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DA175 ML-TQWT *PIC*

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  • DA175 ML-TQWT *PIC*




    I thought I'd revisit Martin King's worksheets to see what the DA175 could do in a TL type enclosure. I started with a high ratio tapered TL. I got some real nice looking plots, but nothing that really improved much over a standard vented box. So I dropped it in the ML-TQWT. I think I found the ideal alignment for this little woofer.

    This alignment allows smooth, deep response well below 30Hz with port lengths between 5 and 7 inches. I think I'll re-do the 2-way with the TBFC and use this enclosure as a small floor stander.
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


    95% of Climate Models Agree: The Observations Must be Wrong

  • #2
    Re: DA175 ML-TQWT


    Pete,
    One of the things I've been cautioned about is that Martin's worksheets make no allowance for room gain. Some simulations have been built which showed a flat response such as yours. They resulted in a "boomy" in-room response. An approach around this is to start with a cabinet having a short port length and "flat" response. Increasing port length ...adding mass loading... extends the lower limit and decreases the amplitude of the response. This tuning allows one to match the system to room conditions.
    HTH
    Mongo only pawn in game of life
    ____
    Ed

    Comment


    • #3
      Re: DA175 ML-TQWT


      I agree. Often, it works a bit better to droop the low end ~2-3 dB. It kind of depends on the woofer size and volume you'll play at.
      audioheuristics isn't around right now...

      Comment


      • #4
        Re: DA175 ML-TQWT


        > Pete,
        > One of the things I've been cautioned about
        > is that Martin's worksheets make no
        > allowance for room gain. Some simulations
        > have been built which showed a flat response
        > such as yours. They resulted in a
        > "boomy" in-room response. An
        > approach around this is to start with a
        > cabinet having a short port length and
        > "flat" response. Increasing port
        > length ...adding mass loading... extends the
        > lower limit and decreases the amplitude of
        > the response. This tuning allows one to
        > match the system to room conditions.
        > HTH

        That's why I showed the 5" version and added that you could go as long as 7".


        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


        95% of Climate Models Agree: The Observations Must be Wrong

        Comment


        • #5
          Re: DA175 ML-TQWT


          > I agree. Often, it works a bit better to
          > droop the low end ~2-3 dB. It kind of
          > depends on the woofer size and volume you'll
          > play at.

          It's only a 7" woofer, and will see no more than probably 10W at the low frequencies, or 92dB @ 1m.

          Still, as a starting point with the flexibility of lower tuning, it offers a smoother response to a deeper frequency than its helmholtz cousin.
          R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

          Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


          95% of Climate Models Agree: The Observations Must be Wrong

          Comment


          • #6
            Re: DA175 ML-TQWT


            I didn't save any of the graphs, but I modeled an ML-TL for this driver and the results looked pretty good, too.
            Paul K.

            > I thought I'd revisit Martin King's
            > worksheets to see what the DA175 could do in
            > a TL type enclosure. I started with a high
            > ratio tapered TL. I got some real nice
            > looking plots, but nothing that really
            > improved much over a standard vented box. So
            > I dropped it in the ML-TQWT. I think I found
            > the ideal alignment for this little woofer.

            > This alignment allows smooth, deep response
            > well below 30Hz with port lengths between 5
            > and 7 inches. I think I'll re-do the 2-way
            > with the TBFC and use this enclosure as a
            > small floor stander.

            Comment


            • #7
              Re: DA175 ML-TQWT


              > It's only a 7" woofer, and will see no
              > more than probably 10W at the low
              > frequencies, or 92dB @ 1m.

              > Still, as a starting point with the
              > flexibility of lower tuning, it offers a
              > smoother response to a deeper frequency than
              > its helmholtz cousin.

              I agree. In general the numbers I get with Martin's sims were F3's lower than the typical box, somewhat. Plus, you get some midrange dampening due to the stuffing. All in all, if you don't mind a bit of a box, I think the TL's and ML TL's are a great way to go...

              audioheuristics isn't around right now...

              Comment


              • #8
                Originally posted by Pete Schumacher
                I thought I'd revisit Martin King's worksheets to see what the DA175 could do in a TL type enclosure. I started with a high ratio tapered TL. I got some real nice looking plots, but nothing that really improved much over a standard vented box. So I dropped it in the ML-TQWT. I think I found the ideal alignment for this little woofer. This alignment allows smooth, deep response well below 30Hz with port lengths between 5 and 7 inches. I think I'll re-do the 2-way with the TBFC and use this enclosure as a small floor stander.
                Can you please share the values for s0 and sl

                Comment


                • #9
                  So, where is the pic?

                  Comment


                  • #10
                    wow - you posted on an 11-year old thread!
                    Paul

                    The "SB's" build page
                    http://techtalk.parts-express.com/sh...-4-(pic-heavy)

                    Comment


                    • #11
                      Originally posted by View Post
                      So, where is the pic?
                      Photobucket sucks.
                      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

                      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


                      95% of Climate Models Agree: The Observations Must be Wrong

                      Comment


                      • #12
                        http://photobucket.com/gallery/user/...MzAzMQ==/?ref=

                        Comment


                        • #13
                          You will excuse me for being the lightweight in the room, but can I get reasonably accurate results using the later versions of HornResp? I'm mostly keen on modelling a simple straight ML-TL at present, and MathCAD is not cheap. HornResp indicates response significantly different from a simple ported box and a need for massive stuffing, but HornResp is not without its' flaws.

                          Comment


                          • #14
                            IIRC you can download the trial version of MathCad ver 8 for free - it's fully featured except you can't save the results to a file. And with the snipping tool that's not a big problem. I believe Martin King is still licensing his worksheets for $25 which would be your total cost.
                            "Everything is nothing without a high sound quality." (Sure Electronics)

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