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Seeking advice on effective wall diffusion?

101.181.209.14

In my new house, the 'listening room' doesn't seem to have any issues (like room-mode anomalies) but I do notice a lack of soundstage depth, compared to what I had in my last listening room.

Just to fill you in:

* the previous room was 27' long x 17' wide and I had my Maggies 5' off the front wall (which was the short wall). And I sat about 12' away from the panels.

* the current room is only 19' wide and 12' deep - and the Maggies are on the long wall. I sit about 8.5' away from the panels.

* unfortunately, no room re-organisation is possible - this is not a 'man cave'! :-((

Now, in the last room, I was able to substantially increase the depth of sound stage by putting some 'Room Tunes' against the front wall, in line with the reflection of the ribbon 'ray' from the front wall to my ears (ribbons were on the inside - to keep them well away from the side walls - so this was a pretty simple exercise).

In other words, diffusing the ribbon reflections gave better soundstage depth.

So I am wondering whether putting some sort of diffusion on the front wall of the new listening room ... would increase my depth of soundstage?

To give you an understanding of the room, here are a couple of pics.

As you can see, the front wall is sloped - this was not by choice but forced upon us by Victoria's Building Regulations. However, this is not necessarily a bad thing - as I mentioned, I don't seem to get any 'bad' things happening. :-))

One WAF-acceptable way of putting diffusion on the front wall, between the speakers, is to put some almost parallel, say bamboo, rods - maybe 5' long, 1" wide and 1" apart? (and painted wall colour), on the sloping front wall, going from the benchtop upwards and sitting maybe 2" off the wall.

I could make this up and then prop it temporarily in place, while I see if it does increase soundstage depth or not - however, this would be a fair bit of effort - so I'm interested in hearing what y'all might have to say about whether it might do some good ... or not.

Thanks,

Andy

Follow Ups:

something like THIS - pictureguy 12:51:29 04/09/16 (0)
I'm working thru a few projects before I try THIS.
I won't use wood, but rather 2" thick EPP foam. The rest is the same.

Too much is never enough
- https://www.youtube.com/watch?v=oHTmNyo_0O0 (Open in New Window)
RE: Seeking advice on effective wall diffusion? - russ69 07:21:15 04/07/16 (6)
You are really close to the front wall. If that situation is fixed then you have to be aggressive with absorbing the back wave. Hanging rugs or tapestries have worked in a few installations I've heard.
- RE: 'You are really close to the front wall' ... - andyr 14:36:05 04/07/16 (5)
  I presume you mean the wall behind my head? (Which I call the back wall! ;-)) )
  
  Yes, I had heard this is problematical. In my last house, I had about 9' clear behind me - to the wall - so in this new room I have put this on the wall behind me:
  
  It is made of 1" thick cork sheets (the shapes are 1/4" cork), glued to a thin board backing ... and I think does what it needs to do - at least, there are no sonic anomalies in the room, except for the lack of depth which I mentioned.
  
  Regards,
  
  Andy
  - RE: 'You are really close to the front wall' ... - Green Lantern 05:37:07 04/09/16 (4)
    Nyyyyyyce setup...
    I looked at your Maggies and after three or four double takes (and a few head scratchings) I went and checked out your profile ; ) brilliant job.
    Side note: is that your art work hanging above the couch? I see the 'AR'.
    
    Edits: 04/09/16 04/09/16
    - RE: I got to my 'Frankenpans' because ... - andyr 02:23:25 04/10/16 (1)
      having taken my IIIas as far as they could go, in terms of tweaking:
      * 3-way active
      * hardwood frames, and
      * braced stands
      
      . . . I wanted to remove the IMD which happens when the mid driver shares the same mylar as the bass driver. Your 20.Xs I think don't suffer from this problem as the mid is separate from the bass driver ... however, because they're all in the same frame, you still have the problem of the vibrations in the frame produced by the bass driver ... shake the ribbon cage.
      
