DIY sound absorbers per Klone Audio

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  • Bob
    Senior Member
    • Jul 2000
    • 802

    DIY sound absorbers per Klone Audio

    Jon,
    I made up some Sound Absorbtion panels using a mixture of your directions and Jon Risch's directions. I have them behind my speakers, on my side walls at the first reflection, and on the ceiling for the first reflection there. Since I had already made built in bass traps in the corners (using the directions at the PS Audio website) I didn't need the DIY bass traps.
    These panels are so easy to make and can make such a big difference in how a room sounds I would like your permission to post directions and pictures.
    After over a year of experimenting with speaker placement, room treatment, and equipment swaps there is no doubt in my mind that proper room acoustics is second only to speakers in how much you can change the way music sounds. To my ears DACs came next, almost as dramatic as room treatment, then amps, then pre-pros. With the electronics you had to really be familiar with how things normally sounded to hear the differences, most of my friends claimed to hear no difference between the amp and pre-pro swaps I did. Most could hear the differences between the 3 DACs I changed around, and all could hear the differences when the Sound Absorbers where removed.
  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15209

    #2
    Hello Bob,

    Glad to hear you got religion!

    All joking aside, room acoustics certainly are one of the most important factors - there's so much that can be done to improve the performance in this way, but short of going in and revamping someone's room for them when they're not looking, and letting them hear the difference, it's hard to convince them of the potential for improvement.

    Please feel free to reproduce this information- that's why we posted it to begin with, so that as many as possible could benefit.

    Best regards,

    Jon




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    Comment

    • Pat
      Super Senior Member
      • Aug 2000
      • 1637

      #3
      Bob, please do post your pictures, directions and your thoughts about the results.
      I have been on the verge of starting this project myself...maybe your post will give me that push I need.




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      • ThomasW
        Moderator Emeritus
        • Aug 2000
        • 10934

        #4
        Bob

        Please post away. I built mine 10yrs ago. At the time there wasn't much need to photo document the project for the internet.

        My friends Tyson and Dennis built a ton of these and took photos. But unfortunately a medical emergency resulted in the photos being on Dennis' computer, and Dennis being 1500 miles away from his computer.




        theAudioWorx
        Klone-Audio

        IB subwoofer FAQ page


        "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

        Comment

        • Bob
          Senior Member
          • Jul 2000
          • 802

          #5
          Here is the link to photos of the basic steps for building your own acoustic panels:

          You might want to look at the photos first before reading the instructions so that the steps make sense to you.
          List of Materials for one panel, 30"x4':
          3- 8 foot 1"x4"
          1- 4'x4' Peg board
          1- Roll of 6-8 inch thick fiberglass insulation with craft paper on one side and no covering on the other side
          1- Roll of 36" wide hardware cloth
          1- Roll of polyester batting, found at any fabric shop.
          2 yards- Burlap cloth, comes in many colors, found at any fabric shop
          1- Box of scrws,
          Staples
          Wood Glue
          Brass tacks or carpet nails

          Tools needed:
          Saw
          Screw gun or screw driver
          Staple gun

          1) Cut the 1"x4"s to the length and width you want (the insulation comes in 15" widths so the width of the panel should be a multiple of that)
          2) Screw the frame together, with the lumber on edge, and cut one more 1"x4" to go down the middle of the frame.
          3) Cut the peg board to the size of the frame and attach it to one side. This will hold the insulation in and make the panel rigid.
          4) Put a layer of insulation on each side of the middle 1"x4" with the craft paper towards the peg board.
          5) Staple a layer of hardware cloth over the insulation.
          6) Put a layer of polyester batting over the hardware cloth and staple it to the sides of the frame.
          7) Now wrap the panel like a Christmas present with the burlap, stapling it to the back. You can use staples, brass tacks, or carpet nails. I prefer carpet nails.

          That's it. Each panel takes about 45 minutes to make. How simple is that? Of course you can always buy the equivilant from Tube Traps for around $350.

          I put short table legs (about 10" long) that I got from Home Depot on the bottom and a L bracket on the top on mine. The L bracket keeps it about 4" from the wall.

          I also made a folding screen from 2"x2"s and polyester batting and burlap that I keep in front of the TV when listening to music. This eliminates the TV in the middle problem. My speakers are over 6' from the back wall and several feet in front of the TV.

