[Matt214]

Hi Everyone, so some of you may have seen my thread where I installed the Alpha One Amp and also installed the full 16 speaker Alpha One speaker package. This of course includes the woofers under the front seats. That thread is located here, for reference:

https://g80.bimmerpost.com/forums/sh...3#post31016583

I did the remote tuning session with Bimmertech and it was a great customer service experience that left my upgraded system in the G80, at a level I would have expected from BMW on an M car. Great sound.

Now, here we are about 10 months later and I pulled the trigger on a JL Audio sealed 12" trunk subwoofer which includes a built in amp. Lots of good reviews. The link to the subwoofer that I and a number of others purchased is here:

CLICK HERE

Crutchfield appears to be the same price as purchasing directly from JL Audio and the word on the street is that Crutchfield has superior customer service but you may have another dealer from which you'd purchase the sub.

You will also need the following (Items are 'clickable'):

Basic Amplifier Installation Kit
Remote Subwoofer Output Knob
1-RCA to 2 RCA (Y-cable)

Optional are the Cargo Pal blocks to help secure your subwoofer box from scooting around the trunk while driving. You might opt for getting strips of velcro to stick to the underside of the box. Both options or a combination thereof, are feasible.

Attaching pictures that have various annotations, during the install. You may have to zoom in on the pics to read the text boxes more easily:

First off we have an overview of the wiring, with both the trunk floor panel removed as well as the side panel that covers the alpha one amp and additional BMW audio system electronics and associated connectors. The Alpha One amp has a single RCA line out connector for the subwoofer sound signal. If your amp to your subwoofer has both a Left and Right line in, it is highly recommended that you get the Y 1 to 2 connection RCA cable that I linked in the intro. You can also see the remaining wiring that contains the positive and negative power cable, as well as the blue remote wire. The JL subwoofer has a quick connect plug into which you insert the wires and lock them in place with screws. Fairly solid and convenient set up.



Next, we see how the wiring bundles are routed after re-installing the side panel of the trunk. You can see that the RCA line out cables and the positive, negative and remote wire bundle all exit from underneath the edge of the side panel, neatly in one location. Use zipties as a neat, convenient way to do so. I installed the inline fusebox (provided in the installation kit) on the positive cable, as you can see. I ran the positive cable neatly alongside the side of the battery that's closest to the rear bumper. The positive connection is under the black plastic covering that easily removes by lifting up.



This view shows a closer look at the inline fusebox, to be installed on the positive power cable, coming directly from the battery.



Next, I need to call out that on my Alpha One amp, there are two wires that come out of the 'remote connector'. There appears to be lack of documentation from Bimmertech that clearly indicates which wire to use. Logically, the 'REMOTE OUT' wire (which is blue with a black stripe) would make sense because it's leaving the alpha one with a signal (going out) to your additional amp that's powering your subwoofer. The Bimmertech subwoofer installation videos, as well as their written how-to instructions for some reason just gloss right over which wire exactly, to use. Some people on various forums say it should be the 'remote in'. With my amp, the 'remote out' wire was capped off with black heatshrink and the 'remote in' was precut so that the wire insulation could be easily removed to use it to signal your subwoofer. Upon connecting my JL Powerwedge to the 'remote in', wire which was pre-cut and ready to use, the amp would not power on. Sure enough, I stripped off the heatshrink and insulation on the 'remote out' wire and connected it and the amp powered right up, as expected. I don't know if someone at the Bimmertech factory got careless and capped off the wrong wire or not but to say the least, that should be a very clear instruction, within their how-to videos and write ups. Hoping this will save some of you some confusion.



View of the 2 remote wires that come from the amp. Note that the blue with white strip wire (labeled 'remote in' on mine) was pre stripped. The 'remote out' was capped off with the black heatshrink.



Once I attached the correct remote wire (the 'remote out' which is the blue wire with black stripe), I used heatshrink to insulate and secure the solder connection and coiled up the excess wiring (which is the solid blue wire from my particular amp installation kit). I tucked the excess away, which is covered upon reinstallation of the side trunk panel. Also, I used heatshrink tubing to re-insulate the 'remote-in' wire, that came pre-stripped from Bimmertech.



This view simply shows where the negative grounding point is for the amp, as well as the Alpha One amp. This also shows how I bundled and secured the wires together to keep them still, and exiting the battery well of the trunk, in one spot. I used some felt to help provide some added cushion between the metal of the car and the wiring bundles.



