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  • JBL PRX718XLF crossover question

    JBL says the internal crossover of the PRX718XLF is 100 Hz DSP controlled 48 dB slope. OK I get that. Then they say the loop out crossover is 120 Hz analog 24 dB slope. So does that mean the crossover to cut off the lows is a different frequency and slope than the one bringing on the highs? This isn't something I've ever seen before. I'm assuming this was done for a reason and JBL thinks there is a benefit. What are the pros and cons of this?
    PA: JBL PRX712, PRX718XLF, RCF 745-A, 522-A, 310A, A&H Qu-16
    Lights: AMDJ Dotz TPAR, Haze Generator, Chauvet GigBAR
    www.nextexitrocks.com | wedding band | Columbus, OH | VIDEO

  • #2
    Remember it's not the way the electrical filter operates but the resulting acoustic result that actually counts.

    There's nothing inherently wrong with using asymmetrical filters. In theory a steeper slope will give you a bit more protection to over excursion but it will come in practice with the penalty of ringing which will sound bad and may in fact create enough extra output to actually increase the chances of over excursion.



    I would assume that the engineers decided to do it the way they did for a good reason. At least to them it was a good reason

    Don Boomer

    Comment


    • #3
      I'm not quite sure of the benefit of using an analog high pass output when coupled with the latency of a DSP based low pass output. It seems like more work than necessary and not a great way to marry up one system to another... except that I can see 2 wrongs making a right here...

      IF the top cabinet also has DSP, and it uses the same platform, the latency correction may be taken care of in the top cabinet's processing. There may also be a HPF in the top cabinets that works with the 24dB slope of the HP out, and the underlap may be the correction for nominal sub gain above unity.

      IMO, there are better ways to handle this that would be more universal when using other manufacture's tops, or mixing and matching with some of their other powered speaker products, but like Don said... to them it was a good reason
      Last edited by agedhorse; 05-21-2014, 12:03 AM.
      -------------------------------------------------------------------------------------------------------------------------------------------------------------------
      Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

      Currently product development engineer: Mesa Boogie

      Comment


      • #4
        I'm voting for, "we happened to have these parts in stock".
        .....

        Comment


        • #5
          Originally posted by Craig Vecchione View Post
          I'm voting for, "we happened to have these parts in stock".

          Really? You really think JBL designs a completey new amp and processing unit for a new line of speakers based on left over parts in stock?

          Comment


          • #6
            Make that "completely". Why in the world won't this site let me edit my own post for spelling?????

            Comment


            • #7
              I'm only notified of threads I start.... not anything I'm subscribed to. Not anything I respond to. Not private messages. I have to rummage through threads to see updates. It's why I only come here a few times a week instead of several times a day.
              PA: JBL PRX712, PRX718XLF, RCF 745-A, 522-A, 310A, A&H Qu-16
              Lights: AMDJ Dotz TPAR, Haze Generator, Chauvet GigBAR
              www.nextexitrocks.com | wedding band | Columbus, OH | VIDEO

              Comment


              • #8
                Originally posted by sibyrnes View Post
                Make that "completely". Why in the world won't this site let me edit my own post for spelling?????
                Because they used parts that they happened to have left in stock
                -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

                Currently product development engineer: Mesa Boogie

                Comment


                • #9
                  Originally posted by agedhorse View Post
                  Because they used parts that they happened to have left in stock
                  Good one! I'm glad my JBL equipment performs better than this forum!

                  Comment


                  • #10

                    Originally posted by sibyrnes View Post


                    Really? You really think JBL designs a completey new amp and processing unit for a new line of speakers based on left over parts in stock?
                    No, not really. I was joking.
                    .....

                    Comment


                    • #11
                      Originally posted by Craig Vecchione View Post


                      No, not really. I was joking.
                      I suspected that, but you know it's hard to tell without a smiley

                      Comment


                      • #12
                        A little Memorial weekend G.A.S. and now I have a pair in my garage.... sigh. I've wanted "real subs" for a long time. These supposedly are +/-3dB to 35Hz, which is half an octave lower than anything I've ever owned. They sound ok as I fart around in the garage. I have a wedding tomorrow and will probably use them.
                        Last edited by abzurd; 05-25-2014, 09:56 AM.
                        PA: JBL PRX712, PRX718XLF, RCF 745-A, 522-A, 310A, A&H Qu-16
                        Lights: AMDJ Dotz TPAR, Haze Generator, Chauvet GigBAR
                        www.nextexitrocks.com | wedding band | Columbus, OH | VIDEO

                        Comment


                        • #13
                          Originally posted by abzurd View Post
                          A little Memorial weekend G.A.S. and now I have a pair in my garage.... sigh. I've wanted "real subs" for a long time. These supposedly are +/-3dB to 35Hz, which is half an octave lower than anything I've ever owned. They sound as I fart around in the garage. I have a wedding tomorrow and will probably use them.
                          LOL!

                          I would be interested in your assessment. My 618S-XLF's have been quite good to me. I really like the clean punch they have. I would say that it took some getting used to this kind of sound since both my folded horn's and the CVA118's I had been using were both much "woofier". Now I find the boomy sound of most subs "less musical".
                          With Greater Knowledge Comes Greater Understanding

                          Comment


                          • #14
                            I'm taking off in a bit for a wedding where I'll use them for the first time. The weight is manageable for one person, but the size not so much. I'm only 5' 7" so it's hard to grab the handles and move it solo. I did it, but I'd rather not.

                            Check out the size difference from what I've been using. I usually use 2 of the small subs, per side, but not always. I'm sure I'll notice the difference, I better, but I have to say pound for pound the little FBT Vertus subs are pretty darn good.

                            Nice, the pic loads sideways.... why would I expect anything else?

                            Last edited by abzurd; 05-25-2014, 10:07 AM.
                            PA: JBL PRX712, PRX718XLF, RCF 745-A, 522-A, 310A, A&H Qu-16
                            Lights: AMDJ Dotz TPAR, Haze Generator, Chauvet GigBAR
                            www.nextexitrocks.com | wedding band | Columbus, OH | VIDEO

                            Comment


                            • #15
                              I am 6 ft and can handle one by myself ..... but I prefer not to. It isn't the weight, but rather (as you pointed out) the size.

                              I can't see the pic's abzurd.

                              Hope your wedding was a success. Next month I have a big workout for me. 3 weeks in a row ending with a gig for the Scorpions (the motorcycle organization .... not the band ). I should get plenty o
                              of opportunities to carry my XLF's around.

                              I replaced my VHT tube amp and cabs (which was the heaviest thing left in the band) and bought a Kemper (11 lbs). I am looking forward to my new (even smaller and lighter) stage setup.

                              I would be surprised if your new XLF's don't have a noticeable increase in bass output over your old rig. Let us know how it went!
                              With Greater Knowledge Comes Greater Understanding

                              Comment



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