      Whereas, when I touch the top of my bass panel frame (when playing some reggae, say), I can feel it vibrating ... but the mid/ribbon frame is not. :-))
      
      Regards,
      
      Andy
      - RE: I got to my 'Frankenpans' because ... - Roger Gustavsson 07:59:07 04/10/16 (0)
        
        In Reply to: RE: I got to my 'Frankenpans' because ... posted by andyr on April 10, 2016 at 02:23:25
        
        Hi Andy,
        Interesting to see your new listening room. 12 x 19 foot is not very much for your Magnepan. It can work, I had my Tympani IIIA lined up in a room measuring 3 x 3.8 m!
        
        http://twin-x.com/groupdiy/albums/userpics/Tympan_III-A.jpg
        
        In the case of my Tympanis, because of their sizebthey blocked most of the reflections from the wall behind the speakers. Basses were not very far from the wall, maybe 60 cm, but there was a full output down to 30 Hz. Sweetspot were minimal...
        As I later "slaughtered" the Tympanis (resulting in two 1 m wide speakers), I used some damping panels in order to block/reduce the refections from the front wall, placed a bit behind the mid/tweeter section, halfway speaker-to-wall. It worked well.
        
        Roger
    - RE: Yes indeed, GL ... - andyr 19:20:30 04/09/16 (0)
      As you can see, I made it in '89. This was just after we had moved into our last house and there was a 15' long part of a (cement-block) side wall in the listening room that needed something on it, to stop 'flutter echo'. So it was an acoustic treatment that looked nice! :-))
      
      In that room, it was made/painted on the floor - so it was actually all in one piece. Unfortunately, when it came time to move it into our new house ... we realised it was too damn long to fit round the corner of the stairs, into the new listening room - so I had to saw it in half and then put those frames around each section!
      
      Andy
    - RE: 'You are really close to the front wall' ... - Satie 12:04:50 04/09/16 (0)
      Yes, that was a really interesting build, a bit of mix and match.
Thanks for all the suggestions, guys. nt - andyr 16:54:42 04/06/16 (0)
.
RE: Seeking advice on effective wall diffusion? - Swamis Cat 11:16:30 04/06/16 (1)
I can certainly imagine that this setup would be challenging for depth. Using the mirror test on the FW, the only FW bounce you are getting on upper frequencies is sound radiating UP from the panels and then bounced back down from the sloped wall. Satie mentions not wanting to add vertical dispersion. The problem is that you are starting with vertical dispersion.

I think the ideas of bamboo make-shift rods is a great experiment. Alternatively, GIK sells very inexpensive four foot Polyfusors ($130 each). If you put these behind the speakers, you would get a bit of an articial vertical wall for the higher frequencies. You may need to move the speakers out a bit more though considering the slope.

I also like the idea of experimenting with 45 degree toe in if possible. Free and would only take a minute. My experience is that extreme toe in dramatically increases center focus. On the other hand, it is likely to further reduce FW bounce, which might make matters even worse.

That sloping FW is an issue for a dipole.
- RE: Thanks, SC ... - andyr 16:53:31 04/06/16 (0)
  Unfortunately, cannot move the panels further into the room (on wifey's orders) but I can play around with toe-in.
  
  Unfortunately, the sloping wall was just one of many compromises we had to make in planning the building. :-((
  
  Regards,
  
  Andy
sd - sd 09:54:27 04/06/16 (1)
You might try a combination of two things. First, in the area below the shelf and above the records you might try exactly what Grant suggests. Auralex makes some interesting bamboo products for this (see: http://www.auralex.com/products/diffusion/sustain-bamboo-diffusors/ ). Then for the area above the equipment you might consider a couple of narrow bookshelves where you stack the books in such a way that their spines move in and out, creating diffusion, but otherwise looking just like a normal bookshelf. You don't need to go higher up the wall than the top of your speakers and the bookshelves usually have high WAF factors.
SD
- sd (Open in New Window)
- RE: Thanks ... - andyr 16:18:11 04/06/16 (0)
  I hadn't thought of treating the vertical area, between the LP storage bins and the benchtop. But that's at least a foot, all the way along the front wall - so it probably does need to be treated.
  
