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RE: Corner Traps - Quantity Over Symmetry?

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In Reply to: RE: Corner Traps - Quantity Over Symmetry? posted by Ethan Winer on January 29, 2009 at 10:00:37

>One inch thick is okay for side walls and ceiling, though two inches thick is preferred. But for the rear wall behind you, bass is a big issue too. So for that location I suggest much thicker.

Okay, Thanks again Ethan! I took some careful measurments last night. Here's my plan for the back wall... does the plan below seem reasonable?

Center of back wall: Build a free-standing frame, 3' wide and 7' tall, out of 1x6 lumber. Fill the unit with 705-FRK and 705 for a total of 4" thick. Place that along the back wall behind the listening chair. Spacing from the back wall, I dunno... how does 4" sound for starters?

Corners of back wall: Build two free-standing frames, 18" wide and 7' tall, out of 1x4 stock. Fill the frame with 2" thick 705 or 705-FRK depending on what I have left over, and space these against the sidewalls, spaced out about 1". I'd like to put more here, but the door needs to open...

Ceiling at back wall: I can build a frame that is 36" wide by 11' long by 5.5" deep, and place it on the ceiling right against the back wall. I have 7" total height space here, so I can do, say 4" thick 705 or 703 spaced up to 3" from the ceiling.

The ceiling would be the last step, and would be an as-needed type of thing. My speakers have almost zero dispersion vertically, so I haven't had the ceiling or floor be a big issue yet. The big-arsed trap on the ceiling above the listening position would really be a bass trap.

Of course this treatment will be in addition to two floor-to-ceiling corner traps behind the speakers and some first reflection treatment.

Thanks again!

Follow Ups:

RE: Corner Traps - Quantity Over Symmetry? - Ethan Winer 13:40:39 01/30/09 (12)
That mostly sounds okay, with these suggestions:

Absorption on a wall close behind you should be thick and not FRK. You need to absorb mids and highs as well as bass.

Traps straddling corners, or near corners, should be FRK and should also be at least 4 inches thick. Two inches thick is not enough.

--Ethan
- RE: Corner Traps - Quantity Over Symmetry? - Ferrstein 17:39:26 01/30/09 (11)
  Hi Ethan,
  
  > Absorption on a wall close behind you should be thick and not FRK. You need to absorb mids and highs as well as bass.
  
  Okay, is regular 705 good or should I go with 703?
  
  > Traps straddling corners, or near corners, should be FRK and should also be at least 4 inches thick. Two inches thick is not enough.
  
  Yes, this is where I run into problems. I could use 4 inch material, but then it would have to be right against the wall. I'll go ahead and do that with the FRK, but I only have four inches available. Too bad, I'd love to go thicker here. I'm hoping the FRK ceiling trap will make up for the fact that I can't put much in the corners back there.
  
  Thanks again!
  - RE: Corner Traps - Quantity Over Symmetry? - Ethan Winer 09:41:23 01/31/09 (10)
    705 is a little better than 703, and nicer to work with, but both are similar. If you have only four inches available, make the traps that thick with no gap. Any floor corners available?
    
    --Ethan
    - Picture of First Reflection Issue - Ferrstein 17:15:01 01/31/09 (1)
      Here's another issue this room has - the window and the radiator. I plan on making a radiator cover that can incorporate some 705 or 703 panels. For symmetry sake, I'll probably make a dummy radiator cover for the other sidewall. I figure I can use it for LP storage.
      
      I plan on covering the window completely. Maybe some 1" or 2" 703 or 705 covered in fabric. I will make two panels and hang one over the window and one on the opposite wall, again for symmetry.
      
      These Acoustats don't disperse much to the side, but I've found that first reflection is still somewhat important.
      - RE: Picture of First Reflection Issue - Ethan Winer 09:58:54 02/01/09 (0)
        
        In Reply to: RE: Picture of First Reflection Issue posted by Ferrstein on January 31, 2009 at 17:15:01
        
        The radiator is well below ear level so I doubt it's doing real harm. Much more important are the windows on the right and the bare wall on the left. Again, at ear level.
        
