2019 (B9 Sportback) RS5 Subwoofer - IS OUT OF PHASE from the factory

[djmika]

For those who feel that the factory B&O system with the subwoofer in the spare tire well sounds poor...

I'd kind of accidentally caught that the subwoofer may have been wired out of phase from the factory browsing threads about my car, which I picked up used last month. I'm an audio geek who has made a career in high end audio and custom integration and I've got a reasonably keen ear. Not that it took that to realize the system as it came from the factory under-performs, objectively speaking.

So this morning, I decided to see if the subwoofer indeed was wired out of phase from the factory. The answer is a resounding YES.

My experiment was simple. I fired up some music in the car and listened to it the way it came from the factory. I tried dialing the "fader" all the way to the front and then all the way to the back. When I moved it back, there was more bass. So, I removed the sub. Easy - two nuts and the hand "knob," then unclip the connector on the top of the sub. Box is out. Five minutes. Fired up the soldering iron, removed the woofer from the box and reversed the wires on each voice coil of the factory sub. I used a desoldering bulb to clean the terminals up which made it easier to put back together. The only minor challenge was getting the wires right so they can run through the channel under the woofer frame and so that the woofer fits back over the pins and screw holes. It'll really only go back one way. Took me 15 minutes.

Tested again. Again I can say unequivocally - there's way more bass. Now the car sounds like it has a premium factory audio system.

The simple science here is that the subwoofer being wired out of phase causes it to cancel bass in a critical range in the audio spectrum. The speakers in the rear of the car don't make much, if any bass so setting the fader to the back reduced the cancellation. However, the speakers in the front do make bass. Concensus is that they play down to around 50-55Hz. That's well in to the mid-low bass region of the audio spectrum. I suspect the factory sub covers from around 100Hz and starts to roll off ~30Hz (with the help of a lot of cabin gain). So mid-bass drivers in the front of the car overlap the sub in a critical frequency range. Wired backwards, they fight or cancel each other causing the weak bass we all hear. But after reversing the phase, they're now reinforcing each other. Net result, I was able to turn both the bass and subwoofer settings way down. I still have way more bass than I did before and the system doesn't have to work as hard. So it has pretty solid bass and plays much more loudly. Again, at a level one should expect from a premium car's premium audio system.


I did also add some "fill" or batting loosely tucked around the subwoofer driver in the enclosure. I had some from an old JL sub I have taken apart (for repair) so I stole the batting/insulation from it. If you want, you can probably get this from Parts Express.

I'm not saying this is better than replacing/relocating. That can unlock a whole other level of potential and is an apples to oranges comparison. But this was easy and for many, I suspect will make them completely happy with the factory system.

I'm happy to answer any questions anyone may have.

[sthulin]

So what is the correct color coded wiring to fix the phase?

[SHCKR]

@Bobby Kinstle thoughts?

[chrisdazzo]

For mine, I just swapped the green/black and yellow/red to the other side, and added some batting. Sounds great. Granted I should’ve used a soldering iron, but wire nuts work, too.

[djmika]

What Chris said...

Plus he was kind enough to take pics. I only had a few minutes before I needed to run out to do Mother's Day duties.

Just swap the wires on their respective terminals. That's it!

MB

[RPMtech147]

NM.. Im dumb

[djmika]

Nah... All good.

In running errands I got to listen a bit. As with many cars, windows down = more bass. A fair amount more.

I still don't think this is a proper substitute for someone who was already inclined to go aftermarket. There's much, much more bass than the way it was originally. But it can be a bit "peaky" in the mid-bass. Certain songs make it sound like there's a 10 back there and other, less so. I think it's definitely hot between 50 and 100 Hz and then rolls off fairly quickly. The factory sub is ported so as a 4th order alignment, it'll roll off fast below the tuning frequency. Even with cabin gain. Conversely, the Basser box that people seem to use a lot is sealed. It'll start it's roll off higher but then do so at half the rate. My guess is that with the right driver, bass from the sealed 10 will be smoother and latch on to that cabin gain and probably have significantly more extension. I'm betting meaningful bass in to the 20-30Hz range.

Still, for someone NOT inclined to upgrade, you really should do this. It's the way it was meant to sound.

MB

[RPMtech147]

The factory sub in my S4 is lack luster and it's blown in my A4 (So I unplugged it) lol. I guess I stopped caring about "bass" in my mid 30's.

(wasn't that long ago = ))

Now it's retirement, taxes and kids...Lame I know.

Good post though. It's funny VAG hooked it up backwards. I'll check the old S4 now.

