4Ohms vs 8Ohms

Discussion in 'Soundcards, Speakers HiFI & File formats' started by ASLayerAODsk, Jul 8, 2011.

  1. SabreWulf69

    SabreWulf69 Member

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    Loudness systems usually just apply a predetermined smiley face based EQ to the sound. Still to be a feature not to take lightly when cranking a system, but as you don't you shouldn't have to worry. 'Nighttime' modes and 'DRC' usually compress the sound in one form or another. If they have indeed mislabelled your amp, then it is actually the 8Ohm mode with the 'tighter and louder' sound that you have indeed been enjoying and preferring afterall :)
     
  2. rewt

    rewt Maha Guru

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    The amplifier in my car supports a 0.67 Ohm load, if you've ever heard of such a thing :) I can connect six 4-ohm speakers in parallel ( 4 / 6 = 0.67). I actually had to install 4-gauge wire with a circuit breaker in-line because I was blowing so many fuses (usually >80 amps). That should tell you something about low resistance & current draw. :nerd: This is also why you should never connect speakers that are lower resistance than your amp supports.
     
    Last edited: Jul 22, 2011
  3. RexAeterna1987

    RexAeterna1987 Member

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    it doesn't matter if you are listening at low levels or even at the DB@1w range. a 4ohm or lower will always pull and push more current and generate much more heat compared to a 8ohm or higher load. even at low listening levels if your amp can't handle it 4ohms can be more stressful due to the common factor that lower the impedance means more current is drawn meaning more heat is generated. power that is not used is lost through heat and more power lost means more heat generated.

    try running an amp with a speaker at 4ohms nominal and then let the amp rest and then test another speaker of 8ohm nominal impedance. even if listening below 1w sensitivity you will notice how much more heat is generated from the amp running a 4ohm load compared to a 8ohm loud cause like i said impedance has nothing to do with watts. speakers are frequency dependent. they have a consent impedance curve depending on frequency presented to the amp and what it sees.

    no matter what level of listening you are doing 4ohms will always be more stressful to the amp compared to 8ohms.
     
  4. Tom F

    Tom F Ancient Guru

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    That's not strictly true.

    5W is 5W, regardless of what the load is. A low impedance load will pull more current for a given voltage than a high impedance one, but if the amp is capable of supplying the power it doesn't matter.

    Even if you put a 0.01 Ohm resistor across an amp, as long as you didn't have a huge amount of current flowing, the amp won't care. It'll be equally happy driving 5W into that as it will into a speaker - the difference is that it will take a smaller input to cause it to drive 5W through the load.

    Power = Voltage^2 / Resistance.

    Unused power is only dissipated as heat in a Class A amp - few amplifiers use this topology because a big enough heatsink to get rid of the heat from even a relatively low power (say 15W) class A amp is very, very expensive.
     

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