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Discussion Starter #1
Call me crazy, but for me the stock stereo system does a pretty decent job. In my opinion and for my current place in ownership of this car, the only lackluster piece of the stereo system is the capabilities of very low tones, and low tones at high volumes. So for me, the only thing I would like to do is add a subwoofer to the current system in the car. However, this is one of the most complex and electronics reliant car I have ever worked on, so I want to make sure to do this right the first time. My goal is to add a sub that I already have to this system, while still leaving the stock sub in place. I would prefer to mount everything below the subfloor with only the box and sub above it, so when I need the storage space I can simply remove the sub and box, and still keep some bass with the stock sub.

My questions are all about how to wire this. I read through the sticky at the top of this section "MUST READ If you upgrade you 2014's stereo to avoid damage", however I'm not entirely certain if this applies to me. I also searched through the threads I could, but it seems like the only threads are of full system upgrades, not just adding a subwoofer. I do understand I will need to tap in after the stock amp so I can retain stock volume, however I don't quite understand if any special adapters are required like a line out converter (I keep seeing the LC2i thrown around in most threads), or if I can just splice into a line coming out of the stock amp and run it right to my sub's amp since I am only adding a sub and not a full audio system.

If possible I would like to make as few to no cuts in the stock wiring as possible since I am still under warranty and am very nervous about doing anything to void any parts of it. I'm working with a 2015 ST3 Sony MFT. Thank you!
 

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Discussion Starter #2
More research apparently means more questions! After browsing through the Line-Out Converter threads again and looking at the wiring diagram that Hoppy posted in this thread, I have a few follow-up questions.

First is about Line-Out Converters: Is a Line-Out Converters sole purpose to change from a braided cable to an RCA connection? If that is true, what are the differences between Line-Out Converters other than general quality of components used inside? Is the fact that the LC2i compensates for Bass Drop-Off the main reason everyone seems to choose it (or a higher model in the same family)?

Next is about the actual wiring of the system itself. According to Hoppy's diagram and what I have been reading on the forum, it appears that the stock Sony sub is a DVC and has two positive and negative leads going to the sub. If I put an LOC in for the secondary subwoofer I plan to install, do I splice all four cables to the LOC or just a single pair of positives and negatives? In splicing the cables, will I be lowering the effective amount of signal going to the Sony Sub lowering its volume? If so, will it be a noticeable difference? Since I plan to keep the stock Sony Sub in place with the addition of the new sub, I would not want it to deaden the Sony Sub much for the times I take the additional sub out.

The last question is more of a personal preference in that I would prefer not to damage or cut into the stock wiring if possible: Is there a pigtail, T-Harness, splitter, or whatever the technical term is so that I can have the stock plug go into it, then to the Sony Amp, then an empty plug that I can use for splicing and connecting the secondary amp to the Sony Amp? If there is not, are the pins in the connector a standard style pin of some kind that I may be able to pop out for the inputs I want and crimp in a second cable?
 

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I would say check out my videos. www.youtube.com/jasongeorgievski
for your uses I would run the LC2i

Word of warning. if you upgrade to a 10" or bigger you will then complain because the bass WILL overpower your stock door speakers. I am going to assume that you never listen to the radio on the freeway with all the windows down. the stock radio can not be heard in that situation doing 65+ MPH. You will need to strip and solder the 2 sets of wires that will be going from the front woofer signal near the amp to the LC2i.
 

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Try tagging Hoppy, he will he more likely to respond...I'll help you:
@Hoppy
 

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Discussion Starter #5
I would say check out my videos. www.youtube.com/jasongeorgievski
for your uses I would run the LC2i

Word of warning. if you upgrade to a 10" or bigger you will then complain because the bass WILL overpower your stock door speakers. I am going to assume that you never listen to the radio on the freeway with all the windows down. the stock radio can not be heard in that situation doing 65+ MPH. You will need to strip and solder the 2 sets of wires that will be going from the front woofer signal near the amp to the LC2i.
I'll give them a look! I don't do much highway driving, and a full system would be in the plans for the future, but this is the first brand new car I've ever bought so I'm still babying it and super cautious of voiding any parts of the warranty. Even just adding the sub in has me a little worried if anything goes wrong down the road that the dealer will immediately just point fingers at that.

What is your reasoning for spending the money on the LC2i over just a cheap basic LOC like these?


Try tagging Hoppy, he will he more likely to respond...I'll help you:
@Hoppy
Thank you!
 