  Regards,
  
  Andy
RE: Seeking advice on effective wall diffusion? - BigguyinATL 07:48:40 04/06/16 (16)
another trick it to move the speakers out in the room an bit and use an agressive toe in - mine are toed in 45 degrees tweeters in. That actually workes out to be a similar angle to tweeters out and your placement. The corners enable natural diffusion - I have my equipment rack in one corner - media storage in the other.

I really like your layout and look though.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
- RE: "tweeters toed in 45 degrees tweeters in" ... - andyr 00:52:57 04/11/16 (13)
  Given your input, this afternoon I had a couple of keen-eared mates over and we played with the toe-in of the mid/ribbon panel. They listened and I moved the panels - repeating the tracks we listened to,
  
  Fascinatingly enough, increasing the toe-in of the mid/ribbon panel so their perpendiculars crossed just in front of the 'sweet spot' - so at the knees of someone sitting there (instead of pointing directly at their ears) - increased the solidity of the centre of the sound stage image. Which is a good thing! :-))
  
  But it didn't change the depth experienced! :-(( So more experimentation is required there.
  
  Regards,
  
  Andy
  - RE: "tweeters toed in 45 degrees tweeters in" ... - grantv 07:41:34 04/11/16 (10)
    With tweeters outside, that's the way to go IME, in my rooms...
    - RE: "tweeters toed in 45 degrees tweeters in" ... - Satie 08:14:12 04/11/16 (9)
      I am thinking that with the wide wall placement you can get better results with tweeters out if there is a constraint on the distance to the front wall. With tweeters out and toe in you can distance the tweeters from the front wall by an extra foot without changing the footprint and you have plenty of distance to the sidewalls.
      In lively rooms such as yours appears to be, you want the tweeters about 3' from the sidewalls - or a bit more.
      
      Try it out.
      - RE: I have just under 5' from the ribbons to the sidewalls. nt - andyr 13:26:38 04/11/16 (6)
        
        In Reply to: RE: "tweeters toed in 45 degrees tweeters in" ... posted by Satie on April 11, 2016 at 08:14:12
        
        .
        
        RE: I have just under 5' from the ribbons to the sidewalls. nt - Satie 06:40:21 04/12/16 (5)
        
        In Reply to: RE: I have just under 5' from the ribbons to the sidewalls. nt posted by andyr on April 11, 2016 at 13:26:38
        
        What is the distance of the tweeter to the front wall at listening height? about 3 ft?
        
        With 5 ft to the sidewalls you have plenty of room to swap the speakers to tweeters out.
        
        In my experimentation the squishing of depth is a result of excess early reflections from the front wall. You can get less of that on long wall placements with tweeters out. The distance between the inner edges of the speakers will likely end up smaller than with tweeters in.
        
        RE: "plenty of room to swap the speakers to tweeters out" ... - andyr 16:31:06 04/12/16 (4)
        
        In Reply to: RE: I have just under 5' from the ribbons to the sidewalls. nt posted by Satie on April 12, 2016 at 06:40:21
        
        Yes, I already have them tweeter out, Satie - and I get a nice wide and high sound stage ... depth is the only thing I'd like to improve. :-((
        
        Distance from the ribbons to the (sloping) wall at listening height - ie. at the benchtop - is about 4'.
        
        What I did on Monday arvo is adjust toe-in of the mid/ribbon panels, with some keen-eared mates present. We found that increasing the toe-in so the perpendiculars from the ribbons cross at the knees - rather than the ears - of the listener ... substantially firmed up the centre of the sound stage! :-)) Unfortunately, it didn't do anything for the depth - so diffusion on the front wall seems to be required.
        
