# Easy B+O Subwoofer Install How-To w/ Photos +Signal Analysis



## macaddict111 (Jun 13, 2018)

Hello TT boys and girls! I love the Bang and Olufsen sound system, but like many people here I was very unimpressed by the bass. The largest speaker in the car is 6", which just doesn't cut it for low notes. Today I'm going to show you how I installed a small Pioneer powered subwoofer behind the driver's seat in about an hour, with no need to remove any interior panels. It's completely fixed the problem, and my bass sounds awesome now. I'm certainly not the first to do this, but I figured I'd put this in a new post for a start to finish guide.

*What you'll need*







•	Pioneer TS-WX130DA Compact Powered Subwoofer: I chose this model after looking at dozens of others because it's one of the smallest and thinnest on the market, fits astonishingly well behind the driver's seat, and another member did a similar install with one
•	4 X Posi-Tap 20-22 gauge taps (the wire in the TT is 0.75 mm thick, so maybe they sell taps by mm size across the pond?)
•	6 X assorted Posi-Twist sizes (for splicing speaker output and 12 V power wires)
•	Fused 12-volt/cigarette socket power supply cable.
•	Wire for splicing speaker output to amp connector
•	10 mm socket with extension (wrench not necessary)
•	Euphoriant beverage (began with English Breakfast tea, became vodka lemonade)

*How I did it*
*1. Unbolt the B+O amp.*







First off, there's a lot of folks who say they took out or unbolted the seat. I absolutely did not need to do this. There was tons of room to work with the seat in the all the way up and forward position, but that's just me. Second, I'm in America, so the B+O amp is under the driver's/left seat. I'm assuming it's still under the left (passenger's) seat in right-hand drive countries, but please correct me if I'm wrong. There are two 10 mm bolts (circled) that were hand tight and came right out with a 10mm socket and extension. Now the amp is loose.

*2.	Disconnect and remove the B+O amp.*







Pull up the amp from the rear and you'll see two things to disconnect. First, remove the MOST (optical) connector by squeezing the clip that's on one side of the connector and pulling back. Be careful not to miss the clip and pull the fiber or correugated tubing out of the connector. It also has a clip that holds it up on the center of the black cover, carefully pull down to free it. Next, disconnect the main harness by pulling the pink plastic lock clockwise, which will detach it and pull back. Pull the plug back all the way free of the connector. Tilt the amp up and slide it out towards the back of the car. Here's what the amp looks like, if you're curious (note the cooling fan on the side).








*3.	Splice the speaker output wires.*







My wiring diagram shows Left Front Bass to be White/Black (+), Brown/Yellow (-), and Right Front Bass to be Grey/Blue (+), Grey/Yellow (-). I had to unwrap some black stuff and carefully dig through the bundle of wires, but it was easy enough to pull these pairs out. BE CAREFUL WITH YOUR HARNESS!!! The cost and effort to replace a damaged harness is mindblowing, but with Posi-Taps and care, you really can't go wrong.







Tap the wires by unscrewing the tap end of the Posi-Tap and seating the wire in the slot, then hold the wire and screw the tap onto the base firmly, which holds and pierces the wire all in one go. These little things really are amazing, and I don't recommend anything else for harness work. Plus they leave the wire with nothing but a small centered hole if you remove them. Next, use some wire (I used DuPont/ribbon wire), and loosen the connection end of the tap, insert the wires into the caps, and tighten onto the tap to secure the outgoing wire.

*4.	Get super nerdy and analyze the speaker output signal.*







Ok so this isn't a real step, but at this point I decided to unleash my inner nerd and analyze the output of the speaker signal to see what's going to be feeding the sub's amp (I'm an electrical engineer don't judge). If you're not interested, keep scrolling before you become nauseated. I was really concerned that the B+O amp would be reducing the low frequency signals fed to those tiny woofers to save power and keep them from distorting. I was pleasantly surprised to find that the amp appears to be feeding the woofers (and therefore the sub amp) with full low-frequency. To characterize this, I connected my oscilloscope to the tapped speaker outputs, and played frequency sweeps with my computer into the system starting at 20 Hz up to about 200 Hz. Below on the top of the screen, you can see the yellow frequency sweep as amplitude vs time. You can see the frequency increase as it goes from left to right (squiggles get faster). Next, I had my scope do a Fast Fourier Transform to produce the purple graph in the "frequency domain" (Oooooo), which shows amplitude vs frequency.