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I would advise getting a relatively inexpensive PAC LOC. They never fail and you can pick one up at any car audio shop for 20-25$. You will want to tap into the wires after the factory amp/DSP. I believe I used the front speakers, I will add a pic to show you which wires to hack into, this provides a full range signal to hijack if you decide to add a 4 channel amp in the future. The silver wires are the ones that run to the LoC's. Btw, the factory speakers sound 100x better by simply adding an aftermarket amp to apply more power to them. I threw a ton of power to them and ended up not needing to replace the factory mids/highs until I broke into the 155DB range (On the windshield).

The middle plug on the amp/DSP holds the wires needed to tap into for the LOC. I have tapped into them all for the Alpine signal processor that I use. It's best to solder and heat shrink all the connections as shown in the pic. It looks more professional/factory and there is no chance of developing a short or intermittent connection. It is time consuming, but well worth it in the end. Having a multi-meter is handy when working with this system.

WITHOUT a 4ch amp, you will only need to tap into the wires in the middle plug. So you don't really HAVE to cut anything.

The plug on the end are your signal wire inputs, don't mess with these. Same goes for the first plug, IIRC, it contains the 12v, (The larger wires) ground, sub and maybe remote and or canbus (god's curse on mankind). Double chk these on the schematic, this is just off the top of my head.

I will share with you a lesser known trick of the trade as well. If you have a 9v battery handy, (or similar) you can touch the speaker leads to the battery to test polarity. Pay attention to which wire is on the Pos + side of the battery and which is on the Neg - side. When you make the connection, if the speaker or sub moves out, the polarity is correct. If the sub sucks in, towards the motor, the polarity is reversed. You can also use this trick to figure out which wires are running to which speakers b/c it will make a small popping noise, hence "popping a speaker".

If you do decide to add a 4 channel amp, shoot me a PM. I can assist you with the easiest way to do this. Basically, after you snip the wires from the middle plug, run the long wires left behind to the speaker outputs of the 4ch. I am running two PAC LOC's and the Alpine DSP, so I needed to cut all the speaker wires. You want to absolutely avoid 5-Channel amps. The "Dedicated" sub channel doesn't provide nearly enough power. In the SPL and SQ competition world, you will never see one used.

Hopefully this helps you out. Apologies for the long rambling. @micro1331 @ddfred



This is the harness for the wires you need for the LoC. As mentioned above, the silver wires are the ones I used.





If you plan on leaving your factory sub hooked up, this is the impedance. Dual 2 Ohm. Wired down to 1 ohm, or wired up to 4 ohm.



My setup:

 

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I'll give them a look! I don't do much highway driving, and a full system would be in the plans for the future, but this is the first brand new car I've ever bought so I'm still babying it and super cautious of voiding any parts of the warranty. Even just adding the sub in has me a little worried if anything goes wrong down the road that the dealer will immediately just point fingers at that.

What is your reasoning for spending the money on the LC2i over just a cheap basic LOC like these?

Thank you!
output voltage on the LC2i goes up to 9Volts. You will be lucky to get 1Volt out of the cheap passive version. this will require higher amp gains and increase distortion levels which can kill speakers
 

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Discussion Starter #9
I would advise getting a relatively inexpensive PAC LOC. They never fail and you can pick one up at any car audio shop for 20-25$. You will want to tap into the wires after the factory amp/DSP. I believe I used the front speakers, I will add a pic to show you which wires to hack into, this provides a full range signal to hijack if you decide to add a 4 channel amp in the future. The silver wires are the ones that run to the LoC's. Btw, the factory speakers sound 100x better by simply adding an aftermarket amp to apply more power to them. I threw a ton of power to them and ended up not needing to replace the factory mids/highs until I broke into the 155DB range (On the windshield).

The middle plug on the amp/DSP holds the wires needed to tap into for the LOC. I have tapped into them all for the Alpine signal processor that I use. It's best to solder and heat shrink all the connections as shown in the pic. It looks more professional/factory and there is no chance of developing a short or intermittent connection. It is time consuming, but well worth it in the end. Having a multi-meter is handy when working with this system.

WITHOUT a 4ch amp, you will only need to tap into the wires in the middle plug. So you don't really HAVE to cut anything.

The plug on the end are your signal wire inputs, don't mess with these. Same goes for the first plug, IIRC, it contains the 12v, (The larger wires) ground, sub and maybe remote and or canbus (god's curse on mankind). Double chk these on the schematic, this is just off the top of my head.