          I feel that these work so well that for my next project I am going to redo the walls in my HT, using this technology. What I am planning to do is put 1"x4"s from the floor to the ceiling where the first reflections are and 2"x2"s every 15 inches after that. Then I will put 2"x2"s horizontal at 4 feet up. Between the 1x4s will be the insulation,batting combo. Between the 2x2s will be a thinner insulation with the craft paper facing outward. Then I plan on covering all with a nice burlap, probably dark grey behind the speakers and light grey on the side walls, with perhaps a different color where the sound absorbtion "columns" are. I feel that this would only be half to 2/3s down the side walls then painted drywall. The purpose of having most of the insulation with the paper towards the room is to stop it from being to dead. Of course I could just put the burlap right on the walls but, I like the idea of adding the 2x2s to the side and front wall to stiffen them.

          Comment

          • ThomasW
            Moderator Emeritus
            • Aug 2000
            • 10934

            #6
            Bob

            Great job, thanks for the pics

            BTW regarding the turtle/ tortoise? What's up with that?




            theAudioWorx
            Klone-Audio

            IB subwoofer FAQ page


            "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

            Comment

            • Bob
              Senior Member
              • Jul 2000
              • 802

              #7
              Thomas,
              The tortoise is as curious as a cat and follows me everywhere. He is from Africa and belongs to the third largest tortoise species in the world. He is only five years old. When I first got him he was the size of a silver dollar. Considering the sound panel is 30" wide you can see he has grown a bit. He is still a baby and won't reach full size for about 10 more years (around 240 lbs). He eats hay and the lawn and sleeps in a dog house with a ceramic heat light over head. Fairly care free and quite amusing.

              Comment

              • Pat
                Super Senior Member
                • Aug 2000
                • 1637

                #8
                Great Job Bob!
                Thanks for sharing your project




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                • James W. Johnson
                  Member
                  • Jun 2001
                  • 68

                  #9
                  Thanks, I have seen written directions for these but never photos.

                  I have some room problems that I would like to deal with but I am not sure where to start.


                  My feeling is that my room is probably hopeless , I would appreciate it if you could take a look at it and some recent speaker measurments I made and give me some advice.

                  http://www.blarg.net/~jameswj/miscpage.htm
                  pics

                  Comment

                  • ThomasW
                    Moderator Emeritus
                    • Aug 2000
                    • 10934

                    #10
                    James

                    First off I can't believe you bought tickets to a Britany Spears concert

                    Anyway.....

                    The mains are too close to the back wall. They should be pulled forward 2'-3'.

                    Again if possible, move the mains in toward each other. The 'ideal' spacing is in 1/3 the width of the room. Of course this is dependant on what you're using for video.

                    The low bass stuff can be tamed with a Behringer DSP1100P/1124P. Don't use it on the top end. It has a very ddddigital sonic signature. That's not a problem with subwoofer frequencies.

                    If you need/want to try and equalize the radiating pattern for the rears; then put a panel on the wall beside the left rear. That will approximate the opposite side where the speaker has no sidewall boundry loading.




                    theAudioWorx
                    Klone-Audio

                    IB subwoofer FAQ page


                    "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                    Comment

                    • Bob
                      Senior Member
                      • Jul 2000
                      • 802

                      #11
                      8O James,
                      Thomas got further than I did by noticing the tickets. I got so hung up with trying to grasp why someone would build a 9'x8' room I had to stop and get out the tape measure. I have to ask, what was it's original purpose? Can't be a bathroom, nobody dismantles a bathroom except to build a bigger one. Was it once a small balcony and someone enclosed it?
                      Any ways, it shouldn't be a acoustical nightmare at all. You do need the speakers further out from the back walls though, and can you bring them in maybe 6" each from the side walls? Also, break them in for a couple of hundred hours before toeing them in. They probably don't need much, even though they are so close to the side walls.
                      The tickets are for a night out with your teenage daughter, right?

                      Comment

                      • James W. Johnson
                        Member
                        • Jun 2001
                        • 68

                        #12
                        When I first got into HT stuff in 98' I could'nt care less about calibrating my system, when I got into subwoofer building I finally bought an SPL meter and began calibrating my system..but even then I would calibrate it then set everything the way I wanted it.
                        Later on I started calibrating it and leaving it that way, most of the time anyways.

                        I have never measured a loudspeaker's performance in my room
                        and the ugly results have made me want to get it right.
                        Although to me it already sound pretty good I want to do this just for the sake of doing it.