        Regards,
        
        Andy
        
        RE: "plenty of room to swap the speakers to tweeters out" ... - Satie 18:22:25 04/12/16 (3)
        
        In Reply to: RE: "plenty of room to swap the speakers to tweeters out" ... posted by andyr on April 12, 2016 at 16:31:06
        
        I should have noticed that the shelf is at listening height.That might just be part of the problem.
        
        Try this- take a couple of towels or fuzzy blankets and put them over the shelf and the stuff on it along the span between the speakers and directly behind them, Don't let the fabric hang too far down below the shelf as all we are trying to do is make it acoustically less intrusive.
        
        Tell us what, if anything, changed in the sound.
        
        RE: "towels or fuzzy blankets over the shelf and the stuff on it" ... - andyr 23:34:36 04/24/16 (2)
        
        In Reply to: RE: "plenty of room to swap the speakers to tweeters out" ... posted by Satie on April 12, 2016 at 18:22:25
        
        Tried this, this afternoon, with a keen-eared mate ... towels, folded into quarters, lengthways.
        
        Did nothing for the depth but might have improved the 'presence' of L Cohen in the room ("Roadsinger"). So I need to play with this concept a bit further.
        
        Thanks,
        
        Andy
        
        RE: "towels or fuzzy blankets over the shelf and the stuff on it" ... - Satie 17:10:08 04/25/16 (1)
        
        In Reply to: RE: "towels or fuzzy blankets over the shelf and the stuff on it" ... posted by andyr on April 24, 2016 at 23:34:36
        
        I am not sure I understand what you mean by "presence". Is that a tonal issue or an improvement in spatial presentation of the vocal? Did the vocal center image move vs. with the naked shelf? Did L Cohen become more concise and defined - like you can imagine his voice as a conical beam of vocal sound?
        
        RE: "presence" ... - andyr 17:28:30 04/25/16 (0)
        
        In Reply to: RE: "towels or fuzzy blankets over the shelf and the stuff on it" ... posted by Satie on April 25, 2016 at 17:10:08
        
        Sure - it's an indistinct description! ;-))
        
        With reference to your Qs:
        1. Is that a tonal issue or an improvement in spatial presentation of the vocal? See answer to #3.
        
        2. Did the vocal center image move vs. with the naked shelf? No
        
        3. Did L Cohen become more concise and defined - like you can imagine his voice as a conical beam of vocal sound? <> <> Sort of; the 'Roadsinger' recording captures the fact that LC has a slight vibrato - this was displayed more definitively with the towels placed just over the end of the shelf.
        
        As I said, though, more 'playing around' to be done. :-))
        
        Regards,
        
        Andy
      - Lively room? - grantv 10:38:48 04/11/16 (1)
        
        In Reply to: RE: "tweeters toed in 45 degrees tweeters in" ... posted by Satie on April 11, 2016 at 08:14:12
        
        I wouldn't consider my room lively...
        I have ~4-5' from the sidewalls, the sidewalls have sound absorption at both mirror points, floor is W/W carpeting, and about 10' from my head to back wall.
        Picture is old, but those side wall pieces are still there, carpet is the same...
        
        RE: Lively room? AndyR's not yours - Satie 11:47:18 04/11/16 (0)
        
        In Reply to: RE: Lively room? posted by grantv on April 11, 2016 at 10:38:48
        
        My miss posting.
  - RE: "tweeters toed in 45 degrees tweeters in" ... - Roger Gustavsson 05:48:20 04/11/16 (1)
    I am also using a lot of toe-in, tweeters out. Still some mates use to complain about a vague central focus. Some recordings are that way, others are not. I use to get a wider presentation with classical music than with panned multi-mono used in almost any other type of Music.
    - RE: "vague central focus?" ... - andyr 13:29:18 04/11/16 (0)
      I most certainly don't get this, with the current setup - but, absolutely, the recording is a major influence on what central focus I do get.
      
