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Thread: Wall behind speakers amount of reflexion

  1. #31
    Super User Brad225's Avatar
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    If you are looking for a DIY approach. There must be a supplier in the area that sells Owens Corning 705 fiberglass panels. 2" thick x 24" wide x 48" long is the most common size for these panels. You can make a frame for them to fit in and wrap it in a fabric of you choice.

    Owens Corning 703 will absorb a bit more low end but is very soft must have a frame work to place it in.

    In my room I used 705.
     

  2. #32
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    Based upon input from others on this thread, and other websites too - I decided to implement some acoustic treatments in the front of my listening room (in the area behind my Martin Logans). I am limited on what I can do in this room with placement of my speakers and the room layout, so I decided to seek improvements treating the room.

    I built base traps for the front corners and absorption panels to go behind my Montis speakers. I built the traps and the panels using 2 inch thick, 2X4 sheets of Owens Corning. The traps are 24" tall and are 6" thick. The absorption panels are 2' wide, and 4' tall (I had to do a cut-out to squeeze the panel between my window frame and the fireplace, but I placed the section that I cut out behind the shutter, just in front of the glass window pane). The panels and traps passed the wife approval test, and we hung them on the walls. I think they look pretty good.

    I am very pleased with the results. I notice a definite improvement in overall imaging and clarity - especially with my bass. I'm still playing around with toe-in and final placement of my speakers. In a perfect world I would move my speakers outward, but my room won't allow for that. (The room is 13' wide X 15' deep.)

    Thank you to everyone for input in thread above.

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    McIntosh 6700 Integrated Amp, Martin Logan Montis Speakers, Sony HAP-Z1ES Server, Pro-Ject Debut Carbon Turntable, Analysis Plus Oval 9 Cables

  3. #33
    Super User C.A.P's Avatar
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    well done . Room is the second biggest part of a system to fix .. How far is your seat from the back wall as it can reinforce bass to.. Its a great tool that many do not use as most sit their char or sofa WHICH is a big sound absorbing blob in the center of the room and wonder why they have no bass. Bass waves are big and need time to get to the rear and reflect
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  4. #34
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    Quote Originally Posted by C.A.P View Post
    .. How far is your seat from the back wall as it can reinforce bass to.. Its a great tool that many do not use as most sit their char or sofa WHICH is a big sound absorbing blob in the center of the room and wonder why they have no bass. Bass waves are big and need time to get to the rear and reflect
    My ears are about 24" from the rear wall when I'm sitting in my chair. I used to have a large piece of artwork (framed with a pane of glass) on the wall behind this chair, but I have removed that picture and now the wall is just drywall. I can't move my chair forward or to the rear much at all.
    McIntosh 6700 Integrated Amp, Martin Logan Montis Speakers, Sony HAP-Z1ES Server, Pro-Ject Debut Carbon Turntable, Analysis Plus Oval 9 Cables

  5. #35
    Super User C.A.P's Avatar
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    24 is fine your getting room gain and that sense of air with rear early reflections.. Well done CHAP!
    Martin Logan... Odyssey...Krell KSA 100s...Krell KRC3 Pre Amp...Krell Connect Media server/DAC
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    With regards to the back wall - is it best to leave it as bare drywall, with no absorption panels or other treatments?
    McIntosh 6700 Integrated Amp, Martin Logan Montis Speakers, Sony HAP-Z1ES Server, Pro-Ject Debut Carbon Turntable, Analysis Plus Oval 9 Cables

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    Super User Rich's Avatar
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    Quote Originally Posted by bikerneil View Post
    With regards to the back wall - is it best to leave it as bare drywall, with no absorption panels or other treatments?
    Normally, I would recommend diffusion on the rear wall. But since you are only sitting two feet away from it, diffusion would likely be ineffective. I would place an absorption panel on it, horizontally oriented at ear level behind your seating position. I expect you would get better clarity and imaging by reducing the rear wall reflections. These reflections, because they come back to your ears so soon after the initial sound wave, will confuse your brain and muddy the imaging. Any "sense of air" they may provide is not worth ruining the excellent clarity and imaging provided by electrostatic speakers.
    Last edited by Rich; 03-01-2017 at 08:17 PM.
    Rich

    This comment is intended solely for educational purposes and should not be construed as conveying any express or implied warranty of fitness for any other purpose. Said comment constitutes merely the humble opinion of its maker and does not reflect the views of the MLOC or of ML, Ltd. YMMV. Trust your own ears.

  8. #38
    Forum Administrator twich54's Avatar
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    Quote Originally Posted by bikerneil View Post
    With regards to the back wall - is it best to leave it as bare drywall, with no absorption panels or other treatments?
    Quote Originally Posted by Rich View Post
    Normally, I would recommend diffusion on the rear wall. But since you are only sitting two feet away from it, diffusion would likely be ineffective. I would place an absorption panel on it, horizontally oriented at ear level behind your seating position. I expect you would get better clarity and imaging by reducing the rear wall reflections. These reflections, because they come back to your ears so soon after the initial sound wave, will confuse your brain and muddy the imaging. Any "sense of air" they may provide is not worth ruining the excellent clarity and imaging provided by electrostatic speakers.
    also to add what Rich has said given your close proximity to the back wall with regards to all things 'reflective', if it were me I'd be treating the corners as well.
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    And one final question:
    You can see in the picture above that I have a large plasma TV on the wall behind my speakers. It's located between the speakers, and above the speakers. I suspect I am getting some amount of sound reflection off this glass screened TV. I am considering placing a blanket or something similar over that TV screen when I am not using the TV (which is 99% of the time). Does the type of blanket I use make a big difference, or can I get 80% of the absorption with any blanket? (or do I need to go and buy a thick wool blanket?)

    Thanks.
    McIntosh 6700 Integrated Amp, Martin Logan Montis Speakers, Sony HAP-Z1ES Server, Pro-Ject Debut Carbon Turntable, Analysis Plus Oval 9 Cables

  10. #40
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    A Blanket that has had a fan blowing on it for a week !

    Those in the know will Know!

    Quilted will work.. No yarn as it wont help.. Just use it for two channel listening and tell your wife the TV was cold !
    Martin Logan... Odyssey...Krell KSA 100s...Krell KRC3 Pre Amp...Krell Connect Media server/DAC
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  11. #41
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    Quote Originally Posted by bikerneil View Post
    And one final question:
    You can see in the picture above that I have a large plasma TV on the wall behind my speakers. It's located between the speakers, and above the speakers. I suspect I am getting some amount of sound reflection off this glass screened TV. I am considering placing a blanket or something similar over that TV screen when I am not using the TV (which is 99% of the time). Does the type of blanket I use make a big difference, or can I get 80% of the absorption with any blanket? (or do I need to go and buy a thick wool blanket?)

    Thanks.
    You will not get 80% absorption with any blanket. It will help absorb some of the high frequencies, but will do nothing to absorb the midrange and lower frequencies. The best you can do is experiment and see if it makes a positive difference.
    Rich

    This comment is intended solely for educational purposes and should not be construed as conveying any express or implied warranty of fitness for any other purpose. Said comment constitutes merely the humble opinion of its maker and does not reflect the views of the MLOC or of ML, Ltd. YMMV. Trust your own ears.

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