[djmika]

I hear ya! Priorities do change, for sure. I'm a 45 year old dad but also an audio nut and this was just too easy.

I had an 05 S4, 6-speed. Such a cool car. The sound of the 4.2, The Recaros... I ended up getting rid of it because the of the chain tensioner... It was getting unnerving and my car had some miles on it.

My grandparents used to live near Mendocino and there were some hairpin turns on the way to their house that he said he always dreamed of driving in a Porsche. He never got to do that but when he was about 80, I took him through them in the S4. He said "this will do, now I can check it off the bucket list."

[sthulin]

thank you for the images. So which of these wires would be considered the positive and the negative? I'm trying to figure out if i wired it correctly or incorrectly when i switched to the kicker sub

[djmika]

I don't think they're marked. The only easy way I know is for someone to touch a 9V battery to each set of terminals of the factory woofer and let us know which color corresponds with the woofer moving in an outward motion. Then, be sure to note whether that person has already reversed polarity or not.

That said, there is a lot more bass when the sub is in phase with the front door speakers. I'm guessing you added a Kicker sub to the factory box based on what you're saying. If that's true, try moving the fader all the way back and see if there is more bass or not. If there's more bass then the front speakers are probably cancelling with the sub and you should try reversing the polarity on your sub. Do be careful not to wire one woofer terminal in phase and one out. You could damage stuff that way. Probably a woofer.

I'll say this to folks who are using aftermarket woofers in the factory box... The factory box is ported. Replacing the woofer in a ported box requires careful selection of a driver which has Thiele-Small perimeters that'll work with that size box and port tuning frequency. I think there's a member whose name is mentioned above, Bobby who tested several drivers in the factory box. I think he found that few actually worked as well or better than the factory woofer. This isn't a surprise. Plugging the port may actually yield overall better performance but likely will also require more power than the factory amp has on tap.

I've been listening since I made the switch over the weekend. I definitely have the bass turned down from where it was. I'm running both the bass EQ and sub volume setting at 1 click past 12. Any more and the bass gets a little unruly, especially the mid-bass and especially with the windows up. Windows down and there's way more bass but it's also a bit better balanced.

[chrisdazzo]

As for the polarity of the wires, I assumed they were the same horizontally across the subwoofer connections. So, red to green, black to yellow, and vice-versa, I think.

[ninjamanRS5]

Very easy procedure with excellent results! Thanks, OP!

[RS-5hadow]

Sorry I'm not audio savvy but just to confirm, you would just swap the black and the green? Then do the same for the other side ( yellow and red?). IMG_7306.jpg


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[Smac770]

It would seem like it would be a lot easier to just repin the harness plug than do all that soldering work on the inside of the enclosure.

For the B9 B&O, the sub is a dual voice coil driven by dual amp channels. Also, two of the wires are inverted for wagon vs sedan.

B9.0:

T38/19 > red/green > pin 1
T38/20 > brown/green > wagon: pin 2, sedan: pin 4
T38/21 > brown/violet > wagon: pin 4, sedan: pin 2
T38/22 > blue/yellow > pin 3

The pins on the B9.5 B&O amp are not the same as the B9.0 B&O amp, for whatever reason:

T38a/20 > red/green > pin 1
T38a/8 > brown/green > wagon: pin 2, sedan: pin 4
T38a/7 > brown/violet > wagon: pin 4, sedan: pin 2
T38a/19 > blue/yellow > pin 3

One has to presume the swapping of the pins is to correct the phase delay due to the differing placement in the chassis between the two body types.

Since no one with pics related the four internal wire colors to the voice coil markings and to the plug pin positions, cannot really determine what the wires from the amp were going to in regards to coil 1 +, coil 1 -, coil 2 +, and coil 2 -. I have to assume the sub's voice coil wiring terminals have + / - markings on them in some manner.

Typical Audi, they get less and less helpful every product release. The B9 communication manual has not a single pin-out of any device in the whole thing, so there's no explanation of which pairs of amp pins define the actual channels, nor their polarity. The designated swaps between two different amp channels seems odd to me. Someone would have to get serious about testing the designated pins on the amp output to determine their relationship so they can be related to the +- of the two coils to really determine anything absolutely.

Note, I only have the 8W wiring diagrams. Someone else would have to confirm the F5 coupe and sportback follow the same wiring configs. It's hard to say if the sportback is using the sedan wiring or the wagon wiring. The wagon sub placement is the same, but the rear glass likely produces a different response timing.

