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Wiring Amp

4K views 47 replies 8 participants last post by  beaureed445 
#1 ·
I'm going to install a Fosgate PBR300x4 to push my Polk DB521's and 651's. The amp doesn't have your "usual" speaker wire plug-ins. Instead, it's got a couple of "pigtails" that click in. My question is this- should I just splice those pigtail connectors into the stock wiring harness on the back of the aftermarket head unit? Or should I run all new speaker wire from each speaker, and plug into the pigtails? Is one process "better" than the other? I'm mounting the amp on the firewall, behind the glove box, so it wouldn't be very hard to plug right into the harness.
 
#2 ·
So the pigtails plug into the amp, and just have bare wire ends on the other side, right? If so, you can definitely use the amp's input wires to run from the radio to the amp - those are just low power input wires. You would be fine with using the amp's output wire too, I am sure Rockford used a sufficient gauge wire for their own amp.
 
#9 ·
The other side looks like this....
Yeah those are your inputs on that side. If you have an aftermarket HU run RCAs from the back of it and plug them into the RCA harnesses from the first set of pictures and plug those into the inputs. Then plug the harnesses with bare wire on the end into the outputs. Then you have to connect speaker wire to the bare ends of those harnesses and run that to your speakers.
 
#11 ·
As in cut the existing speaker wire at the harness and splice them with the ones coming from the amp? That would work but the stock speaker wire isn't very high quality. It would be a way to avoid having to run the wire though. You can't tie it in directly to the harness but the cut and splice method would work.
 
#12 ·
That's exactly what I was trying to figure out. You bring up a good point- stock speaker wire probably isn't good quality.....I'll just have to suck it up and run all new speaker wire. NOW, follow up question- is the speaker wire for the sound bar run under the roll bar padding, Or is it run inside the roll bar?
 
#15 · (Edited)
Ok let me put this all in one post here...

This first side is the Input side. This means the Power/Ground/Remote lines and the plugs with the RCA's get plugged into this side.



This side is the output side of the amp. These 2 ports are the ones that connect to the speaker wiring. You should be running new speaker wire to each speaker.


Since you've installed a new head unit you should be installing an aftermarket head unit to stock wiring harness. It should look something like this:


Whenever you install an aftermarket system into your car you want to install everything new. That way you keep everything separate from the stock system. That way if there's an issue it will not effect the Jeep in any way; plus if you even sell the Jeep you can quickly return it to stock since all the connectors are still there to use and re-install the stock parts.
 
#17 ·
Ok, so here's where I am- I'm going to put the pbr300x4 under the passenger front seat. I've run power wire to it, under the carpet, and run new speaker wire to sound bar.
I'm going to put the pbr300x1 under driver seat. Here's my current questions- my head unit has two RCA outs on the rear- do I run one set to each amp, or do both go to the 4 channel, for fronts/ rears? Since amps are not right next to each other, can I ground each amp separately?
 
#18 ·
Ok, so here's where I am- I'm going to put the pbr300x4 under the passenger front seat. I've run power wire to it, under the carpet, and run new speaker wire to sound bar.
I'm going to put the pbr300x1 under driver seat. Here's my current questions- my head unit has two RCA outs on the rear- do I run one set to each amp, or do both go to the 4 channel, for fronts/ rears? Since amps are not right next to each other, can I ground each amp separately?

Do you have the HU make and model number? If you have 3 sets of RCA's on it usually there is a set for front/rear/sub... usually in that order too.

So the front and rear set go to the pbr300x4 and the 3rd set should be the sub and only that will be going to the pbr300x1.

Yes you can ground them separately. Use one of the seat bolts (the ones that bolt into the frame) as those will be the best. Try to make the power and ground wires equal lengths. What I mean by that is, run the power wire (should be a 4 gauge) to a distribution block and split it down to an 8 gauge to each amp. Those 8 gauge lines should be close to the same length as possible. Also if your power wire is 8 gauge your ground should be the same.
 
#20 ·
Well based on what I quickly read about the HU doesn't actually support a sub channel in any way... So your going to have to split the rear channel and then tune the amp to use just the low frequencies.

You'll need 2 of these:


Plug each black into the rear RCA channel on the head unit. Then make the red go to the sub amp and the white to the rear channel on the pbr300x4. This will split the rear channel and crudely 'create' a channel for the sub.

Either that or just return that HU and pick up one that has a sub channel. Which honestly would be better sound wise... but that would depend on your situation.
 
#22 ·
I must have missed that in the quick read in the manual... but what that means is it can run a sub or a rear channel... but not both...

This Alpine CDE-HD138BT head unit has 3. It runs $289.99 on wooferetc.com

This is what it would look like if you had a three channels...
 
#23 ·
The reason I like that HU is that it has nice tuning equalizer built in.
 
