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RE: Simulating impact of TV in middle (primarily, size change)

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In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by JBen on April 25, 2012 at 16:55:02

Wendell likes to listen in the dark, to avoid vision from interfering with the imaging. He told me that it makes a difference whether he listens in a dark room, or with his eyes closed! Which makes sense when you consider that our brains integrate every sensory input.

I think several things can cause the "U" image effect. But I'm not sure what they all are. With Maggies, though, I usually find that it's the corners/side walls, at least it doesn't seem to happen if I put them along a long wall. When I listen facing my fireplace, I get a great sense of depth on the right, where the long hall is, but on the left, where there's a corner, the sound tends to wrap around -- not terrible since it's way off to the side, but I do hear it. When I face the other way in the room, so I'm facing a plain wall with walls on either side (plus windows but I flush them out with plexiglass and a narrow beam), the image is much better but it does wrap some at the sides.

Wish I had the luxury to worry about what's behind, but in that room, I'm pretty much sitting against a surface. Eventually, I'll have to put some absorption behind my head.

Follow Ups:

RE: Simulating impact of TV in middle (primarily, size change) - JBen 17:58:22 04/26/12 (11)
Earlier today I forgot to reply to this particualar post.
I had originally planned to spend last evening trying to configure as similar a situation to yours as I could. That way I could, perhaps, figure out something to help with the challenge. It was a good thing that I was too tired to do it. The reason is that I am a moron by nature.
I thought that I had no real way to emulate that open hallway of yours, other than by heavy damping. BUT OF COURSE I DO!
All I have to do is think in reverse. The left MMG has a door right next to it. And guess what? Leaving it open rolls out additional imaging impression on that side, like you seem to perceive on the right side. I normally close it for listening because I have no matching one on the right side. Things get unbalanced a little if I do. I already have a slight bias in that direction due to the sofa.
Which, suddenly, brings up a possibilty. Nowadays, I have far more absorption material at hand than when I tried to balance for the door with damping on the right side. Hmmm, I may be a beneficiary of the excersise, as well. I hope that I get Saturday "free" to play with my toys.
Anyway, on Wendell's observation, I also agree. Closing eyes is no good. More with SACD (the TV is off) than with Red Book via PC, I tend to dim the room. Imaging is more enjoyable because the eyes have less impediment to refocus as told by the ears. They can't focus on anything when closed, I guess. With the extra stereo imaging that some SACDs display, the experience gets a really nice boost.

Edits: 04/26/12
- RE: Simulating impact of TV in middle (primarily, size change) - josh358 19:01:31 04/27/12 (10)
  It works totally differently if you do it on the left than if you do it on the right. :-)
  
  Seriously, I wish I knew how to bottle that extra space and apply it to my walls, but if you just absorb the reflected sound I think you'll get less depth than you'd get with the door. As far as I can tell, we're using artificial reverb to create that sense of depth. There's reverb on the record, and you might think that if you eliminated the room reflections entirely it would create a space the size of the original recording venue. But in practice, if you put a pair of dipoles outside, that doesn't happen, the depth shrivels up. My best guess as to why this happens is that the ear doesn't interpret reflections as depth cues if they come from the same direction as the loudspeaker. They have to be IIRC 10 degrees separated. So to get good depth with two-channel stereo, you have to have a delayed reflection coming from another angle. You might have more luck with diffusion.
  - RE: Simulating impact of TV in middle (primarily, size change) - JBen 20:46:34 04/27/12 (9)
    To tell you the truth, it did not work the first time I tried, very long ago. Two things are different now. (And then, there is an observation that gives hope.)
    
    One is that the objective is not the same. In those days I was merely checking out solutions for the right side "problem". I had resisted the obvious, that I had to create a corner truncation to match the structural one on the left. I kept that door, which is next to the MMG closed; it was not the issue. Now, I would do the same but trying to match the spaciousness that the door open on the left side brings about.
    
