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Thread: How far down in frequency will the JBL 2482 (phenol) load on a 140 Hz tractrix horn?

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    How far down in frequency will the JBL 2482 (phenol) load on a 140 Hz tractrix horn?

    Hi,

    I consider getting a pair of JBL 2482 (phenol) drivers, but only of they load down to 200 Hz (or lower) on a pair of 140 Hz tractrix horns (my bass horns don't sound good above 200 Hz). Will the 2482 do that?

    Thanks!

    Best regards
    Peter

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    Hi Peter,

    The 2482 data sheet specs say it's usable range is from 300Hz as is its lowest recomended frequency. It is one hell of a tough driver but I wouldnt like to run it any lower.

    Allan.

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    Senior Member Hoerninger's Avatar
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    Hi Peter,

    even with a proper hornloading the drawbacks are dissortion and small sound pressure level at the low end. Even worth - you risk damage I suppose.

    For the low/mids it is better to use a cone driver with the horn.
    Do you have any pics of your horns?
    ___________
    Peter

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    Hi Hoerninger and Allan,

    Thanks for your replies! Just to clarify, I will only use the driver for home use (not PA), and I can use high order (digital) active high pass on the driver/horn. I have no pictures, sorry. I will not go for the horns, if the combo will not load down to 200 cycles or below!

    Best regards
    Peter

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    Senior Member Hoerninger's Avatar
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    Quote Originally Posted by PeterK View Post
    I can use high order (digital) active high pass on the driver/horn.
    This will not prevent from (much too?) large excursions in the low range. You simply have to try it out.
    I will not go for the horns, if the combo will not load down to 200 cycles or below!
    Too bad there are no pictures. In case you did not built the bass horn yet, what about this one, I used it up to 500 Hz (with a slight decrease). There were built four but In a living room one per side are sufficient.
    ____________
    Peter

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    Hi Peter,

    Thanks for responsding. Well, I thought you meant the 140 Hz low-mid horns:-) The bass horns are built!

    Here is a picture (the bass horns are the same, the mid/high horns are no longer the same):
    http://gallery.audioasylum.com/cgi/u...=&w=1000&h=750

    Best regards
    Peter

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    Jbl2482

    Hi PeterK & Allan & Peter .....
    My practical long use 2482 on a WE66A horn....
    It's a "acousical-musical illusion" to go down below 300Hz ....
    If so you have a real "dip" in music (micro) information & acoustic power (& mismatch).....
    In fine: Respect the tech data sheet Fxover 300Hz (or higher) even in "domestic" use ...(cfr.: Allen) ...
    Allez, salukes and good musical experiences.
    Karel

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    Hi Carolus and all others!

    Thanks for your reply, Carolus. Well, I guess I have just have to drop the idea then! Thanks to all for taking the time to respond!

    Best regards
    Peter

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by PeterK View Post
    I consider getting a pair of JBL 2482 (phenol) drivers, but only of they load down to 200 Hz (or lower) on a pair of 140 Hz tractrix horns...
    Are your tractrix horns 70Hz cut off or 140Hz cut off. I ask because many people don't realize that the cut off frequency must be at least one octave below the lowest crossover frequency. To get a horn loaded midbass down to ~140Hz, there are some crazy expensive solutions from ALE Acoustics, but I think your best bet would be to use a 10-12" horn loaded cone driver.


    Widget

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    Dang. Amateur speakerdave's Avatar
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    There's also a rare Emilar.

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    Thanks for responding Speakerdave and mr. Widget!

    Mr. Widget:
    I haven't got the tractrix horns yet (and I doubt that I will now that it turns out that the whole idea may be based on a wrong premise). The tractrix horns I had in mind was 140 Hz horns (not 70 Hz horns) from Stereo Lab (Germany).

    At the moment I am actually using a horn loaded cone, but, as you know, some of us can't help thinking about possible improvements.-)

    Speakerdave:
    I remember that Mike Bates (aka 'Magnetar' on the AA board) had a pair of 6" EC600 Emilar compression drivers on very large horns at some point. These may be the drivers/horns you are thinking about. The ones I am thinking about sure looked great by the way:-)

    Once again, thanks for your help! I guess my idea is history now!

    Best regards
    Peter

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    Senior Member spkrman57's Avatar
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    Cone driver in horn for that low a frequency

    Here is a prototype I threw together using a midhorn and Eminence Delta 10A that is -3db @ 300hz and -10db @ 150hz. You can just see the dustcap in the pic of horn in the middle.

    Regards, Ron

    Forgot to add: this is a conical horn. A tractix horn for the same flare frequency would only work down to approx 400hz.
    Attached Images Attached Images  
    Last edited by spkrman57; 03-01-2009 at 11:45 AM. Reason: added info
    JBL Pro for home use!

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    Senior Member Hoerninger's Avatar
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    Quote Originally Posted by PeterK View Post
    At the moment I am actually using a horn loaded cone, but, as you know, some of us can't help thinking about possible improvements.-)
    Good alternatives are nevertheless
    18Sound6ND410 and
    AUDAX PR 170 M0
    Both are very high efficient 6 inch cone drivers.
    ___________
    Peter

  14. #14
    Dang. Amateur speakerdave's Avatar
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    Might also be worthwhile studying JBL's use of horn-loaded cone midranges recently in sound reinforcement products. They have a couple of special drivers for that, one being the 8" 2250.

    http://www.audioheritage.org/vbullet...highlight=2250

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    Senior Member Steve Schell's Avatar
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    PeterK I think you are on the right track. You have been given some good and conservative advice, but my tendency would be to build it and try the results. You are unlikely to harm the 2482 as long as it is adequately loaded by the horn. This driver is intended for very high output down to 300Hz., so 200Hz. shouldn't stress it in a home system. The longer the horn and slower the flare the better. Haven't measured a 2482, but an Altec 290 phenolic driver on a plane wave tube is flat to 100Hz. or so. If you can make this work you will enjoy the dynamics, attack and clarity of a compression driver down to 200Hz., a very worthwhile goal.

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