I'm am totally lost. All I know is that houses run 8 ohms and cars run from .5 to 4 ohms. what is the difference between running a sub at say 300 x 1 at 2 ohms and 200 x 1 at 4 ohms? What are ohms exactly?

Resistance to electron flow.

I have some 4 ohm speakers in my house & 8 ohm speakers in my car.

X2.

There's absolutely no requierment to run a certain impedance in the car or in the house.

There isn't really a difference in the 4 ohm and 2 ohm example you gave except for power. All you really need to do is match the amp with the sub so that you get the power output that you want.

ll I know is that houses run 8 ohms and cars run from .5 to 4 ohms.

I've seen things with 32 ohm impedances down to an 1/8th of an ohm

As long as the amplifier is happy and you're getting enough volume, what impedance everything is at is secondary.

ll I know is that houses run 8 ohms and cars run from .5 to 4 ohms.

I've seen things with 32 ohm impedances down to an 1/8th of an ohm

As long as the amplifier is happy and you're getting enough volume, what impedance everything is at is secondary.

What Jim said x2

Here's something to read up on. A little bit of Ohms law. Not needed for basic car audio at all just kind of fun to look at.

I guess I am just a nerd.

http://en.wikipedia.org/wiki/Ohms_law

Edited April 29, 200817 yr by todd.brust

Think of the amp as pushing current out to the speakers just like water out of a garden hose. The resistance of the speaker keeps too much current from frying the amp like a complete short would (0 ohms). Just like the hose the amp will run current against that resistance like a nozzle on a hose keeps water pressure in the hose. If you took the nozzle off your hose the pump would not blow up, but you see what I mean. With less ohms to drive against, the current the amp can produce will be higher (the higher wattage ratings at lower ohms) to the point the amp can not handle the current (below its ohm rating). Some amps can run lower or be setup to do so, but it is important to match them up properly and run the right load. Some amps will protect if too low. More load (ohms) will be easier on your amp, but you will get less volume of sound out of the speakers. A speaker voice coil has "X" ohms, that does not change. How you wire it to your amp and what ohms the speakers you buy have will determine what load the amp sees, and how much wattage it can deliver into it. Speaker efficiency can change how much sound comes out a given ohm speaker, so an 8 ohm driver might sound the same as a 4 ohm driver on the same amp. There are plenty of variables. Most amps do not really double wattage at half ohms, and some do not increase any or a limited amount depending on how it is built. Hope this helps. Also if you wire two 4 ohm speakers in series one after the other, the amp will see both resistances for 8 ohms. If you wire parallel the amp will see 2 ohms, as they are both allowing power to flow through them for less resistance. Once you get the idea of 'flow' it should be easier to understand resistance.

Some amps out there can drive a dead short, but an open (no load connected) situation causes bad things to happen

Others, it's the reverse...and some amps actually have more output power at higher impedances.