                        Usually I have a 6' wide screen and my Kit281s are forced to sit in the corners up pulled away from the wall a little bit.
                        My projector broke and I am still looking for the right one, I may wait a year or so to get another one.
                        For now I am using a tiny TV to get me by. Also I am currently using some JBL S312s in front which I am uncertain if they will stay or not. Anyways these are big speakers and I pulled them out from the wall more and brought them in further, this is the best I can get it. I take some measurments tomorrow and see if that
                        did anything.
                        I guess I will have to get some sattalite speakers or something when I get another projector if I want a flat room....NAH! I would rather live with the room response I have now.

                        Thomas those graphs were for the Kit281s and S312s alone without a sub..run those speakers with the sub and it really gets nasty(according to the SPL meter).

                        Go ahead and poke fun of my home all you want bob, The house was built in the 30s during the depression and small houses like this were common.

                        I am going to see Britney because my girlfriend wants to go BTW those tickets bought me alot of &@$#* and..well I better not get into the details.
                        pics

                        Comment

                        • James W. Johnson
                          Member
                          • Jun 2001
                          • 68

                          #13
                          Speakers repostioned, you can see how they will be in the
                          way when I get another projector.

                          Rear speakers and a new sub location it usually sits outside of the HT area near my bedroom, I get almost 125db@20 in this position from 1 meter -->my listening position , I will move the speakers out
                          a little bit as well as move them closer together per your guy's 1/3 rule and give it a whirl.
                          pics

                          Comment

                          • James W. Johnson
                            Member
                            • Jun 2001
                            • 68

                            #14
                            Bob, also the 9' is from the center of the couch to about 6" from the wall. The room is actually 17' long total--- from the back of the couch to the front wall is 12' and the back of the couch to the back wall is 5' so my sub is just over 3' from the back of my head...and it won't be too long till I build a subwoofer that will stomp this one into the ground.
                            pics

                            Comment

                            • Bob
                              Senior Member
                              • Jul 2000
                              • 802

                              #15
                              James,
                              I live in a beach area where most of the original houses were 800-1200 sq.feet vacation cottages so, I know what you got going there. Still, 8'x9'!
                              Your pictures show your delimma. Clearly the front projection screen and those speakers can't live together. Unless, you keep them in the corners for movies and then move them out for music. If they are not to heavy that may be your best solution, or just leave them in the corners and put a 15" sound panel benind and on the wall side of each speaker to tone down the bass. Hopefully someone with more experience will give you better suggestions.

                              Comment

                              • Pat
                                Super Senior Member
                                • Aug 2000
                                • 1637

                                #16
                                Ok...so I had to special order black burlap...only had whites and tans in stock.
                                I started looking at the batting material and there are many different thicknesses to choose from...I believe they are measured by weight. IIRC they had 2oz, 4oz, 6oz, 8oz and 10oz to choose from.
                                Which one would be the "correct" one...I am thinking the thickest one...which would be the 10oz.

                                Thanks...hope to start soon




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                                • Bob
                                  Senior Member
                                  • Jul 2000
                                  • 802

                                  #17
                                  Pat,
                                  My understanding is that the batting by itself is great for sound absorbers. In this case though, it is being used mostly to keep in the fiberglass and to cover the wire to protect the burlap. I opted for the lighter weight myself but, don't think it really matters.
                                  I must have gotten lucky with the fabric store I went to. It had black, grey, blue-grey, several tans, white, red, cranberry, and two green colors to choose from.
                                  Good luck with your project. Have you also experimented with moving your speakers to see if there is any room for improvement? I tried several "methods" of speaker placements. The Vandersteen one seemed to work the best in my room and I stayed with it for quite some time. Then I read all the issues of the Audio Perfectionist and found that in my room that following the advice given worked best. I also mixed the advice on room acoustics with what I learned using the DIY absorbers and it is as if I bought new speakers.
                                  The best part is that it was so inexpensive to do. I added another layer of drywall (horizontal) along the front wall and along the first 16 feet of the side walls. I stiffened those areas by putting 2x2s veritically every 15 inches, and horizonally every 4 feet. At the first reflection points I simply built columns 30 inches wide that are sound absorbers (using the DIY method described). Except that I reversed the fiberglass for the the top 3 feet, making it reflective. In between the 2x2s I also put in fiberglass that has the paper facing outward. Over all of this I stretched burlap, black on the front wall, grey on the side walls, black for the columns. Then covered the seams and top and bottom edges with molding painted a dark wine color.
                                  It cost less than buying one bass trap from ASC!!! I still need to make 2 DIY bass traps for the back, the front wall doesn't need them because I have built in bass traps using the method described in the PS Audios website. The room sounds just right, neither dead nor to lively. You can walk throughout the room and your voice never changes.

