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  1. #1

    Unhappy 2ohm vs. 4ohm???

    what is the difference between 2 and 4 ohm, other than the obvious 4 ohm. Is it just a larger amount of signal? Does it give better sound? If i have 4ohm subs and 4 ohm amps will it be fine?

    I really jus need some good background info on differences and help with what is 'easier' and what sounds better.

    Thanks for any help...


  2. #2

    Member Sales Rating: (4)

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    Dec 2002
    Location's in Egypt.

  3. #3
    Polk Customer Service
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    Join Date
    Jul 2001
    Polk Audio


    "Oh give me a Ohm where my woofers can roam".... I know, I know, don't quit my day job!!
    With a low impedance or resistance of 2 Ohms connected to the amplifier, this will allow for more voltage and current to passed through the load. This will allow for a increase in power rating but at the cost of sound quality. The damping factor of the amplifier is usually cut in half. This is the ratio of the internal output impedance of the amplifier to the load presented to the amplifier. ( Woofers, drivers, etc. ) With low impedance loads this figure is reduced and with higher loads this figure increases. From a sonic standpoint you will find that when the amplifier is presented with a higher impedance of 4 Ohms, the bass definition, detail and extension is usually much better. Current consumption from the vehicle's charging system is also greatly reduced. With low impedance loads the bass kind of takes on a "hard sounding" characteristic that seems to lacks definition and detail. But judge for yourself to see what you prefer. Plus there maybe thermal issues to contend with depending on the amplifiers design and total heat sink area. This can be stressful for the output transistors also. My recommendation for what it is worth... If your goal is sound quality then present the amplifier with a 4 Ohm load
    and enjoy the music!!
    Last edited by Kim; 09-12-2003 at 01:38 PM.

  4. #4

    Member Sales Rating: (0)

    Join Date
    Aug 2002
    Buffalo, NY


    lowering impedance will only allow increased current flow, it will not increase the voltage across the load, which is completely "up to" the "decision" of the amplifier / source unit. current goes up, which makes power go up, but voltage stays the same.

    as far as sound quality decreasing, that's something that depends on the setup -- if you buy an amp that is designed for a 2 or even a 1 ohm load (regardless of class), it will perform at its best through that load. buy an amp that's designed for a 4 ohm bridged load, and sure it'll degrade at a lower impedance -- but hell it might blow up before you notice it...

    impedances have very little to do with the characteristic sound of the woofer. two dual 4 ohm coil subs (parallelled to 2 ohms each sub) running in parallell (down to a single 1 ohm load) running off a 1 ohm bridged class AB amp that is designed to function at that impedance will not sound of any less quality than two 8 ohm subs parallelled on a 4 ohm bridged AB amp.

    damping factor will drop - sometimes drastically, and this is why (again i stress) it is important to buy an amp / sub combination that were "meant for each other". as long as your amp is running within specifications then dont sweat it.

    also keep in mind that a 2 channel AB bridged into a 4 ohm load is actually running (sound quality wise / power wise / efficiency wise / damping wise.. yada yada yada) like its in 2 ohm stereo mode.

    and since the quality of some off the shelf 2 channel AB's these days tend to look worse and worse, you might as well just run a D at 2 ohms mono because the numbers are going to get pitiful anyway.

    however, in the end, putting aside the kind of 2 channel AB's that you can actually run at 1 ohm bridged or 2 ohms bridged and get their top performance level, and putting aside the kind of subs you'd want to run on those amps... then i'd have to agree w/ kim, in general, if you're shopping circuit city / best buy / crutchfield / sounddomain, etc etc... then ya -- for the "creme de le creme" sound quality go with a mid sized 2 channel AB bridged at 4 ohms to a single 4 or dual 2 ohm coil sub... or go with a large 2 channel AB bridged to two single 8 ohm coil subs or two dual 4 ohm coil subs wired to present a 4 ohm load.
    "With your own attitude it is hard to survive here... But who gives a damn, we are here to change the world, and we dont need a password for that."
    - Anurag

  5. #5

    Unhappy Whoa!

    wow thanks alot for all the feedback!
    I'm new to car audio, so the info was kinda overwhelming.
    But as far as i understood, if i buy subs that are recommended on a particular 2 channel amp then i will be ok, and i can have a play around trying it at 2ohm and bridged at 4.

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