[ninjamanRS5]

That’s what the OP says to do. :)

Sorry I'm not audio savvy but just to confirm, you would just swap the black and the green? Then do the same for the other side ( yellow and red?). IMG_7306.jpg


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[djmika]

Ninja and RS-5 - Yep! Dead on.

I keep on playing with settings in MMI. Ultimately, the system is better since I reversed the polarity but bass can be "peaky." Today I tried turning bass down and sub up. For some music I like it better. Some, it was a little light weight.

Ultimately, I definitely still prefer it the way I have it now. There is a part of me that wonders if Audi reversed the phase purposefully because it does cancel some of what may be perceived as excess mid-bass energy. That'd be pretty lame. A little massaging with DSP/EQ could have probably taken the system to the next level.

Regretfully, I neglected to mention that I'm working with the B&O system. I've not heard any other options so I don't know if this translates. At the end of the day, the design is still flawed. The sub is pretty well sealed off from the cabin. Mine could even be worse because I have a WeatherTech mat in the back. The enclosure is also clearly tuned high-ish. On tracks with energy in the right frequency band, the system surprises me at times. But the next track could just as easily sound lackluster.

Smac - I think your point is fair. It really depends on people's comfort level with soldering. For me, it's something I've done for 30+ years and am good at. This whole experiment took me under a half hour. So that path was easier than trying to change pins. And I think my mild OCD would get me if there as a clear correlation between wire jacket color and marked polarity on the woofer, but that's certainly not the case.

I'm still considering my next move. I have a local audio fabrication shop that I do some business with for my Custom Integration business. We may fab up a lighter box with a woofer chosen specifically for alignment and that also leverages cabin gain strategically. I just need to find the time. But if/when I do, I may see if we can make it available for purchase. I'd also be looking for a step-up from the Kicker amp. No knock - it's just $250 and I think there's more performance to be had.

[sthulin]

What are people using for the "Sound Effects" settings? I noticed a huge increase in bass changing the focus from All to Front.

[djmika]

I have all of the "nonsense" stuff turned all the way down. Surround Sound, 3D... For me it boils down to less processing = better. I didn't notice an increase in bass when I played with the focus setting but it's possible that there is one. I do remember feeling like the rest of the range and general "fullness" of sound suffered on anything but "all."

I think there is some subjectivity here. My perspective is pretty well rooted in Hi-Fi which as I say, is an industry I've been part of for decades. I'm a McIntosh dealer and I use their top preamp and stereo amplifier with a nice pair of speakers and subs and the system doesn't so much as have an EQ. It's a little unfair to compare that to the factory B&O system in my car but I am a purist so the blatantly processed stuff goes against what I believe to be the fundamentals of good sound reproduction. Fortunately I think, for me, I've resigned myself to living with the factory systems in my cars. There is so much tied together these days that the cost and risk involved with heavily modifying these systems is a non-starter. So IMO, all processing = off, focus = all and then I add a bit on the treble dial to offset the slightly sterile, mid range-forward nature of the system. Then, a reasonable solution to getting smooth, extended bass out of the system without tearing the car apart or modifying anything past the point where I can easily return it to stock.

[chrisdazzo]

That’s what the OP says to do. :)

Noooo. I understood I had to switch red to green, and yellow to black. Did I fuck it up?

[RS5-TP]

So I was skeptical. For the heck of it I took the box out, turned on the soldering iron. I heated each terminal and pulled the wires out, used an awl to clean the holes for the re-soldering and slapped it back together. I wanted it to look factory for any warranty purposes. I did all this in 30 minutes, and all I can say is HOLY CRAP! What a difference! I actually sat there and laughed for a bit. It actually felt like there was something back there. I initially had my settings at focus to the front and medium surround. Now I am focused in ALL, and high surround. I think it sounds 10x better. I used a fair amount of polyfill as well. I have quite a bit of range. This is too funny.

[ninjamanRS5]

Yeah the bass hits much harder. It’s still not like having a 10” sub in the back but it’s definitely more along the lines of what you’d expect from a premium system. I’ll have to pull it all apart again soon and do a better soldering job though lol.

[djmika]

Glad people are finding results inline with mine. For people who won't upgrade the system in any way, it's kind of a shame not to do this. The car just sounds better after performing this small task. And even if soldering isn't your thing, maybe you know someone or can take it to a shop and pay $100 +/- and have it done. IMO, it's worth it.

That said, I've bit the bullet and am going to upgrade the sub. I have a couple objectives. #1 - better sound, obviously. #2 - I want a better place to store the jack than floating around on top of my WeatherTech mat.

