Help wiring dual amps in f-250

[mwe-maxxowner 10+ year member]

I own a '99 f-250, extended cab with a powerstroke diesel. My currently installed audio setup is a sony head unit, infinity kappa 680.9cs (6x8 coax speakers) in the front doors, stock crappy speakers in rear doors, and a jl audio 8wv1 8 inch sub. I have a jl audio slash 300 watt 4 channel amp. The amp is pushing the front infinity kappa door speakers and bridged pushing the sub.

I recently purchased a set of focal 5.25" component speakers to install in the front doors, as well as a nicer kenwood head unit with two sets of preamp outputs. I plan to move the infinity kappa's to the rear doors. They are very nice speakers and sound great, and there is nothing wrong with them, so I still want to use them in the truck.

For now, I'm going to keep everything wired up as is, only with the infinitys in the rear powered by the head unit only, and the focals in the front running off of the amp.

I would like, however, to be able to push the rear door speakers (infinity kappas) off of an amp instead of the head unit, for nicer, clearer sound, and of course more power.

I've already picked out a jl audio 250 watt mono amp I would like to use to complete this task. Using the current slash 4 channel, and a mono, I'll run all 4 door speakers off the 4 channel, and the sub off of the mono amp.

I'm not 100% sure how to wire it up, though. Been researching it on Crutchfield.com, and still can't answer all of my questions. Since my truck is a diesel and has 2 batteries, would I be best just to run a power wire from the other battery to the mono amp once I get it? Or, should I just get a distribution block, and use that. The distribution block I'm sure would be the cleanest. I have one 4 gauge power wire running in the channel below my doors right now, not sure if there's room for another in there lol.

Pretty sure I should just use a distribution block and run wires from it to each amp for power. My largest concern is actually what to do with the remote wire(s) not sure how I should go about providing each amp with the little blue remote wire.

Aside from that, I think I've got it. The mono amp I want has a built-in preamp output, so I'd run the rear rca outputs from the head unit to the mono amp. Then, run another short set of rca outputs from the mono amp into the rear channels of the 4-channel amp. I'll just run the front channel rca outputs from the head unit to the front channel inputs on the 4-channel amp.

I figure I should just run a short ground wire from each amp just like I have my current single done right now. I read on crutchfield that I should ground each amp close together, is this true?

I've had people tell me not to worry about the speakers in the rear doors of the truck, but I just can't help thinking nicer speakers back there, especially amped, are gonna help add some nice mids and highs to my sound system. I was told those speakers are only fillers and that I wouldn't be able to tell the difference there between good speakers/bad speakers- amped/not amped, but right now, at times, I have more bass than highs/mids to match. I feel with those infinitys amped in the back to match the focals up front, I'll have enoughn highs to balance everything out.

Thanks guys,

Mitchell

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[mwe-maxxowner 10+ year member]

Anyone know how I could go about wiring these dual amps? I know I could possibly just go to a six channel amp, but can find used jl mono amps much cheaper than 6 channel.

 

[helotaxi 5,000+ posts]

What size power wire do you have currently? If it is big enough (at least 4ga) you can wire a distribution block to the end of that wire and then short sections of wire to each amp from there. If your current wire isn't that big, replace it with a big enough wire (use 2ga at least if you're going to the trouble) and then use a distro block.

 

[mwe-maxxowner 10+ year member]

I have a 4 gauge power wire from rockord fosgate. From the distribution block to each amp, is it best I still use 4 gauge, or will 8 gauge suffice?

Still not sure how to get the remote wire to each amp. I saw something on crutchfield about using a relay on the remote wire, but I really didn't understand it at all.

If I run my rca cables as I described, I wouldn't be able to adjust my sub seperate from my rear door speakers (from the head unit) would I? Not a big deal though.

 

[helotaxi 5,000+ posts]

You can daisy chain the remote wire since you only have 2 amps. Simply run another length of wire from one remote terminal to the other. IIRC, the JL amps have signal sensing power on. You could use that and eliminate the need for a remote wire altogether.

I would stick with the 4ga out of the distro block. A "T-block" from Stinger will do what you need. If you stepped down to 8ga, you would need to use a fused distro block to keep it safe.

As far as the RCAs go, run the front set to the 300/4 primary inputs and move the selector so that all channels get signal from that pair of inputs. Run the other set of RCAs to the sub amp. Use the gain on the amp to adjust your front/rear fade to where you want it and then the fader on the HU acts as your sub level control.

 

[mwe-maxxowner 10+ year member]

Wow, thanks, that's some good info! I'll just go with the 4 gauge wire from the dist block then. No use in spending all the money I already have on good amps, quality wire, quality speakers, just to skimp a little there when I wire that part of it. Should just be able to purchase a short length of 4 gauge wire. Should I know anything about placement of the amps in relation to each other to minimize the possibility of noise? If they're too close together will it cause any problems.

I have the 4 channel amp set up with only one set of rca cables now and all 4 channels getting the signal from that pair, so I'd just have to leave it as is, and run the rears to the sub amp as you mentioned. That simplifies things quite a bit, really appreciate it.

Also, I should ground the amps close together, right? I've (obviously) never messed with more than one amp before. In fact, this is the first quality sound system I've put together, and it's already been a learning experience to this point, and still have a good way to go I'm sure.

 

[helotaxi 5,000+ posts]

You can ground the amps to the same spot.

 

[mwe-maxxowner 10+ year member]

One more question. Where all do I need my fuses, and how big? I think I'm currently runnning a 30a fuse on the slash, do I just need to put fuses after the distro block @ 30a for each amp? Or a 60 before the dist block, then 30a before each amp after the block?

 

[helotaxi 5,000+ posts]

If you want separate fuses for each amp, just get a fused distro block. 30A should be fine in the block. You should already have a main fuse at the battery. Replace it with a 60A.

 

[mwe-maxxowner 10+ year member]

Thanks!

I'm imagining a non fused distro block would be cheaper, if it's a significant difference, would only a 60 amp fuse close to the battery be enough. And yes, I currently have a 30 amp fuse a few inches away from the battery terminal.

 

[helotaxi 5,000+ posts]

JL claims that the amps don't need individual fuses because of the protection circuit. The fuse by the battery is to protect the wire and your truck.

 

[mwe-maxxowner 10+ year member]

Okay, cool, I'll go that route then. One 60 amp fuse it is!