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Unknown Source - Transmission Line Full-Range Cabinet Plans - TB W8-1772

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  • Unknown Source - Transmission Line Full-Range Cabinet Plans - TB W8-1772

    Hello, I am looking for cabinet plans for 8" full-range drivers (probably Tang Band W8-1772) and I found these (please see below) on-line someplace, but I don't know where they are from. . . I just found the image. I wonder if anyone recognizes them or could comment. I am also considering some designs from Bob Brines and from the TB website, as well as Madisound BK-20s. I like the "unknown" plan below because it is a true TL design and looks pretty easy to build, plus they are not as large as some. I hate to build it on blind faith though! Click image for larger version

Name:	Full Range 8 Inch Driver Cabinet.JPG
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    Any advice on cabinet plans for TB W8-1772 would be great. Thanks!!

  • #2
    There are several possible configurations for a transmission line that will perform well but this one is not one of them because having the driver, especially one that's full-range, located at the very beginning of the line results in a very large dip in the response at the 3/4-wavelength resonance of the line. There will also be other dips in the response higher in frequency, and in order to smooth all of them out acceptably, especially that first one, via stuffing the line, the bass response will be detrimentally affected severely. A better way to end up with a smoother response, in addition to locating the driver at either 1/5 or 1/3 of the line's length from the closed end, is to use a larger taper ratio (this line is sorta tapered).
    Paul

    Originally posted by slowcheetah View Post
    Hello, I am looking for cabinet plans for 8" full-range drivers (probably Tang Band W8-1772) and I found these (please see below) on-line someplace, but I don't know where they are from. . . I just found the image. I wonder if anyone recognizes them or could comment. I am also considering some designs from Bob Brines and from the TB website, as well as Madisound BK-20s. I like the "unknown" plan below because it is a true TL design and looks pretty easy to build, plus they are not as large as some. I hate to build it on blind faith though! [ATTACH=CONFIG]n1335435[/ATTACH]

    Any advice on cabinet plans for TB W8-1772 would be great. Thanks!!

    Comment


    • #3
      Thanks very much for the input. I think I see what you mean, Paul, by the driver being at the beginning of the line. I think I'll pass on that one.

      I'm also thinking of this one below from the TB website. I see that the driver extends into an area with space behind it before the line starts. I really appreciate that input. The TB cabinet is huge and looks somewhat complex to build but there are detailed plans there.

      Thanks Mike; actually, I did purchase the plans for that box from Bob Brines' web site so am considering that. It's an MLTL which is somewhat different. I think Bob has an excellent reputation so I have no qualms about it. It uses a contour filter. I'm leaning towards it. I'm confident in that one after reading about it.

      One more I'm considering (but can't find plans; I see they sell a flat kit though) is from Madisound, the BK-20. I pasted below.

      Thanks again. By the way, these would be to use with a 2 WPC tube amp that I built from a kit.

      Click image for larger version

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      Click image for larger version

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      Comment


      • #4
        Those are rear loaded folded horns. You don't see them used much because they have a response dip where the front and rear waves meet 180 degrees out of phase. Stuffed TLs don't have that problem, as when the line is sufficiently stuffed the only output from the line terminus is at and near the pipe frequency, while everything above that frequency is suppressed by the stuffing. The trick is getting the amount of stuffing right to suppress the unwanted frequencies while letting the 1/4 wavelength frequency through.
        Rear loaders are somewhat popular with those who want to use high sensitivity full range drivers, primarily those from Fostex and Lowther. They tend to have low Qes and short xmax, making them bass output shy. That can be overcome with the horn loading of the rear wave, but at the cost of that response dip, a compromise that those who build them are willing to accept.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

        Comment


        • #5
          I did some exploratory modeling using the T/S measurements for the driver published by Bob Brines in 2009 on the DIYaudio forum. A tapered TL will work but an ML-TL will perform much better (like the one from Bob in the link that Mike provided).
          Paul
          Last edited by Paul K.; 06-16-2017, 12:39 PM.

          Comment


          • #6
            Originally posted by slowcheetah View Post
            By the way, these would be to use with a 2 WPC tube amp that I built from a kit.
            Only 2 watts? Just imagine how they would sound with 20 watts!

            Comment


            • #7
              yeah, I'm sure you are right about watts. I could use other amps with these.

              ANYWAY, I purchased Bob Brines' M18 plans and I've nearly decided to try them. (also, it looks like Bob closed his business last week, FYI.) These plans call for a BSC which will knock back the efficiency some, which seems like a disadvantage in my case, but I'm leaning towards that design anyway as the BLHs look really challenging to build given my minimal free time. We'll see!

              Also, bought the drivers and plywood . . . This place has great baltic birch: https://crlumber.com/ , if anyone is looking.

              I appreciate all the input.

              Comment

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