    The other difference is that I used light material then. I did not have all that much at the time. However, I now have piled up several types of materials that I bought along the years to experiment with. I would have had more had I not given some of it away, the pricey commercial stuff. I did it largely, because not much absorption was not really needed. Burlap, which is really not much absorption, does the trick when I need it.
    
    The hope mentioned earlier is this. With a double layer burlap on the corners that I am now testing, the sides' imaging started behaving in the same direction as the door open effect. Not as pronounced but they mimic some of it. I had forgotten this until you described your experience. It triggered the recollection.
    
    Except, that I really never took it to the next level: that perhaps this experiment on your behalf would allow me to keep the door open. So, let me make a clarification, I say absorption when in reality it will probably be a mix of commonly available household materials. Some to absorb more, and others to diffuse rather than absorb.
    - RE: Simulating impact of TV in middle (primarily, size change) - josh358 06:38:37 04/28/12 (8)
      If you want to play with diffusion, you can make a good QRD or skyline diffuser out of Home Depot styrofoam. Then it can always be recreated in wood if it has a good effect (I think you'll probably be able to hear a subtle sonic signature from the styro -- though maybe not, since it's diffusing the sound).
      
      I was just upstairs looking at my listening room. What hit me again (it's always more obvious when you're in the room than when you're thinking about it or looking at a drawing) was that the best course would be a couple of bookcases with transparent doors to flush the wall out to the front of the fireplace. Transparent to keep the room from getting too claustro. I'm tempted to give up the closet (really don't want to knock a new hole in the wall, now that the renovations are done -- of course I've already thought of a million other things I wish I'd done too). The only thing is, I set up the closet to house noisy equipment like the computer. I could put the computer back in my home office but the cable conduit I ran goes into the closet, so I'd still have to get there if I changed everything.
      - RE: Simulating impact of TV in middle (primarily, size change) - JBen 07:14:36 04/28/12 (7)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by josh358 on April 28, 2012 at 06:38:37
        
        It will rain heavily; that means that the other plans had to be set aside. So, your project is on. Right now I am trying to solve a minor issue while at the same time I also plan for the test. I only have 3 hours, which is a bit limiting but perhaps I can continue on Sunday.
        At this point, I think I will:
        - Listen/measure at standard imaging settings
        - Listen/measure at standard imaging settings plus door on MMG side open
        - Listen/measure as above while testing various right wall combos
        - Listen/measure as the above but with simulated chimney hole of sorts, LOL.
        I hate styro's effect on sound here but I may have to cut some of what I still have in the storage to scale the chimney hole. How large is it? I can still aprox, based on your pix and relative to my 12' wide room... yours being 13'. Given so many other variables, it may not be critical. It's a bit of a stretch anyway but then again, who knows what it may still show.
        
        Edits: 04/28/12 04/28/12
        
        RE: Simulating impact of TV in middle (primarily, size change) - josh358 08:34:08 04/28/12 (6)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by JBen on April 28, 2012 at 07:14:36
        
        I just measured, the fireplace opening is 34" x 26". I did try putting a sheet of plexiglass in front of it when I was experimenting, and while the difference was audible, it didn't seem to have much of an effect on the main problem I was having in the room, that it was bunching up at the mantle.
        
        As far as I can tell, the sense of depth depends on the contours of whatever is on the wall. Sort of like sonar. I'm not entirely sure why this should be the case, since the first reflection is just from one part of the wall. I guess we can interpret the later reverberation, but man, the amount of brain power required to do that is mind boggling, since you have to take about a zillion things into account.
        
