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JBL PRX 418s blown I think?

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  • JBL PRX 418s blown I think?

    Saturday  a week ago My Band played at a nice venue which had their own PA and a sound tech.  Anyway, when I got there, the sound guy didn't show up, so they asked me if I would help them out.  God, what a mess, I have never seen a bigger mess of chords, tangled and wrapped around each other. I've seen over cooked spaghetti that looked better. I noticed there wasn't any low end, but I thought I'm not going to bother with this mess. So I went ahead and dialed everyone in, the best I could. Put my wife on the mixer, tuned up my bass and just played some music, got paid and went home, end of story. Nope, I get a call this week, sound guy a no show, asked me  to run sound. I said, OK but I'm not going to trouble shoot at the last minute. I get there 5 minutes before show time. Anyway, checked things out and no low end. I walk over and look at the rats nest and I could see the pw amp was getting a signal and that's as far as I went. No way was I going to try to get behind that rack. So I finished the night, got paid and grabbed my stuff and was about ready to go home and the manager ask me if I would stop in soon and see why the subs weren't working. They offered to pay me, but I said, I would take a look as a favor. It seems that the speakers (subs) are gone. I unplugged one sub and plugged the speaker cable into another speaker and it worked. So tomorrow I'll take the speaker out, test it with my ohm meter. I wonder do those subs have a fuse or any type of protection before the speaker? PS they have a crown xls or xti 4002  on each sub bridged, from what I can see, way way to much power right?


  • #2

    Yes, WAY too much power, especially in a less supervised situation. Remember these are 4 ohm boxes with 600 watt (RMS) rated drivers that are best powered with ~800 watts unless really good DSP limiting and HPF are applied. The XTi-4000 is rated at 3200 watts into 4 ohms bridged. Very dumb choice IMO. Stereo would be about right.

    Comment


    • Stingray5
      Stingray5 commented
      Editing a comment
      Thanks will pass it on.

  • #3

    Stingray5 wrote:

    Saturday  a week ago My Band played at a nice venue which had their own PA and a sound tech.  Anyway, when I got there, the sound guy didn't show up, so they asked me if I would help them out.  God, what a mess, I have never seen a bigger mess of chords, tangled and wrapped around each other. I've seen over cooked spaghetti that looked better. I noticed there wasn't any low end, but I thought I'm not going to bother with this mess. So I went ahead and dialed everyone in, the best I could. Put my wife on the mixer, tuned up my bass and just played some music, got paid and went home, end of story. Nope, I get a call this week, sound guy a no show, asked me  to run sound. I said, OK but I'm not going to trouble shoot at the last minute. I get there 5 minutes before show time. Anyway, checked things out and no low end. I walk over and look at the rats nest and I could see the pw amp was getting a signal and that's as far as I went. No way was I going to try to get behind that rack. So I finished the night, got paid and grabbed my stuff and was about ready to go home and the manager ask me if I would stop in soon and see why the subs weren't working. They offered to pay me, but I said, I would take a look as a favor. It seems that the speakers (subs) are gone. I unplugged one sub and plugged the speaker cable into another speaker and it worked. So tomorrow I'll take the speaker out, test it with my ohm meter. I wonder do those subs have a fuse or any type of protection before the speaker? PS they have a crown xls or xti 4002  on each sub bridged, from what I can see, way way to much power right?


    sorry about the OT but are you interested in selling your Proels?

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    - Hughes Kettner Edition Tube 20 (the early Voxy sounding one) Sounds &amp; looks good. $250 + shipping. <b>SOLD</b><br />
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    Comment


    • Bugzie
      Bugzie commented
      Editing a comment

      Tbone    where are you located?


  • #4
    Of course there's more to the story... There always is dang generally it's most amusing and sad at the same time.