I will share with you a lesser known trick of the trade as well. If you have a 9v battery handy, (or similar) you can touch the speaker leads to the battery to test polarity. Pay attention to which wire is on the Pos + side of the battery and which is on the Neg - side. When you make the connection, if the speaker or sub moves out, the polarity is correct. If the sub sucks in, towards the motor, the polarity is reversed. You can also use this trick to figure out which wires are running to which speakers b/c it will make a small popping noise, hence "popping a speaker".

If you do decide to add a 4 channel amp, shoot me a PM. I can assist you with the easiest way to do this. Basically, after you snip the wires from the middle plug, run the long wires left behind to the speaker outputs of the 4ch. I am running two PAC LOC's and the Alpine DSP, so I needed to cut all the speaker wires. You want to absolutely avoid 5-Channel amps. The "Dedicated" sub channel doesn't provide nearly enough power. In the SPL and SQ competition world, you will never see one used.

Hopefully this helps you out. Apologies for the long rambling. @micro1331 @ddfred



This is the harness for the wires you need for the LoC. As mentioned above, the silver wires are the ones I used.


If you plan on leaving your factory sub hooked up, this is the impedance. Dual 2 Ohm. Wired down to 1 ohm, or wired up to 4 ohm.


My setup:
Thanks for the info! I'm assuming the Ohm rating of the stock sub would only be important if I were to power it off of the aftermarket amp as well? My original plan was to have the stock sub powered by the stock amp, with the aftermarket sub hooked up to the aftermarket amp, pulling the signal from the stock amp.
 

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Thanks for the info! I'm assuming the Ohm rating of the stock sub would only be important if I were to power it off of the aftermarket amp as well? My original plan was to have the stock sub powered by the stock amp, with the aftermarket sub hooked up to the aftermarket amp, pulling the signal from the stock amp.
stock sub output will not drive an aftermarket subwoofer. that will be a waste of time and money.
 

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Discussion Starter #13
stock sub output will not drive an aftermarket subwoofer. that will be a waste of time and money.
No no no. Sorry, I know I worded that weird. Below is a very crude diagram of my original thought, but now I think Ill just splice the aftermarket sub off of one of the speaker outputs as Hoppy suggested rather than off of the sub output.

Crude Diagram.jpg
 

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No no no. Sorry, I know I worded that weird. Below is a very crude diagram of my original thought, but now I think Ill just splice the aftermarket sub off of one of the speaker outputs as Hoppy suggested rather than off of the sub output.

View attachment 107467

@micro1331
What I was trying to say earlier is that the factory sub is quite resilient. I was going to do a video of me blowing the bejeezus outta the stock sub. I had it wired up @ 1ohm, strapped to two Digital Design M4a's. I assumed it was gonna blow the Voice Coils through the cone like a Javelin Missile. But after seeing that little sub fight for dear life as long as it did, I gave it a new lease on life and the opportunity to possibly beat again one day. It actually sounded really good, at very low power obviously, but I was impressed by it. It produced really clean, tight bass, in a very wide frequency range. It did not, however, like low frequencies very much. I'd guess around 45hz or lower would significantly lower it's life span.

Depending on the stability and power of the amp you are getting, you could potentially hook the stock sub up along with the aftermarket sub. If, for example, you get an amp that is 1/2 ohm stable, or 2 Ohm stable, and an aftermarket sub that is Dual 2 Ohm to match the stock D2 ohm sub, you could wire em to 1/2 ohm parallel or 2 ohm series/parallel.

If I were shooting for a smaller system with nice SQ and tight bass, I would def give it consideration. I'm betting not many people have tried to feed the beans to our lil stock woofer. Ya never know!



I'm sorry I hijacked your thread, Imma start a build thread soon, or built, I just got around to uploading all my pics and etc etc. But I love helping others out with their builds, it's just a passion of mine.






Here are some of the components I am running, this is pre-install:




Electrical:




Nifty little machined aluminum pieces, so I can shove tons of 2/0 power and grounds into each amp.





This was the toughest decision of my whole build, couldn't decide between the DD9915 or the Dual 15.... tough call. @ddfred, did I make the right decision?

