OK guys, i have been reading a lot and still a little confused. I have a Q-Logic sub box under the back seat with a Rockford Fosgate 10" sub, 4 ohms powered by an Alpine MRD-M300 amp. I read (much too late after i purchaed the sub) that the amp can run in either 2 ohm at 300 watts or 4 ohm and 150 watts. I guess i need to purchase a 2 ohm sub. I assume it connects just the same, right? How much difference will this make? Anyone offer insight? I never thought about it until the other night, now i can't sleep...
I don't think it will be twice as loud, i just want it louder...

Also, what are some good 2 ohm 10" subs...

THanks!

 

It wont be twice as loud but your amp will work harder. When you cut the speaker impedence in half you double the amps working load. Most manufacturers make 2 ohm subs now. You can also get a dual (4 ohms each) voice coil sub and wire it for 2 ohms.

Good luck.

 

But i could not use a sub with dual voice coils 2 ohms each. THat would make it 1 ohm.. am i correct? I guess the amp will only operate down to 2 ohms?

 

OOps. That would give you a 4 ohm load or a 1 ohm load depending on weather you wire it in series or parallel. Sorry. I was thinking about my pair of 2 DVC speakers.

Yeah... Just find a 2 ohm sub or a dual 4 ohm sub (for 16 ohms or 2 ohms) if you are unhappy with the results of your 4 ohm sub

 

If you could find the exact same sub in a 2 ohm or dual 4 ohm, you would see a 3 db increase. That may or may not be a huge difference. If you switch subs, look at the sensitivity rating of the sub you have now versus the one you would get. If you get a sub with a lower sensitivity rating than your Rockford, you may not have any change. For example, if your Rockford was rated at 90 and you got a sub rated at only 86, the extra watts would only amount to 89. These are just numbers but, something to think about.

 

Cool! Thanks for the help guys..

 

My only restraint is finding a dual voice coil that is small enough. The mounting depth in my box is 5 3/4" and most are deeper than that.

 

Image Dynamics IDQ, Arc Audio, Adire Koda. Just to name a few really good ones that are shallow mount.