        RE: Simulating impact of TV in middle (primarily, size change) - JBen 21:56:30 04/29/12 (1)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by josh358 on April 28, 2012 at 08:34:08
        
        Gruesomely long afternoon into late evening. I did sort of an about face. Tore apart the room and changed it to have bare walls behind MMGs, like your room. The covered corners were never needed for good imaging here. I tried more combinations in one day than I remember ever doing. It kept raining but I took advantage of pauses to measure.
        Summary (remember that this is still, largely, relative to my room/setup):
        1. On balancing for your hallway (the left door open, in my case)
        A. Today, the door open (with no counteraction on the other side)yielded a change in L/R balance that could easily be missed by many! With bare walls behind, the image behaviors that I describe in my previous post for "the door open next to the left MMG" are much less severe. The previous post was about what happened yesterday, when I still had the corners covered with burlap. Today I remembered that you have no damping in there, that's why I had to break things apart here and make them bare. The difference is remarkable, IN THIS CONTEXT.
        B. Ironically, after much swapping materials back and forth, it was absorption that really did the trick. A rather thin layer of it in a similar shape to the door but flat on the wall, on the opposite side.
        C. In this manner, balanced imaging was achieved that essentially matched my standard imaging settings. Other sound characteristics could be called equal or better than I get on standard imaging settings. I could not compare any of this in the "enhanced imagings settings". In any event, never did I feel I was getting a "flawed delivery", just slightly different.
        D. This difference in behaviour mentioned in "A" was a major revelation to me and has implications for my own consideration. Somehow, I hit on a combo that I had never tried before. This, despite the fact that I had done somthing like "B" before.
        2. Completing the HOLE story. (the hole plus the treatment above)
        A. The smallest "fireplace hole" had to be 33x28. However, this hole could not cause a major problem. Neither could any larger size to over 33x60. These all cause a loss of bass but still leaves more bass than the average MMG.
        B. When the hole was reduced under 33x37, no major imaging artifacts ensued. Somewhat different sound, yes, but in the "quite acceptable" and still delightful range.
        I can't say that the "fixing agent" agent was the TV/rack. I am pretty sure that it is the larger part of the reason it all worked here, even if I can't afford to remove it all to prove it. Also, these truncated corners may have played a role. The good thing is that you can try with your MMGs first and see where it leads.
        More to follow but it may take a day or two. I'll be too busy but I have to find time to draw stuff. Also, the charts are unavailable for now. I had to isolate that PC totally from the network and can't access them just now. In the meantime. the room, as drawn in the link below, has changed little. The positions are the same, minus "fireplace hole" behind the center rack and minus absorption in the shape of the door opposite the one on the left.
        
        Sorry for typos, I am entering "zombie mode" this late in the night but wanted to provide some info.
        http://www.nicx.com/ClientSets/JBen/JBen-MMG%20Room%20early% (Open in New Window)
        
        Edits: 04/29/12
        
        RE: Simulating impact of TV in middle (primarily, size change) - josh358 07:47:23 04/30/12 (0)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by JBen on April 29, 2012 at 21:56:30
        
        Ineresting. Truth is, I hadn't given much thought to balancing the left and right parts of the soundstage because I was having so much trouble with the mantle! But I did wonder if I could do something about the corner on the left. I've never liked what corners do to dipole sound and I've been wondering whether those truncated corners you have would improve things, or whether it would make more sense to use a bit of absorption or diffusion on the corner bounce.
        
        I think I'm past the window on MMG experimentation, because while they're a lot easier to move than the IVa's I'm too eager to hear the IVa's! Listening room is now ready for them but I have to cut some sheet vinyl flooring that I'm putting in another room so that's currently occupying the floor. I think I'll be cutting it today, if I can manage to weight down the wrinkles it got while it was rolled up. Then I'm going to start putting up the full account of the Magnepan trip and once that's done, build my HTPC and test the IVa's. Not sure what direction they'll be in, I'm going to have to try it every which way to see what works. Which should keep me happy for the next few months. :-)
        
        I think I'll try them with my chair in the fireplace first to get a baseline, because I know that works best in this room. Then see if I can get the same effect facing the fireplace or, if necessary, facing across it, the way I used to. I'll probably get some big pieces of styrofoam to experiment with, e.g., to see if my bookshelf idea would work. Also to see what I could do with some QRD diffusers on either side of the fireplace.
        
