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tunings for JBL 4751

roobart2000roobart2000 Posts: 4
edited January 2007 in PA General Discussion
Hi can anyone help with the tunings for JBL4751 :D


  • GadgetGadget Posts: 4,915
    well, I couldn't find ANYTHING about this speaker...nada.. zip... zilch, and thats very odd.. are these really old? usually there is SOMETHING somewhere, not this time...so unless there is someone with these also (very slim possibilities) you are going to have to provide as much info as possible about them... OR try and get JBL to help(lotsa luck there).
  • Hi Gadget
    It's a UK Model from the old sound power concert series from the late 80's

    in the states it's known as 4851 same cab different model number

    it's a trap box with 2 x12\" 1 x 2\" Horn & 2 Baby bums

    Bi amped cab with passive x-over on the tweeters
  • GadgetGadget Posts: 4,915
    So this box has the 7K -22K baby butt cheeks,
    and they are crossed to a 500 hz to 16K exponential horn (2380A) with a passive crossover...and the 2204 woofers with a 3db down point of 50 hz...I believe they don't cross the horn that low (500hz) I would guess 750-1000 hz probably the later...the driver would last longer the higher you cross. The driver I just found and its a 2\" diaphram which means I'd probably cross closer to 1200 hz.. the power handling @ 500 hz is 100 watts, at 100 hz its 150 hz...All components are negative.. that means with a positive signal at the black terminal the diapram/cone will move out away from the magnet...

    With the driverack its not too difficult to experiment a little. I would start at 1200 hz with an L/R 24 filter. I'd sweep through the delay on the horn and land where it sounds the best.... they would perhaps know this model at the prosoundweb.com LAB (live audio board) they are pro's there and a lot more of them so please be careful what you say... they EAT newbies with impertinent questions..read a bit and learn first. Let me know if there's anything else I can do...

  • Hi Gadget. with a bit of searching I've found these plans

    http://www.jblproservice.com/pdf/Sound% ... /4770A.pdf. the 4771 has the 2 x 2404H tweeters added

    the subs i'm using with them are

    http://www.jblproservice.com/pdf/Sound% ... /4785A.pdf

    I'm currently using a Crest P4801 on the hi's and 2 C Audio SR707's 1 on mids & 1 on subs,
    the plans clearly state the x-over settings,
    so I'm realy after any PEQ settings you might have
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