 

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Discussion Starter #15 (Edited)
@Hoppy
Definitely a smaller system. I would be going more so for SQ than I would SPL. For reference as well (probably should have just included this in the first post), the amp I have is a Pioneer GM-D8500M and the sub is a Diamond Audio D3 10" DVC 4ohm that I typically have wired to 2ohm for that amp (It's so old that they made a second version D3.2 and that's the only documentation or reference I can find online anymore which is why I didn't link it).

The final question I have before ordering the remaining parts (wiring, new box, etc) is whether or not the speaker that I choose to run the LOC off of for the sub will be receiving less power than it would have without the LOC spliced into the line. The reason I ask is because if it will be somewhat quieter, I may choose to splice off of a rear speaker instead of a front so I won't notice it as much.
 

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Discussion Starter #16
So here is a modified version of my original diagram, and @Hoppy 's. I'm going to choose to use the rear right speaker, for a few reasons; If there is slight signal loss, it will be less noticeable for me in the drivers seat, I will not have navigation/phone voice going through the sub, and because it appears to be a full range signal instead of something already crossed over. This will allow me to adjust the LPF on my Pioneer Amp to exactly where I want it to be (which will probably be lower than Sony's crossover split anyways, but better safe than sorry). I'm still uncertain if the resistor is needed since I am not removing any speakers to place an amp in, but I ordered one anyways, so I'll hook everything up with the resistor in place and see if there are any issues that way first, again to be on the safe side of things. Let me know if anything looks off, I'm certainly no electrical engineer.

Sub Addition Diagram.png
 

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New to the ST world and interested in doing the same thing! My Alpine amp has a built in LOC that should work, I assume we won't need the resistor either. I've done this in my past 2 cars but this is the first with a "premium" sound system.

Look forward to an update to the completed project! Any wiring tips or tricks welcomed!

Edit: I'll see if I can find it in search but can we tap into the amp for 12V Remote?
 

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Discussion Starter #19
New to the ST world and interested in doing the same thing! My Alpine amp has a built in LOC that should work, I assume we won't need the resistor either. I've done this in my past 2 cars but this is the first with a "premium" sound system.

Look forward to an update to the completed project! Any wiring tips or tricks welcomed!

Edit: I'll see if I can find it in search but can we tap into the amp for 12V Remote?
The plan is to do this install this weekend, so I should have pictures and updates coming soon. IIRC it seems like most people are using an add a fuse in the rear fuse box, but I need to look again to see which fuse location they are using. I'm not sure I've read of anyone using the stock amp for the remote lead.
 

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Discussion Starter #20 (Edited)
Okay, so I wrapped up my sub addition this weekend and everything went fairly smoothly. Unfortunately by the time I was finished installing everything, it was fairly dark, so I don't have too many detailed picture of the actual setup, however I'll post what I have now and load some more up the next chance I can take them. A big note to anyone who has a 2015 Focus ST, it appears that the fuse locations have changed from the 2013 diagrams posted in the Electronics' section, so check your manual's for proper fuse locations, and I have posted pictures of the new fuse locations in my manual here: 2015 Focus ST3 Fuse Locations

So to start off with I needed to remove trim panels and the glove box, which luckily since I was only adding a sub meant I only had to remove the passenger side's trims pieces which meant a little less work. I removed a total of 6 trim pieces, however depending on the size of your power cable you may need to remove a 7th piece as well. I was using 4 gauge wire from Stinger for this installation. The first thing to remove was triangle trim piece on the side of the glove box. This piece is held in by only clips, so grab a trim removal tool and start prying gently. If my memory serves me correctly there are 3 clips in the triangle section and 1 or 2 in the pillar section (including the set of clips that locks into the adjacent trim piece). Once that is out, begin removing the 5 torx screws holding the Glove Box in place.

I did not take any pictures of this particular section unfortunately as it was one of the more frustrating parts. This post here explains the Glove Box removal process quite well and has good pictures of the screen locations. The only thing I would add to that post is that there are a total of 4 plastic posts with metal clips on them, and one plastic clip holding the glove box in after the screws are removed. Two metal clips are hidden on the left side behind the glove box where no human hand can reach, two on the right side behind the glove box where you can kind of reach, and one on the side behind where the triangle trim piece was. The top left metal clip was the only one that made things difficult for me as it was bent from the original install and I ended up having to shove a screw driver in to bend the metal clip off the plastic post so that it wouldn't break the plastic post. Aka, BE CAREFUL WITH YOUR GLOVE BOX REMOVAL.

