In case anyone is ever interested, I thought I’d share my audio setup and DIY guide. I have a 2012 JK Sport S with the barebones stereo and 130n receiver. Like everyone else, I was not happy with the speakers. I didn’t want to replace the head unit for a few reasons: added cost for a new one, added cost for wiring harness adapters, fear of theft.
I’ll try to add some pics to this thread.
Here’s what I installed
Front: Polk dxi 6500 components (less than $100 on Amazon)
Soundbar: Polk db 651s (around $50 on Amazon) Note, these are the “s” version which seats the tweeter shallower than the normal version.
Amp: Alpine ktp-445u (purchased at Best Buy for $145ish—I think it was on sale)
List of installation items you’ll need
18-gauge speaker wire
12 18-gauge fork/spade connectors (optional...I used them to connect the wires to the front crossovers)
At least 16 sets of male/female 18-guage connectors (optional. You also could use butt connectors or solder connections, but with the lack of wire available from the factory harness, I would advise against soldering most connections)
1 16-guage wire quick connector
1 16-guage wire ring connector
1 package of wiring harness adapters (optional…I used these for the soundbar speakers, but will run new wires)
2 sets 6.5” XTC speaker baffles (though you could probably find something else)
Polyfill (I used the sheet kind and the pull apart kind)
10mm and 7mm sockets
Small flathead screwdriver
Velcro, zip ties, and plastic tubing (optional, depending on how neat you want to be with the install)
First, disconnect the negative terminal on the battery.
This is probably the most intimidating part, but it isn't that difficult.
Once you get the dash removed, pull out and disconnect the receiver. If you are keeping the factory radio, you're going to need to cut the 8 speaker wires from the factory wiring harness and the 4 RCAs off the Alpine harness. Do not cut the factory yellow power, black ground, or the other wire grouped with them (I want to say it’s white/orange). Do your best to leave several inches of wire connected to the harness. Depending on where you want to install the amp, you'll want to add some speaker wire because the Alpine harness only gives you a few inches of wire. I installed the amp directly to the left of the head unit, but I do plan on moving it to under the steering wheel for easier access in the future. Here's how to pair the speaker wires:
Front Left +: factory Gray/Violet goes with Alpine White
Front Left -: factory Grey Yellow goes with Alpine White/Black
Front Right +: factory DarkGreen/Violet goes with Alpine Grey
Front Right - : factory DarkGreen/Yellow goes with Alpine Grey/Black
Rear Left +: factory Grey/LightGreen goes with Alpine Green
Rear Left -: factory Grey/DarkGreen goes with Alpine Green/Black
Rear Right +: factory DarkGreen/LightGreen goes with Alpine Violet
Rear Right -: factory DarkGreen/Grey goes with Alpine Violet/Black
Next, connect the harness wires to the amp. If you are using the speaker level input (not the RCAs), then you do not need the remote turn-on wires, so just tape them off.
Then run the outbound wires from the amp to the speakers. Again, you'll need to extend these depending on where you want to locate the amp. You can connect them back into the factory wiring if you want, but my personal preference is to run fresh wires…and quite frankly, it’s easier.
If you do not want to run a power wire to the battery, you do not have to, which is another bonus of this amp. I used a quick connecter to splice the yellow wire into the factory yellow power wire. No problems so far. Last part is connecting the ground. Find a screw with bare metal and secure it. I used a ring connector.
Here’s a guide on replacing the speakers
Installing the speakers and adapter bracket to the pod will warp the pod and not make for a tight seal, leaving you with terribly distorted bass at higher volume. I went back in there and installed XTC speaker baffles to create a tight seal. I cut the bottom out of the baffles so they don't hinder bass response. This helped tremendously with the sound. I also put some polyfill in there, but not a whole lot.
These weren't that difficult to install. The factory tweeters pop right out. Use a small (precision) flathead screwdriver to pry it out. I dremmeled out the tombstone to make the tweeters fit, which sounds scarier than it really is. You just have to remember to take it slow, trim a little at a time, and try to fit them often.
After running the wires from the amp to the crossovers, I connected them with spade connectors. I also used the connectors for the component speaker wires. I removed the factory wiring from the plastic pods. The rubber grommets pop right out, but you’ll need to get creative to feed the new wires through the hole (I just drilled a bigger hole through the grommet). I secured the crossovers to the speaker pods using Velcro. I set the tweeters to 0 on the crossovers, but that’s a personal preference and easily adjustable.
The install is pretty simple. I used speaker harnesses to connect the speakers, but will eventually run fresh wires from the amp. I STUFFED the soundbar with polyfill, and used XTC speaker baffles to create a tight seal to help reduce distortion.
Now that the speakers are installed and the amp is hooked up, reconnect the battery.
Before you close up shop, you'll want to play with the amp settings. Reconnect the head unit. Play a bass heavy song, or a few. Leave the gain settings on the amp all the down and the equalizer settings in the head unit flat. Increase the volume on the head unit until it distorts, then lower it a few notches (I think 18 – 20 sounds clear and loud and should be able to go louder). Next, increase the gain on the amp until it distorts, then lower it a little (mine is set around 7-8 o’clock). I used the fader/balance controls until I was happy with the sound for front and back and to pin point rattles.
You’ll also want to play with the high-pass filter settings on the amp. I have my fronts turned off (up position), rears set at 60Hz, but 80 may work better (this all depends on what speakers you go with and if you add a sub). The other two switches are for your setup and are self-explanatory (4ch or 2; using RCA or speaker level input).
Overall, I'm blown away by the sound I have now. I do not have any plans to add a sub, but if I do, it'll be an Infinity BassLink or the Kicker Hideaway. The Kicker is compact (I'm not sure if it'll fit under a seat or not) and has a quick-connect harness that should make installation/removal simple.