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  • JBL LX44 Cabinets

    Top o' the day gents! I just got a pair of these speakers from a friend that uses my rehearsal space. They are in great shape, and are fairly stout feeling enclosures. I will hook them up tonight to see how they sound. My question is, for those of you familiar with these speakers, are these boxes of a high enough quality that you would reuse them to build a much higher level of speaker? (drivers, crossover, binding posts) If the answer is yes, what could you see making out of them? Thanks, I'm just contemplating and curious. Glenn.

  • #2
    Well I hooked them up to my bedroom amp and the woofer is blown in one of them. Crackle sputter spit. The voice coil was rubbing and grinding when I hand checked its movement. I'm aware of the internal volume in regards to woofer choice and port size/length as to tuning of the box. The mids and tweets function as they should. I tried to find T/S parameters for the 408G woofer and came up with nada. I am highly suspect as to the factory rating of 91db on the speaker, and the generic driver listed as a replacement from simplyspeakers lists no usable data other than a list of speakers to dump the woofer into. I have read that the woofer was the weakest link in this system, so if I could find a better option to work with the factory crossover, or modify the low pass on the woofer section that would be a possible choice. Keep in mind that I am learning as I go. Glenn.

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    • #3
      Originally posted by Drummer View Post
      Well I hooked them up to my bedroom amp and the woofer is blown in one of them. Crackle sputter spit. The voice coil was rubbing and grinding when I hand checked its movement....
      An aftermarket 408G Recone kit ( w Voice Coil ) runs $28.
      "Not a Speaker Designer - Not even on the Internet"
      “Pride is your greatest enemy, humility is your greatest friend.”
      "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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      • #4
        Originally posted by Sydney View Post
        An aftermarket 408G Recone kit ( w Voice Coil ) runs $28.
        If it were you, Sydney, would you go that route , or change out both woofs to RS225's? I talked to PA's tech department and the 225 was recommended as a replacement drop in. These were free and I don't mind the cost of both 225's if it would be worthwhile from a performance standpoint. Glenn.

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        • #5
          Did they assure you the crossover would need no work if you use RS225s?
          Francis

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          • #6
            Originally posted by Drummer View Post

            If it were you, Sydney, would you go that route , or change out both woofs to RS225's? I talked to PA's tech department and the 225 was recommended as a replacement drop in. These were free and I don't mind the cost of both 225's if it would be worthwhile from a performance standpoint. Glenn.
            I have used recone kits, so for me that is viable, for you probably easier and more sensible to go RS225.
            Also consider they both were probably pushed hard together, one died, maybe the other got injured as well.
            "Not a Speaker Designer - Not even on the Internet"
            “Pride is your greatest enemy, humility is your greatest friend.”
            "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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            • #7
              So... MANY on here have purchased the "DATS" ($100), and SOME here have built a "jig" (as you could) for maybe $15 in parts that lets you use FREE software (ARTA) that would let you measure your good woofer's "T/S parameters". Knowing THOSE would help you find a woofer that would work OK in your cab. Maybe someone near "Indy" would offer to measure your woofer for you?

              For a vented (ported) 1.3cf box, the RS225-8 would go deeper, but at a loss in sensitivity.
              The RS225P-8A (paper version) won't go as low (but likely just as low as the orig.) but plays about +2-1/2dB louder (rated at 88.8dB).
              I'm looking at its rolloff characteristics w/a 2nd order filter: 3.1mH coil and 52uF cap (per the manual).

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              • #8
                Originally posted by Drummer View Post

                ... and the generic driver listed as a replacement from simplyspeakers lists no usable data other than a list of speakers to dump the woofer into.
                I needed new woofers for my Large Advents (originals missing) and looked at the SImply Speaker site. IIRC I found specs for their Advent drop-in" woofers. Models indicated they would not perform well at all in the Advents' 1.55 ft3 sealed enclosure, no way. The RS-225s are great woofers. You could look at MCM speakers sold via Newark Electronics. Great value for the money and they have T/S specs for all and FR graphs for most.

                JBL lists the 2nd order LP for the woofer at 800 Hz. And here's a link to the LX44 tech manual

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                • #9
                  Originally posted by fpitas View Post
                  Did they assure you the crossover would need no work if you use RS225s?
                  Yes. I was told that it would be a direct replacement without having to modify the low pass, but he did say the aluminum cone and it is down a few db from the paper cone RS. Glenn.
                  *

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                  • #10
                    [QUOTE=Chris Roemer;n1374628]So... MANY on here have purchased the "DATS" ($100), and SOME here have built a "jig" (as you could) for maybe $15 in parts that lets you use FREE software (ARTA) that would let you measure your good woofer's "T/S parameters". Knowing THOSE would help you find a woofer that would work OK in your cab. Maybe someone near "Indy" would offer to measure your woofer for you?

