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Thread: Plan for 300 Hz horn without vanes?

  1. #1
    scorpio
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    Plan for 300 Hz horn without vanes?

    A while ago I inquired about plans for TH-4001 like horns, thanks to others on this forum, I got copies of two interesting Japanese plans similar in look but not identical to the TADs, and both using vanes. Now, based on other lectures here, I'd rather try to find a shorter horn and without any vanes in the soundpath before I get the tools out. Anyone here have an idea where I could find something like this, it would be for a 2" driver and to be used a 600Hz and above,
    Thanks,

  2. #2
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    Quote Originally Posted by scorpio
    A while ago I inquired about plans for TH-4001 like horns, thanks to others on this forum, I got copies of two interesting Japanese plans similar in look but not identical to the TADs, and both using vanes. Now, based on other lectures here, I'd rather try to find a shorter horn and without any vanes in the soundpath before I get the tools out. Anyone here have an idea where I could find something like this, it would be for a 2" driver and to be used a 600Hz and above,
    - If the Japanese plans ( which you presently possess ), are understandable & executable ( and are 300 hz cutoff horns ) / then just build one of the two, leaving out the vanes . You can't go to a shorter horn without raising the horns cutoff frequency ( &/or EQing in the short-fall if you want to live dangerously ) .

    - Throat-vanes are included to enhance the spread of HF content . Without the vanes / you'll be building simple "Radial-style" horns ( with their attendant HF beaming ) . The Altec 511 & 311 come to mind as good basic designs to copy / with a 511 modified to accept a 2" entry, being the first place I'd start .

    - If you don't enjoy HF beaming ( which you will get with the typical radial ) / then you need to build up a Constant Directivety ( CD - style ) horn .

    - John W. has built himself a pair a modified H9800 "CD" style "BiRadial" horns. I'd suggest PMing him and asking for some advice .
    - Also, do a search for threads started by John W. . You'll find lots of info within those threads about his excellent work.


  3. #3
    scorpio
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    Thanks Earl, I xas thinking of doing what you suggest, built a pair and try it with and without the vanes, it should not be to difficult to do. In the end, however much there is to learn from other experience, the only way to know is to try. Pity it's so much work (and that nice wood is so expensive).
    Cheers

  4. #4
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    Quote Originally Posted by scorpio
    snip,,,In the end, however much there is to learn from other experience, the only way to know is to try. Pity it's so much work (and that nice wood is so expensive).
    - Make prototypes out of mdf / or even / layered up pine strips .
    - The operative word is too get some experience in horn building .
    - IMO, it's a real false sense of economy ( in the big, big, big picture ) to study this stuff for too long. One just needs to get on with doing it and learning from the experience .

    - Pretty wood horns can come later . ( BTW ; Dr. Bruce Edgar now turns most of his "salad-bowl" tractrix horns in softer wood ( such as pine ). Apparently, for the purposes of damping .



  5. #5
    scorpio
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    Maybe poplar woudl be good (if I remember Dr Edgar used it too?), not a nice color but reasonably light and fine grain, it should help shaping using a plane rather than a router, pine can be tricky, doing splinter at the worst moment.
    Thanks for the tip

  6. #6
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    Quote Originally Posted by scorpio
    Maybe poplar woudl be good (if I remember Dr Edgar used it too?), not a nice color but reasonably light and fine grain, it should help shaping using a plane rather than a router, pine can be tricky, doing splinter at the worst moment.
    - Yes ( thanks for the correction ), poplar is the wood that I should've mentioned in my post ( not pine ) .
    - You're right / pine can split at the most inoppurtune time .



  7. #7
    pocketchange
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    FWIW What about balsa?

    It shapes like a dream, is lite, relatively cheap, and hobby stores have it in all sorts of sizes. As for strenth, I've built more than a few RC's that have survived some stout impact with Mother Earth. Laminating to generate a panel would be easy. I'm thinking of attempting a Smith Horn if I could locate a print.

    Question: is beaming that much of a problem with a mid driver/horn at normal listening dbs. and at what freq. does the beaming situation occur or is it more of an amplitude related situation?
    pc

  8. #8
    scorpio
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    Hi pocketchange,
    Personally I don't like working with balsa, it only shapes well when working along the grain, once you have to shape it across the grain, it's a pain. Besides, I hate to sand balsa...

    Send me your e-mail via pm, I have a set of drawings for the 2397.

    Cheers,

  9. #9
    scorpio
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    Quote Originally Posted by hjames View Post
    I sure wouldn't post a personal email address on the open web.
    Spammers have "robots that spider the web and collect addresses for later Spamming purposes.

    You probably want to delete that public post and just send it to him via Private mail (PM) -
    Just click his username in the left column to get a pop-out menu with the PM option.
    You are perfectly right, that's why I asked for a pm - anyway I got the e-mail before it apparently got removed - no risk of spam from me, just a reply.
    Cheers,

  10. #10
    RIP 2009
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    Quote Originally Posted by Earl K View Post
    Throat-vanes are included to enhance the spread of HF content . Without the vanes / you'll be building simple "Radial-style" horns ( with their attendant HF beaming ) .
    I was under the impression that because of the "airfoil" shape of the vanes of horns like the 2397, (same in 4001?), that their cross section would also have to be accounted for in the overall expansion rate of the design, and if you left the vanes out, it seems to me this would add up to a fairly significant area, with the result being a different, faster expansion rate, especially in the section of the horn close to the throat. Won't this make a noticeable difference in the response curves?

    John

  11. #11
    Senior Member Steve Schell's Avatar
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    Johnaec, you are absolutely correct about the vanes in a Distributed Source Horn. They not only help steer the high frequency energy into a wide horizontal pattern, their area establishes the exponential flare taper of the horn. Without them the horn would be a conical (straight sided) design. The main difference in performance would be a loss of low frequency response, as the slower expanding exponential horn offers greater loading to the driver at low frequencies.

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