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Thread: 900hz Smith Horn for 1.5 Drivers

  1. #1
    Senior Member John W's Avatar
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    900hz Smith Horn for 1.5 Drivers

    I just finished a pair of smith horns for a pair of 2345 drivers, and did some measuring this weekend.

    I started with the design drawn up by yggdrasil in the 1200hz thread. http://audioheritage.org/vbulletin/s...ead.php?t=5454, then scaled it up for a 1.5 in driver, which comes out to 900hz. A lot of the design aspects are covered in the original 1200hz thread.
    I’ve attached the spreadsheet with the modified numbers. If you have a hard time deciphering the spreadsheet, basically:
    • the horns are an arc with a 12.75 inch radius
    • fins are 7.29 inches long and 1.18 inches high
    • the throat is 1.5 inches diameter
    These horns are mahogany and the material is 1in thick.
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    Senior Member John W's Avatar
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    a couple more shots
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    Senior Member John W's Avatar
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    Here are a few in-room response plots from the horns. The first is the horn only, no filter, with the mic about 1 meter away pointed directly at the mouth of the horn. You can see the response gently rises to about 15k then drops off.
    The second is horn only at a little higher volume level, and the mic about 2 meters away. For some reason this flattens the slight rise.
    Finally here is a plot from about 2 meters crossed over to 15” E145 woofers at 800Hz using a Behringer DCX2396 digital crossover flattening out a couple of the peaks, and boosting the VLF response. This is a 2 way setup, the tweeter is not hooked up.

    They sound very good. Especially at moderate volumes (mostly because of the room)
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    Obsolete
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    Looking good!

  5. #5
    Registered User paragon's Avatar
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    Smith

    Very good work ! Good response. Excellent !!
    Love it !

    Eckhard

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    Senior Member spkrman57's Avatar
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    Very nice!

    Shows what good thinking will come up with!

    Ron
    JBL Pro for home use!

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    RIP 2011 Zilch's Avatar
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    Beautiful work, John.

    [And nice measurements, too!! ]

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    Senior Member John W's Avatar
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    Thanks.
    Back to Mr. Timbers notch filter, which I've been trying to figure out.
    I can see the CLR filter to flatten out impedence peaks, and some attenuation. What else is it designed to do? Would most of it bennefit a passive crossover?
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    RIP 2011 Zilch's Avatar
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    It works with either active or passive highpass.

    Recall, for example, how 4430's compensation filter remains in play in the active mode.

    The specific compensation is optimized for a particular driver/horn combination, but the design also illustrates a topology which may be applicable to others, with modifications.

    Unless you're fluent in filter theory, you'll need to put it into Spice to analyze it; the operation of the elements is interrelated....

  10. #10
    Senior Member grumpy's Avatar
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    Nice! I'm glad someone did this.

    It will be interesting to see how long these live in your system
    (as a measure of how well you like 'em).

    -grumpy

  11. #11
    Super Moderator yggdrasil's Avatar
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    Good looking John.

    How do they compare to the 2441/2397 combo you made?
    Johnny Haugen Sørgård

  12. #12
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    Quote Originally Posted by John W View Post
    Thanks.
    Back to Mr. Timbers notch filter, which I've been trying to figure out.
    I can see the CLR filter to flatten out impedence peaks, and some attenuation. What else is it designed to do? Would most of it bennefit a passive crossover?
    This compensation filter was designed for use with an active filter. It can be adapted to work with a passive filter. The shots below show the effects of the notch. Note that there is only one notch filter at present. Systems like the K2-S9800 and DD66000 use three. Notch filters could be added to this filter and then evaluated for performance. One at ~ 5.5 kHz perhaps, but only if it sounds like it needs it. These compensation filters are horn/CD specific.
    Quote Originally Posted by John W View Post
    Behringer DCX2396 digital crossover flattening out a couple of the peaks, and boosting the VLF response.
    Probably the best plan of action for most people.
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  13. #13
    Senior Member John W's Avatar
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    Quote Originally Posted by yggdrasil View Post
    Good looking John.

    How do they compare to the 2441/2397 combo you made?
    They are a lot lighter.
    The combination before was actually using 2440s. I haven't been able to do a side by side comparison, but from what I recall, the 2345s have a lot more detail and I don't need to add on the tweeter to get out to 15kHz.

  14. #14
    Senior Member John W's Avatar
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    Quote Originally Posted by Giskard View Post
    This compensation filter was designed for use with an active filter. It can be adapted to work with a passive filter. The shots below show the effects of the notch. Note that there is only one notch filter at present. Systems like the K2-S9800 and DD66000 use three. Notch filters could be added to this filter and then evaluated for performance. One at ~ 5.5 kHz perhaps, but only if it sounds like it needs it. These compensation filters are horn/CD specific.
    Thanks Giskard, this is very helpful.

  15. #15
    Administrator Robh3606's Avatar
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    Hello John

    Those look great!!! How do you like the 2435's??

    Rob

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