        I don't want to get too crazy about it, too, since I'm planning to move in the not-too-distant future and my new place will have only two requirements: high speed Internet, and a bigger listening room!
        
        RE: Simulating impact of TV in middle (primarily, size change) - JBen 13:38:49 04/29/12 (3)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by josh358 on April 28, 2012 at 08:34:08
        
        Hi Josh,
        
        Nothing went the way I wanted on Saturday. It rained heavily , it thundered, the airport 30 miles away changed the flight pattern to cope ... and to keep our ambient noise levels too high.
        
        Despite this, I got a few things out of the way. Among them, I retested with the door open at the side of the left MMG. Upon listening, this confirmed that, aside from the delightful extra imaging, it causes a significant imaging balance shift. No surprise, it always did. However, this time I did a frequency sweep. The sweep, as can often be the case, did not reveal a major shift in frequency. Also, this time around I was able to pin down a couple of music examples where the imaging phenomena can be easily defined. It will serve to compare with what will happen as the tests continue. So far, so good.
        
        Then I was briefly able to open the back door behind the MMGs (not yet a "chimney simulation"), listen and then measure. That open door caused a change in sound character that could not be called "bad" in the short period I was able to listen. Surprisingly, soundstage imaging hardly changed though it obviously became more affected in the center. Still, altogether it was the same height, width and layering as normal. Frequency response DID measure much more different than with the door next to the MMGs open, largely below 300hz. Yet, the music that I was able to play in this brief period did not appear to suffer much for it.
        
        Next, and barely beating the arriving wave of heavy rain, I was able to listen with both doors open. The main difference heard was that AGAIN, the door on the left side shifts everything. Your hallway has to have a similar effect at your end. It may not be a perfect comparison but at least I know that if this gets "somewhat cured" in testing here, there's more hope for you.
        
        The next round of attempts begins shortly.
        
        RE: Simulating impact of TV in middle (primarily, size change) - josh358 08:03:14 04/30/12 (2)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by JBen on April 29, 2012 at 13:38:49
        
        I haven't really noticed any image shift with the open hallway on my right. I'm not quite sure why this is but I'd guess it's because the speakers are far enough away from the walls (at least 5') so that the reflections are all out of the image shift window, which is pretty much within the first 10 ms. The only exception to that would be the sidewall first reflections and in my room, those are way behind the opening.
        
        RE: Simulating impact of TV in middle (primarily, size change) - JBen 17:12:30 04/30/12 (1)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by josh358 on April 30, 2012 at 08:03:14
        
        Still trying to get to start putting things together.
        
        In the meantime, after reading Mart's first impressions on his new 20.7, I am thinking radical thoughts. Like buying a pair of 20.7s and moving to live at the nearby park. Right now I am trying to figure out how many solar panels I can tent around them and still have power to move them. Cooking is optional...
        
        ...Sterno, anyone?
        
        Anyway, poorish for now... There was some shift of imaging elements here with the door open and the corners bare. It was just not nearly as much as when I had the corner walls covered. No one would know unless familiar with the the normal positionings on the soundstage.
        
        Then, adding the light absorption in the shape of the door, but directly on the other side, corrected the minor shifts. That was uncanny.
        
        One other notable thing. Normally, I can turn my head to "look at" the imaging presented from the outer sides of the MMGs, and from any place behind the plane of the MMGs, for that matter. Soundstage elements that are perceived behind this plane or, at times, slightly forward of it, can be "looked at" by turning the head to them. Neither walls, MMGs, TV or rack matter...but being behind that plane does. It is a boundary of sorts for solidity and stability.
        
        The rest of the room, with some recordings, can have perceived surround & directionality from the wall sides next to you, behind you and even over you. However, it is "ghost" imaging. You only perceive it while looking at the system straight ahead. It vanishes the minute you turn your head to look at it.
        