Next I'll show the graph with 20 and 200 Hz marked:







You can see (if your eyes haven't glazed over), that the frequency response is nearly flat from 40 Hz all the way to 200 Hz, where the mid-range speakers take over. And there's a very normal roll off from 40 to 20 Hz. So to summarize, very good signal for the sub amp to be getting.

*5.	Run the 12V power cable.*







I'll admit there's a million ways to do this and people will have different preferences. I chose to power the sub from the 12V outlet in the trunk. This sub's power input wires are 18 gauge and the manual tells me it's not really pulling more than 50 watts continuously, so the 10 amp socket is fine and never even gets slightly warm. Tapping off a 12 V line somewhere in the trunk is probably more professional, but this works great for me, was easy to do, easy to remove, and feeds the sub with power that's cut off when you lock and leave the car (aka no way to accidentally make the battery go dead). I found a really rugged 10-foot 12V socket with wire lead on Amazon that has an internal fuse with 14 gauge wire. I ran it under the trunk mat and foam by the spare tire well, and there's no weight on the wire despite how it looks in the photo. Next, fold the left rear seat down, and there's a ton of room to feed the wire down low left of the seat, and between the gap of the seat bottom and rear plastic all the way to behind the left front seat. The folding seat also doesn't pinch the 12V wire at any spot, so it seemed very safe.

*6.	Reinstall B+O amp, connect and tidy everything.*







Slide the B+O amp back in towards the front of the car to re-engage the two plastic holders. Seat the main harness in the connector, and rotate the pink handle counterclockwise to pull it in and lock it. Reconnect the fiber optics, and secure the center fiber optic clip. Lower the amp back down flat, ensuring your new taps are fitting in the space and not catching on anything. I used Posi-Twists (basically super-secure wire nuts made by the same company) to splice the speaker outputs and 12V wires into the subwoofer's harnesses. This model needs its switches to be set to Speaker-level input with Normal input gain. The blue remote wire is not used, it powers on automatically when the B+O amp powers on. Tidy up and that's basically it! I drive with my seat in the lowest position, and I'm 6 feet tall and had no issues moving the seat back to my usual position. I don't know if it would go ALL the way back&#8230; Here's how it looks finished, it's uncanny how well it fits into that space. You almost can't even see it.














I should note this unit has a controller with gain and crossover settings that has to be connected all the time for speaker-level inputs. Once I dialed in my settings it secured nicely to the side of the sub or under the seat, and I can control the bass very well via the audio settings on the virtual cockpit. I actually had to turn the car's bass level way down, this little sub has a lot of oomph!

I'm super happy with the results. I wasn't looking for a crazy level of bass, just the amount in other Bose car systems I've had, for example, and this really delivers. This is just one way to do it, and I hope this guide helps someone. Let me know if you have any questions!


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## simon3868 (Feb 26, 2011)

Excellent write up and really helpful, thank you so much-it's on my wish list to do!
Cheers, Simon.


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## kevin#34 (Jan 8, 2019)

excellent tutorial! 8)


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## gAgNiCk (Dec 25, 2017)

Thanks for the write up, I know what my next project is


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## kevin#34 (Jan 8, 2019)

to _macaddict111_
just read again (but more carefully) your excellent write-up....

some questions:
- you took +/- signals from the B&O amplifier, so you didnt' use the line inputs of the Pioneer but the speakers level ones, can I ask you why?
- I'm slightly taller than you, and I usually drive with the seat all the way back, it would be possible to confirm if your seat can still go fully back, without interfering with the sub?
If not (or you cannot test), do you think it would be feasible to install the sub under the passenger's seat (enough space?) and reach the B&O ampli wires in an invisible manner?
thanks


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## macaddict111 (Jun 13, 2018)

kevin#34 said:


> to _macaddict111_
> just read again (but more carefully) your excellent write-up....
> 
> some questions:
> ...