                                  Comment

                                  • Pat
                                    Super Senior Member
                                    • Aug 2000
                                    • 1637

                                    #18
                                    I have moved the speakers around.
                                    How do you know when it is "right"
                                    They sound good to "me"




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                                    • ThomasW
                                      Moderator Emeritus
                                      • Aug 2000
                                      • 10934

                                      #19
                                      I used muslin it was a good match for the off white walls in the house. It's very thin.

                                      The thicker the absorbers the more bass they absorb. Also Poly batting and fiberglass absorb different frequencies.

                                      Do you have any equipment to measure the FR in the room? The untrained human ear is a fairly poor piece of test equipment.




                                      theAudioWorx
                                      Klone-Audio

                                      IB subwoofer FAQ page


                                      "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                      Comment

                                      • Pat
                                        Super Senior Member
                                        • Aug 2000
                                        • 1637

                                        #20
                                        The only "test" equipment I have is my computer (not a laptop), a RS SPL meter and couple of "test" CD's.

                                        I suppose if I want to do this right I will have to move the computer downstairs to do some testing, and download EFT or some other spectrum analyzing software.




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                                        • ThomasW
                                          Moderator Emeritus
                                          • Aug 2000
                                          • 10934

                                          #21
                                          Pat

                                          If you can run a signal wire from your PC to an input in the sound system download the little tone generator from Swift Sound. Use it with the RS meter and an Excel spread sheet to create a plot of the room.

                                          If you have the bucks the TrueAudio TrueRTA program is exellent and works in real time. The 1/6th octave version is fine for most people's needs. ETF is also good but much more complicated to use, and it works is 'quasi-realtime'.

                                          Jon and I are currently testing the Behringer ECM 8000 mic for less than $40 this looks very good. It needs a mic preamp with phantom power. We're also currently testing some low buck mic preamps (around $70ea) and will post the results when we're finished.

                                          The Behringer mic combined with a low buck preamp and TrueRTA or ETF will give the user a very nice, affordable, and accurate speaker testing rig




                                          theAudioWorx
                                          Klone-Audio

                                          IB subwoofer FAQ page


                                          "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                          Comment

                                          • Brian Bunge
                                            Super Senior Member
                                            • Nov 2001
                                            • 1389

                                            #22
                                            Thomas,

                                            So would you say that TrueRTA would be the better program to use for the novice without needing huge amounts of measurement capabilites? At what point would you think that ETF would be a more viable option?

                                            Brian

                                            Comment

                                            • Pat
                                              Super Senior Member
                                              • Aug 2000
                                              • 1637

                                              #23
                                              I've downloaded EFT and picked up some cables at Radio Shack.
                                              I'm not real sure what I've found out.
                                              Seems to be a steep learning curve, but I think I've uncovered that I don't have a very good system
                                              At least the way I have it setup sucks.
                                              Going to keep trying different placements, hopefully I find the right combo.




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                                              • ThomasW
                                                Moderator Emeritus
                                                • Aug 2000
                                                • 10934

                                                #24
                                                Pat

                                                Here's a website that helps explain how to use ETF 5.0



                                                BTW I find it difficult to use too. There are huge online helpfiles, I printed them out for reference. Also there is a toll free number and he will provide free support for the demo version

                                                Try downloading a copy of TrueRTA from http://www.trueaudio.com

                                                Email me when you get it installed

                                                Brian

                                                TrueRTA is just a very good real time analyser.

                                                ETF will do quasi-real time measurements (there is a time delay), MLS measurements, waterfall plots, and other complex measurements. So it's a much more sophisticated measuring tool. The next step up from ETF is something like SpectraPlus 2.32 and that costs a little under $1K for the version with all the options




                                                theAudioWorx
                                                Klone-Audio

                                                IB subwoofer FAQ page


                                                "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                                Comment

                                                • Pat
                                                  Super Senior Member
                                                  • Aug 2000
                                                  • 1637

                                                  #25
                                                  Ok, I'm still playing with EFT and now have downloaded TrueRTA.
                                                  Tom, YGM

                                                  I think I figured out how to read some of the graphs in EFT and it wasn't as bad as I originally thought.




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