        Well, I said all this because the segment of the imaging that appears so engagingly improved into the room when one opens the door, cannot be looked at. It vanishes when you look at it, as if it were on my side of the boundary. Yet, it is behind that plane. It breaks the "rules"!
        
        The same thing happened with imaging coming from the absorption "door" on the opposite side, when present.
        
        I have to revisit this for my own benefit later.
        
        RE: Simulating impact of TV in middle (primarily, size change) - josh358 17:35:04 04/30/12 (0)
        
        In Reply to: RE: Simulating impact of TV in middle (primarily, size change) posted by JBen on April 30, 2012 at 17:12:30
        
        That's interesting. I don't remember noticing that when I was listening, but I don't recall turning my head to look at anything -- not intentionally, anyway.
        There's gotta be a way we can bottle 20.7's for people like us with small rooms! I mean, if the Mini Maggies bottle 3.7's for people with desks . . .
        It's the bass that's the issue, no reason you couldn't make a tall, narrow true ribbon tweeter line source for the mids and highs. I mean, you could always use a sub, but it just doesn't sound the same. Maybe a dipole sub like Davey made . . . wouldn't be a line source, but I imagine it would blend better than a box.
        
        Edits: 04/30/12
RE: Simulating impact of TV in middle (primarily, size change) - JBen 05:59:45 04/26/12 (3)
Josh & Satie,

I was reading Satie's post and remembering about related observations on the U effect. I am not sure about the corners causing it, either, at least, not alone. Bear in mind that I never made a major point of studying the U, more like observing when it happened. However, it did eventually, become part of the justification for me to see what happened when I removed everything in the center, at home, for one day. I never got a major U at home that day. The worst of the center stage depression still left some depth in the middle where layering, even if compressed, could be perceived. Not my cup of tea but at least it showed some floating center elements, if a bit too ethereal.

Contrast this with the first time I conciously heard the U with planars, which was on my first exposure to 3.6s at the dealer. I've mentioned the incident, long ago, including that we cured the problem by dragging in a cart with TV & equipment. But what we then cured was a rather severe U. The center was devoid of depth and was just wall splatter.

The dealer's room corners were deliberately "truncated" with light cloth absorption. Mine are truncated, one of them is structural, the other I made to match. Covered or not, at home they were not able to cause as severe a U.

Things that had stuck in my mind from that first 3.6 day were how "too damped" the room seemed and, particularly, the heavier cloth art they had at the center back. So, at home, during the day with no stuff in the center, I tried it by hanging various heavy cloths behind, in the same relative area. It made things worse but not to the degree that I expected. That left me wondering, was it the overall room damping at the dealer? Perhaps the room height? A combination of things?

Well, the next bad case of the U that I heard was when I was in Tampa one day for business. I had some free time, kicked up Craigslist. Pair of LFT-8 locally on sale. I had heard the 8b a few times earlier, but not yet the older version. I called, he was moving but we agreed to an audition. The gent was a British national attached to MacDill AFB, contractor duty. Remarkably, centuries earlier, as an AF ROTC cadet in training at MacDill, I had been a guest of an exchange officer from the RAF. Back then, he and I had two pleasant evenings listening to his rather nice system.

The coincidence helped. He was more willing to trust the stranger, help along and also fill in with details. The room was a bit of a mess and we decided to move some boxes to the back. This left the room sides clear. The wall fixtures had been packed for the move, bare walls. The decent audio gear on the floor to one side had been warmed up and ready before I arrived. We sat to listen, went through a few of his CDs. The U promptly reared its ugly face. We both agreed.

He said he did not have it in the past, when the equipment rack was in the middle and there were fixture on the walls. Since the rack was packed for the move, we stacked a couple of boxes in there. The U was gone and soundstage imaging was more even. The overall sound and imaging were still not great but, given the naked walls, it was to be expected.

So, I looked around more closely. Carpeted, like all else (dealer, my home and others). The room was taller than mine, about 9'+, which is closer to our dealer's room. In all, 13x22x...9nish, the realtor specs did not say. Mine is 12x25x8, though irregular at the back. This was a clean rectangle, like our dealer's, but with typical corners. He said he did use plants of some sort at the corners behind the LFTs, in normal times.

