Overpowering and Impedance Issues...

Discussion in 'Amps and Cabs [BG]' started by Bassline_Delux, Jan 6, 2004.

  1. If I was to run this with a head rated at 475W@4Ohms would I be killing the cabs?

    1 x 15" : 150 watts @ 8 ohms
    2 x 10" : 150 watts @ 8 ohms

    I know the total impedance would be 4 Ohms, but even if the power is split into two thats still 262.5W per cab, will it damage them?
  2. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Whether you might be "killing the cabs" in thsi scenario depends really on how you'll be using the gear. You'll probably be just fine if you don't go crazy with the volume. Just don't try to push the amp too hard too much of the time. Remember, when you have a 475 W amp, that doesn't necessarily mean you are using all 475 W all the time; it just means you have 475 W available for use. OTOH, remember also that when you really drive an amp hard, it can put out *more than* (up to two times) its rated power, and if you spend too much time at those elevated power levels, you could indeed hurt the speakers.
  3. That "extra" power you have available is called headroom and can actually save your speakers from damage caused by amplifier clipping. I like my amplifiers to have twice the power of my speakers rated power.
  4. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    That'll be fine as long as you don't boost the lows below the tuning frequency too much or run the amp into clipping. I presume that's a Firebass head, in which case leave the DDT switched on and turn down if the DDT/clip LED starts flashing. If you crank up the bass EQ it may be possible to drive the speakers beyond Xmax (that's where the speakers move beyond their linear region) but you should hear that as a kind of growly distortion and be able to reduce the extreme lows before any damage is caused.

    150W seems a very low rating for a 2x10" - what's the cab?

  5. Ya it is a Firebass :) So you think I should be fine? Even for gigging? And what about just one of the cabs, so that would be like 275W into 8Ohms.. with a rating of 150W hm..
  6. Petebass


    Dec 22, 2002
    QLD Australia
    Actually it will be more like 330w into a 150w cab. Halving the impedance doesn't halve the wattage output. As a rough rule of thumb, it reduces it by about 30%. Personally I wouldn't do it, and if I did I'd be turning down at the very first signs of distortion.

    What cabs are they? 150w does seem low by today's standards.
  7. Again I have changed my mind. I'm gonna go with the Peavey 410TVX:
    Frequency Response: 30Hz - 15Khz

    I think that should do nicely.