Now we see the floor panel of the trunk reinstalled and the amp connected, via the quick connect plug. It's hard to see in the pic but the RCA Y-cable, as well as the amp wiring bundle, are exiting out from the edge of the trunk floor panel and the side panel. I wrapped the whole wiring cluster in some felt to simply help provide some added cushion, where they pass between the two panels.



This view shows the Cargo Pal fasteners on the two right side corners. The left side of the box is already supported/secured by the left side trunk panel edge. I also added one strip of velcro under the edge of the subwoofer box, closest to the rear bumper. That thing really stays in place. No issue after whipping the car around any number of curves at speed or blasting off WOT from stoplights.



Now, it's definitely recommended to get the JL Audio output knob. It is plug and play and designed for your JL Audio amp. If you are using a different powered amp setup, I definitely advise sourcing the equivalent as this will allow you to adjust the amount of subwoofer output, from the inside of the vehicle, without having to go out to the trunk and mess with knobs on the amp itself. Your remote tuning session with Bimmertech/Alpha One will help you make these settings as well. We begin by preparing the drivers area for the knob. Remove the underdash panel (two 8 mm bolts if memory serves me correctly). This will allow you to reach behind the sunglass stow cubby (whatever you want to call it) to fish the wire into it.



Next, you'll need to drill a hole for the wire. I used a 1/2 inch bit and placed the hole in the lower left corner of the cubby. The extension wire that runs from the knob, to the amp in the trunk, has what looks like the old fashioned landline telephone connector on it and so the hole has to be big enough to accommodate that. Pass the extension wire in from the back and then connect to the knob. The extension wire is easily hidden completely from sight as it can exit the back of the cubby and then run along the left panel of the footwell and into the trim, along the threshold of the front door, then to the back door and then up along side the edge of the rear seat cushion and into the trunk.



In the previous pic, we see the mounted switch. Please note, it made sense at first to mount it neatly on the black plastic, inside the hatch but the way BMW designed the cubby/hatch door, it slides up and over the inside of the floor of the cubby which nocks right into the knob if you mount it there. So, I used velcro to secure it to the inside of the door itself. You may experiment with different mounting options but I thought this was a neat and stealth way of doing it. In this pic, you can see where I originally mounted the switch and quickly discovered it was not an option.



Finally, once it's connected, you should have subwoofer output! It won't sound just great, from the start. A remote tuning session to change the DSP file settings of your Alpha One amp is necessary. I have been working with Mac, at Bimmertech Audio and he has been outstanding. Patient and very much an experienced master of his craft.

Once the correct adjustments are made to the Alpha One amp, you should be more than impressed. The audio system in this car now is what I would call exceptional after the Alpha One Amp, full 16 Alpha One speaker upgrade and now the subwoofer. It definitely cost plenty to do all three but if you truly love great sound and wish our M cars had that from the start, then this is for you. I hope this helps and I want to give a big shout out to cobrar97 who was awesome and gave me a lot of pointers along the way. He has also done the subwoofer upgrade and also done the remote tuning session with his Alpha One amp set up.

Let me know if any of you have questions!

[cobrar97]

This is a fantastic write-up and covers each detail exactly. For anyone doing the AlphaOne and/or subwoofer upgrade, follow these directions, and you'll be successful.
And, as mentioned already, you MUST have a tuning session done by Mac over at Bimmertech or you won't realize the significant benefit to all of this work and $$$...but when you do; it'll be one of those upgrades that you'll thoroughly be happy with.

[nearwater4me]

Great writeup.
How do you like the powered JL sub?
I have an old RF one that I've used for many years... curious how the newer ones perform.

As for the component/amp upgrade, it's a bummer that there's not enough aftermarket support for the G chassis yet.
I'd love to get a drop-in set like the ones Integral Audio offered.

[Matt214]

Originally Posted by nearwater4me

Great writeup.
How do you like the powered JL sub?
I have an old RF one that I've used for many years... curious how the newer ones perform.

As for the component/amp upgrade, it's a bummer that there's not enough aftermarket support for the G chassis yet.
I'd love to get a drop-in set like the ones Integral Audio offered.

So far after having it in the car and tuned for over a week, I've really been enjoying it. It really does provide that fullness to the sound that lacks from the factory. I don't have a reference point with regards to any older subs, I just know that a number of us have gone with the JL option and they do have good reviews. The JL appears to have plenty of power and delivers what I would call clean/crisp bass notes. It's not punchy or muddy, if that makes sense. The sound resonates and complements the overall sound profile within the vehicle.