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how do i bridge a 2 channel amp

thewishkah

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1994 explorer xlt
ok as I've said in another post this past weekend i bought a rockford fosgate 2 channel amp its model # p3002 and is rated at 300 watts @ 4 ohms bridged and 75w continuous @ 2x 4ohms and my sub is wirerd for 4 ohms which i believe means its only getting 75w rms? its a power acoustic 1800w max and 700w rms the sub is set up for 4 ohms.

My question is after much research is this how to bridge a 2 channel amp into a mono amp to give the full 300w x1 @ 4ohms bridged? the little drawing at the bottom is the sub.

4ohmsamp.jpg
 



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no on the amp where speaker wires come out you should see on amp itwill show stereo use these or mono these.Mono will use one wire from each channel where stereo use 2 wires per chanel from back of amp
 






Nope not like that!

You will use the + from one side and the - from the other.
The amp should have instructions for this.
Do not attempt before you CONFIRM the amp is bridgeable.
 






ok so i dont need to connect a wire between the pos and neg . well both bestbuys website and crutchfield's website show power rating for it bridged so i would assume it is bridgeable? and i dont have the papers for the amp i lost them to the wind while doing the install =(
 






Look up rockford Fosgate online, I would NOT trust retailers sites
The jumper wire would be if you were wiring a dual voice coil woofer, your woofer is a single coil (has 1 + and 1 - lead)
 






That amp IS bridgable. Use the left + and right -. Its stamped on the amp. Just make sure you have at least a 4 ohm load.

x575P3002-o.jpg
 






yeah see + lead from the left and - lead from the right.
 












actually it is a dual voice coil sub it has 2 + and 2 - so what do i do now? i did bridge it with the left positive and right negative and it is working but what was that about the dual coil ? i dont understand. here is the sub http://poweracoustik.com/fubr.html
I wired the neg from one side to the posotive of the other side(other voice coil) and then one positive from one coil then one negative from the other coil then ran it to the box hook ups which the paper that came with the sub indicates as being 4ohms.
 
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Series wire the sub, you have the option to series or parallel the coils. You have two coils each with a positive and a negative, 2 ohms resistance.

Take one positive from one of the coils and wire that directly to the negative of the other coil. Use the leftover terminals as-is, one positive and one negative. Sounds like you did it right from your description.

Just wired 4 subs last night like this lol.
 






but what about the amp someone mentioned if it is a dual voice coil that you use the other wire with the amp?
 






Huh? You're bridging the amp correct? Do the series wiring method like I said, and you'll have a positive and a negative coil left. Wire the positive terminal on the sub to the positive terminal on the amp designated for bridging. Then wire the negative terminal on the sub to the negative terminal on the amp designated for bridging. No other wires that's it.
 






ok thanks. one more quick question what should the cross over be set to ? lp-ap-hp?
 






Careful! You said this was a 4 ohm sub? It is only a 4 ohm sub if you wire it that way, what you have is a dual voice coil 8 ohm driver most likely, when you wire the two voice coils together thats how you determine the ohm load you will draw fromt he amp.

Basically a DVC sub is the same as two 8 ohm speakers. As you have learned when you wire two 8 ohm speakers together (properly) from one channel on the amp you half the load (draw 4 ohm laod fromthe amp) If you dont do it right you can screw up the woofer and amp. This is called the OHM law, there are two ways to wire this sub, in series or parallel.
 






this is a dual voice coil each coil is 2 ohms and 4 ohm when wired to be so atleast thats what power acoustik says-

COMMON FEATURES FOR FUBR SERIES

* Dual 2 ohm voice coil
* Die cast aluminum
* Metal-flake Royal Blue Finish With Diamond Cut
* Non-pressed paper cone
* Chrome finish front & back plate



* Large foam rubber surround
* 1-piece rubber gasket
* Black spider
* Woven tinsel lead through spider
* Chrome screw terminals
 






It's a dual 2 sub, the power acoustik FUBR model.. he posted the link above. And I said series wire the sub for 4 ohms mono - which is correct for bridging an amp into a 4 ohm mono load.

x-over settings, you'll want to set to LP, try starting high @ like 120hz and working down getting a good match with your full range speakers.
 






this is how its wiered on the sub/amp the green on the right is a neg but when i drew the wires it made it look like a positive.
4ohmsub.jpg
 






I must be losing my mind :) I deleted this because apparently I am wrong :)
 
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i dont know then? cause the paper that came with the sub showed it wired like that for 4 ohms and there website says they are daul 2 ohm coils. this is my first experience with amps/subs so im getting confused and dont know what to think now.

this is the specs right here:
FUBR-12

* 1800 watts power handling
* 700 Watts RMS
* 200 oz. magnet
* 2” ASV voice coil
* SPL 91 dB
* Fs: 33.5 Hz
* Vas: 1.72 cu.ft.
* Qms: 4.66
* Qes: 0.55
* Qts: 0.4939
* Xmax: 0.6"
* Sealed box: 1 cu. Ft.
* Ported box: 2.2 cu.. Ft.
* Tuning: 34 Hz
* Port Size: 4”(dia)x10.25”(length)
* # of ports:1
 



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You have it wired correctly that is a 4 ohm load on the amp.
according to the instructions for that woofer.
 
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