      Andy
      .
- RE: Thanks, BG ... - andyr 16:06:12 04/06/16 (1)
  Your arrangement - in terms of distance from the panels - looks very similar to mine ... except my seat is against the back wall, not 1/3rd of the way in like yours is. So my room is not as deep as yours but allows approx double your distance from the outer edge of the panels to the side walls (19' x 12').
  
  Unfortunately, I can't move the panels any more into the room - but I can play with the toe-in of the mid/ribbon panel. So i will play with this. :-))
  
  Regards,
  
  Andy
  - RE: Thanks, BG ... - BigguyinATL 06:53:12 04/07/16 (0)
    yes my room is a workable 15W (front) 19deep. That acoustical space behind helps. I your case I'd first add diffusion on that back wall behind your head. your vertical bamboo is a good idea - or a DYI difusor like pictured
    "The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
RE: Seeking advice on effective wall diffusion? - neolith 07:25:08 04/06/16 (5)
Andy,
I did a quick google search on diffusion panels and came across this site . I did not read it in detail but you may get some ideas. BTW what is the average distance of the speakers from the sloped wall (I assume the slope is for earthquake protection?). I like those cubby holes for the LP's - very WAF friendly.
- RE: Thanks for the link, neo ... - andyr 15:43:38 04/06/16 (0)
  They look like a good option.
  
  No, sloped wall is not for earthquake reasons ... it's imposed by Oz inner-city building regulations. (As you go up in height, you need to set back more from the boundary.)
  
  Panels are about 3' from the LP spines, 5' from the bottom of the sloping wall, at the benchtop, and maybe 4' at the top of the panels.
  
  Thanks,
  
  Andy
- RE: Seeking advice on effective wall diffusion? - Satie 09:48:29 04/06/16 (3)
  Good find,
  
  This is what you should do. I prefer keeping away from the 3d diffusors and sticking with 2D diffusors to avoid introducing vertical asymmetry.
  
  Do the diffusors to as close to the length of the speakers as you can get.
  
  The diffusion at the center should do the job and reintroduce depth. The other diffusor strategy would be the fake ficus tree placed between the speaker (tweeter) and the first front wall reflection.
  - RE: Thanks, Satie ... - andyr 15:59:29 04/06/16 (2)
    OK, can understand about 2D diffusion for maintaining vertical symmetry.
    
    But what do you mean by " Do the diffusors to as close to the length of the speakers as you can get "?
    
    The diffusors will be on the sloping wall, above the benchtop. Say the panels are 6' high ... as the benchtop is 3' high, if I use 6' long bamboo poles - starting from the benchtop - then the top of the poles will be nearly at the ceiling?? I would've though - particularly as there's a sloping wall behind the panels - that at most, I would have to take the diffusor up to the height of the panels? So 3' long bamboo rods would be fine?
    
    And I'm pleased to hear that central diffusion (ie. between the panels, on the wall) should deliver depth.
    
    Regards,
    
    Andy
    - RE: Thanks, Satie ... - Satie 21:16:09 04/06/16 (1)
      I meant above and below the shelf to keep the reflections from top and bottom diffused otherwise you will have localization of reflections at the bottom but not the top and that would potentially mess with vertical cues and give you two sets of reverberation times from the room and thus smear the recording venue's boundary cues..
      - RE: Aah, yes - of course. Thanks. nt - andyr 21:33:59 04/06/16 (0)
        
        In Reply to: RE: Thanks, Satie ... posted by Satie on April 06, 2016 at 21:16:09
        
        .
RE: Seeking advice on effective wall diffusion? - grantv 06:59:25 04/06/16 (8)
Love the built-ins, maybe tough to get to, but the records look great in that cubby slot.
I think 1" wide and 1" apart is too little to make any appreciable difference. Would you consider making something like what I have in my room? Make it out of material that the spouse is OK with, maybe even appreciates?
P.S. I would cut the back side at the wall angle so the protrusions are level with the floor.