    Comment


    • Stingray5
      Stingray5 commented
      Editing a comment

      Well, I went over to the club today and had the speaker recon guy meet me there. We took out the subs and ran my ohm meter on them while the owner stood and watched, totally open. Got a call from the speaker repairman later and he told me they were really fried, but most of you already new that. Here is how pitiful this is, the owner told me a guy from Guitar Center did the installation, over $30.000.00 worth. In my opinion, 2 PRX powered speakers and 2 PRX 118 powered subs would have done the job. I this place is not that big. Another sign that gave me the impression that he was ripping him off, a Sonic maximizer!!! Didn't spell that right sorry. The story will continue tomorrow going to get some sleep, good night everyone. 


  • #5
    I see this kind of thing regularly.

    Comment


    • #6
      It's cheaper and just as effective to choose the right sized amp with internal limiter. This is exactly how the defend device works. It's a power side pwm limiter.

      Comment


      • twostone
        twostone commented
        Editing a comment

        agedhorse wrote:
        It's cheaper and just as effective to choose the right sized amp with internal limiter. This is exactly how the defend device works. It's a power side pwm limiter.

         

        Not sure how the limiters work on a amp but the D-fend raises the ohms so the amp doesn't send the driver a huge amounts of voltage cause by a square wave coming into the amp.

        Anyway doesn't matter and was just food for thought.


    • #7
      Yup, 1600 watts in that kind of installation is just going down the same road. Way too much power STILL

      Comment


      • Stingray5
        Stingray5 commented
        Editing a comment

        This is what JBL recomended. They had 2400 wts going in the subs and 1150 into the tops. each I was thinking maybe 7 or 8 in the subs and 500 in to each top but I figured I'll go with what they said especially since I didn't want any legal action blaming me. Looking back I should have demanded he have Guitar Center come out and fix it. Dumb Me!!


    • #8

      Half way through the show the BE says..."Whats that burning smell? You smell that?"

      2X power is assuming the operaters of the system know what limiters are, and how to set them.

       

       

      Comment


      • #9
        JBL is not the only manufacturer doing this. The advice is poor IMO, but there is plenty of poor advice out there, and you of all people have been guilty of offering some if the poorest advice on this forum with regard to powering speakers.

        Comment


        • RoadRanger
          RoadRanger commented
          Editing a comment

          agedhorse wrote:
          JBL is not the only manufacturer doing this. The advice is poor IMO, but there is plenty of poor advice out there, and you of all people have been guilty of offering some if the poorest advice on this forum with regard to powering speakers.

          Feel free to post links to my posts doing that . The only thing close to that I can think of is the PV118's driven by 500w each belonging to a band I was BEing for (now defunct ). They were willing to use what they had at the volume they needed with the understanding that the drivers might blow at any time. I have no problem with folks abusing their crap (or abusing it for them ) as long as all understand the risks and it doesn't fall back on me if/when they cook . I think you even told me you had some custom Omega Pros (or somethin') that would work in those cabs when they finally blew? Actually turned out those 200wrms rated subs have 300wrms drivers in them - Peavey derates them so that they can publish a 400w program rating for them, kudos to Peavey for that .

          And yes, all the manufacturers are doing that - my point was that JBL is not differentiating themselves from the others so gets no respect from me on that point. OTOH their differential drive LF drivers are awesome tech - too bad the shortage of neo has caused them to drop the SRX line .


      • #10
        It's the poor running of gear aided by an excess of power that's responsible for a majority of problems IMO.

        I understand the power test. When the numbers it returns suggests that the driver is more robust than it really is, it opens the door to damage by those who may be educated beyond their own intelligence.

        Comment


        • dboomer
          dboomer commented
          Editing a comment
          Sorry Andy ... I was responding to a different post. It appears with the new format responses don't get threaded correctly. The other problem is apparently you cannot quote a post from an iPad ( someone enlighten me please)

          So basically what we are both saying is don't expect pro proformance without pro knowledge. If you don't have pro knowledge ( and why should you if you are a musician) then buy self powered speaker systems. Then you won't have to worry about it and you can simply go play music. Why get bogged down?

          If you know what you are doing then using an amp that can deliver 2x or 4x power will return max performance with minimal risk of failures. Otherwise don't give loaded guns to children
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