DIY bass reflex speaker cab

Discussion in 'DIY' started by RxDx, Dec 16, 2012.

  1. RxDx

    RxDx Speaker collector Subscriber

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    894
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    I built these cabinets out of a magazine in the mid-60s (not Popular Mechanics, apparently), but I can't find it now. A search on Google books has yielded nothing. I'd like to find the original article, and I'd like more information about the design (like how to tune it for a specific speaker).
     

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  2. elnaldo

    elnaldo Addicted Member

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    I think you need to search for "transmission line enclosure", and you'll find how to tune that box...
     
  3. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    Bass reflex means sealed cabinet.
     
  4. doucanoe

    doucanoe Registered Audio Abuser

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    Is this the opposites game?

    RC
     
  5. RxDx

    RxDx Speaker collector Subscriber

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    894
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    Wikipedia calls it a ported design. But it's not a transmission line, like my example.
     
  6. Binkman

    Binkman Addicted Member

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  7. RxDx

    RxDx Speaker collector Subscriber

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    894
    Location:
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    Very nice, thank you.
     
  8. cubby01

    cubby01 aka Buck

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    Maybe check Popular Electronics, Sept '66. I believe there was a 2-sheet plywood plan for T-line speakers, they called them phase inverting speakers.

    If you find it I'd like to know if that's the one you were looking for.
     
  9. RxDx

    RxDx Speaker collector Subscriber

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    894
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    That rings a bell, but I haven't been able to find anything online. Oh well :)
     
  10. TerryO

    TerryO Super Member

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    Learn something new every day.

    You're quite sure of this? :scratch2:

    Best Regards,
    TerryO
     
  11. Binkman

    Binkman Addicted Member

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    The speaker design is referred to as "Open Baffle" with a "Single Driver" design. If this is what you want to replicate. Question is: What driver are you trying to match up?

    This type of design is very very efficient with the right driver however, I do think that the dimensions just looking at it, isn't as efficient as other designs and is simply too short.

    I'll post up some links as I'm editing my speaker links.
     
  12. dumptruck

    dumptruck Lunatic Member

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    That's not an open baffle speaker, nor will the sealed box volume calculator be helpful. It's a transmission line or a bass reflex that simply looks a bit like one. There are a few calculators for transmission lines, but there's no real recipe. You have to experiment. Here is a site with two calculators:
    http://www.mh-audio.nl/tml.asp

    For normal bass reflex, though, simulation software is everywhere.
     
  13. fastbike

    fastbike Well-Known Member

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    830
    Location:
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    The box is tall enough to have quarter wave characteristics, but it's more like a vented box using a slot port. As a transmission line, there are better designs and methods in use.

    You really need to have the Thiele-Small parameters for the particular speaker you want to use and start from there.

    There is software for T/L design. Start here: www.quarter-wave.com

    For Binkman, that would be the first time I've seen a closed box call open baffle.
     
    Last edited: Dec 17, 2012
  14. Binkman

    Binkman Addicted Member

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    RxDx

    DumpTruck.... Fastbike... and me are hitting on the basics for cab design around your chosen driver and their points are well taken for the techo requirements. Your driver stats are needed to make most calculations anyway and that's why I asked what driver?

    Your driver mfg should have the recommended Cubic dimensions along with all the other Theile-Small data required as mentioned.

    If you the brand driver and no data.. I'm sure we can come up with a pretty solid cabinet design.
     
  15. RxDx

    RxDx Speaker collector Subscriber

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    894
    Location:
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    Not sure on the drivers yet. I've got a copy of the magazine coming, and I want to look at the article. The truth is I don't really need more speakers (presently I'm listening to two pair of AR3as), but of course that has no affect on the addiction :) Thanks to all for the feedback.
     
  16. cubby01

    cubby01 aka Buck

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    Ken,
    These are some articles from the 60s that appeared in a couple magazaines of the time. There's some basic theory there.

    •Non-resonant Loudspeaker Enclosure Design - A. R. Bailey - (PDF 549kB)
    http://diyaudioprojects.com/Technical/Papers/Non-resonant-Loudspeaker-Enclosure-Design.pdf

    •Non-resonant Loudspeaker Enclosure Design - Letters to the Editor - (PDF 201kB)
    http://diyaudioprojects.com/Technic...er-Enclosure-Design-Letters-to-the-Editor.pdf

    •Transmission Line Loudspeaker Enclosure - A. R. Bailey - (PDF 499kB)
    http://diyaudioprojects.com/Technical/Papers/Transmission-Line-Loudspeaker-Enclosure.pdf

    (They are housed, among other places, on the diyaudioprojects site http://diyaudioprojects.com/Technical/)
     
  17. RxDx

    RxDx Speaker collector Subscriber

    Messages:
    894
    Location:
    Virginia, the colonies
    Looks like the Popular Electronics phase inverter article is the same box design as the transmission line cabinet shown in the earlier Wireless World article from 1965.

    I'm interested in exploring the TL concept, but lately the designs I was seeing were for fairly small drivers. I've got room for a design that would do justice to a 10" or 12" speaker, plus I'm interested in a 'full' range sound- down to, say, 25 hz.

    The only spare drivers I have now would come from an AR2, which is, of course, a sealed box. So I'll start exploring some other options.
     
  18. RxDx

    RxDx Speaker collector Subscriber

    Messages:
    894
    Location:
    Virginia, the colonies
  19. RxDx

    RxDx Speaker collector Subscriber

    Messages:
    894
    Location:
    Virginia, the colonies
    Stumbled across some Stromberg Slimline 12" woofers, the ones with the bigger magnets. audiphool has the story, at the end of the pictures (RW-489 woofers were 1960 and 61 models only).

    Here are their stats. I give. It won't let me attach a readable image. Here's a link:

    [​IMG]

    More pics in this thread
     

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    Last edited: Oct 21, 2014
  20. knasty

    knasty Active Member

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    Hmmmmmmm, Altec A - 7's have BIG vents and they are Bass Reflex.
     

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