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post #1 of 32 Old 12-30-2006, 11:24 AM - Thread Starter
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I'm wanting to start treating my room this week and I have planned to start with bass traps in my front two corners. I have read through numerous diy threads and sites, but I still have a few questions that I hope all of you can help me with. First I'm debating between a panel style that would straddle the corner leaving an air space behind. The other would be to cut the fiberglass into wedges and fill the corner to the wall. Is one method superior to the other? I would think that the wedges would be better since I would have a significant amount more of insulation, but there would be no space for the sound to pace through and come back. I can not treat my back to corners because one has a door and the other is part of the staircase going upstairs.

I also have base trim around the room. I think the easiest thing to do would be to remove the trim and cut it so that when reinstalled it would butt up to the trap. If anyone has other suggestions I'm all ears.

Concerning the fabric to cover the traps, I know that most people use GOM. I do work at a retail furniture store and have access to a huge selection of fabric. Is there a certain content that I should stick to (polyester, etc.)? From what I have read the GOM is not real stretchy so if I did go with another material I would cover that base. I am more concerned about it being to reflective.
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post #2 of 32 Old 12-30-2006, 11:48 AM
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All else equal, the solid will be better. The airspace behind is a benefit due to distance from the boundary to the leading edge of the absorbtion. The air vs absorbtion in that space isn't the issue - the absorbtion will provide more control deeper down.

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post #3 of 32 Old 12-30-2006, 12:04 PM
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I would never treat a room with bass traps until the room is finished and the equipment is running.

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post #4 of 32 Old 12-30-2006, 01:51 PM - Thread Starter
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Bryan,
Thanks for the input. I was leaning that way but wanted to make sure before jumping in.

As far as the room is concerned it is finished with all of my equipment in it. (All that I have right now until I add some more . I'm in the process of slowly converting it to a dedicated space.

If anyone has links for some corner trap designs and would take the time to post them I would greatly appreciate it. I have read many but wouldn't mind checking out some more before I start. I'm not a big diyer so I will need all the help I can get.
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post #5 of 32 Old 12-30-2006, 06:55 PM
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Corner Absorber Plan
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post #6 of 32 Old 12-30-2006, 08:15 PM
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Take a gander at this page:

www.avsforum.com/avs-vb/showthread.php?t=700442

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post #7 of 32 Old 12-31-2006, 09:35 AM
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Quote:
Originally Posted by GB_KSU View Post

If anyone has links for some corner trap designs

See this:

www.ethanwiner.com/acoustics.html

It not only explains how to make bass traps, you'll also learn a lot of the theory and where best to place them etc.

--Ethan
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post #8 of 32 Old 12-31-2006, 01:48 PM - Thread Starter
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Thanks for the link Ethan. I printed that out so I would have it as a reference. I am at work now but quickly skimmed through the article. I was thinking of buying 703 cutting it into wedges that would fit flush into the corner. This design would have no air gap between the fiberglass and the wall. I would end up with greater mass of fiberglass though. The only thing that I saw in your article regarding this type of design was in "The Numbers Game" and it was a foam material.

I guess my biggest concern is that I am only able to treat two of four corners where my side walls meet so I would like to have the most efficient design as possible.
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post #9 of 32 Old 01-01-2007, 07:52 AM
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Quote:
Originally Posted by GB_KSU View Post

I was thinking of buying 703 cutting it into wedges that would fit flush into the corner.

Yes, that's the most efficient type of broadband bass trap.

> I am only able to treat two of four corners where my side walls meet so I would like to have the most efficient design as possible. <<br />
That's not enough for great results, though I guess it's better than nothing. You should also consider treating as many wall-ceiling corners as you can, and even wall-floor corners if possible. The more corners you treat, the flatter and tighter the low end will be.

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post #10 of 32 Old 01-01-2007, 10:38 AM - Thread Starter
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I plan on adding some treatment to the wall-ceiling corners as well, I'm just starting with the front corners. I have a low ceiling in the room and I can't decide what the best design would be for the wall-ceiling corners. I was thinking of doing them similar to the front corners and designing a triangular frame and using wedges of 703. I do have three small daylight windows in the room. When doing the wall-ceiling traps do the need to be symmetrical with respect to parallel walls, should I stagger them, or does it matter?
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post #11 of 32 Old 01-02-2007, 08:20 AM
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Quote:
Originally Posted by GB_KSU View Post

When doing the wall-ceiling traps do the need to be symmetrical with respect to parallel walls, should I stagger them, or does it matter?

