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could a 225w amp at 8ohms push a 300w cab???

Discussion in 'Amps and Cabs [BG]' started by steve_man, May 29, 2002.


  1. steve_man

    steve_man

    May 15, 2002
    I may be getting an aguilar 112 iwthin the next month or so. One thing I need to know first would 225 watts be enough to push it at 8ohms?
     
  2. Yes it would.

    The difference in sound level between driving a 300w cab with a 225w amp or with a 300w amp would be less than 1db which is too small a difference for the human ear to detect.

    Does that answer your question?
     
  3. steve_man

    steve_man

    May 15, 2002
    How did you know that?:confused:


    is there some sort of equation you can use to find out or something?
     
  4. I would be careful not to drive the amp too hard. You CAN blow the cab with a 225w amp, if it is clipping. Something about when the signal clips it appears as DC (direct current) to the speaker or something like that. Be careful.
     
  5. How did I know that?? I've been playing a long time and it's just one of those bits of information you read about in magazines or hear about.

    The rule is that to increase SPL (sound pressure level) output by 3db (decibels) you have to double the power input. Or put it another way around, if you have a speaker and you are putting 50w into it, if you increase the power input to 100w you won't get double the volume out of it. You will only get an extra 3db which is a pretty small amount. Only just audible to the human ear, particularly at high volumes.
     
  6. peteroberts is right though. What he means is that if you use an underpowered amp to drive a speaker you may have to turn it up so far that the power amp will start to clip, which produces square wave distortion which is the most unpleasant sound known to mankind (well, bass players anyway) and can damage your speaker coils.

    But you can drive any amp too hard. If you used a 300w amp you would have a little bit more headroom, but not that much, and it would be just as damaging if you turned it up too far for prolonged periods.

    Bass cabs are pretty robust. The makers know what sort of abuse they are going to get and build them accordingly.
     
  7. Another thought. I used to have a Peavey 115BW which was rated at 700w and I used to drive it with a 350w amp with no problems.

    The thing to remember is that you should be getting a clean undistorted sound. If it starts to distort then the amp is clipping and you need to turn down.

    If your clean sound is not loud enough then you need a more powerful rig or an extension speaker or both
     
  8. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    but a square wave coming from a nice fuzz face... OOooo, now that's some pleasantries... :D
     
  9. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Sure, it's enough. The cab doesn't really care how much power you're sending it as long as it's not too much for too long. They don't need any set amount of power to be healthy. Efficiency is generally measured with 1 W of power, and that doesn't hurt anything.

    The question you *should* be asking yourself is, is a 225 W amp enough power for the *gigs* you'll be doing with this rig? If it is, and you never have to use the amp near its limits (e.g., quiet singer-songwriter coffehouse gig), you're golden--it won't matter what the cab's power rating is. If not (e.g., metal gig in huge club), you'll probably have to turn the amp up too loud, and bad things could happen. The solution to that would be a bigger amp, more efficient speakers, or both.
     
  10. my amp is 240w @ 8ohm, and 400w @ 4ohm..

    i run one 2x10 cab on it, that is rated 300w / 8 ohm.

    it works perfect, but if i push the volume past 80 %, it starts clipping.

    but then again.. if you have to push your volume past 50 %.. your amp / cab is too small :)
     
  11. quote:
    --------------------------------------------------------------------------------
    Originally posted by steve_man
    I may be getting an aguilar 112 iwthin the next month or so. One thing I need to know first would 225 watts be enough to push it at 8ohms?
    --------------------------------------------------------------------------------

    It should work... I'm pushing an aguilar 112 with 150 watts and it's working great!

    If you want to know more about low power clipping, Rane published a white paper titled Power Amplifier Clipping and its Effects on Loudspeaker Reliability. It can be found at: http://www.rane.com
     
  12. steve_man

    steve_man

    May 15, 2002
    thanks
    :)

    that clears some things up for me