Matching wattage btwn heads & cabs - how important is it?

Discussion in 'Amps and Cabs [BG]' started by jebo, Dec 28, 2014.

  1. jebo

    jebo

    Apr 25, 2009
    I don't know much about this. Say, for example, you're using a head that runs 350 watts @ 8 ohms with a 250-300 watt 8 ohm cab. Will this be bad for the cab (might blow the speaker at high volumes)? Or for another example - a head that runs 750watts @ 4 ohms w/ a cab that is 700 watts?

    Last summer I blew the speaker in my Bergintino AE112 (300 watts, 8 ohms) w/ an Aguilar AG500 (250 watts @ 8 ohms) so I've been more curious about proper head->cab parings lately.
     
  2. RoadRanger

    RoadRanger Supporting Member

    Feb 18, 2004
    NE CT
    A typical cab can handle safely about 1/2 its continuous power rating on bass. They generally aren't burned up but damaged due to overexcursion.
     
  3. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    THE MADDEST SCIENTIST
    To answer your questions - yes it will be bad if you push it too far. Use your ears and know your gear's limitations. That's about the best you can do.
     
    Scottkarch likes this.
  4. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Pretty much, just use common sense. If you push your amp hard, and dial in a lot of lowend, you'll need to be careful with ANY spkr cab, nevermind the ratings.
     
  5. Scottkarch

    Scottkarch

    Sep 11, 2012
    Chicago
    the above posts are right on the money. Use your ears and listen to your speaker.. if it starts struggling, you'll hear it.. farting out when overexcursion, or possibly a drop in volume if you are cooking the voicecoil.. if you've been maxing out the cab's volume and you start getting quieter, you need to turn down or off until the speaker voicecoil cools down. over excursion damage seems to be more common, though, especially if you turn the bass up at high volumes.

    Plenty of people use amps with higher power than their speakers with no issues... and plenty of people use amps with much lower power than their speakers can handle. Nothing to worry about as long as you listen to the sound and stop playing or turn down if something just doesnt sound right.. or the sound changed noticeably while playing.
     
  6. jebo

    jebo

    Apr 25, 2009
    Ok thanks everyone. Lastly, would it make sense to pair a head like a GK MB800 (800w @ 4ohm, 500 w @ 8 ohms) with two 8 ohm cabs equaling 650 watts total, or would that be an obvious overkill for the speakers?
     
  7. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    You can pair any head with any cab if you use the common sense referred to before. But if you have an itchy volume finger, I might recommend against it.
     
  8. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    THE MADDEST SCIENTIST
    ^What Jimmy said.
     
  9. jebo

    jebo

    Apr 25, 2009
    great, thanks Jimmy. I was basically wondering how much is too much when using amps with higher power than their speakers.
     
  10. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    THE MADDEST SCIENTIST
    It's only too much if you mess up and push the speakers too far. Usually you can hear them stressing before bad things happen. I've been known to do that from time to time.
     
  11. jebo

    jebo

    Apr 25, 2009
    So if I wanted to use a powerful amp like the GK MB800 with a light weight 1x12 cab would it make much of a difference to upgrade to a cab with a slightly more powerful speaker? (I have the Bergantino AE112, which = 300 watts). The newer berg 1x12's are 350 watts, and I've heard that DNA makes 1x12's that are 400-450 watts I think...
     
  12. christw

    christw Get low!

    May 11, 2008
    Dayton OH
    THE MADDEST SCIENTIST
    Probably not enough to make a significant difference. A 1x12 can only do so much and you've got a lot of power at your fingertips. Your amp could toast any of those.

    My solution has always been to turn it up at home breifly until it farts out so I know where my limits really are. Keep that sound and volume level in mind and you should be good to go.
     
  13. beans-on-toast

    beans-on-toast

    Aug 7, 2008
    A good rule of thumb is the cab should be able to handle twice that rated RMS output of the amp. So if your amp is rated for 300W RMS, a 600W or greater cab is a good match. This won't guarantee that you will be safe so don't forget to listen for sounds of distress. Not only the volume level comes into play but also the tone settings. If the bass settings are turned up, the volume may need to be turned down.
     
    seamonkey likes this.
  14. Scottkarch

    Scottkarch

    Sep 11, 2012
    Chicago
    what beans said too... if you are worried about accidentally turning it up too loud and just blowing them.. you might be best being extra safe and only using speakers that can handle the full load of the amp. It's a very conservative and more expensive approach. But just being somewhat careful and listen to your speakers will keep you from blowing them up.... most likely. And it will save you a lot of money.
     
  15. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    How'd you manage that?!? This comes from a guy running a Crown 2500 into a single 3 X 10. Conventional wisdom would hold that your Bergie / Aguilar pairing was a pretty good match to start with.

    Riis
     
  16. Raf Seibert

    Raf Seibert

    Dec 16, 2013
    Texas
    Sadly, it's just not as simple as lining up the numbers. It would be handy if you could just match the ohms and the watts and say that's it! You're good. Unfortunately, it doesn't work like that. That's why all the advice you've been getting here is so important. You really do have to learn to judge when your cab is getting too much power, and what to do about it.

    Raf
     
  17. MIMike

    MIMike

    Jan 1, 2013
    West MI
    I'm a believer in the complete opposite of this. A high power amp will be able to deliver clean power and volume to whatever cab you have. If it can't get loud enough for your application you need to add more drivers or cabs to the equation. Make sure to keep the impedance matched with the amp (more important than matching watts). With the available power these days it's getting harder to find a cab even rated at a power equal to the amps rating. As said above, use your ears more than your eyes and don't let too much volume make bad sounds. Based on you setup, I would say you need more speakers to get the volume you want...not necessarily a higher power rated speaker.
     
  18. There are different ways to look at it:

    As many watts as possible and the cab I need for a certain situation.

    Big gig, big cab. Small gig, small cab. And who gives a $hit about watts?


    The cab kind of defines what volume you can get. 200W in a 810 is big fun. 200W in a 112 is less. So the power of the amp does not really matter, as long as it's not too weak. Just don't try to get something out of a cab that it cannot produce, like too much volume or too much bass.
     
  19. ok so I consider myself pretty safe with my lh500 and my harke 810xl which can handle up to 800 watts rms what can a hybrid 500 watt head peak out at though?
     
  20. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    1000w.