Hey Kevin:
- There are no line-level signals anywhere. The audio input to the B+O amp happens over the fiber optic cable, so the only place to get a low-frequency analog audio signal of any kind is from the woofers in the front doors. This pioneer amp uses the same connector for either line or speaker level inputs, and you flip a switch to choose.
- I don't think the seat will go all the way back. It just starts to rub and slow down on the sub when I get it to the position I'm normally in, but not too bad. I wouldn't want to take it all the way back in the full-down position. However you can either elevate the seat a bit, or nobody says the amp has to lay flat back there, you could always position it upright or at an angle. Up to you for how to keep it from moving around, but there's plenty of flexibility back there.
- Passenger seat-well would work too! You'd just have to run wires from the left footwell over the hump to the passenger's, and obviously get the 12V there too, but you can easily route it there under the trunk. My first step in all this was to carefully unbox the sub and put it where I was thinking to see if it worked with my seat position. Then you can feel comfortable it will all work out, or you can return it, no harm done.


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## kevin#34 (Jan 8, 2019)

very clear, thanks a lot again!
I have a long _to do list_ but would like to add this mod too


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## blackvalver (Jan 6, 2020)

brilliant write-up and on my list now too 
out of interest, what difference do you think the EA model would make over the DA?

DA
Frequency response	DEEP Bass Mode: 20 - 200 Hz
DYNAMIC Bass Mode: 40 - 160

EA
40 - 200

DA
Sensitivity	DEEP Bass Mode: 95 dB
DYNAMIC Bass Mode: 100 dB

EA
98 dB


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## Gnasher (Oct 21, 2020)

Just a quick addendum for people who want to do this but DON'T have the factory B&O system...

The speaker level signals can be tapped into behind the glovebox - you only have 4 full range channels of outputs to choose from but to interfere less with the sound, probably best to use the rear feeds. It's tight behind the glovebox though.

I've taken the feeds from there to feed my Audison bit ten (once I've finished installing it all lol)


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## MrOCD (Feb 9, 2021)

Gnasher said:


> Just a quick addendum for people who want to do this but DON'T have the factory B&O system...
> 
> The speaker level signals can be tapped into behind the glovebox - you only have 4 full range channels of outputs to choose from but to interfere less with the sound, probably best to use the rear feeds. It's tight behind the glovebox though.
> 
> I've taken the feeds from there to feed my Audison bit ten (once I've finished installing it all lol)


Nice 

Any pics?

I'm sorely tempted to do this myself... but need to find a sub that can go under the passenger seat or under the carpet in the boot...


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## Gnasher (Oct 21, 2020)

MrOCD said:


> Gnasher said:
> 
> 
> > Just a quick addendum for people who want to do this but DON'T have the factory B&O system...
> ...


Sorry, no pics. I've currently only replaced the speakers with Focal components and completed the wiring. Just in the process of creating an amp rack to fit in one of the storage compartments under the boot false floor for a 5 channel amp and the signal processor.

In essence, it would be the same process as described above but the speaker wires are behind the glovebox.


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## MrOCD (Feb 9, 2021)

Gnasher said:


> MrOCD said:
> 
> 
> > Gnasher said:
> ...


What I need really is a picture of the plug with the speaker wires to help identify the wires for the rear speaker feeds. I'm assuming four channels with passive filters on the tweeters.


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## Gnasher (Oct 21, 2020)

MrOCD said:


> What I need really is a picture of the plug with the speaker wires to help identify the wires for the rear speaker feeds. I'm assuming four channels with passive filters on the tweeters.


Whilst I've not got photos, here's what I found...

1. The 4 speaker connectors are within the one multi-plug that is connected to the back of the DVD player.
2. They correspond to the industry standard colours (Green, grey, purple and white pairs).
3. The tweeters do indeed have a passive filter on them, the woofers get full range.
4. You'll need to strip back the outer woven cloth covering to get to the wires.
5. The glove box is a bit of a pig to get out. There's multiple screws (including one behind the dash end panel)
6. There are lots of connectors (approximately 6, including the airbag disable switch) some of which are quite hard to get to for disconnection.
7. If you need to turn on the ignition with the glovebox out, you'll get an airbag light come on. This can be reset with OBDEleven (or other code resetting tools).

Can't think of anything else though but feel free to ask any specific questions either on here or by PM - good luck with it!


