Question about ohms, please help...


Bronze Member
Username: Justinw303

Mobile, AL U.S.A.

Post Number: 13
Registered: Jun-05
I'm very new to the car audio scene, and I have a question. I just called a guy at a car audio place and asked him a question, and his response brought up this question.

Alright, let's say I have two 4 ohm subs (50-200 rms). I also have a 2 channel amp. Here are the specs:

200 watts RMS x 2 at 4 ohms
300 watts RMS x 2 at 2 ohms
600 watts RMS x 1 bridged output at 4 ohms
4-ohm stable in bridged mode

Now, I asked the guy if I could run one sub per channel, seeing as I have 2 subs and a 2 channel amp. Well, he said I would have to run it in bridged mode.

This is where I get confused. He said that since the subs were 4 ohms, it would be running 300 watts to each sub at 2 ohms.

So, does this mean when you bridge an amp with 2 subs you take the ohm rating of the subs and half it to know how many ohms the amp will encounter?

Also, How come he said I could bridge the 2 subs on the amp, and when I look at the specs on the amp the only time it mentions bridging is when it says 600 watts RMS x 1 bridged output at 4 ohms. So, what's up?

And the lowest number of ohms the amp can handle bridged (according to the specs) is 4, so how could I do what he told me to do?

I would really appreciate some help with this. I'm trying to learn as much as I can.

I realize the equipment is cheap, but please bear in mind that I'm a novice.


Silver Member
Username: 54danny54

Post Number: 399
Registered: Nov-04
u dont have 2 bridge it lol...u can cause more watts will get 2 it but u dont have 2

Gold Member
Username: James1115

Wilton, Ct

Post Number: 3351
Registered: Dec-04
ok man here ya go. if you bridge 2-single 4 ohm subs you can wire them two ways. 1) parellell/parellell and you will get a 2ohm load, or 2) series/parellell which will give you a 8 ohm load. the 2 ohm load is to low of a resistence for your amp so that is out of the question so that leaves us with a 8ohm load which you will get 300 watts 150/sub or you can wire them in stereo and get 200x2

Bronze Member
Username: Justinw303

Mobile, AL U.S.A.

Post Number: 18
Registered: Jun-05
Ok, I think I may have some of this down.

Parallel = the + wires for both subs going into the same connector thing, same for - wires.

Series = that complex setting where the - of one speaker and the + of another go into the amp, and another wire connects the 2 speakers with the remaining - and + connectors.

Is that right?

Now, since the series set up would be 8 ohms, how did you figure out how many watts the amp will push to the subs?

Gold Member
Username: James1115

Wilton, Ct

Post Number: 3355
Registered: Dec-04
200 watts @ 8ohms
400watts @ 4 ohms
800 watts @ 2 ohms
1600 watts @ 1 ohm
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