some subs are 2 ohms, some are 4. what does this mean and whats the difference between the two?

ohms are a measurment of resistance. The higher the ohms, the more resistance and the more the power that is needed to play. Most factory tweeters are 2 ohms so the low power amp can play them well. When I did sound systems, I always had 4ohm dual voice coils. That way they can be wired however I want. On 1 sub, if you run the power to 1 side to the ground of the other, and then hook up to an amp, the amp will "see" 8 ohms. If you run power to power and ground to ground then hook to the amp, it will "see" 2ohms. If you have a high powered amp, it will handle the 2ohm subs. BUT if you run the 2ohm subs into the amp in series, the amp will see 1 ohm and overheat. Hope that helps.

There isn't a quick and dirty answer for this but I'll try.

Ohm(s) are the units of resistance, with respect to current flow. 0 ohms being an electrical short and as high as 10 megohms (10,000,000), being an electrical open. Amplifiers are generally rated in watts (units of power/work) at 4 ohms of resistance.

For example, if you have an amplifier developing 100 watts of power connected to a 4 ohm speaker, it theoretically will deliver 100 watts of power across the voice coil of the speaker. If you take the same amplifier and connect a 2 ohm speaker, half the resistance, it will allow the amplifier to deliver double the current, due to half the resistance, 200 Watts. Keep, in mind this will be working a "normal" amplifier past is designed limits, unless its designed to be 2 ohm stable. Not uncommon now a days, even 1 ohm, .5 ohm stable amps can be found. $$$

The difference in the two types should be obvious now, one has 2 ohms of resistance and the other has 4 ohms. The reason you see variations is to allow end users to combine speakers in series or parallel to adjust the load the amplifier will "see".

If you looking to do some relatively simple upgrades or what have you to a vehicle and aren't looking to make gobs of power or compete, stick to the tried and true 4 ohm stuff. :ro)

Hope this helps, feel free to ask more if you don't understand or I didn't explain something well enough.

ok thanks guys so is one type a more responsive sub?

No. Find the sub you like, then buy the right impedence for your amp. It all depends on whether the sub is dual or single voice coil and what impedence those coils are and how many subs you're planning to run and how you wire them.

For instance: I'm running a single sub setup. My amp can run 400 x 1 @ 4 ohm bridged. My sub is a dual voice coil 2 ohm, wired in series so the amp see's a 4 ohm load.

If I had 2 subs I would have gotten subs with 4 ohm dual voice coils, then individually wire the coils in series, and then the subs in parallel to the amp which would also present a 4 ohm load to the amp.

keep in mind the lower the ohms the hotter ur amp will run, 4 ohm subs are best in my opinion, and get a good amp that is 2 ohm stable, try the two different settings out. Obviously the 2 ohm setup will hit harder, but 4 ohm is so much easier on ur amp.

ok this is sort of makin sense now. i dont really get how an amp could "see" a 2 or 4 ohm setup depending on how you wire it though. maybe ill just get it done somewhere instead of doin it myself

The term "see's" can be a little mis-leading. It basically refers to the amp. having the speaker resistance matched to the design load of the output transisters. Too much or too little can damage the amp. by allowing its electrical output to be high or low. It's a mathamatical example of Ohm's Law. With the voltage constant, varying the resistance (speaker resistance) results in high or low current.

ok that makes more sense, i actually just got done learning all about ohms law and stuff in class :). maybe ill actually put to use something i learned at school now :rolleyes: