2015 base stereo upgrade and custom corner woofer

[wjfawb0]

I have a 2015 Mustang GT that came with the base stereo (6 speakers and no factory amplifier external to head unit). I also daily drive a 2015 jeep wrangler with the upgraded Alpine speaker system. It has great sound and bass for a soft top jeep. It made the mustang sound pitiful.

After reading for a few weeks, I decided I knew enough about the car to dive in and tear it apart. I liked the idea of better midrange sound from slightly better speakers and more power. I also decided $750 or $800 for the JL Audio box and woofer, or $280 for the other box option wasn't going to happen for me. I did however have a huge collection of tools, 10 year old 1/2" MDF, and quite a bit of time. I built a box for a 12" dual voice coil Alpine sub while I was installing a 45Wx4 amp under the front passenger dash and replacing the 6.5" stock speakers with infinity reference two ways with silk tweeters.

I'm an electrical engineer that's worked in electronics R&D and power utilities, so I've got experience all over the place that I take for granted. One of the good things about getting older.

Youtube links used for info on the car:

2016 sub install:


2015 sub install:


Door speaker install:


Removing factory radio:


Here's what I bought:

Remove front panel, display, bluetooth and CD player. Then fish harness out from behind sharp steel frame to start breaking into speaker wires:

Add female and male connectors so that amp can be easily removed later if desired:

Solder high level in and speaker outs on amp connectors:

Tuck harness behind steel, connect wires appropriately and reinstall CD box, bluetooth, display, and front panel:

I mounted my small 45W x 4 amp under the passenger dash. It's easy to get to to change settings, and using velcro straps, it's easy to drop down out of the way for cabin air filter changes.

Pull the passenger front inner fender plastic by pulling out many plastic trim pins:

Route your power cable(s) down from the battery box under heat shielding to the firewall grommet where the body harness passes through. Protect cables from the exhaust header using factory heat shields and appropriate loom:

Huge cable ties or tie wraps are the bomb for this. Cut the nipple on the grommet and route wires into passenger foot well:

I connected my small amp and trailer light buffer to the relay box screw:

I connected the sub amp directly to the battery:

I'll add more details later...

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[Ugly John]

I can't wait to see what you did for the corner sub...

 

[wjfawb0]

I bought a $25 walmart 8 awg amp wiring kit with 16.5 feet of red 8 awg power wire, and a short black 8 awg ground wire. It also included low volt RCA cables and a tiny power turn on lead wire about 16.5 feet long. I used 12 awg for the 45Wx4 amp. The 16.5 feet of cable was just long enough to reach the sub amp in the rear corner of the trunk after being routed along the passenger side vehicle harness.

To avoid the bass roll-off in the factory rear speaker leads, I connected the line level in on my sub amp to the front right and left channels. I simply y-connected the speaker wires at the small amp input up front and ran them to the rear amp as well. There was plenty of room to run the two speaker wires, PTOL, and 8 awg power to the trunk.

Clean down to the bare steel for the ground:

At this point I powered up the small amp to run the factory speakers, and it sounded stronger and better than stock. I then moved on to building the subwoofer box. I used the molded rear passenger trunk liner on the floor, some cardboard, framing squares, and tape measures to figure the rough shape of the box:

I built the box with the footprint and subtracted from the corner where necessary:

The above pictures don't show how I shave the top rear corner to fit up against the plastic trim in the rear of the trunk. You can see it in the finished but unpainted box pictures below:

More to come...

 

[wjfawb0]

The speaker in worked to turn on the 45Wx4 Alpine amp (feature), but I didn't trust it. I used an add a circuit on the micro 2 fuse position 23 from the kick panel per the video linked at the top. IT's the bottom right red 10A fuse here:

I noticed in a hard to reach place that a ground screw was apparently left barely installed from the factory. When I got a knuckle and extension on it, it was not that easy to turn, but I was able to get it tight. There is no telling the problems this was causing. I did have a couple strange electrical issues...

Bad ground from factory about kick panel fuse box:

 

[wjfawb0]

The blue power turn on lead wire I ran with the power and speaker wires to the trunk connected the output PTOL on the small amp to the PTOL input on the sub amp to make sure both came on at the same time, all the time.

After the sub was in and working, I moved on to replacing the front door and rear deck 6.5" speakers with Infinity Reference shallow mount coaxials with silk tweeters. I believe their power handling is around 55W.

The youtube videos helped with door and deck removal. I was impatient and soldered the rear speaker in. The metra connectors came in the next day, so I used them for the door speakers.

The rear speakers took a small 1/4" drive ratchet and I believe 7mm socket to remove the three screws. I used the metra adapters to mount the new speakers. I installed the included topper tape type foam gasket to seal the plastic adapter to the deck and front doors.

Soldering due to lack of adapters:

 

[wjfawb0]

For the front doors I followed the install video at the top. I removed the two lower screws, handle trim and screw, window switch trim and screw:

Use needle nose or pliers to push in retainers and push back and out of mount:

Door cards sure are complicated today:

Stock speaker:

Adapter:

I wonder what might go here? Hrmm.....

Stock right speaker versus infinity in metra adapter ring on left:

Foam tape on back of adapter:

Drilled a hole big enough for metra terminals to fit through next to speaker terminals:

Used leftover foam to seal hole for wires:

D-U-N, done with left door:

 

[wjfawb0]

Some type of workout flyer was in the driver's door. Otherwise it was the same:

 

[wjfawb0]

Shiny:

 

[wjfawb0]

Note that I have not changed the factory head unit's output using forscan or any obdII programmers. The small 45W x 4 amp says to set the gain no higher than 25% or 9 o'clock position when using speaker level inputs. I actually turned the gain on both front and rear channels to minimum to balance it and get a good listening level at 50% volume or 15 on my head unit. The stock tweeters are in place and in parallel with the fronts. It sounds pretty good.

The sub amp is adjusted to about 25% gain. Any higher and it is overpowering even with the rear seat folded up. I have the dual 4 ohm voice coils in parallel hooked to the single output 500W amp. Thump-thump.

If anyone has any questions, ask soon before I forget. It's been a week or two already. I have around $700 in this install. I already had the old MDF, hardware, connectors, tools, etc. The worst part was being upside down in the passenger seat with my head in the floorboard trying change the settings on the amp.

 

[SQ_S550]

Whats the overall diameter for the OEM rings? Curious if I might beable to fit my L8SEs in the doors without much modding or continue with th eAudiofros I have planned.

 

[Keith_PDX]

Great job documentary this. You might want to verify that the rear speakers are not hitting the carpet when playing music. From the looks it would appear they would. I added some dense foam around mine to help lift the carpet a little. Worked excellent. Cannot tell its there when assembled.

 

[SergeyMelnik]

I would have used some components up front especially if you already went through the trouble of installing an amp. The tweeters on the infinitys point too low and you have the stock tweeters still playing which totally mess with the tonal balance of the infinitys. You should disable the factory tweeters at least and then disable factory eq.

 

[mumbles]

Couple of comments;

1. Thanks for documenting!
2. Good job spotting that ground screw!
3. Whats the deal with the Yamaha in the background? (Sorry, dirt bike rider from way back )

 

[wjfawb0]

I looked at components, but honestly I didn't want to spend any more time researching what fit or how much modification was necessary. My biggest complaint about the stock system was no bottom end response. There are many more pictures of the process on my webspace. I only posted up ones that I directly reference in this thread. If I get some free time I'll consider looking at the quality, but I'm not that big of an audio guy.

I'll check into the rear speaker surround and cone clearance. I noted the foam on the stock rear deck speakers. It appeared to me that the rear deck cover floated above the aftermarket mounts.

I do have the OBD II bluetooth tool to mess with Forscan. I've registered and all that jazz. I'll look into the factory equalizer disabling eventually. I need to make sure everything I do is easily reversible. I could keep this car for a long time or a couple years. If I convert the factory radio to low voltage output, all I have to do is solder RCA ends onto the leads going into the sub amp. It has separate low and high line inputs. The small 45Wx4 alpine takes low and high in the same wires and has dip switches on the rear to switch between the two.

I was impressed that nothing broke during the remove and reinstall process. Even with all of the plastic fasteners, it held up well.

At the moment the front amp channels are crossed over at 80Hz 12dB/octave. The rears are at 120Hz 12dB/octave. The sub is at 80Hz 24dB/octave.

 

[wjfawb0]

Couple of comments;

1. Thanks for documenting!
2. Good job spotting that ground screw!
3. Whats the deal with the Yamaha in the background? (Sorry, dirt bike rider from way back )

It's a WR250R dual sport I hardly ride anymore. I may be taking it to a get together in a week, though.

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