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Add like this: two 8ohm subs equals 16. 16 divided by # of subs: 2 that equals 8. A bridged amp sees half of that. You get 4. Now if you were doing the same thing in stereo the amp would be seeing 8 ohms. Only when you bridge the amp does it "see" half. Now if you ran your subs in series wiring it would be completely different. Like Chris said you would need to get two 2ohm speakers. If you ran two four ohm subs in series you would be getting 8ohm impedence at the amp.

Since you have a four channel amp get two 4 ohm subs and run one to each bridged channel to get what you want. Or get two 8 ohm dvc subs and wire those in parallel to each bridged side to get four

If your completely lost right now have a car audio shop hook them up for you.

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I'm not hating on ya, but your calculation is wrong. This is how you calculate impedance (resistence). Remember, nominal impedance or resistence is not constant and will vary. The number and calculation that I will provide assumes constant and static conditions (i.e. voltage, current, etc...). The number that the amplifier manufacturer provides is sort of an "average" of what the amp can and will handle safely without overheating. Generally speaking, the lower the load that you run on your amp, the hotter it will get. You can run an amp lower than it's recommended load rating, but you run the risk of burning up your amp. However, if you could devise a way to keep the amp cool, you might be all right.wyolegend said:

Add like this: two 8ohm subs equals 16. 16 divided by # of subs: 2 that equals 8. A bridged amp sees half of that. You get 4. Now if you were doing the same thing in stereo the amp would be seeing 8 ohms. Only when you bridge the amp does it "see" half. Now if you ran your subs in series wiring it would be completely different. Like Chris said you would need to get two 2ohm speakers. If you ran two four ohm subs in series you would be getting 8ohm impedence at the amp.

At any rate, here are some calculations:

Parallel:

This is when you run a speaker wire from the positive terminal on one speaker to the positive on another, and the negative to the negative on the other. Then you take the positive and negative from one of the speakers (the same speaker) and run them into your amp .

1/R = 1/r(1) + 1/r(2) + 1/r(3) + . . . 1/r

R = Total resistence

r = resistence on each of the speakers

So for example, if you have 2 4 ohm speakers you have:

1/R = 1/4 + 1/4

1/R = 2/4

Take the inverse of both sides (simple algebra):

R = 4/2

R = 2

With 3 4 ohm speakers, you have:

1/R = 1/4 + 1/4 + 1/4

1/R = 3/4

Take the inverse of both sides:

R = 4/3

R = 1.33333333333333333333

Series:

This is when you take a wire and connect the positive terminal on one speaker to the negative terminal on the other speaker. Then you take the remaining terminals and wire them to the amp.

I hope this makes sense to you. I'll try this way, speaker A has a + - and speaker B has a + -. You take a wire from A+ and wire it to B-. You then wire A- and B+ to your amp. This is a series connection.

Calculating Resistence on a series circuit is easy. My variable are the same as above.

R = r(1) + r(2) + r(3) + .... + r

So for 2 4 ohm speakers you have:

R = 4 + 4

R = 8

With 3 4 ohm speakers you have:

R = 4 + 4 + 4

R = 12

I hope this helps.

somebody did there homeworkSushiLicious said:

I'm not hating on ya, but your calculation is wrong. This is how you calculate impedance (resistence). Remember, nominal impedance or resistence is not constant and will vary. The number and calculation that I will provide assumes constant and static conditions (i.e. voltage, current, etc...). The number that the amplifier manufacturer provides is sort of an "average" of what the amp can and will handle safely without overheating. Generally speaking, the lower the load that you run on your amp, the hotter it will get. You can run an amp lower than it's recommended load rating, but you run the risk of burning up your amp. However, if you could devise a way to keep the amp cool, you might be all right.

next lesson: electrical current and resistance; from theory to practice. we will discuss

ok, ok...i'll spare y'all the booooooooring disertation

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LOL, yes please educate me. I dropped out the Electrical Engineering program before we got to the practical part of the curriculum. I got my degree in CIS instead , make more dough selling than I do designing the product, go figure....koper187 said:

somebody did there homework

next lesson: electrical current and resistance; from theory to practice. we will discusswhythose equations are correct. hehehe

ok, ok...i'll spare y'all the booooooooring disertation

it's been over four years since I took E&M, and since I haven't really used any of it, I'd have to go find my lecture notes. Plus, I hated that class: too much damn maths!SushiLicious said:

LOL, yes please educate me. I dropped out the Electrical Engineering program before we got to the practical part of the curriculum. I got my degree in CIS instead , make more dough selling than I do designing the product, go figure....

oh-well

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