacoustics) says that the just audible side to side position shift corresponds to a shift in inter ear sound level by 1 to 2 dB.

Please do.

But what is the point of minimizing sonic image alignment because somebody might hear something different than we do?


I’m not so concerned that someone else can hear exactly what I hear. I’m first interested in that I can hear what I think I’m supposed to hear. I’m not worried about what someone else thinks, I’m worried about what I think.

Oh, I agree completely. I obviously gave you the wrong idea of where I am coming from. My mention of others was to show how I got to the idea. If people hear differently than we do ( and this image example was appropriate to the thread and reinforced the point) then I went one step further. WHY do I assume my right ear is exactly the same as my left?

Two different people have different hearing, why not our own two ears also have two different 'hearings'?

In your 'example speak' that is amplitude panning (total vol rise or fall across the spectrum) to centre the image.

But what if I (me, personally, for my OWN enjoyment no-one elses) only need to 'level shift' the range of 200-1600 to the right by two db??? (made up example) . That might be the range that overrides all the rest to shift the image, but surely then the image is still not as precise as it could be because I have ALSO changed all the frequencies which did not need to go right, to the right by two db?

You are attributing a shift at 400 hz (say) to the room interaction. I wonder if it could be that my ears have that innate imbalance.

So what you might turn up in the research is very much looked forward to.

Sorry for the long post! You got me gabbing first thing in the morning!!
 

fas42

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Fascinating stuff, Art, the conversation is zinging along very nicely now ...

Just a couple of answers for your "survey". I listen in a very relaxed, non-attentive way if the sound is "right". And either the sound is working or it's not. If it's not OK then I put on my engineer's or tweaker's hat and madly fool around until I've sorted out at least part of the problem. When it is OK, then it is "big", that is, dynamic, "powerful" as someone has mentioned, massive soundstage, without harshness. At this point I can relax and I just move around the house doing things, or if it is some driving rock I just dance around the room or so until I'm nice and sweaty: I virtually never sit in a special spot and attentively "listen". The latter I reserve for when I visit a friend's place where we are trying to progress what he has: typically straightaway when I arrive there is some issue with the sound quality, so then a process of tracking down the problems starts. It's become a standing joke between us that about 2/3rds of the way through the listening time we get the sound to snap together, and then I just listen for enjoyment. And, yes, I would say plenty of head movement, like going right up to the tweeter and listening with my ear next to it! No closed eyes or dim lights, the sound has to be there in the bright glare of full sunlight for me to be happy ...

Frank
 

fas42

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Jan 8, 2011
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Guess I spoke too soon, we've gone dead again! So I'll add a bit a bit more, to fill up the space ....

If we have lots of early reflections, we just get a huge non focused image hanging between the speakers and no matter where we sit in the room, the image just sits there hanging between the speakers. Heck, you can go to the next room and there behind the wall you sell see the imaging hanging between the speakers. At least that happened to me, and it was at a manufacturer’s home/party in LA but we weren’t loaded. It was the fantastic, full-range omni Walcott, something that looked like a moon-lander.

I guess I can track the hypothetical, different strokes for different folks. I know that the size of the sweet spot means something. What of the speaker setup is so awful that the sweetspot is the size of a grapefruit while your head is the size of a cantaloupe? I’d guess it would be pretty hard for anyone to agree what was where. This leads us to a test. Just how stable is your center image? or how big is your sweetspot?

That’s right. Dial your center image in and then sway to the left and then to the right. How big of a sway can you do and still have a center image. If it moves as soon as your head moves, the sweetspot is too small, or your head is too big. I’d say good sweetspots seem to be about 18” wide, maybe 2’ tall and 3 to 4’ long, and in a banana shape. Flat down front and tapered up towards the back.
That's my type of soundstage; and I aim for the sweetspot to be anywhere in the room. As regards the head sway, we've already been there, in a previous thread: pretty difficult to do, but can be got to extend past the left of the left speaker, and similar for the right ...

Frank
 

Phelonious Ponk

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Jun 30, 2010
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There is no way theoretically to get the image you hear in the "center" sweet spot to be the same anywhere in the room with plain old stereo...no way...it changes as you move off of center if it is a stereo recording.

Frank, you will beat your head against the wall till hell freezes over and this fact will not change.

Tom

I'm not sure I agree that the sweet spot is too small if it moves with your head. Mine certainly does, though listening in the near field pretty much guarantees a small sweet spot. Still, when something is mixed to dead center, that means it has equal weight in left and right channels in stereo. If you have good, precise imaging, the phantom center has no choice but to move with the listener. As the listener gets closer to the left speaker, the phantom center channel moves left. As he gets closer to the right, it moves right. There is really no way around this, if the imaging is precise. Perhaps more precise imaging = a smaller sweet spot. It's all trade-offs, as far as I can tell, though there are many in this hobby loath to admit any weaknesses in their systems counter-balancing strengths.

Tim
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 22, 2010
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That's a different definition of sweet spot than I have used over the years. Not saying it is wrong, just different. In my case, I have always used something along the lines of "range of listening positions that provide the best sound", realizing "best" is subjective. If I move over a foot I move away from the centerline, true, but as long as the sound stays stable, image clear, no comb filter effects, etc. then I call it "best". To me, a large sweet spot means a large area where the image and soundfield does not change, allowing for the fact that the center "stays put" as I move. When I hear imaging artifacts due to comb filtering, resonances (peaks and nulls), changes in perceived image, sound field, and FR etc. with respect to where it should be, then I consider myself out of the sweet spot.
 

tony ky ma

Industry Expert
Aug 21, 2010
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In my experience, a multi amps system ( cross over front of power amp) will have good imaging and sound stage more easily especially to horn speaker with diffuser that wherever listening position move the image still there in same position, this is my system shows, for calibrate the room will only effect the sound quality (musicality ?) to me
tony ma
 

Phelonious Ponk

New Member
Jun 30, 2010
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Let me make sure I understand what some folks are saying here. Let's say the voice is mixed to dead center and you're sitting at the perfect sweet spot in a rolling chair. You roll to the left until you are nearly in front of the speaker...the voice image remains dead center, so it is not to your right, between the speakers? Do I have that right?

Tim
 

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