Hey, I dont understand the whole ohms thing. For example: The rockford fosgate power 550s says 135x2 at 4 ohms, 275x2 at 2 ohms, and 550x1 at 4 ohms bridged. All that is confusing!! Can some one please explain all that for me. I want 2 12" Pioneer COMP DVC's. 600w/300w max/rms. They are dual voice coil and 2 ohm or 8 ohm rated. I just want an amp that will power those good and is not too expensive. Thanx for all your help!!

 

I hope I don't get stomped on for trying to answer this but in simple terms...

A speaker is sort of like a resistor. Depending on how you wire a DVC sub, it will make it easier or harder for an amp to push a signal through. Less ohms means it's easier for the amp to give it power (less resistance). An amps rating for power/ohm load is based on the same thing. If you have a DVC setup for 2ohm operation, the amp will be able to push more wattage through it because it has less resistance than if you set it up to operate at 8ohms. If you have too low of an ohm load for the amp, it becomes too easy for the amp to push power through and it ends up overheating itself or blowing a fuse (if you're lucky). It's kind of like flooring the gas pedal in neutral.

There's my simple illustration. I hope I could help. I'm pretty sure someone will come up with a more scientific explanation for you soon enough!

 

For a more mathmatical approach:

Power = voltage * current (p=v*i); according to ohms law, voltage = current * resistance (v=i*R). Now for ohms law, solve for current (i) and you get i=v/R. Substitute that into the power equation (p=v*i) and you get p=v*(v/R) = v^2/R.

Now, assume the amplifier is producing a constant voltage (v). According to p=v^2/R whenever R (resistance) is large, power will be small, when R is small power will be large.

IE:
*assume v is constant @ 10volts*
take your DVC sub (with coils wired in parallel, which gives 2ohms)
p=10^2/2=50watts.
now wire the coils in series (r =8)
p=10^2/8=12.5watts.

So, the smaller the resistance the greater the power output. This isn't exactly how it works, but its along those basis, and its a good way to explain it.

Now, when an amplifier is in the design stage, they decide if they want max power at 2ohm, 4ohm, or whatever. The details of how they do that by design isn't something I care to get into on here.



For your setup you could wire the coils of each sub in parallel (giving it a 2ohm load) then wire the two subs together in series for an overall 4ohm load. With the amp you mentioned that will give you 550rms which is a near perfect match for that pair of subs.