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Advantages and disadvantages of different ohm ratings?

Discussion in 'Amps and Cabs [BG]' started by Mr_Shrapnel, May 26, 2005.

  1. Mr_Shrapnel

    Mr_Shrapnel Guest

    Mar 20, 2004
    hey im aware of the differences concerning ohms, but im not really sure what the advantages and disadvantages are.

    i mean, lets say i have an amp which kicks out 300 watts at 8 ohms and a cab to match. but i also have an amp the outputs 300 watts at 4 ohms, also with a matching cab.
    what are the advantages and disadvantages of both? or is there essentially no difference at all?

    any explanation would be perfect! thanks!
  2. BillyB_from_LZ


    Sep 7, 2000
    Assuming that you'll only want to use one cabinet with either amp, there are no advantages/disadvantages to either scenario since the cabinet's impedance matches the amp's capabilities.

    Amplifiers usually put out more than half their 4 ohm power at 8 ohms. What this means to you is that running an amp that is capable of driving a 4 ohm load into an 8 ohm cabinet, the volume difference shouldn't be noticable, the amp would probably run cooler at 8 ohms (heat is caused by current and the output current per watt is lower at 8 ohms than at 4) and you can always add another 8 ohm cabinet to enhance your tone, volume, stage presence :D , etc.

    This help?
  3. Mr_Shrapnel

    Mr_Shrapnel Guest

    Mar 20, 2004
    yeah i think so man, thanks. so really there is no major difference btween running say: 300watts @ 2,4 or 8 ohms, but presumably a higher number of watts are more easily available at 4 ohms as opposed to 8 cos as you say it seems 300w 4ohm amps eem to have about half that at 8 ohms. cool thanks very much man, thanks kinda what i thought, but wasnt really sure.

    its just ive personally got a 300w 8ohm cab, but a 300w 4 ohm cab, so i guess that means that im probably only gona be able to get around 150w out of my cab. so might have to think about getting a amp which runs 300w @ 8ohms.

  4. If you only ever plan to run 1 cab, 300w is 300w, no diff as long as you don't accidentally bring the 8 ohm cab with the 4 ohm amp. Then you'd only be getting around 200W or so.

    For flexibility I'd pick the 300W @8 ohm guy, since I could later add another 8 ohm cab and end up getting around 500W @4 ohm.

    So as long as it WILL drive a 4 ohm load, the 300W@8 ohm amp is more powerful than a 300w@4 ohm amp. More flexibility for the future.

  5. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Pasco, WA
    In your scenario both rigs would be equally loud. 300w is 300w.

    It's all about what cabs you want to use and their combined impedance. Or if one cab, it's impedance.


  6. Mr_Shrapnel

    Mr_Shrapnel Guest

    Mar 20, 2004
    ok cool thanks!
  7. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    There are no inherent differences between one—300 W into 8 ohms—and the other—300 W into 4 ohms, but they could be different due to different cabinet designs, different ways of handling the signal, different gain, etc.

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