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Am I in danger of harming my cabinet?

Discussion in 'Amps and Cabs [BG]' started by garethCV, Oct 1, 2004.

  1. garethCV


    Sep 7, 2004
    PDX, Oregon
    I'm running a GK 1001RB-II through an Ampeg PR410HLF, the amp is rated at 700 watts @ 4 Ohms, and the cab is rated 600 watts RMS @ 4 Ohms. Am I in danger of harming any components of my rig? I barely ever play at over 3'Oclock with this setup, even when my band is going full-tilt, but do I have anything to worry about if we ever need to push louder? Any insite from the local TB amp gurus would be much appriciated.
  2. Dan Molina

    Dan Molina TalkBass Secular Progressive

    Jul 17, 2002
    Murr Town, California
    No, actually there is nothing wrong with head room. You definately should be fine.
  3. zoran


    May 10, 2002
    No, wait till someone recommend you 1200W amount of power at least :D
  4. kyo


    Jul 6, 2004
    wait....if this is not going to harm the cab, then what will?
  5. bigbeefdog

    bigbeefdog Who let the dogs in?

    Jul 7, 2003
    Mandeville, LA
    A lower-powered amp. Sounds bass-ackwards, I know - but it's not.

    The 700W amp should present no danger to his cab, because when he turns up, it has the power (headroom) to remain CLEAN.

    But take a lower-powered amp, and try to drive it to volumes beyond it's capacity to keep up with bandmates, and it distorts. An amp pushed past it's limits does some very bad things to the signal it is sending to your speakers. Bad things, man. It makes those speakers dance in a way they were not designed to.

    And it is those clipped, square, non-musical waves that will eat the lunch of the drivers in your cab.

    Now, you wouldn't want to take this too far. You wouldn't want to put a 2,000W amp into a cheap 3" paper computer speaker, for example.

    But a 700W amp into a 600W-rated cab? He's fine.
  6. kyo


    Jul 6, 2004
    ive got a 200w at 4 ohm head going into a 8 ohm 200w RMS cab. so basically the head is running at 100w. i never have to turn it up past say 10 o'clock though, so it doesnt really distort. thats not a problem is it?
  7. bigbeefdog

    bigbeefdog Who let the dogs in?

    Jul 7, 2003
    Mandeville, LA
    Shouldn't be.

    As long as you don't ask the rig for more than it can deliver (e.g., turn it up so loud it distorts), it's no problem at all.

    If you do find yourself in a situation where you need more, you'll need to add a second cab (you can add a second 8-ohm cab to your existing setup with no danger), and/or look for a more powerful head.

    Do be careful, however, with the "o'clock" method of judging how hard you're pushing it. Depending on how hot the pickups are in the bass, gain settings, effects (if you have any), volume can be greatly affected by things other than the amp. And this can dramatically change the master vol "o'clock" position at which the amp's output starts to distort.

    Trust your ears. As long as it's sounding clean, your rig is safe.
  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    What few people realize is that the relationship between power and sound pressure levels is not linear. Yes, your 700 watt amp could burn up the voice coils of your 600 watt speaker system IF you were running the amp at 100% output for extended periods. However, chances of that are slim. Power versus sound pressure level is a logarithmic relationship. If you play your amp at what your ears perceive to be 1/2 of its potential volume the actual dB level is 10dB below maximum. With your 700 watt amp that translates to an actual power output of 70 watts. Even with the amp running at what your ears perceive to be 90% of full power that translates to a differential of 3dB below maximum, which is 350 watts.

    Where you may toast your drivers is with high power transients; your 700 watt amp is quite capable of delivering 7000 watt transients over a very short period of time. While your speakers are also capable of handling far higher transient peaks than 600 watts, if you hear hard distortion when you pluck/slap/slam your strings you should get a compressor/limiter to control the transients. This will also prevent hard clipping, which can fry drivers at power levels considerably lower than the speaker power rating.
  9. garethCV


    Sep 7, 2004
    PDX, Oregon
    Thank you, everyone, for putting my worries to rest. Its much appriciated.
  10. kyo


    Jul 6, 2004
    cool. my house starts shaking and the window blinds start buzzing before the tone distorts so i think im set :cool:
  11. Here's a good benchmark to work with. I have run a 200w cab with my QSC USA 900 bridged mono (900w) without any problems. I obviously wasn't cranking the amp all the way up but I knew I was in no danger of clipping the signal.

    To me it is as simple as listening to your ouput. If your clipping a lot you've got a potential problem. If your speakers are experiencing over-excursion you will definately be able to hear it.

    The numbers are simply guides. Listen to the results.
  12. orskard


    Mar 17, 2004
    your fine, what im doing isnt.

    210 watts into a 600watt avatar cab.

    i used to crank it too. thats why i need a new head. plus the 2x10 just kinda farts out my low E. at loud volumes it doesnt really play the E well.