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## blackvalver (Jan 6, 2020)

I'm working on an install of the 'EA' version of the Pioneer amp, this is essentially identical to the 'DA' version but 2/3 of the price at the moment, it just has a gain control underneath the unit rather than a remote which is no big deal as I'll set it once and leave it anyway.
I've decided I don't want it visible behind the B&O amp and preventing anyone (unlikely but...) sitting in the back getting their feet on the floor, so I'm fitting it fully under the driver seat (UK RHD so B&O amp is on the other side).
This has been a little tricky as the seat forward/back adjustment bar underneath on the standard seats fouls the top of the unit so I've had to cut into the carpet much like the B&O amp does on the other side, I'm then taking power from the under armrest power socket wiring and going under the centre console to the B&O amp for the speaker level inputs. This was fun too as needed lifting the carpet and back of the centre console a little and of course this is a seats out job.
I'm going to leave the cut carpet folded back around the speaker as with strips of velcro around the amp sides it secures the amp very well.



















before trimming the under carpet felt down lower:


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## chelspeed (May 6, 2017)

blackvalver said:


> I've decided I don't want it visible behind the B&O amp and preventing anyone (unlikely but...) sitting in the back getting their feet on the floor, so I'm fitting it fully under the driver seat


Nice work, impressed.


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## blackvalver (Jan 6, 2020)

I've fitted and wired this in now, one minor correction to the original thread post, the blue 'remote activation wire' needs to be powered to turn the amp on, so you can just connect it to the same feed as the power (yellow wire), e.g. an accessory power socket (centre armrest power socket is the nearest) as in my pics.
This little unit definitely gives a big boost to the low end of the B&O install, if you have the standard sound system I'd say it's even more important 
So, I'd recommend the "EA" suffix unit (no remote) as it's £50 cheaper than the one with the remote and I can't see the benefit of the remote anyway really, I might turn the gain down a smidge on the unit itself from the supplied new position (about 1/2 way) after listening to a variety of music already, but that's only as you get a bit of distortion when you get to 3/4 volume on the B&O, which was hurting my ears by then anyway :lol:
I can feel the bass on my chest and now backside too...


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## hwmouton (Aug 12, 2019)

I have the 9 speaker Audi Sound System with 110 watts I swapped out 8 of the speakers for Focal plug and play from Skipton Car Radio. I was never able to find the amp, but there is a MOST fibre connector on my MMI. I tapped into the white and grey front speaker wires on the Quadlock connector behind the MMI in the glovebox. I connected to a Line Out Converter to provide line level signals and a turn on signal to my powered amp in the boot. Note that the rear speakers, just like your surround speakers at home, are digitally controlled/staged by the MMI and are not a good source for a consistent low frequency signal that your sub requires. The LOC requires constant 12v power and the red/yellow wire on the Quadlock is perfect for this as it turns off 5 seconds after you close and lock the car! I ran RCA cables and the blue turn on wire from the LOC behind the glovebox and along the door sill, under the rear seat and into the boot. I taped wrapped and then tie wrapped them to other existing wires so there is no rattling. I even ran the sub controller wiring along the same route to give me the ability to make adjustments from the glovebox. I have an 8" powered MTX tube packed in the boot that I connected directly to the battery with a fuse and to one of the many ground connections in the boot area. After some minor fine tuning, I can turn it all the way up with zero distortion and dial in more bass via the MMI when required. It is not as loud as the B&O system, but it provides way more bass. I actually feels nice even at low volume levels.


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## hwmouton (Aug 12, 2019)

Door sill


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## hwmouton (Aug 12, 2019)

More photos from the install. I did not have any black wire so you will see a red wire being used as my ground. It has black ends. If you have any question, please ask.


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## motodenta (Sep 16, 2021)

blackvalver said:


> I'm fitting it fully under the driver seat (*UK RHD so B&O amp is on the other side*).


On the higher models with magic carpet ride aka magnetic suspension, the suspension module is under the
driver side (right-hand side).
Besides that, there is much space to hide any decent box.
*Electronic Suspension Control Module | 8V0907376H 
8V0907376F OOOO
CTE-CTE24.06.1941350477







*


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## b1ggles (6 mo ago)

Interesting that the original post says a 6" driver doesn't cut it, of which there are two, but the sub only has a single 6.7" one.

Just saying


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