newb question - ohms for sub and amp

[bassjunky]

Sorry, I am a complete newb to car audio. How are Ohms supposed to match up between the sub and amp? Say I have a 500rms @ 4ohm sub, then I will need an amp that does the 500 @ 4 too? What about dual 4ohm sub? TIA.

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[supraman1379 10+ year member]

You mean, you have a 500rms @ 4ohm amp.

You need to find a sub the can handle that much power (rms)

For example:

My amp specs are:

400rms x 1 @4 ohm

800rms x 1 @2ohm

1100rms x 1 @ 1 ohm.

You can get any sub and put it on an amp. But if the sub has a RMS rating of say 500, and you get a sub that has a rms rating of 1000, then you would be underpowering a sub.

So it is better to get a sub that matches or is slightly under the rms of the amp.

And the dual voice coil subs handle more power the single voice coil. But you prolly already knew that.

Lets use my amp again for an example.

Since it is one ohm stable, I need two Dual Voice Coil subwoofer that are 4 ohm. Then I can wire it to one ohm . Or If I want to run the amp at 4 ohm, I just wire my DVC (dual voice coil) subs to remain at a 4 ohm load.

Using my amp again as an example. Lets say you have three subs. and you would like to run them at a one ohm load. (BTW: One ohm stable amps put out the most power at 1 ohm). But anyways, you have three subs that you want wired to one ohm.......You cant run DVC 4 ohm model subs. You need DVC 2 ohm models. That way when you wire it, it will come out to either 1.33 or 1.66 ohm. I would have to read up more to see which one it is.

But its the same if you have four subs. You cant use DVC 4 ohm, it has to be DVC 2ohm subs.

Then some amps are not 1 ohm stable. You have to adjust DVC subs accordingly. That way you can run what ohm load you want.

I apologize if thats too confusing. Maybe someone will say it differently.

 

[thch 10+ year member]

you will want to look up some wiring guide or such for dual coil speakers.

the amp's output is a voltage. resistance allows current to flow from the amp's output.

too high and you simply don't get as much power.

too low and the amp tries to protect itself or becomes damaged.

you can combine coils in 2 ways to get different resistances (also called impedances, load impedance, or load.)

avoid calling it an ohm load... it just makes you sound stupid.

the amp maker will give you what the "ideal" load would be. like 4ohm (bridged connected) = 500W. if the goal is to get the 500W, you would need to attach a 4ohm load to the amp. simple examples would be a 4ohm single coil woofer, or two 4ohm dual coil woofers wired in a creative way to allow the amp to see a 4ohm load. in the 2 woofer case, each woofer should be rated at 250W or higher, and in the single woofer case the woofer should be rated at 500W or higher.

you will likely want a gain setting tutorial as well. the jist of the gain setting guide is -- if you set the gains lower, you can turn the HU up more. also, too much gain (for a given volume setting) introduces distortion and more power (as distortion), which might not jive well with the speakers.

* all wattages listed are long term "RMS" values. no one except marketing departments use the peak power rating.