Followup to felt on baffle

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  • Brandon B
    Super Senior Member
    • Jun 2001
    • 2193

    Followup to felt on baffle

    You guys responded to a question on felt around the tweeter over at HTF, and I had a followup.

    If I'm building an MTM and putting felt on the baffle around the tweeter right up to the mids, would it be preferable to leave a slight recess in the baffle so that the felt would be flush with the remainder of the baffle once it is applied? In other words, flush mount the felt?

    Also, I am looking at making my baffle non-rectangular for aesthetic reasons mostly, and was planning to have triangular wedges off the front side edges so the baffle would end up looking like a pair of mirrored trapezoids with their longer bases together at the center. This would make the baffle the widest at the tweeter, which seems to be the wrong choice, however, it would be no wider than if I made it per the original kit design, just narrower at the top and bottom.

    Mistake? Should the felt go clear to the edges?

    BB
  • ThomasW
    Moderator Emeritus
    • Aug 2000
    • 10933

    #2
    Brandon

    You don't need to flush mount the felt, we glue it dircetly on the tweeter.

    The width of the baffle is usually incorporated in the XO design. So changing the width may change the performance.

    Up to recently we used a single piece of felt covering the entire area. With his latest design, Jon is using 2 strips with the center open. I haven't tried that yet.

    Here's an example of the new design



    I'm finishing up a smaller version of the above speaker and will be experimenting with both the one large piece vs the split design.

    Here's a pic of the original pad design. I'll make a split set and compare.

    This is an area where you can experiment. Try a couple of patterns and see which you prefer. But remember don't make a circular cut out for the tweeter, it must be a square



    How to make split felt pad tutorial




    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

    • Brandon B
      Super Senior Member
      • Jun 2001
      • 2193

      #3
      My tweeters are the accutons, so the square cutout makes more sense even from a looks standpoint.

      Out of curiosity, why is a square cutout preferable? To vary the timepoint the soundwave encounters the edge of the felt to smear out any small effects it might have in time?

      Another question - is the improvement from applying felt relevant in a speaker that has grills on? I will have grills in the near term, but some year may have a room where it is unnecessary.

      What level of XO components do you guys think are appropriate for a speaker of this quality (the Orca Aria 5A with the accuton tweeter and the Focal 5W's)? I was planning on trying to spend $50-100 per speaker on the parts (2 inductors, 3 capacitors each). Also, I have a small piece of 1/4" teflon I was going to anchor them to (I have no other real good use for it), any reason not to?

      BB

      Comment

      • JonMarsh
        Mad Max Moderator
        • Aug 2000
        • 15311

        #4
        Hi Brandon,

        Thomas and I tend to be bottom feeding high enders, if that makes any sense. We wind our own coils in most cases (AWG 15 air core), but sometimes buy Solen or Northcreek coils when low DCR is paramount.

        Caps, our favorites are polypropylene GE's from Madisound (very low ESR; we hand measure and match them), but we've also been known to use Solen on occasion.

        Your teflon board can't hurt anything, but the dielectric constant for the mounting board of a low impedance crossover is unlikely to be a big influence.

        One place we spluge a little sometimes is internal wiring; for "low end" systems I use Silver Sonic T14, but for the nice stuff I use Cardas hookup wire, which requires a solder pot; about 15 AWG for tweeters, but their bigger conductors (13AWG if I remember correctly) for the main inputs and woofers. It makes a difference, in the right system, IMO.

        Best regards,

        Jon




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        Comment

        • ThomasW
          Moderator Emeritus
          • Aug 2000
          • 10933

          #5
          What is the saying? Oh yeah

          "Nothing sticks to teflon"

          The round cut out will correspond to a frequency depending on the diameter. The square won't




          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

          • Brandon B
            Super Senior Member
            • Jun 2001
            • 2193

            #6
            Actually, 3M sent us a glue that took 2 pieces of of untreated and untextured teflon about 3" long x1" wide x1/8" thick, stuck some on the face at one end of each (lap joint), and they were stuck. Everyone in my department yanked on them with pliers for a year until one guy finally pulled it apart by putting it in a vise and grabbing the other end with a big pair of lineman's pliers, putting his foot against the workbench and wrestling with it for 5 minutes. I haven't seen it advertised as a production adhesive though, just a sample 3M gave to us for grins. It was called DP400 or something close to that (this was 3 years ago).

            Worked on PP and PE too.

            I was just going to tiewrap all the parts down to the board, and screw the board to the cabinet, so the no stick problem didn't matter to me. I just hate working with PVC (smelly).

            BB

            Comment

            • ThomasW
              Moderator Emeritus
              • Aug 2000
              • 10933

              #7
              Yup I've worked with Teflon prettty tough stuff.

              We just hot glue the XO parts to a piece of 1/4" Masonite




              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

              • Patrick Sun
                Super Senior Member
                • Aug 2000
                • 1380

                #8
                Okay, curiousity has gotten the best of me:

                What's the rationale for keeping the shape of the felt in square shapes?




                PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
                PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

                Comment

                • ThomasW
                  Moderator Emeritus
                  • Aug 2000
                  • 10933

                  #9
                  Patrick

                  A circular cut out will correspond to a cerain frequency/frequencies depending on the thickness of the material and if it's bevel cut. So there will be more absorption there. This issue is eliminated with a square cutout


                  BTW now that I've told you the big secret you will be shot




                  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

                  • Patrick Sun
                    Super Senior Member
                    • Aug 2000
                    • 1380

                    #10
                    You got a couple of time zones ahead of you if you are wielding a projectile launching device in my direction.




                    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
                    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

                    Comment

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