#24 ·
Thanks for the help/ direction. I'm going to shop for a new head unit, but I'd like to keep it in the $150 range. While I wait for that to get here, I'll get everything else buttoned up. I still need to run wire to front speakers, and wire up the pbr300x1 to the sub (I replaced the stock sub with a 6.5" Kicker). I'm assuming that I'll disconnect the stock wiring harness, and connect it with speaker wire. Am I on the right track?

By the way, thanks again for your expertise!
 
#25 ·
No problem, happy to help. I can help look around for you too.

You can replace the sub easy enough. Just make sure the volume is right for that sub. I don't remember exactly off hand but I'm fairly confident that should be just fine. Don't cut the harness off. Just unplug it, drill a small hole, feed the speaker wire into it and seal the hole back up with black silicon. ;)
 
#33 ·
Ok. Stopped for tonight. Speaker pods are all wired up, and reinstalled. I also ran all new wire and connectors to fronts. 4 channel amp is almost all done- I need a connector to ground it to my seat bolt. 1 channel amp needs speaker wire run to the sub. Everything is run to the head unit. I'm waiting to run power from battery until the end.
 
#36 ·
Also judging from the picture it looks like a panisonic or a pioneer harness you are holding. The selectable sub out means there is a programmable feature in the head unit that will turn your rear RCA outputs into a SUB out. You will lose the fader on the head unit. By changing the rear to a sub out it will allow you to control the frequency cutoff going to the amp and then you can fine tune it at the amp settings.
Also I saw some talk about RCA splitters earlier in the thread. Some amps will allow you to run a single (stereo) set of RCAs and plug into the front RCA channels on the amp, there is a splitter built into the amp and you can select it with a switch. Now thats on some amps not all, read the books to find out.
 
#41 ·
Also judging from the picture it looks like a panisonic or a pioneer harness you are holding. The selectable sub out means there is a programmable feature in the head unit that will turn your rear RCA outputs into a SUB out. You will lose the fader on the head unit. By changing the rear to a sub out it will allow you to control the frequency cutoff going to the amp and then you can fine tune it at the amp settings.
Also I saw some talk about RCA splitters earlier in the thread. Some amps will allow you to run a single (stereo) set of RCAs and plug into the front RCA channels on the amp, there is a splitter built into the amp and you can select it with a switch. Now thats on some amps not all, read the books to find out.
That's interesting, and I'll play with it before I lock everything down. My 4 channel amp does have a switch that says "2 channel/ 4 channel." Maybe that's a built-in splitter.....
 
#37 ·
I don't want to confuse the OP, but in my opinion if you are gooing to use the HU to send remote turn on signals to 2 amps, you should use a relay. Basically let the HU "flip" a relay and have battery power run to the relay and off to the amps once turned on.

The reason is some HU have a limit on the draw of the remote out. In some cases, 2 amp remote turn ons could be greater than the HU remote out amp max and you could blow a pico fuse (Pioneer units mostly). Just something to consider.

For my system, the Pioneer unit powers up the relay which connected to battery power feeds the remoate turn on to my amp (and a few other things). Plus you get that nano second delay and prevents the amp to sub "pop" (noise).

Again not tryin to add more confusion. But a relay is really the way to go to power more than 1 amp from the HU remoate out (blue wire).

Also I agree to get a HU with 3 sets of RCA pre-outs. This is all I run. And get a harness adaptor and DO NOT splice off of the factory harness. Plug in your harness adaptor and run all splicing off of the adaptor.
 
#38 ·
I don't want to confuse the OP, but in my opinion if you are gooing to use the HU to send remote turn on signals to 2 amps, you should use a relay. Basically let the HU "flip" a relay and have battery power run to the relay and off to the amps once turned on.

The reason is some HU have a limit on the draw of the remote out. In some cases, 2 amp remote turn ons could be greater than the HU remote out amp max and you could blow a pico fuse (Pioneer units mostly). Just something to consider.

For my system, the Pioneer unit powers up the relay which connected to battery power feeds the remoate turn on to my amp (and a few other things). Plus you get that nano second delay and prevents the amp to sub "pop" (noise).

Again not tryin to add more confusion. But a relay is really the way to go to power more than 1 amp from the HU remoate out (blue wire).

Also I agree to get a HU with 3 sets of RCA pre-outs. This is all I run. And get a harness adaptor and DO NOT splice off of the factory harness. Plug in your harness adaptor and run all splicing off of the adaptor.
I've successfully run 4 amps off of the amp wire from my Alpine head unit. If you have a quality amp they don't draw much and are in essence a relay to begin with. Not knocking the idea, it's just extra wires that you have to hide and not needed in a two amp setup, but it is Boss and what the pros do.
 
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