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Thread: 2397 horn - varnish and adapter

  1. #1
    Senior Member gerard's Avatar
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    2397 horn - varnish and adapter

    I am planning to biuld a 2397 horn for my 2420 driver .

    I do have drawings for a 130 ° horn , 5 island 21°67 each other and i need advise for the following .

    1. Should I varnish or not inside of the horn ( better or not for the sound ? )

    2. I have to make an adpater like 2328 I believe from 1inch round to 4 inch square ( 10 cm ) about
    It should be in wood as I can't get original .

    An otehr option would be to make a direct opeing 1 inch on the horn instead of 4 ich square but i ma afraid the opening would not allow the air and sound to go in all the side of horn ; wiht zn adapter it would open better the diffraction !.

    Any advise .

    Best regards

    Gerard

  2. #2
    Administrator Mr. Widget's Avatar
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    I will post a couple of drawings of the 2328 throat adapter and of a prototype 1" to 1.375" X 4" adapter. I will need to convert them to jpgs and scale them. Got to go to work now...

    Widget

  3. #3
    Senior Member gerard's Avatar
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    Mr Widget .

    Thank you so much i shall wait for it.

    Best regards

    Gerard Mihel

  4. #4
    Registered User paragon's Avatar
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    2397

    My god,
    Casablanca, Humphrey Bogart, great.
    Yes, try a 2397.
    It`s the best horn i have heared now for the 2441.
    You doen`t hear a horn is working !
    Widget knows a mouch about.

    Best Regards
    Eckhard

  5. #5
    Administrator Mr. Widget's Avatar
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    2328

    Here are the interior dimensions for the 2328. The surfaces are quite complex and I can not begin to draw all of the subtle transitions. If you blow this drawing up to full scale you will be able to get reasonably close.

    Widget
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  6. #6
    Administrator Mr. Widget's Avatar
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    1" Prototype Adapter

    This is a simplified 1" adapter that has a conical section that increases in size from 1" to 1.375" in the vertical and to 1.517" in the horizontal plane before changing to a 65 degree sloped side. This adapter will outperform the 2328 and 2327 combo.

    I hope this makes sense.
    Good luck!

    Widget
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  7. #7
    John Y.
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    Re: 2328

    Originally posted by Mr. Widget
    Here are the interior dimensions for the 2328. The surfaces are quite complex and I can not begin to draw all of the subtle transitions. If you blow this drawing up to full scale you will be able to get reasonably close.
    Widget
    Excellent contribution to our data base. It would help if you could generally define the cross section of the bulge at the point where it reaches the 2.545" maximum point. Is it elliptical, or does it have flat top and bottom with smaller radii to blend with the sides?

    This adapter could be made by making a solid and using that as a form with which to mold fibreglas or other resin material. The solid could be made of several pieces that would disassemble for removal from the finished piece.

    John Y.

  8. #8
    Administrator Mr. Widget's Avatar
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    Basically the shape is a blend of many radii. It is nearly circular at the bulge with four distinct surfaces becoming evident after the bulge as it approaches the rectangular opening. My guess is that it was described in a multi-view drawing much like the one I have created, but with additional dimensional call outs and then left to the pattern maker to sculpt it out of wood and bondo. The transitions are not very well defined. I have compared half a dozen of these to get these curves. Oldmics lent me one that was from the earliest series. It has a different outer shape and bolt pattern. It is 4" wide at the opening and 4" long. All of the newer ones are shorter and have a variety of opening widths with the widest ones approaching 4".

    On top of that, since they are sand cast, they are all a little different changing as the pattern wears. Each new series would theoretically return closer to the original. I would expect the original drawings are gone, but maybe they will turn up.

    I started to make a new pattern to sand cast a new run of 2328s, but decided it was easier to buy them so I lost interest in the project. The current eBay prices for 2328s made the idea more interesting, but I would need to sell 20 pairs or so at $125 per pair to make it worthwhile. I don't see that happening.

    Widget
    Last edited by Mr. Widget; 09-25-2004 at 03:02 PM.

  9. #9
    Senior Member gerard's Avatar
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    Mr widget
    thank for the drawing .

    Question : should I varnish the inside of adapter and horn or not ? or shall i use a special product to get the best reflection ? .

    thanks for advise .

    gerard .

  10. #10
    Administrator Mr. Widget's Avatar
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    I have been told by two sources more knowledgeable than myself that the interior surface of horns is very critical to the final sound. One swears by a special paint made by 3M called Nextel. It has a light texture and almost rubber like feel. The other source says that you want the surface to be a smooth as glass and as hard as possible... these two sources are absolutely contradictory.

    I have heard horns made by both of them and they both sound good.

    For my wood horns I finish them inside and out to 600 grit and carefully oil them. I think my horns sound pretty good too.

    JBL seems to have made their horns ranging from rough sand cast, texture paint, rubber like paint, sonoglass that is highly polished... I guess they aren't very consistent either. Now in their case I don't think all of their horns sound pretty good, but I doubt it is the finish.

    Widget

  11. #11
    Senior Member gerard's Avatar
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    Widget

    ok I will go to oil inside

    bestv regards

    gerard

  12. #12
    Super Moderator Hofmannhp's Avatar
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    2397 with 2420

    Hi Gerard,

    I don't want to get you off of your cloud....but I have to tell you that my experiances with 2397 and different drivers like 2441 and 2420 told me (very clear) that it's a big difference in sound to use a 1" driver with the 2328 and an additional 2327 throat adapter on the 2397.
    The sound is very different (for my opinion)...short....a 2" driver sounds a lot better.


    (my 2 cents)

    HP
    Please help us save more info about the vintage systems. Let us register your speakers and drivers.

  13. #13
    Administrator Mr. Widget's Avatar
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    HP,

    That is exactly why I also included the 1" adapter throat. It should offer a significant improvement over the 2328-2327 combo. I agree however that the 2441 is more ideal.

    Widget

  14. #14
    Senior Member gerard's Avatar
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    ok

    I have a 2420 so I have to go with it .

    i will make the new adapter ....

    regards

    gerard

  15. #15
    Administrator Mr. Widget's Avatar
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    I am building a similar adapter that will allow me to use a 1.5" driver on my "Westlake" version of the 2397.

    Let us know how your project turns out.

    Widget
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