Edits: 04/06/16
- RE: Yeah that's brilliant, Grant ... - andyr 15:34:49 04/06/16 (7)
  Something like what you've done was another option I was thinking of - but it would be much more labour intensive.
  When you say " I think 1" wide and 1" apart is too little to make any appreciable difference. " - are you thinking that I meant just having 2x bamboo rods behind each speaker?
  What I meant was ... an array of bamboo rods taking up the space between the panels, on the sloping wall. If they were 1" in diam and 1" apart, that would be about 37 poles (extending a total of 6' and going from the benchtop to the height of the panels - so about 4' long).
  And what did you mean by " P.S. I would cut the back side at the wall angle so the protrusions are level with the floor. "? I can't picture it!
  
  Regards,
  Andy
  
  Edits: 04/06/16
  - RE: Yeah that's brilliant, Grant ... - grantv 19:00:21 04/06/16 (6)
    Having the bamboo only protrude 1" or so into the room is not enough to do the job IMO, that was my intention.
    If you built something like mine, I would cut the rear at an angle the same as the back wall so all pieces are "level", I can do a drawing if I'm still not making sense... I just think it would scatter better, and would look nicer as well.
    I do think a 3D diffuser is better in your case with the sloped front wall. Just my opinion.
    - RE: Certainly could be, Grant ... - andyr 04:18:16 04/07/16 (3)
      " a 3D diffuser is better in your case with the sloped front wall ".
      
      But IYO, would having the bamboo rods, say, 3" away from the sloping FW give an acceptable result (compared to right against the wall)?
      
      I think your 3D diffuser has merit - pertickly if the back is sloped to match the 17 deg wall-slope (so the front faces are vertical) - but it would be a lot more effort than a bamboo array.
      
      Andy
      - 3" or more (if possible) away would be much better! - grantv 06:49:26 04/07/16 (2)
        
        In Reply to: RE: Certainly could be, Grant ... posted by andyr on April 07, 2016 at 04:18:16
        
        Yes, that would make a lot of difference; leave enough space in between for the sound to get in there. I think layering them would be better, sort of like a bamboo lattice (which might look nicer also); upright in front, horizontal 1-2" behind, still with large openings between otherwise you remove the effectiveness of them being away from the wall.
        So maybe 4-5" away from the wall; verticals. 1-2" behind them horizontals. And say 3" opening between.
        (Right part is the end view)
        
        Edits: 04/07/16
        
        RE: 3" or more (if possible) away would be much better! - pictureguy 10:59:21 04/30/16 (0)
        
        In Reply to: RE: 3" or more (if possible) away would be much better! posted by grantv on April 07, 2016 at 06:49:26
        
        I'd design such a diffusor to a 'rule'. Regular spacing is your enemy.
        
        Vary either the diameter OR the spacing of the elements. You can ALSO place the elements along a curve, like a French Curve or some other log shape. Regular spacing will be best at one frequency.
        
        Perhaps a PHI shaped curve would work as well.
        Too much is never enough
        
        P.S. - grantv 07:43:09 04/07/16 (0)
        
        In Reply to: RE: 3" or more (if possible) away would be much better! posted by grantv on April 07, 2016 at 06:49:26
        
        You could slope this to match front wall also. Either way, ensure whatever you do, that the first reflection point/span is what you base the size on, and where you hang the diffusor(s).
    - RE: Yeah that's brilliant, Grant ... - rosendds@frontiernet.net 03:56:30 04/07/16 (1)
      What is a example of a 2D diffuser? Do you have any issues with feed back having your turntable on the F.W. close to the back of the speakers?
      - RE: Yeah that's brilliant, Grant ... - grantv 06:52:37 04/07/16 (0)
        
        In Reply to: RE: Yeah that's brilliant, Grant ... posted by rosendds@frontiernet.net on April 07, 2016 at 03:56:30
        
        Example of 2D diffuser; mono-directional slats:
        Never had any issues with my CDP there, which is long gong now. That's a pretty old picture...

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