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New amps, blew 18sub need advice

Discussion in 'Live Sound [BG]' started by mward69, Sep 27, 2009.


  1. mward69

    mward69

    Jan 20, 2007
    Conyers, GA
    Hey folks, so my cover band has a Peavey PA system. The mid highs are 2-15's /horn and 1-18. I think the system are the SP-4s
    Now...singer bought 2 new amps..behringer europower 4000's :crying:
    We hooked one to drive the mid-highs left/right {2000w each} the speakers are 4ohms, ran fine all night...HOWEVER..the 18's which are 8ohms, we're ran via bridge mono using banana clips plugged in +1 and +2 {or the 2 red plugs} well, started smelling that famous electrical smell and by the 3rd song last night.lost the stage right 18...we unplugged it, the stage left 18 ran for 3 more hours without any issues....any reason you sound guys can think why this happened?
    The rating for the 2 -15's are 2000 watts rated
    the 18s are around 1000
     
  2. modulusman

    modulusman Banned

    Jan 18, 2004
    montana
    The Behringers output at 4 ohms bridged is 4000 watts and your running it into a pair of speakers rated for half that.
     
  3. mward69

    mward69

    Jan 20, 2007
    Conyers, GA
    I understand that part..but the amps were only ran at the 10-11 o'clock position, thought behind it was having more juice would mean not having to push the amps as hard a the old ones we were using when we had to crank to full....
    Why did it only smoke the 1 sub and not the other? The banana clips were plugged in "stacked" if that makes since...
     
  4. GregShadoan

    GregShadoan

    Sep 1, 2008
    Oregon
    Sounds like the speaker got too much power. Bridge mode on those things are 4000 watts into 4 ohms, which means that you were feeding 2000 watts per speaker, about double their intended rating, which is fine, if they happen to be up to it, and the amp isn't getting hit that hard.
    Most likely the speaker that blew was already comprimised in some way. When the bad speaker was unplugged, you were sending 2800 watts into the one 1000 watt speaker.
    That is if the amps specs are to be believed. My guess is also at that point you were not hitting the one you left as hard, ie. you maybe turned it down, or something.

    It might be a good idea, to get an intelligent crossover/ DSP unit to get limiters for this rig. Get the speaker repaired with goods parts at a reputable shop, and try it again. This could become a nightly occurance, unless you take some steps. Until then I recommend you just run the amp in stereo mode. Connect both 8 ohm speakers off one channel, or one per channel. Either way they will be getting about the same power. Also, make sure you NEVER see a red light on that amp. It might also be a good idea that the speaker wires are matched. Guage=12, and length is the same.
    Optimitly, it would be best to add 2 more of the subs, and run the system in stereo or parrallel, with 2 4 ohm loads. I am not an amp expert, but Bridge mode can get wonky. I never use it, ever. Every time I have, bad things have happend.
     
  5. modulusman

    modulusman Banned

    Jan 18, 2004
    montana
    Doesn't matter where you have the attenuation knob set on the amp. It can still put out full power. The other speaker may be damaged just a matter of time before it fails.:rollno:
     
  6. Micky-D

    Micky-D

    Apr 7, 2009
    Townsville
    We seem to see this quite a bit, and the fault often lies in the fact that the front attenuation control is NOT A VOLUME KNOB.

    As it has been said before in the thread, just because you have backed off the attenuator does not mean the amplifier cannot reach full power. The gain knob does not set maximum volume.

    To prevent this happening again, go and buy a Limiter, and limit those hot signals to something your drivers can handle.

    Cheers,
    Mick
     
  7. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Song Surgeon slow downer. https://tinyurl.com/y5dcuqjg
    * 2 x 2,000 Watts into 2 Ohms; 2 x 1,400 Watts into 4 Ohms; 4,000 Watts into 4 Ohms (bridge mode)
    * Precise Power, Signal and Clip LEDs to monitor performance
    * XLR and 1/4" TRS input connectors for compatibility with any source
    * Professional speaker connectors and "touch-proof" binding posts support most speaker wiring systems
    * Selectable low-frequency filters (30 Hz or 50 Hz) remove distracting infra-sound frequencies
    * Independent limiters per channel offer reliable protection against overload and distortion
    * High-current toroidal transformer for ultra-high transient response and absolute reliability
    * Ultra-reliable Toshiba/Fairchild power transistors
    * Independent DC and thermal overload protection on each channel automatically protects amplifier and speakers without shutting down the show
    * "Back-to-front" ventilation system including air filter for reliable operation
    * "Built-like-a-tank," impact-resistant, all-steel 2U rackmount chassis
    * High-quality components and exceptionally rugged construction ensure long life
    * Conceived and designed by BEHRINGER Germany

    from: http://www.behringer.com/EN/Products/EP4000.aspx

    Manual
     
  8. totallybacan

    totallybacan

    Mar 30, 2009
    21804
    It helps having a built in limiter, but it's no use if they are still set above what the amps can handle.
     
  9. RicPlaya

    RicPlaya

    Apr 22, 2003
    The Mitten
    1.5-2 x the RMS is a standard power ratio to run your cabs with. So 4000 watts into a 1000 watts cab? Yeah you fried it. 1500-2000 watts would be optimal.
     

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