        --Ethan
    - Speaker Wall Picture - Ferrstein 17:09:46 01/31/09 (2)
      Here's a detail of the front wall.
      
      Ethan, to answer your earlier question about any floor corners available... yes. I will eventually be moving my equipment racks to the closet behind my listening chair. I can put some 4" thick 705 or 705FRK traps at 45 degrees at the floor/back wall interface, as well as the back wall/ceiling interface.
      
      I can also put a 705 trap on the ceiling/wall interface over the listening chair at the other end of the room.
      
      As for the speakers, that's a long story. I have been an Acoustat freak for two decades. I own just about every model Acoustat has ever made, and for the last decade I've driven them with direct-drive servo amps. I've found that the servo amps allow (and require) a larger speaker-to-room ratio. I realize these look huge in the room, but I will also be trying a slightly narrower model. These have three panels per side (they are model 3s). I also have some two panel per side speakers that I will try. I also have some even wider, but I'm thinking they won't work in this room.
      - New Speakers (already) - Ferrstein 05:14:21 02/04/09 (0)
        
        In Reply to: RE: Speaker Wall Picture posted by Ferrstein on January 31, 2009 at 17:09:46
        
        And the winner is... Monitor 4s! Who knew. Yep, they look way too big for the room. I almost didn't even try them. Sonically they are head and shoulders above the Model 3s and Spectra 22s. The bass is smoother and more natural, the midrange projected forward a bit, images were appearing ahead of the speakers... really just a whole lot better. Just goes to show you it's always best to experiment!
        
        Anyway, that's good news. I'm still planning on building corner bass traps and a rear wall trap, but I'm much more confident that these speakers will work.
      - RE: Speaker Wall Picture - Ethan Winer 09:59:49 02/01/09 (0)
        
        In Reply to: RE: Speaker Wall Picture posted by Ferrstein on January 31, 2009 at 17:09:46
        
        Floor reflections may also be a problem. Throw rugs are a good solution.
        
        --Ethan
    - Detail of Door Issue - Ferrstein 17:04:32 01/31/09 (2)
      Here is a close-up of the door issue. I have only 4" available.
      
      Question: with only 4" available, would I be better with:
      a) 4" 705 flat against the rear wall, or
      b) 3" 705 flat against the rear wall, and a 1" piece of 705 on the door
      
      Of course I would copy whatever I do here on the other side of the room.
      - RE: Detail of Door Issue - Ethan Winer 10:01:27 02/01/09 (1)
        
        In Reply to: RE: Detail of Door Issue posted by Ferrstein on January 31, 2009 at 17:04:32
        
        Ideally you'd have four inches thick on the door and on the wall, and accept that the door will never open all the way. If you leave the door open that's almost the same as having a bass trap. Otherwise, maybe use two inches plus two inches, door and wall. Or get a bass trap on a stand that can straddle the corner and be moved out of the way.
        
        --Ethan
        
        RE: Detail of Door Issue - Ferrstein 10:39:00 02/01/09 (0)
        
        In Reply to: RE: Detail of Door Issue posted by Ethan Winer on February 01, 2009 at 10:01:27
        
        > Or get a bass trap on a stand that can straddle the corner and be moved out of the way.
        
        Now that right there is a great idea. Or maybe put it on the wall with hinges or something. I'll look into that.
    - Picture of Back Wall - Ferrstein 17:02:00 01/31/09 (1)
      Hi Ethan, and thanks once again for your help here. While I'm happy to be starting with a blank slate, there are also several sticky issues with this room. Below is a picture of my back wall. As you can see, it is hard to maximize trapping there while maintaining symmetry. Looking at the picture, I have 18 inches from the left wall to the left side of the closet door. Because of that, I can make two 18" wide floor-to ceiling traps. The thickest I can go here is 4" because of the door on the wall in the opposite corner.
      - RE: Picture of Back Wall - Ethan Winer 10:03:02 02/01/09 (0)
        
        In Reply to: RE: Picture of Back Wall posted by Ferrstein on January 31, 2009 at 17:02:00
        
        The biggest problem I see here is that you are sitting directly in front of a reflecting wall. You really need absorption on that wall, especially directly behind your head.
        
        --Ethan

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