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Midwest Audio Fest

It’s that time audio enthusiasts!

Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project.
We are excited to see all returning participants, and look forward to meeting some new designers this year, as well!

Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans.

We hope to see you this summer!

Vivian and Jill
2 of 2 < >

Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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Transmission line enclosure

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  • Transmission line enclosure

    Anyone know of a suitable bookshelf-sized transmission line enclosure for Peerless 850122 6-1/2" woofers? I've seen 1/4 wave floor standers but I'm looking for a bookshelf.
    * Power handling: 150 watts RMS * Voice coil diameter: 1-1/4" * Voice coil inductance: 1.3 mH * Nominal Impedance: 8 ohms * DC resistance: 6.1 ohms * Frequency response: 38-5,000 Hz * Fs: 38 Hz * SPL: 87 dB 2.83V/1m * Vas: .98 cu. ft. * Qms: 2.22 * Qes: .53 * Qts: .43 * Xmax: 5.5mm

  • #2
    A TL is a 1/4 wavelength device. 1/4 wavelength at 38Hz is 7.4 feet. That's why TLs are floorstanding, not bookshelf.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #3
      I don't know much about TL speakers, but I googled your woofer and found the "Peerless Pipes" a 2003 DIY design which looks like a transmission line: it's 43" high, 10" wide and 11" deep - so as Bill says above, it's a large cabinet. No idea how it sounds, or whether it's a good design for a TL anyway.

      Geoff

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      • #4
        Maybe you just need a really really big bookshelf?
        Francis

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        • #5
          Thanks for the replies. I was aware of the "Peerless Pipes" so I thought I could just fold up the line into a more manageable size cabinet for my purposes.

          Comment


          • #6
            1. Look at how PMC bookshelf speakers are designed - they are quasi TL / aperiodic . Here is an analysis / diy thread https://www.diyaudio.com/forums/mult...30a-dc28f.html

            2. Consider a tapered TL (this will allow you to builder a smaller enclosure)

            3. Consider a higher target frequency for the 1/4 W frequency (maybe 50 - 60 Hz). TL's roll off more gradually than bass reflex designs and complement room gain.


            Hope that helps

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            • #7
              FWIW, I did a quicky model of a single-fold TL with a taper ratio of 30:1 that had a line length of just under 37" that could be built into an enclosure with internal dimensions of 8"W x 18"H x 16.25"D. I didn't spend any time optimizing it but its f3 was in the mid-30s I think and the overall response was smooth. The terminus, however would be on the back panel, so the box couldn't be literally shoved up against a wall or the back of a bookcase.
              Paul

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              • #8
                Paul, thank you for responding. I was hoping to get some input from a transmission line specialist! I intended to use these cabinets on stands, not on a desk top, so a rear terminus wouldn't be a problem at all. Any way I could get a diagram?

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                • #9
                  I want to spend more time on the modeling as I'm considering an alternate possibility. I'll let you know what I come up with.
                  Paul

                  Originally posted by B King View Post
                  Paul, thank you for responding. I was hoping to get some input from a transmission line specialist! I intended to use these cabinets on stands, not on a desk top, so a rear terminus wouldn't be a problem at all. Any way I could get a diagram?

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                  • #10
                    Paul, anxiously waiting for your reply. Got the urge to make some sawdust!

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                    • #11
                      Do you have any specific requirements regarding cabinet size and/or shape as well as hoped-for f3?
                      Paul

                      Originally posted by B King View Post
                      Paul, anxiously waiting for your reply. Got the urge to make some sawdust!

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                      • #12
                        I was thinking something along the lines of an 8" or 9" wide and 18-20" tall, front baffle. Depth isn't as critical. I will be using these on 24" stands and ideally I'd like to have the tweeter at 32"-36" from the floor.

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                        • #13
                          Those dimensions are definitely doable. I'll try to get you something by Saturday. I've been playing with a 2-fold, 3-segment ML-TL that looks very, very promising.
                          Paul

                          Originally posted by B King View Post
                          I was thinking something along the lines of an 8" or 9" wide and 18-20" tall, front baffle. Depth isn't as critical. I will be using these on 24" stands and ideally I'd like to have the tweeter at 32"-36" from the floor.

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                          • #14
                            Thanks Paul. Above and beyond the call. If this will work, I'll document the build of these bad boys. No big hurry as we are leaving on a trip Sunday and we'll be gone for a couple of weeks. As soon as we get back, I'll fire up the table saw.

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                            • #15
                              What are you using to model Paul?
                              Copy of Lou C's speaker pages: http://www.rob-elder.com/LouC/speakers.html

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