Symmetry matters, but maybe a little less in the rear of the room behind your head.

--Ethan
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post #12 of 32 Old 01-06-2007, 11:12 AM - Thread Starter
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Does anyone have a recommendation for the best place to buy GOM fabric online?
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post #13 of 32 Old 01-08-2007, 07:38 AM
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Fabricmate has great prices and quick delivery
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post #14 of 32 Old 01-11-2007, 03:25 PM - Thread Starter
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Thanks for the input Jdubb. I checked out Fabricmate, but in the end I decided to go with just a regular burlap fabric and save myself some money. I ordered that along with 18 sheets of 703 today. I searched for a local dealer that had 703 with no luck so I just ordered it online. It should all be here no later than Tuesday, which is perfect because I have Tuesday's and Wednesday's off. I spent the last couple of days ripping down chair rail, stripping wall paper, and prepping the walls for paint. All that I have to say is that I'm not very fond of the previous owners. Wallpaper in every room with paint over the top. I'm painting the room in two tones of gray and the fabric for the treatments will be black. I can't wait to get started and will keep you all posted.
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post #15 of 32 Old 01-11-2007, 03:31 PM
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hi
these guys make interesting resonators
i'll get one next week and will comment
www.jocavi.net roundbasscorner model. seems very good for 30-125hz range

as Ethan says on his excellent website, there's isnt "too" much bass absorption in a room.
the budget here would be about $2,000 for 4 resonators/bass traps
and if all corners height are worked, imagining an 8ft ceiling, that is $4,000 in bass traps.

i'll start with two then two more.

i think these will be much more efficient than even the mega lernds foam traps from Auralex wich are just... foam traps and not brodband resonators.
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post #16 of 32 Old 01-14-2007, 07:22 PM - Thread Starter
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I think that I should have about 4 sheets of 703 left over that I can use for first reflections. If I am using 2" panels is there an ideal spacing from the wall? I don't know if I will have enough to do anything with the ceiling. If I do I don't think that I will be able to space those at all. Would it still be worth the effort if they could only be mounted flush?
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post #17 of 32 Old 01-15-2007, 11:22 AM
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Quote:
Originally Posted by GB_KSU View Post

If I am using 2" panels is there an ideal spacing from the wall?

That too is explained in detail in my Acoustics FAQ linked above. The answer is the ideal air gap is equal to the panel thickness. Or two inches.

> Would it still be worth the effort if they could only be mounted flush? <<br />
Yes!

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post #18 of 32 Old 01-18-2007, 03:57 PM - Thread Starter
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I spent the majority of Tuesday and Wednesday working on the room. Three cases of 703 arrived Tuesday while I was shoveling the mixture of ice and snow off the drive. Anyone reading this that does not live in the midwest should be happy they don't. That was without a doubt the hardest shoveling I have done for such a little amount of accumulation (about 2"). I finished all of the painting in the room except for the faux application on the staircase. Wednesday I spent the morning taking care of some odds and ends and started in on the fiberglass after lunch. I'm using the "super chunk" design for the corners and also the soffit, except that I made 1' wedges vs. 2'. Let me tell you that is some absolutely tedious work. I did pick up a cheap carving knife which I highly recommend to anyone considering working with this product that would require cutting. Regardless transforming 2'x4' sheets into 1' wedges drained my enthusiasm rather quickly. I finished the evening by building the framing for the corners and installing like a billion 1' wedges. I am planning on putting a late night in tonight with the high ambitions of framing my soffit and installing it with the 703. We will see how that goes.

On another note the fabric that I ordered came in Wednesday. It is just a simple black burlap, but I think that it will really look sharp with the rest of the room. I ordered it from ATS Acoustics. If anyone needs a good source for inexpensive fabric or 703 I was 100% satisfied with their service.
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post #19 of 32 Old 01-18-2007, 07:07 PM
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Ok bass trap guys, I have a question...

I have floor to ceiling bass traps (2' wide) in each corner of the HT room that use a single piece of 5.5" acoustical cotton mounted in a frame. The frame is positioned diagonally across each corner.

