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ohms and loudness

Discussion in 'Amps and Cabs [BG]' started by mrWr0ng, Jun 10, 2003.

  1. just a quick question, hopefully i can get a straight answer.

    I've got an amp that can put out 500 watts at 8 ohms (per channel), or 850 watts at 4 ohms (per channel). Which would be louder? My automatic sense is to think the 850 ohms would be louder, but then it may be that the increased resistance of the 4 ohm cabinet would make less 'efficient' use of the power, and their loudness level would be similar. So which would be louder? I'm looking at getting a new 15 or 18 sub and trying to figure out which I want to go with.
  2. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    It will be louder @ 4 ohm, but the difference might be less significant than you may imagine.

    Volume is a logarithmic value, if you double the amp power, you'll get +3 dB (decibel), but for +10 dB, which would be perceived as doubled volume, you'll need <b> 10 times</b> the power.

    Strike that part
    that's nonsense, 4 ohm is a lower impedance [resistance in an AC circuit) than 8 ohm. Period.
  3. Petebass


    Dec 22, 2002
    QLD Australia
    The general rule is this:-

    If you're planning to get a second cabinet at some stage, get the 8 ohm cab. If you only ever intend to have one speaker cab, get the 4 ohm.
  4. well right now i've got the mackie 2600FR power amp, and 2 8-ohm amps: an eden 410XLT 8ohm and an eden D115 8ohm.

    i currently run the 410 through the mackie, and the 115 goes through my WT400, because it's rated at 200 watts and receiving the 500 from the 2600 FR would probably blow it up.

    the way it's set up, the cabinets should be ear splittingly loud, but as it is, i have to max both to be heard over my guitarist, who is playing a marshall TSL100, so I want to make really effective use of my volume.

    so if there's no discernable difference between volumes, then i'll probably replace the D115 with a 115XL or 118XL that can take the 500 watts and use the mackie's filter passes to get as much volume as i could out of my rig.
  5. Petebass


    Dec 22, 2002
    QLD Australia
    Bloody guitarists..... punch him in the ego. Then make him turn down. Oh and buy ear plugs to protect your ears...
  6. we all use earplugs :)

    we can always turn down, but I'm fighting to get a good tone as it is, and I want to make sure that when we're playing a gig, that I'm able to be heard loud and clear. I've never had good luck with going through PA's, and usually prefer to go on my own power. I know that generally you should have 4X the power of the guitarist, and he's running a 125 watt head, so it kind of confuses me why I'm not able to shake the room with the amount of power this thing should be putting out.