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Thread: 1200Hz Smith horns for 1" driver

  1. #1
    Super Moderator yggdrasil's Avatar
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    1200Hz Smith horns for 1" driver

    From other posts on this forum I have gotten the idea that it is possible to improve on the H91.

    So I have found some info on the smith-horns, and with help from Widget I tried to resize them to 1200Hz.

    I have also made a prototype from MDF, thinking that I would have to do this many times.

    Here are the construction drawings used.
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    Johnny Haugen Sørgård

  2. #2
    Super Moderator yggdrasil's Avatar
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    Some pictures of horns and adaptors.
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    Johnny Haugen Sørgård

  3. #3
    Super Moderator yggdrasil's Avatar
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    Have not been able to try them much. Family you know...


    First impression is H91 - goodbye.

    It will be a hell of a job to redo the baffle...
    Johnny Haugen Sørgård

  4. #4
    Senior Member Ian Mackenzie's Avatar
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    Nice work.

    Very tempting, how did you craft the curves..with a router?

    About the baffles..been there done that...LOL....messy and it tends to be one way trip. I have to say the 2397s were fun but tended to take over at times according to my neighbours. Used correctly however they are most transparent, open and non sounding horn.

    Don't panic, I am not going to hack into the 4345's (yet) next on the list is is quad amping and 275nd drivers.

    I think an array of 2397 style horns would be very interesting, say 250-800, 800-4000, 4000-daylight.

    Ian

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    Administrator Mr. Widget's Avatar
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    Very nice work! I guess if you like them as much as hoped you may want to try a crack at them in a nicer wood. I may have to bang out a set and get some measurements of them....

    Widget

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    Administrator Robh3606's Avatar
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    Those look nice!!!

    Rob

  7. #7
    Super Moderator yggdrasil's Avatar
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    I crafted the curves in two steps, and there might be some problems with my english now, but I'll try.


    Step one I used a cutter to give the edge a 90 degrees curve with the base lowered 4-5 mm.

    Step two I used an angle grinder with a 40 sand paper on to smoothen the transition. Next time this step will be done with a band grinder because I have never ever seen so much dust. I was totally white afterwards.

    I have had a few minutes listening to them today, and I can say for sure that this is a huge improvement.

    Will have to make a pair that is more representable. The rest of the speaker is in pine veneer, so maybe pine is a good solution. Will have to think about it for a while, at least a day or two.
    Johnny Haugen Sørgård

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    Good Work

    I have communicated this to Johnny privately but as I am no expert on Smith horns so thought it worthwhile to canvass publicly. While the horns themselves look great, I am not sure the throats are optimal. The adaptor board has a 1" circular hole which I would guess to be about 1/3" thick. It is then mated with the a sort of rectangular hole which Johhny has somewhat modified to fit with the 1" hole. Would it be an improvement to also shape the hole in the adaptor board so it has no discontinuities with the horn throat?

    This arrangement is quite different from the JBL 2328 adaptor. Not sure what type of adaptor Westlake use on their horns. And Widget posted details of an alternative adaptor, he designed, some time ago.

    I understand the throat design is very important especially for HF response. Can anyone, perhaps Widget, advise on this aspect of the design.

    Regards
    Ted

    PS Johnny, might also be helpful to paint the inside of the throat and adaptor board with a hard varnish or epoxy and sand to get a smooth finish.

  9. #9
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by aust-ted
    I understand the throat design is very important especially for HF response. Can anyone, perhaps Widget, advise on this aspect of the design.


    PS Johnny, might also be helpful to paint the inside of the throat and adaptor board with a hard varnish or epoxy and sand to get a smooth finish.
    Two good points!

    I was surprised the modification to the horn was necessary. I thought it was going to be made 2.54cm tall and not need to be eased. I think this could work well none the less. I do agree that I would try to minimize the mounting plate thickness by using an aluminum plate, but this configuration could work very well as is. Based on my experience, I would expect it to work better at the upper frequencies than one with a 2328, but loose some of the lower frequency performance. As long as there are no discontinuities the HF performance should be fine.

    Widget

  10. #10
    Super Moderator yggdrasil's Avatar
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    I have enlarged the throat area and transtion in this drawing. As you will see when laying the driver throat on top of the horn throat there is actually a very small transition needed. It may be significant with regards to high frequencies, I just don't know. What I do know is that when all these parts were finished the needed transition was very small.


    The mounting plate / adaptor is 14 mm thick.

    Think maybe I will make new and thinner mounting plate / adaptor later, but for now, living in a metric country, I was unable to acquire 1/4" flush screws!

    Actually I made one mounting plate / adaptor on sunday, very eager to get the first listening experience. This was kind of disaster with a rough, uneven inside. After acquiring new tools yesterday I was able to make a better mounting plate / adaptor. The first version gave a hint as of what these horns can do. The second version was a major improvement to the higher frequencies.

    Will do testing shortly, but - I still have phenolics. I have one d16r2425 that I can put in for the test.
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    Johnny Haugen Sørgård

  11. #11
    Steve Gonzales
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    Thumbs up Your're A TIGER!

    Well done Johnny!. I want to tackle this project too. Thanks for posting your results.

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    Very nice. I have been thinking about a similar project, although far into the future. Please post your progress. And thank you for sharing.


    John

  13. #13
    Super Moderator yggdrasil's Avatar
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    BEAUTIFUL!!!!

    Have been listening a little now and then. I can't find words to describe these beauties.

    Won't have time to do measuring until sunday. My wife is 40 and having a major celebration on saturday. Any more speaker work now and I'm dead... Have you ever got the feeling - my wife don't understand me?
    Johnny Haugen Sørgård

  14. #14
    Super Moderator yggdrasil's Avatar
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    Today I finally got the time to do some testing.


    Testing equipment is far from adequate. Will have to get a decent mic and software. Probably also better hardware for signal generation.

    Here's the results with phenolic diaphragm.
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    Johnny Haugen Sørgård

  15. #15
    Super Moderator yggdrasil's Avatar
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    And here's the result with the titanium diaphragm (d15r2425).
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    Johnny Haugen Sørgård

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