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Thread: ohms

  1. #1
    Newbie 93blacksrv's Avatar
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    ohms

    Aren't car speakers 4 ohm while home speakers are 8 ohm and if so, what effect will this have on car speakers given the fact that the computer outputs 8??

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    and as another question, what is the difference between running car speakers at 4 ohms and running them at 2 ohms (besides the wattage gain)?
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    well a speaker has what it has u cant just take a 4 ohm speaker and run them at 2 ohms (nless they have 2 voice coils but that is normaly a sub) the only thing that is effected is the amp. car amps are set up to handle a serten amount of ohms if it is a 4 ohm stable amp and u run 2 ohm speakers on it u could kill it. doesnt mean that it will definetly kill it just could. the reason u get more wattage is because of ohms law (Power = voltage squared divided by resistance) so when u have half the resistance u have twice the power. as far as your computer it is putting out line level which u need to put into a amp so that doesnt matter it doesnt got to your speakers
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    Nic
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    Quote Originally Posted by 93blacksrv
    Aren't car speakers 4 ohm while home speakers are 8 ohm and if so, what effect will this have on car speakers given the fact that the computer outputs 8??
    well you run your computer output into an amp and then into the speakers, you cant run them straight into the speakers, and car amps are generally made for 4 ohms

    and as a general rule its easier to build more precise speakers at higher impedences, the reason why car speakers are lower impedence than home speakers is that higher impedence speakers require more voltage to drive. Its hard to get high voltages in a car environment when the source is 12v
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    Newbie 93blacksrv's Avatar
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    So the ohm level when the output is driven through the amp returns to 4 ohm from the original 8 ohm source? How does this happen?

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    I think you're getting things mixed up...

    The low-level (that's the name since it's not amplified) signal from your car-stereo (RCA plugs), home reciver (the RCA plugs) cd-players and stuff like that have nothing to do with speaker impedance (4/8 ohms).

    Most soundcards have one output (the green one) with the possibility to connect headphones to them, but they go no way near the power required to hook up to your speakers directly... so thats why almost all speaker kits for computers have built in amplifiers.

    In your car, you feed thease low-level (is it 3 or 5V ? ) signals to an extarnal amplifier, which in it's turn "power" the speakers.
    Now, the normal impedance is 4 oms, but if you for example want to hook up two subwoofers then you can either put then in serial, making the (impedance) double... 8 ohms and the power output half (generally speaking) of the rated output at 4 ohms... so in this case its better to connect them paralell... making the impedance half as much, 2 ohms, and therefor the power output double (need to be a 2ohm stabile amplifier).
    The advantage of this is that you don't have to buy two amplifers.

    /M

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    Nic
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    yes, i dont think you are understanding the concept of "ohms", ohms is a measure of impedence which is basically the AC equivalent of DC resistance. the input on the amp will be generally be in the hundreds or even thousands of ohms range, so the computer will actually be seeing that particular input impedance which has nothing to do with the speaker impedence
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