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Thread: Smith Selsted Tweeters

  1. #1
    Senior Member Steve Schell's Avatar
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    Smith Selsted Tweeters

    Hi group,

    Due to the continuing interest in the Distributed Source Horn design pioneered by Dr. Bob Hugh Smith, I thought I would post some pictures of the rare tweeters I was able to buy on ebay several years ago.

    Dr. Smith was a professor at U.C. Berkeley, and was very much a part of the northern CA audio scene from the late 1940s through the 1960s. He authored several articles, made several contributions to the art, and was highly respected. As far as I know he never commercialized any of his designs, but was an audio enthusiast equipped with the skills and education to do significant work. His most lasting work is probably the DSH design, used by JBL (2397) and many others over the years.

    In the late 1940s Smith was fascinated by the prospects of designing a practical tweeter to cover the top octave. At the time there had been very few real tweeters built; most notable were Leo Bostwick's Bell Labs design that was built by Western Electric as the 596A in the early 1930s for their Wide Range systems, and the Jensen model Q. Smith enlisted the help of his friend Walter Selsted, one of the top engineers at Ampex, to help with the project. After numerous prototypes, they built a small run of tweeters to use and to give to friends. They were never sold commercially. Smith and Selsted co-authored an article on the design that appeared in the January 1950 issue of Audio Engineering magazine. If there is some interest I will post the article on this thread.

    Anyway, after I bought these tweeters I contacted Walter Selsted. He was surprised and pleased to hear that any of these tweeters were still around, as they had only built between 20 and 25 of them in 1949.

    As you can see from the pictures, the diaphragm was spun from aluminum. The aluminum wire voice coil has no former, but is mounted directly to the diaphragm to save mass, just as in Bostwick's design. The motor is field coil rather than permanent magnet. The horn is formed from two identical cast aluminum sections. The voice coils of both of these drivers have continuity, but the lead outs need repair. I haven't gotten around to fixing them, so have not heard these units sing yet.
    Attached Images Attached Images      

  2. #2
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    I would love to give it a read!!!

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    Senior Member trueview's Avatar
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    those sure are pretty Steve...
    thanks for sharing

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    Senior Member pelly3s's Avatar
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    those look rather interesting. i would love to hear how they sound

  5. #5
    Senior Member Steve Schell's Avatar
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    Smith Selsted article

    Okay John, here is the article:
    Attached Images Attached Images    

  6. #6
    Dang. Amateur speakerdave's Avatar
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    Thanks for that, Steve. That looks like an idea worth fooling around with. A copy of the article posted or by PM would be appreciated.

    Thanks,

    David

    Edit: You must have been posting while I was writing my response. Thanks.

  7. #7
    RIP 2010 scott fitlin's Avatar
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    Where do you find these things Steve? Amazing!

    They probably will sound terrific, Baby Smith Horns.

    So cool!

    Fix em, and give a detailed report, please!

    scottyj

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    Senior Member jbl4ever's Avatar
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    Awesome work Mr Schell, can you post some dimensions on those horns.
    Very informative article thanks for the knowledge. Boy you are very lucky to find something this rare still around. Thanks Dave

  9. #9
    Senior Member Steve Schell's Avatar
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    Pellys, I agree. I should be shot for not repairing them before now.

    I'm pretty sure that this work by Smith and Selsted was influential in the design of many later commercial tweeters. During the 1950s there were dozens of tweeter designs introduced. The Jensen RP-302 is another noteworthy early effort, likely designed at about the same time as the SS tweeter or slightly after. Two Jensen project engineers wrote an article on the RP-302 that was published in Audio Engineering in 1952 (I think). It was marketed as an add-on tweeter, and was also part of the Jensen G-610 Triaxial system.

  10. #10
    Steve Gonzales
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    oooo-la-la!!

    You never cease to amaze me Steve!. Thank you for a glimpse of rare and INTERESTING technology.

  11. #11
    Super Moderator yggdrasil's Avatar
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    Thanks for posting Steve. I look forward to getting some time to read the whole article carefully.
    Johnny Haugen Sørgård

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    Those would have to take the award for the rarest horn & drivers know to man and complete with documentation!

    Very nice!
    Mike Caldwell

  13. #13
    norealtalent
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    What have I been saying for a year? If they ain't Smith, they ain't horns. Thanks Steve.

  14. #14
    Senior Member pelly3s's Avatar
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    is anyone else thinking what im thinking..... a new lens for ring radiators

  15. #15
    Administrator Mr. Widget's Avatar
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    Steve, you do never cease to amaze!

    Thanks for sharing.


    Widget

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