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2Ohms would be a fun roll of the ol' dice haha. Realistically, I'm not sure if the OHM settings sound any better. I hope someone can correct me on this if I'm wrong, but my interpretation of it would be the lower the ohm rating the more power TO the cab, yes? So if you're running one head, with 2 cabs, each cab rated at 8ohms, you would want double the power (less resistance) from the amp, running the amp at 4ohms would distribute enough power to power both of those cabs. I don't really know the exact science behind it but I'm hoping someone can help out with this. Ed?
Well put Ed. How low of an impedance a normal solid state amp will drive is pretty much a function of it's ability to get rid of the heat, PLUS what the designer did to make the amp stable at low impedances and/or short-protection. 2 ohms is VERY close to No Ohms...or a dead short.
Cutting the impedance in half rarely doubles the power. If an amp can produce 100 watts at 8 ohms, it may only do 160 watts or so at 4 ohms.This is because the transformer can only deliver SO much current, it "sags".
Well put Ed. How low of an impedance a normal solid state amp will drive is pretty much a function of it's ability to get rid of the heat, PLUS what the designer did to make the amp stable at low impedances and/or short-protection. 2 ohms is VERY close to No Ohms...or a dead short. Speakers are motors, and produce a BACK EMF, or electromotive force, which comes flying back down the line at the output transistors. So while the transistors are trying to control voltage and current to the speakers, the speakers are also sending voltage and current back at the transistors. You can see this by hooking a voltmeter up to the speaker terminals, and thumping on the cone with your fingers ( careful...don't poke a hole in it !). Depending on the phase of this complex voltage/current/impedance mess, the back EMF can appear to be a short to the amp at low impedances. A well-designed amp will HOPEFULLY protect itself and shut down if it thinks it is shorted....but some will just fry the outputs, or lock up to one of the rails and fry itself and the speakers. OUCH. It's best to not use an amp at an impedance lower than what it is rated for. Cutting the impedance in half rarely doubles the power. If an amp can produce 100 watts at 8 ohms, it may only do 160 watts or so at 4 ohms.This is because the transformer can only deliver SO much current, it "sags". Remember, twice the power is NOT twice the volume...it's only 3 db louder. Twice as loud is 10 DB....ie 10 X the power. So, going from 100w at 8 ohms to 160 watts at 4 ohms is only 2 db louder...really not much of an increase. Going to 2 ohms would probably only add about another 1 db, and may risk frying everything. Not worth it.The best and safest way to get louder with a given amp is to use a higher sensitivity speaker. Look at the sensitivity rating for the speaker... XXX DB at 1 watt, 1 meter. By using a speaker that is 3 db more sensitive, you get the same result as doubling the power, without any risk to the amp. Hope this helps.