Car amplifier RMS question?
If a given amplifier claims to be stable outputting 400 Watts @ 4 ohm. Could the amp then output 200 Watts @ 2 ohms? It makes sense to say it can be inferred based on the original 400W @ 4 ohms RMS or am I wrong? Less resistance means more current can pass at once, and less voltage is required to pass an equivalent amount of current to satisfy the power needed to drive the speakers. if power = V x I, in the 2 ohm scenario you need 2x current and 1/2x voltage to do the same thing as with the original 400W @ 4 ohms? is that how it will work?
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No, because the voltage out of the amp is essentially constant.
It varies due to the demand of the music and the volume - but if you take the rms voltage of the music and assume a given % of HU volume - you basically have constant voltage from the amp.
So if you have 400w at 4 ohms that means the amp is producing 40v -- from ohm's law E = sqrt(PxR)
When impedance is cut in half and voltage stays the same power would theoretically double by P = E^2/R.
However, not many amps are built with a strong enough power supply to provide the extra current needed to double power going from 4 ohms to 2. So with a 400w at 4 ohms you'll commonly see ~600w at 2.
Reducing the ohms will draw more current from the amplifier, not less. While it is possible to power 2 ohm speakers from a 4 ohm amplifier, there is a risk of overloading the amplifier. If the amp can deliver max power into 2 ohms the amp spec will say so. Otherwise its best to stick with 4 ohm speakers.
To some extent what you say is right, that the amp will deliver 200 watts at a lower voltage, but at 2 ohms you will be drawing the same current as you would delivering 400 watts into a 4 ohm load.
It would be better not to do this because of the chance of turning the volume up to a level where you draw a current the amp cannot safely deliver. You will run the risk of frying the amp and possibly killing the speakers too if the amp clips.
Before you get that technical, you need to be more specific on brands, and the fact that alot of car audio brads are not cea-2006 compliant.. Also count the fusing ( as only a quick reference, each 10 A = 100W..) so a 1K Watt Boss amp, with 2 20A fuses. . . For example..
The less resistance means bigger wire, not the amp itself..
And is the 4 ohms stereo or mono? Also, the 400 @ 4 ohm rating, or all of the amps ratings are at rest, in a perfect environment.. That does NOT account for excursion, when the woofer moves out, when the/if the subwoofer's resistance drops dramatically..
A little more detail would be great!!
It is possible i suppose but the lower the ohms is usually a lower wattage power...400watts at 4ohms means at 2 or 1ohm the amp will put out more power...i dont have any math to go with this but i have been workin on my own systems for years so its common knowledge for me
The extra watts that are presented to the subwoofer the louder and harder this is going to hit, alpine and kicker the two make great 1000w @ 2 hom amps. in case you have deep wallet id recommend gazing the JL 1000w amp.