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Sub wiring question


August 7, 2004
Reaction score
City, State
Atlanta, GA
Year, Model & Trim Level
'03 XLT
okay i have a 30 x 4 watt RMS amp at 4 ohms impedance.

If i wire 2 channels to the rear speakers, and bridge the second channel..the second channel is then 120 watts rms into a 4 ohm load per the manual...

If its bridged says 120 x 2 at 4 ohms bridged.

Now If I buy 2 8 ohm Kicker free air subs and wire them in parallel.... that would be a 4 ohm load seen by the bridged channel of the amp right??

Thus each speaker is receiving 120 watts? Does my math sound right? Would this do a decent job do you think?

I have had it bridged to Subs before and it pushed them decent..was only 1 sub per channel, but trying to set up a system in my new X with stuff laying around the house mostly.

Still have an old crappy 2 channel Kenwood thats about 30 x 2 rms for the front channels.

Let me know



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ok here goes:

U have 8 ohm subs and a 30x4 (60x2) @ 4 ohms. So that should be 120 x 2 @ 2 ohms.

I assume these are SVC subs.

However, u cant wire two 8 ohm subs to a 2 ohm load, only a 4 ohm. So each sub will be getting 60w.

I could be wrong, i havent gotten much sleep in the last few days so i could just be making things up, but thats what i think u'll be getting, 60w a sub.

Per the amp manual

Per the amp manual.. its an old Rockford Fosgate 4.6x

30x4 at 4 ohms RMS
60x4 @ 2 ohms RMS
120X2 @ 4 ohms RMS

Thats the shortcut to the pdf file of the manual.

But your right...I thought most amps gave you the power rating @ 2 ohms when its bridged... thats why i wanted to check here before i went out and bought everything and was disappointed. Maybe the manual has a misprint?

But of course If i did 2 8" 4ohm speakers, and wired them parallel, then it would definitely be a 2ohm load and each speaker would be getting 120 watts RMS right?

Thanks for the help...sad think is I use to take electrical engineering courses in College... but seems like i forget more every day.


So any ideas?

So does that sound more correct?

Need to clarify - at one point you list (2) 8 ohm subs, the next time it is (2) 8" 4 ohm subs - which is it, if it is (2) 4 ohm subs then you can wire them for a 2 ohm load but your amp is not stable at 2 ohms bridged, it may still work but heat will be an issue.


Sorry think i bounced back a couple of ideas.... I was thinking of buying 2 8" 8 ohm speakers...but i do think that in my previous one was asking If maybe i should get 2 8" 4 ohm speakers instead.

Trying to figure out how to push 2 8"s off the amp and still have enough power for them.

Thanks...sorry for the confusion.