All of this, kind of threw my hyphothesis off. Ok, then, I thought, maybe it did have to do with height. Or maybe with having irregularity at the back of a room. Or, maybe something else I missed. I say all of this so that we can all keep observing.

BTW, at the dealer, they took off the heavy damping center art from all Maggie rooms at some point later. The corner treatment remains. In recent years they have also tended to show Maggies with the equipment rack in the middle, just behind the plane, not too backwards or close to the wall. This is how the 3.7s and 1.7s have been set up each time I've been there in recent times. (For box speakers, they appear to keep the rack at the room sides.) They also display the Mini's on a desk with, by default, a laptop PC open to normal screen angles.
- RE: Simulating impact of TV in middle (primarily, size change) - Satie 01:28:43 04/27/12 (1)
  I had to experiment with what affects the center image because of the truely weird effects that I had with the hk/Limage setup (see light blue colored speaker marker on the drawing). I did move the Vandersteens - now functioning as absorbers into various spots around the corners with no effect on the center. But when I covered the front of the rack with an absorber the center image of the piano in piano concertos stopped being ethereal and weak and became more like the image I am used to. The backstage images became much more specific and far more solid.
  
  The monstrous close miked piano delivered into your lap in the HK/Limage setup without absorbing the rack reflections went back to being a piano in the proper place and in another recording the orchestra portion behind the central piano was improved a great deal. The incredible stretching of the front of the orchestra without the absorbers was truncated a little with them, but the overall soundstage other than the center was unchanged no matter what I did to repair the center image.
  
  Right now, I am still working on the basic positioning of the speakers for the Rooze arrangement. But doing that with the nearly 5 foot wide Tympani is really not an easy thing.
  - Post with drawing (Open in New Window)
  - RE: Simulating impact of TV in middle (primarily, size change) - josh358 19:27:09 04/27/12 (0)
    I can readily believe that, after my unfortunate experience with the fireplace.
- RE: Simulating impact of TV in middle (primarily, size change) - josh358 06:49:53 04/26/12 (0)
  I think that the U effect can be caused by more than one thing. I think there may also be more than one kind of U effect. There's one kind in which the sound seems to begin at the speakers, then arch back in a U. And another in which the soundstage sort of wraps around at the sides, but is way beyond the walls. That latter is the one I get in my room when I face away from the fireplace. The former is what I first heard on a friend's KLH-9's years ago. They were well out in a big room and along the long wall (but with a mantle behind them). This may have had something to do with the fact that they were so beamy, or maybe to the fact that they weren't in mirrored pairs, they didn't know to do that back then so both had their tweeters on the same side.
  
  Also, I think I read somewhere once that distortion can cause sound to appear to emanate from a speaker, not sure if that's true. But for me, Maggies always disappear, and as far as I can tell from my limited experience, the sound doesn't wrap if there isn't a nearby corner or sidewall -- though I've been limited in my opportunities to hear them set up that way.
  
  Not sure about height, either. I haven't had much of an opportunity to experiment, most of my Maggie listening has been in two rooms.
  
  The problem I think with general descriptions of rooms is that you don't see the actual geometry. I like this illustration on Linkwitz's site, because it drives home that what we're actually listening to isn't one but a whole bunch of speakers. And the ear uses the delay and angle and relative intensity of those reflected speakers to determine the distance of the mirror, and so the size of the room. So what we hear is going to be very dependent upon specifics of geometry. For example, depending on toe-in, you might not hear the reflected speaker at the side at all, because you'll be in the dipole null. You will eventually hear a reflection there, but it will be a second reflection from somewhere else in the room. So there will be a longer delay and the brain will conclude that the wall is farther away, just as it would if you saw the second reflection in the mirror and noticed that the reflected speaker was smaller.
  - Room reflections (Open in New Window)

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