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"Full loss transmission line" for midrange drivers?

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  • "Full loss transmission line" for midrange drivers?

    I've heard of folks using either a fairly long well-stuffed transmission line to completely kill the backwave from a midrange driver. Has anyone tried this? How well does it work to prevent internal reflections? Is the backwave significantly attenuated over just using an OB configuration?

  • #2
    Re: "Full loss transmission line" for midrange drivers?

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    • #3
      Re: "Full loss transmission line" for midrange drivers?

      I wouldn't call it "full loss", it's just a classic tl. They are sealed and well stuffed and the goal is to COMPLETELY absorb the back wave so you end up with the driver's IB response. Supposed to be very nice and clean bass.

      I've never tried one but I'm sure they work great if that's what you want... they are bigger than a regular sealed box though. Definitely bigger than OB but the OB won't have as much bass.
      Don't even try
      to sort out the lies
      it's worse to try to understand.

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      • #4
        Re: "Full loss transmission line" for midrange drivers?

        Originally posted by spasticteapot View Post
        I've heard of folks using either a fairly long well-stuffed transmission line to completely kill the backwave from a midrange driver. Has anyone tried this? How well does it work to prevent internal reflections? Is the backwave significantly attenuated over just using an OB configuration?
        Depending on the LF knee it can take very little damping to kill the backwave of a mid. IMO a closed chamber is usually the better option, while use of a TL is only of real benefit if the terminus output is being utilized.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          Re: "Full loss transmission line" for midrange drivers?

          I've been contemplating this concept for awhile and plan on doing something similar sometime. I have designed a new MT cabinet for a version of the BaSSlines with this type of mid instead of the open baffle/dipole. I'd like to allow a little output from the TL terminus to give just a little extra ambiance, but not so much as to restrict room placement, like you have with an open baffle or open back mid and to kill any backwave reflections through the cone.

          I've modelled it several times and you can get pretty close to a sealed performance/roll off, yet keep the terminus output about 20db down or more. Allowing a little output from the terminus would seem to make it more likely that you could completely kill reflections back through the cone.
          Dan N.

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          • #6
            Re: "Full loss transmission line" for midrange drivers?

            I am, a I write this, listening to a pair of stuffed, open ended tubes with B3n midranges. Very nice midrange performance considering the cost. Don't know how they would sound otherwise as this is the only alignment I have used them in. There is some output at the terminus of the tube but it is well attenuated. I tried these with end caps but I prefer the open tubes. They just sound a little more open and full. This is definitely a "Dan Neubecker-esque" design. Not sure I would want to eat up the floor space with these in a traditional horizontal arrangement. http://s829.photobucket.com/albums/z...MySpeakers.jpg

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            • #7
              Re: "Full loss transmission line" for midrange drivers?

              You may not need a true TL for this application but there's nothing wrong with trying one. OTOH if you simply have a tube behind the midrange driver that's open all the way to the back of the cabinet, you can stuff it to please your ears, allowing complete absorption or less for a bit of added ambiance.
              Paul

              Originally posted by spasticteapot View Post
              I've heard of folks using either a fairly long well-stuffed transmission line to completely kill the backwave from a midrange driver. Has anyone tried this? How well does it work to prevent internal reflections? Is the backwave significantly attenuated over just using an OB configuration?

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              • #8
                Re: "Full loss transmission line" for midrange drivers?

                Originally posted by Paul K. View Post
                OTOH if you simply have a tube behind the midrange driver that's open all the way to the back of the cabinet, you can stuff it to please your ears, allowing complete absorption
                That's what Thiel did in the CS3.6, except closed at the back wall. And stuffed to the max. Very clean midrange . . .
                "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                • #9
                  Re: "Full loss transmission line" for midrange drivers?

                  Check out Siegfried Linkwitz's Pluto over at linkwitzlabs.com. I believe that's an example of what you're asking about.
                  Live in Southern N.E.? check out the CT Audio Society web site.

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                  • #10
                    Re: "Full loss transmission line" for midrange drivers?

                    I'm very interested in this thread as I want to build a closed TL using the little jordan JXR6 HD

                    experts say that for fullrange/bass, you need to make it half wavelength, as bass frequencies will come back up the line, even with stuffing (B&W Nautilus is closed half wavelength)

                    ..but for midrange the consensus on here is that this is not the case? ie could u tune it to quarter wavelength?

                    Also, at what frequency does midrange become bass? I want to crossover around 180 HZ to a sub.

                    Thanks
                    Will

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                    • #11
                      Re: "Full loss transmission line" for midrange drivers?

                      Originally posted by bill poster View Post
                      I'm very interested in this thread as I want to build a closed TL using the little jordan JXR6 HD

                      experts say that for fullrange/bass, you need to make it half wavelength, as bass frequencies will come back up the line, even with stuffing (B&W Nautilus is closed half wavelength)

                      ..but for midrange the consensus on here is that this is not the case? ie could u tune it to quarter wavelength?

                      Also, at what frequency does midrange become bass? I want to crossover around 180 HZ to a sub.

                      Thanks
                      Will

                      I suspect that 1/2 wavelength only works with an open tube, though with the amount of stuffing you'd want to use for something like this, it likely wouldn't matter.

                      180hz is generally considered too high for a subwoofer - if you're using only one sub, you'll get significant localization, and very few drivers that work as proper subwoofers can play very high. For a 2.1 setup, 100hz is generally the maximum; however, for a stereo sub setup at 180hz, a large sealed box - a so-called "infinite baffle" configuration - should work pretty well.

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                      • #12
                        Re: "Full loss transmission line" for midrange drivers?

                        Originally posted by spasticteapot View Post
                        I suspect that 1/2 wavelength only works with an open tube, though with the amount of stuffing you'd want to use for something like this, it likely wouldn't matter.

                        180hz is generally considered too high for a subwoofer - if you're using only one sub, you'll get significant localization, and very few drivers that work as proper subwoofers can play very high. For a 2.1 setup, 100hz is generally the maximum; however, for a stereo sub setup at 180hz, a large sealed box - a so-called "infinite baffle" configuration - should work pretty well.
                        Thanks for the reply- I'm just going by a couple of threads on diyaudio about closed TLs - the general opinion was that a closed TL must be 1/2 wavelength inc a reply from an expert on TLs
                        ..but this may not be an issue for me anyway, as its not for bass duties.
                        The sats will have stereo subs placed below each, therefor I'm guessing that the crossover point should be ok?

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