From there you will want to remove the straight floor trim piece first. This one is very easy and has three pop clips located in the picture below:



Next you will want to remove the rounded triangle shaped trim piece in the front passenger footwell (unfortunately do not have images of this particular piece).

To make the next part easier, I highly suggest flipping the rear seat bottom up which is by far one of my favorite features on this car for some reason. There is simply a metal clip holding the passenger side in place and the seat is on a hinge. The drivers side rear seat does the same thing, but has two clips instead of just the one. (this will also allow the seat back to fold complete flat, which was helpful once I got the cables to the trunk)




Next, you can remove the rear cubby hole compartments. (please note I only removed the lower section and I was able to fish the wire through the upper section without removing it. When trying to remove the upper section I accidentally snapped off a plastic post because the metal clips were too tight. Please be careful if you choose to remove the upper section)





After this, the B-Pillar panel will need removed. Pop clip locations are pictured below:




With all of these panels removed, it was time to run the power wire from the engine compartment, through the grommet behind the glove box, along the floor (would not fit directly under trim pieces), and into the trunk. At this time I also ran my remote turn on wire and the remote bass adjust knob cable from the trunk to the glove box following the same path as the power cable. (Power cable is red cable in picture)





There are quite a few more safety features in this car than there have been in any other car I've done installs on, so please be cautious of what you tie your power cables to and where you run them.

The third biggest issue (1st being removing the stinking glove box, 2nd being getting a whole it that super stretchy grommet) was finding a ground in the trunk for the amp. As you can see, even with everything torn out of the trunk, there isn't really a viable grounding bolt already in place, and the two posts holding the stock sub box in place are painted. I ended up using the middle seatbelt bolt for the rear seats as it was the closest unpainted bolt to use as a ground point. I did have to widen the hole on my 4 gauge terminal for the seatbelt bolt to fit through it however.



So at this point your ground work should be finished, and unfortunately it was extremely late at night and very dark inside my garage so I don't have many more pictures, or any pictures of the actual wiring to my amp. I will update this thread with more pictures of the wiring the next chance I can take out my sub floor with some good lighting.

Next it was time to throw the sub in the box, and get ready to wire up the amp.



I ended up using T-Taps to tap into both rear speakers to hook up my Line-Out Converter. Luckily even though the Fuse locations have changed from @sda3 's original post, it appears that the 2015 has maintained the same Sony Stereo wiring setup that is in @Hoppy 's amazing wiring diagram.

I then used an add-a-fuse to tap into the Heated Steering Wheel fuse in the passenger fuse box location as non of the rear ones would fit my add-a-fuse, and the Heated Steering Wheel was the only one I found that was actually switched on/off with the ignition. Even the freaking Sun Roof, which will only open when the ignition is on, remains active even with the ignition off (how the hell does that make any sense Ford?!?).

After that, it was simply wiring up the normal stuff to my aftermarket amp: RCA's from LOC to Amp, Ground cable, Power cable, Remote-On cable, Bass Remote cable. The last bit I did was cut up some of the foam storage to make some room for my aftermarket amp. I removed a dividing wall below where the stock amp sits, and then cut out a side wall by the spare tire since my aftermarket amp was too long for that space. This allows me to keep both amps in the same cubby, with enough airspace around the amps for adequate cooling.



And Voila! You are completed with your install. Just hook your sub up to your amp and you're good to go.



I went this route, because I did not think the speakers needed any additional help, just the sub and low notes were lacking. This setup is exactly what I was looking for, and I honestly do not expect to want any further upgrades to this audio system. This has made my car sound exactly as I wanted it to, with a clean and simple installation. The BEST part about this installation is that all of the stock equipment stays in place, so when I need the extra storage space, I can remove the sub with two wires, and have my full trunk back in just a few moments. The sub box is even held in place by one of the interior panels quite nicely.



For anyone looking to add a little more bump to your 'upgraded' Sony system, I highly recommend simply adding in a secondary sub. For those interested I plan to update this thread with the finalized wiring diagram I used, some more pictures of the actual wiring, and a list of parts I used for this install. Please feel free to post any questions you may have.

As a final note, I did not end up using the resistor I ordered because as I suspected, since the stock speakers are still being driven off of the stock amp, there is still a sufficient load on them. Neither amp has heated up in the location they are in more so than normal operating temperature, but please note the longest test I've had a chance to do so far is 30 minutes. I also did note a small reduction in the rear speaker output because of tapping off of them, but it is not anything noticeable from the drivers seat.
 
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