                    For a vented (ported) 1.3cf box, the RS225-8 would go deeper, but at a loss in sensitivity.
                    The RS225P-8A (paper version) won't go as low (but likely just as low as the orig.) but plays about +2-1/2dB louder (rated at 88.8dB).
                    I'm looking at its rolloff characteristics w/a 2nd order filter: 3.1mH coil and 52uF cap (per the manual).[/Q

                    So the P looks like the one that I would have to use due to the higher sensitivity. I'm not comfortable going the route of DATS, as I have no idea on how to measure and have a clue as to what I was doing. Do you think that the 91 db rating of the stock system is to be trusted compared to the rating of the Daytons? Thank you for checking that out, I appreciate you taking the time to look into it. Glenn.

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                    • #11
                      Originally posted by Millstonemike View Post

                      I needed new woofers for my Large Advents (originals missing) and looked at the SImply Speaker site. IIRC I found specs for their Advent drop-in" woofers. Models indicated they would not perform well at all in the Advents' 1.55 ft3 sealed enclosure, no way. The RS-225s are great woofers. You could look at MCM speakers sold via Newark Electronics. Great value for the money and they have T/S specs for all and FR graphs for most.

                      JBL lists the 2nd order LP for the woofer at 800 Hz. And here's a link to the LX44 tech manual
                      Thank you. I will do some looking when I can. I've used Human Speakers to do a full rebuild of a beautiful pair of Genesis Physics 210 speakers that were toasted, and they are very enjoyable speakers to listen to. The GP's run the woofer wide open and are spec'd out to use the woofer in a pr box rolloff. I've always wanted to hear the RS drivers based on all the love that they've been shown. Glenn.

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                      • #12
                        I'd have to give the nod to the (paper) RS225P-8A here. It likes 1.3cf (vented) tuned to 40Hz (a 7" long, 3" id "Precision Port" would do the job) with an F3 of nearly 40Hz (besting the orig. woofers "rated" performance of 45Hz?).
                        In the intended use pass band it should deliver +4dB more sensitivity than the aluminum 8" RS 8ohm. I'd highly recommend adding a "bypass" circuit across (in parallel with) the 3.1mH coil. It would consist of an 8ohm resistor (10w) in series w/a tiny 0.68uF cap. This will act as a notch (or "tank") filter to suppress the 3kHz cone resonance by an additional -12dB.
                        Probably a better option than a few other Dayton 8"ers (like the DA215, DC200, and DS215).

                        The mid and tweeter already have some padding resistors, so it would be possible to raise or lower their levels if need be.

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                        • #13
                          Originally posted by Chris Roemer View Post
                          I'd have to give the nod to the (paper) RS225P-8A here. It likes 1.3cf (vented) tuned to 40Hz (a 7" long, 3" id "Precision Port" would do the job) with an F3 of nearly 40Hz (besting the orig. woofers "rated" performance of 45Hz?).
                          In the intended use pass band it should deliver +4dB more sensitivity than the aluminum 8" RS 8ohm. I'd highly recommend adding a "bypass" circuit across (in parallel with) the 3.1mH coil. It would consist of an 8ohm resistor (10w) in series w/a tiny 0.68uF cap. This will act as a notch (or "tank") filter to suppress the 3kHz cone resonance by an additional -12dB.
                          Probably a better option than a few other Dayton 8"ers (like the DA215, DC200, and DS215).

                          The mid and tweeter already have some padding resistors, so it would be possible to raise or lower their levels if need be.
                          You were spot on, Chris. I found a review that said the paper RS made the speakers sound better than new, and that was without modding the lp. PE is out of stock for 20 days so I'll have to wait on the drivers.* I'll let you know how it works out. Any recommendation on specific parts for the tank?* Thanks for helping with your time and expertise. Glenn.

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                          • #14
                            Dr. Roemer cures another ailing patient ....*

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                            • #15
                              #016-8.2 (8ohm 10w resistor)
                              #027-408 (0.68uF poly cap)
                              just wire these in series w/each other, and use them across (in parallel with) the woofer's 3.1mH (iron core) coil.
                              It probably won't sound horrible w/out this mod, but dropping the cone breakup down another -10dB is never a bad thing. Co$t maybe $3-4?

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