Wiring an 8ohm subwoofer to a 4ohm amp

[rlm1014 10+ year member]

Can I do this and how? I am using a Rockford Fosgate T400.4 with components on the front of the amp and now I want to wire an RF 12" 8ohm sub to the rear of the amp. When I wire it directly music comes out but no thump, and it has a slight scratchy pop in it. I would think it has something to do with the ohms not power. The sub is only 150 watts RMS. Please help if you can, I am trying to finish this this afternoon. Thanks.

Also, the sub is a SVC.

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[XHiFiX 10+ year member]

Did you wire everything correctly?? This diagram is from the owners manual //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

The T400.4 is (under)rated at 200W x 1 @ 4 Ohm Bridged. Actual power is about 300W RMS bridged at 4 Ohms. So, if you wire your 8 Ohm sub to the rear channels bridged it should be getting its RMS rating of 150W more or less.

 

[oldschool4me 10+ year member]

sounds like you have the crossover on high pass.

 

[johnecon2001 5,000+ posts]

I'm with oldschool. Your crossover settings are wrong.

 

[johnecon2001 5,000+ posts]

Also, the ohm load you present to the amp doesn't have anything to do with the vocals coming out.

 

[rlm1014 10+ year member]

I will check but I think the crossover settings are set for HP front, and AP (all pass) rear. Let me go see.

 

[rlm1014 10+ year member]

Well, I messed with the sub and its setting some more but, it still is not acting correctly. Is ther any other way to test it? I think the sub is just bad.