I have some spare cotton material. If I cut it into triangles and place it behind the existing frame will I gain much absorption? If so, will it just be marginal theoretical improvement (defined as < 10% performance improvement)or is it something I should be able to hear and feel in the low range?

Thanks in advance.
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post #20 of 32 Old 01-19-2007, 07:13 AM
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If it's spare, sure, throw all your scraps back there.

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post #21 of 32 Old 01-19-2007, 07:31 AM
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Thanks Ethan.

One other performance concern...do you think I can get too much absorption in the corners. Could it make the room "dead"?
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post #22 of 32 Old 01-22-2007, 10:45 AM
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Quote:
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do you think I can get too much absorption in the corners. Could it make the room "dead"?

It's not possible to have too much bass trapping. You'll never get the room perfectly flat, so the best you can aim for is as much bass trapping as possible. You can definitely make a room too dead at mid and high frequencies though.

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post #23 of 32 Old 01-22-2007, 11:32 AM
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Ethan,
I plan on painting a few acrylic on canvas paintings for an art gallery look inside my theater. Being that the art will be placed at standing eye level, would you recommend defusing or acoustic treatments behind the canvases?
I figured that I'll get a boomy drum effect if I leave them untreated.

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post #24 of 32 Old 01-23-2007, 12:32 PM
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would you recommend defusing or acoustic treatments behind the canvases?

Diffusion behind canvas is useless. Even absorption is only partially effective, depending on how reflective the canvas is. But absorption is definitely better than diffusion there.

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post #25 of 32 Old 01-25-2007, 12:30 PM - Thread Starter
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I finished the major work with the corner traps and soffit traps on Tuesday. I just have to do a little trim work to clean it up. I have yet to take any measurements, but I can say without a doubt the effect that it had on the listening environment was rather substantial. I have never had the luxury of treating any of my listening rooms prior to this. I have lived with the gear I have now for about five years and to say that I knew its characteristics would be an understatement. Never before have I experienced the amount of detail and dynamics with my gear as I do now. My wife had doubts about what I was doing and in the end she loves the room aesthetically and could not believe the difference that it made. The best part of this next to getting great sound is being able to say, "I told you so!" Of course I don't say it out loud, just to myself.

I will try to get some pictures uploaded soon along with some measurements. I do have five 2'x4' sheets left over. If I treat the first reflections it would more than likely take all five. I have not done anything behind the seating position. Should I go ahead and treat the first reflections and worry about what's behind my ears later?
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post #26 of 32 Old 01-25-2007, 12:36 PM
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If I treat the first reflections it would more than likely take all five. I have not done anything behind the seating position. Should I go ahead and treat the first reflections and worry about what's behind my ears later?

It's all important. If the wall behind you is less than 8 to 10 feet away, absorption (or diffusion) there is just as necessary as at the first refection points.

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post #27 of 32 Old 01-25-2007, 01:44 PM - Thread Starter
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The wall behind the seating area is probably a good thirteen feet away. In my planning for the room I was thinking of building diffusers for a portion of the back wall along with a small section of the wedge soffit that I used in the front section. My only concern was that this would put almost all of the absorbtion for the room at and in front of the listeners ears. Is this a bad idea?

Again I will try to get some photos up this evening that might give you a better idea of the layout of the room.

Your input has been valuable, thanks again!
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post #28 of 32 Old 01-26-2007, 10:13 AM
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Quote:
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I was thinking of building diffusers for a portion of the back wall along with a small section of the wedge soffit that I used in the front section. My only concern was that this would put almost all of the absorbtion for the room at and in front of the listeners ears. Is this a bad idea?

Absorption is best spread around the room rather than focused all in the front or all in the rear etc. And with bass trapping you simply can't have too much, so any treatment plan should include bass traps in as many corners as possible anyway, including the rear. But you could trap the rear corners, and any other parts of the rear wall where there are no diffusors.

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post #29 of 32 Old 01-26-2007, 04:34 PM
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Sounds like a good plan.
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post #30 of 32 Old 10-12-2007, 04:08 PM
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When constructing "chunky" corner bass traps made of triangle shaped 703, can I just stack them 8' high or do I need some type support say 4' up so the lower ones don't compress over time?
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