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playing trough PA?

Discussion in 'Amps and Cabs [BG]' started by therex, Sep 26, 2008.


  1. therex

    therex

    Jun 24, 2007
    lima
    is it safe? the PA is a crate 150 watts of power, and the speakers are peaveys of 300 watts
    the speakers are 15"
    BTW this is just for band practice
     
  2. rbonner

    rbonner

    Sep 25, 2008
    I remember 1969 with my HS garage band before we had a PA, we plugged the vocals into my Bassman because it had a second channel. The bass cut up the vocals really bad. Will you kill your PA? NAH. But these days I'm for having as much power in the bass rig as possible and not even miking the bass into the pa when everybody else is. If you need a practice amp go spend $250 bucks and get one. :) BOB
     
  3. therex

    therex

    Jun 24, 2007
    lima
    is not that i need it
    but it will be ok for bandpractice right?
     
  4. rbonner

    rbonner

    Sep 25, 2008
    If it sounds like the speakers are tearing in half turn it down. Sure it will be OK. BOB
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The bass is in the PA at every concert. Whether your PA is adequate to handle it is another question entirely. Inexpensive PA speakers for the most part aren't designed to handle it.
     
  6. deekay911

    deekay911 Supporting Member

    Nov 4, 2007
    Charleston SC
    Safe - yes.
     
  7. fireincairo

    fireincairo

    Jul 8, 2008
    PA drivers should be safe, but really crappy ones may not hold out. I've got a couple of low-end Fender 1x12 wedge cabs that I've used for years on PA. When I started running bass through the PA it eventually blew one of the speakers. I have since replaced that with an eminence PA speaker, which is much more sturdy and handles the low frequencies with ease.
     
  8. fireincairo

    fireincairo

    Jul 8, 2008
    yup
     
  9. Ezbass

    Ezbass

    Apr 3, 2008
    U.K.
    DIing into the PA for rehearsal should be fine, the 15" speakers will be very broad range and able to handle your bass, I do this in rented rehearsal spaces.
     
  10. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
  11. srptopdog

    srptopdog Greyhounds make good sound engineers - Big Ears!

    Feb 24, 2008
    Philadelphia, PA
    OK, please correct me (assuming you've still got any patience for it)!
     
  12. will33

    will33

    May 22, 2006
    austin,tx
    This has been done to death....To the OP, you may be tempted to turn up the bass control on your channel as the PA cabs are likely too small to put out deep bass, listen to your speakers for distortion or stress and back off when you need to. In the bass world, I've found more speakers blown from exceeding mechanical limits rather than thermal.
     
  13. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    What kills speakers is overpowering them, and nothing else. If a square wave tore up speakers, we couldn't amplify synths or use distortion pedals.
     
  14. srptopdog

    srptopdog Greyhounds make good sound engineers - Big Ears!

    Feb 24, 2008
    Philadelphia, PA
    Yes, you are correct. I stand corrected.
     
  15. srptopdog

    srptopdog Greyhounds make good sound engineers - Big Ears!

    Feb 24, 2008
    Philadelphia, PA
    I just read your article, twice. And I need to read it again! But I see basic misconseptions I had about this topic, so thanks for the link.

    I'm guessing the majority of people who read/participate-in this forum are mostly musicians, not electrical engineers, so there are likely many of us who are not able to fully take advantage of your writing, as good as it is.

    Is it possible to write a "for dummies" version of your treatise the majority of us can grasp a bit easier? I'm sure many would appreciate it.

    Signed,

    "an old dog learning new tricks"
     
  16. will33

    will33

    May 22, 2006
    austin,tx
    The long and short of it is if you forget about amps, cabs, etc. and just look at the driver (speaker) as a device in and of itself there are only 2 ways it can fail

    1. Thermally, too much power, the voice coil can't dissipate the heat fast enough and it burns.

    2. Mechanically, it physically moves back and forth further than it's designed to and physically comes apart.

    Doesn't matter what signal you put into it, if it fails it's because of one of these two reasons, or both.

    It takes a lot of exursion to put out lower frequencies at volume, I've seen plenty of bass speakers with burnt voice coils but it's still usually because of mechanical failure. The thing moves too far and the voice coil hits the backplate of the magnet and shorts out. It's still burnt, but it shorted (burnt) because of mechanical failure, moving too far and hitting the backplate. There are plenty of speakers who's voice coils can handle 400-500 watts consistently before burning up but only take about 80-100 watts before hitting xmax and maybe 200 watts before xmech.

    xmax = how far it can travel before losing the ability to put out any more bass. Starts farting, distorting.

    xmech = how far it can travel before total failure, ie. shorting out against the back of the magnet or ripping the cone apart and flying out the front.


    You can use a 1000 watt amp on a 200 watt speaker and be just fine because you're not really using all 1000 watts unless everything in the chain is cranked to the max. As far as underpowering goes, speakers are tested using 1 watt of input, can't get much more underpowered than that and it works just fine.
     
  17. In Absentia

    In Absentia

    Jul 5, 2008
    Kudos to you. It is refreshing to see someone admit they might have made a mistake on a public forum. Good on you, and rock on! :bassist:
     
  18. srptopdog

    srptopdog Greyhounds make good sound engineers - Big Ears!

    Feb 24, 2008
    Philadelphia, PA
    I'm on my 4th read of your article, and I'm starting to see how the pieces fit together. Your extra input here helps too. I now basically understand the "burnt-out voice coil" and "underpowered" misconceptions. Thanks.

    Salvatore ~
     
  19. srptopdog

    srptopdog Greyhounds make good sound engineers - Big Ears!

    Feb 24, 2008
    Philadelphia, PA

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