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Thread: JBL L150 speaker help

  1. #1
    Royd
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    JBL L150 speaker help

    I won a pair of L150A cabinets w/crossovers on eBay. I have 044, 044ti, le5-2, le5-5, le5-9, 104h-2, 122A, 123A, 2213, loose drivers. I don't have the passive radiators. Is it possible to install a pair of functional woofers where the passive radiators should go? Can they be wired so that both woofers in each cabinet would work, or is the passive radiator mandatory? Thank you for your assistance.

  2. #2
    Administrator Robh3606's Avatar
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    Well until you get them why not figure out the port needed for that cabinet size and just make a cover plate with a port?? Then you have a functional design where if you try the passives and don't like them you can always go back to just a simple reflex port.

    Rob

  3. #3
    Royd
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    JBL L150 Help

    That sounds like a plan. Since I have so many loose JBL 12" drivers, I was wondering if 2 woofers would be better than 1 woofer and 1 passive radiator. Thank you.

    Originally posted by Robh3606
    Well until you get them why not figure out the port needed for that cabinet size and just make a cover plate with a port?? Then you have a functional design where if you try the passives and don't like them you can always go back to just a simple reflex port.

    Rob

  4. #4
    RIP 2011 Zilch's Avatar
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    Re: JBL L150 speaker help

    Originally posted by Royd
    Is it possible to install a pair of functional woofers where the passive radiators should go?
    Yes, BUT,

    1) Unless the them woofs are 16 ohm, the impedance gonna be wrong for the crossovers, and,

    2) You'll have to cut a port to tune the box and perform the function of the passive radiator.

    SO, bad idea probably.

    Not gonna hurt anything to try it on an interim basis, tho.

    Maybe just use speakers in place of the passives without hooking them up. Tuning will be wrong, but, again, we're talking "interim," no?
    Last edited by Zilch; 10-03-2004 at 09:49 PM.

  5. #5
    Royd
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    Re: Re: JBL L150 speaker help

    Good point about the 16 ohm requirement. Look like 2 8 ohm woofers will not work. I'll have to shop eBay for the PR300 radiators, or try fashioning my own ports. Thank you.

    Originally posted by Zilch
    Yes, BUT,

    1) Unless the them woofs are 16 ohm, the impedance gonna be wrong for the crossovers, and,

    2) You'll have to cut a port to tune the box and perform the function of the passive radiator.

    SO, bad idea probably.

    Not gonna hurt anything to try it on an interim basis, tho....

  6. #6
    Senior Member GordonW's Avatar
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    If you strike out trying to find PR300s to buy, I may be able to build you something functionally equivalent. Since it's a passive, the basket isn't that important... a generic 12" basket would work OK, as long as it'll fit into the cabinet. That, loaded with a JBL-spec 12" cone and spider (like that used to recone a 128H) and set up with the right hardware to allow mass adjustment plates/washers to be installed, should probably work.

    That, and the pair of 122A woofers you have, should work OK in those cabinets. The 122A isn't that terribly much functionally different from a 128H (a little more mass on the cone, so it's like a fractional dB less efficient than the 128H)...

    For a midrange, I'd be inclined to try the 104H-2. Should be more like the sound of the LE5-12 that was in the later model L150s.

    As for tweeters- rather than cutting up the cabinets, I'd be inclined to find someone where you could buy/trade for a pair of 033 or 034 tweeters. But, if you wanted, there's no reason that pair of 044 tweeters shouldn't work- you'd have to turn down the L-pad on the tweeter lower than stock, but it should work.

    Regards,
    Gordon.

  7. #7
    Royd
    Guest

    JBL L150 help

    Thanks for the offer on the passive radiators. I'll be in touch if nothing shows up on eBay. In the meantime, would putting in a woofer without hooking it up work? Thank you.

    Originally posted by GordonW
    If you strike out trying to find PR300s to buy, I may be able to build you something functionally equivalent. Since it's a passive, the basket isn't that important... a generic 12" basket would work OK, as long as it'll fit into the cabinet. That, loaded with a JBL-spec 12" cone and spider (like that used to recone a 128H) and set up with the right hardware to allow mass adjustment plates/washers to be installed, should probably work.

    That, and the pair of 122A woofers you have, should work OK in those cabinets. The 122A isn't that terribly much functionally different from a 128H (a little more mass on the cone, so it's like a fractional dB less efficient than the 128H)...

    For a midrange, I'd be inclined to try the 104H-2. Should be more like the sound of the LE5-12 that was in the later model L150s.

    As for tweeters- rather than cutting up the cabinets, I'd be inclined to find someone where you could buy/trade for a pair of 033 or 034 tweeters. But, if you wanted, there's no reason that pair of 044 tweeters shouldn't work- you'd have to turn down the L-pad on the tweeter lower than stock, but it should work.

    Regards,
    Gordon.

  8. #8
    Administrator Robh3606's Avatar
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    It might but you would be much better off tunning the box correctly instead of hit or miss. You really won't know what you have going that way. Do you have software?? All you need to do is plug in the woofer you want to use and then change the box volume to your box size. Then adjust the tunning frequency to see what the response will be.


    http://www.linearteam.dk/default.aspx?pageid=winisd


    That is a link to WinIsd. It's a free box program you can use to play around with. Your bass drivers are all preloaded all you have to do is select them from the driver database.

    Rob

  9. #9
    Alex Lancaster
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    Smile

    Since You have them, I would try the woofer as a PR, tell us how You like it.

  10. #10
    Administrator Robh3606's Avatar
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    OK

    Here are the numbers to port. Using 2 2" ports 5.23 long 3.97 Cu Ft. 25Hz

    Rob
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    Last edited by Robh3606; 10-04-2004 at 02:12 PM.

  11. #11
    Senior Member DavidF's Avatar
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    The closest match to box and components seems to be the 122A woofer (close to 128H in spec), 104h mid (similar acoustically to LE12), and the 044 tweeter (actual driver). I would not suggest using another woofer, unconnected electrically, as a passive substitute. The mass loading would be too low and would not compliment the bass response without modifying the woofer. A round plate fitted to screw into place over the hole for the passive would work much better, with a vent 4 inches in diameter and 6.5 to 8.5 inches in length. This could easily removed if later you find a pair of original passives or you use another make.

    David F

  12. #12
    RIP 2011 Zilch's Avatar
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    All right, smarties,

    What passive network could be connected to the teminals of a speaker substituting for a passive radiator to "tune" it for desired performance?

  13. #13
    Royd
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    JBL L150 speaker help

    I'm amazed at the knowledge base here. I really appreciate all the advice from you experts. I'll try the 2nd woofer first as an experiment. If that doesn't sound good, I'll purchase some wood and plastic pipe to fashion the baffle cover and port. I still haven't given up on getting a pair of passive radiators, but I now have other options. Thanks again.

  14. #14
    Senior Member GordonW's Avatar
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    Man, actually, you guys are right... the 044 IS the right tweeter. Dunno where I got it in my head from, that it was an 033. No futzing about required- just bolt the 044 in!

    As for the PR- does anyone have the cone assembly effective moving mass measurement on a factory PR300? If so, it'd be EASY to duplicate it. As long as the mass and cone area are right, nothing else will matter much...

    Regards,
    Gordon.

  15. #15
    mrbluster
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    ME120HS

    Any thoughts on using one or more Me12OHS drivers in a L150 I have T/S parameters, If someone could cruntch the numbers for me. Also, what about sub dividing the cabinet Ala K2 S5500 and using Two woofers?

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