Q7 DIY subwoofer replacement
 

Coming from a JGC and Yukon (ugh... truck) to the 2018 Q7 Prestige is night and day. It's just a pleasure to drive. Having said that, I was disappointed that the "boot" (for my Brit friends) storage compartment didn't actually have any storage available as it is taken up by the Bose amp and sub. The sub is decent but is simply a storage hog. I decided to replace the stock Bose sub with a homemade box, sub, amp. This gave me a good amount of storage in the middle to keep a hitch, tools, supplies, etc. I also removed the foam container for the tire pump, which gave me additional room.

Items:
- 8" Kicker CompRT DVC 2ohm sub (wired in parallel to 4ohms): $110 @ Ama
- Alpine MRV-500 (300w @ 4ohm): $110 @ Ama
- 20' 4g power (only need about 11' from battery to sub... used short amount for ground to bolt on trunk latch): $30 @ Ama
- Metra carpet: 30 @ Ama
- 2'x4' 1/2" MDF and other supplies (yes... 1/2" is fine for an 8" sub): $20 @ HD

Dimensions for the box are 13"x12"x5" (interior is 12"x11"x4" or about .30cuft which is perfect for the slim 8" sub). Built the sub and carpeted. Used 1/2" aluminum rod for l-brackets to screw down at 3 points from old Bose sub. Tapped into line going to Bose sub to high-level input on Alpine. Mounted Alpine amp under sub.

Sounds 3x better, louder, more punchy than Bose sub and gives me extra room in the "boot". Does not shake the car next to me but that's not what I'm going for. It's a win, win! Maybe could have gone with a 10" sub but would have needed to build a slightly bigger box. The 8" Kicker only needs .2 cuft so it was perfect for this application. BTW, ran the power up the passenger-side channel by the doors into the boot. Tapped ground on the trunk latch bolts. Smaller box than the stock sub gives me about 14"x14"x8" space in the middle for hitch, tools, med kit, tire pump, etc. Lots more room.
https://cimg8.ibsrv.net/gimg/www.aud...fb5568a79.jpeg
https://cimg0.ibsrv.net/gimg/www.aud...794cdfde0.jpeg
https://cimg1.ibsrv.net/gimg/www.aud...05cfe97f6.jpeg

Can we get more pics of the box after the install. Like take the other stuff out and get some close up of the mounting. Also the amp mounting too.

Pretty please.

I'll try to throw a video together to show the installation, etc..

Video of the installation. Hope this helps anyone considering the switch..
Part 1: Part 2:

Interesting. I have a kicker 10" sub-in-a-box which I took out of my other car because I wanted the extra trunk space. I wonder if it will fit in the Q7.

NICE!!! You're doing the lords work jptri. I'm real glad the battery is where it is. In my younger days I always hated getting a thick power cable from under the hood in to the trunk.

Very nice work! I have zero experience working on car audio and always envy those who are able to DIY stuff like this since I don't have any local car audio shops that I would trust doing a nice clean stealthy install like you did. Props.

Yeah, I'm glad the battery is where it is as well. Made running the 4awg wire much easier. A couple of things I forgot in the videos:
- 2ohm sub is wired in series, so 4ohm load to amp. Could have purchased the 1ohm CompRT and got down to 2ohm (450w rating on Alpine.. I think) but 300w is fine for this application.
- Tapped off the subwoofer line going to the Bose sub into the high-level inputs on the Alpine amp. Alpine is signal-sensing on the high side so no need to find and wire for a blue remote. Made the installation easier.
- For the ground connection, you just pop off the chrome looking trim where the trunk lid closes (and maybe the back wall.. can't remember). Pretty simple to do.
- The right-side footwell trim (front and back one piece) is easy to pop out as well, no screws.

Part 3: responding to a dfew questions...

What's under the seat on the left? Is that a safe?

How’s the sub and the amp been treating you so far? Curious why did you have the sub pointing down, does it sound better like that?

Just finished the exact same install only with a premised box, a 12” MB quart woofer. Wow what a difference. Thanks for the details write. Sounds amazing now.

How are you guys wiring the amp to get a signal from the factory radio?

Off the factory sub.

@jptri I know I’m reviving an old thread here but this was very interesting and potentially problem solving for me. Do you see any reason why this wouldn’t work on a 2017 Q7 that came with their short-lived base audio system (no Bose amp, and generic speakers)?

If not, I’d be inclined to try this and then also upgrade the rear door speakers with Kickers as well (6.5”) for what should be a decent audio upgrade.

Do you any reason why this would work for the 2017 base audio package that doesn’t come with the Bose amp in the back? Trunk foot print is the same and includes a factory sub (no amp).

I don’t see any reason why it wouldn’t.

Thanks! I had a few typos but you got what I was asking. Do you happen to have any pictures or you create a build thread?

Has anyone tried relocating the Bose Amp on the left? Last I looked at it, and it is on a bracket that suspends it off the floor by a good 4-5 inches... I'd imagine you could clear up even more room if you are able to rotate that up along the left wall.

I imagine it would work as long as their is some kind of sub in the back. All you're doing is tapping into an audio lead to feed to a sub amp.

I'm normally on the A5 subforum side.

But I do a cable that you guys can use to add in an aftermarket amplifier and Subwoofer without cutting any cables.

See https://www.audiworld.com/forums/aud...ables-3000733/

There is a high powered speaker connection running from the amp to the sub. I think I saw earlier that someone sourced the connector (sub-side) to that plug. I just tapped into that wire before the plug (without cutting the plug off) by using a tap splice from Home Depot. It's clean.

Which 2 wires on the alpine adaptor did you tap into? Also, the Kicker sub...you plugged that directly into the speaker output on the alpine amp correct?

Thanks, youre a hero. I won't do that mysel, but i have a good sound guy i can trust.
cheers,
Bob