Most go with a 10" sub in the Basser box, powered by the Kicker Key amp. Some leave the factory sub, some don't.

I'm going a different path. I've purchased and am awaiting arrival on the following list of parts:

1. Hertz Mille Legend ML2000.3 - a very high quality 8" driver. My goal here is not to be limited by the size of the enclosure. I also bough the Basser box but am just using it to model. (I'll be selling it after I'm done).

2 .Audison SR 1.500 mono amplifier - Again, a high-quality amplifier with high level input. This amp has what they call USS (Universal Speaker Simulator) which should allow me to remove the factory sub completely without worrying about the sub amp channels shutting down.

3. Elite Audio EA-PROK4 4ga wiring kit - This also looks very high-quality.

I was considering also doing the AudioControl LC2i Pro but for now, I'm going going to. I'm thinking I really won't need it but we'll see.

I'll be building an amp "platform" + jack mount that'll also support half the weight of the spare tire like the factory sub does. Also, important to me is that I can easily return the car back to stock.

I'll post as the project progresses.

[sthulin]

So i went and did this today with the kicker sub (also verified that from the factory green and yellow are wired as positive and black and orange are wired as negative. So now that ive swapped it, it for sure seems like there is more bass fill, so this is great find. Now to play around with redialing this in.

[RS-5hadow]

Question: so if you swap the stock wires and have it in correct phase, will I also have to swap the Basser sub box I have as well? Wonder if that is perhaps out of phase as well...


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[djmika]

5hadow - It's very possible. A lot of amps will have a 0-180 deg. dial or switch which makes it easier to test. But if the signal going to the factory woofer was out of phase from the factory and you followed the same wiring and your amp is non-inverting, then yes. It'll probably be out of phase. There are a lot of factors that can muddy the waters though. For instance, DSP in a Kicker amp probably introduces some latency which messes with time which may impact phase. Best thing you can to is test. The way our cars are set up, with the front door woofers and the sub overlapping between say 50 and 100+ Hz, it should be fairly obvious when you've got phase right.

[RS-5hadow]

5hadow - It's very possible. A lot of amps will have a 0-180 deg. dial or switch which makes it easier to test. But if the signal going to the factory woofer was out of phase from the factory and you followed the same wiring and your amp is non-inverting, then yes. It'll probably be out of phase. There are a lot of factors that can muddy the waters though. For instance, DSP in a Kicker amp probably introduces some latency which messes with time which may impact phase. Best thing you can to is test. The way our cars are set up, with the front door woofers and the sub overlapping between say 50 and 100+ Hz, it should be fairly obvious when you've got phase right.

Thanks bro!

I did the OEM first and it didn't make too much of a difference until I turned off my Basser/Kicker. Then it really hit -much better than factory. But as I turned up my aftermarket sub, it started getting muddy and sloppy and I lost some of the deeper bass/impact. So that made me think and after swapping, it sounds SO MUCH BETTER. So I think it's safe to say both were out of phase?


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[Mugatu]

What I don’t understand is that if the masses agree that the sub is wired incorrectly from the factory, how is this not recalled officially from Audi to fix?

[RS5-TP]

What I don’t understand is that if the masses agree that the sub is wired incorrectly from the factory, how is this not recalled officially from Audi to fix?

I couldn't imagine convincing a SM that there is something wrong with the sound of something that is emitting sound. Not worth the effort if you ask me. It's arguable if the sounds are out of the requirement scope as engineered. Not sure.

I fixed and moved on

[ucisigma]

I performed this simple mod on my kicker subwoofer. I’m very pleased by the significant increase in bass. It is what I expected to hear after upgrading the stock subwoofer. Thank you!

[Lensch09]

Welp folks - rather than ripping a bunch of stuff apart (Kicker Comp RT in stock sub location, Kicker Key 500.1 and JL 10W1V3-2), I decided to re-pin the factory harness to the sub. Just did it, took some pictures, will report back.

-DL

[Lensch09]

Alright folks - I just reversed phase of my entire rear subwoofer system.

Components (full build over on AudiWorld):
Kicker CompRT 48CWRT672 in place of stock 6.75" woofer (encloser laced with polyfill)
Kicker 47KEY5001 Amp (Key 500.1)
Kicker CK8 wiring kit
Bruce Miranda/Mironics subwoofer splitter cable
Basser Box (sourced from Maxxcount.DE to avoid importation issues) - Also laced with polyfill
JL Audio 10W1V3-2
JL Audi SGRU-10

Rather than ripping apart my Bruce Miranda/Mironics cable, my factory location sub wiring/box, and/or custom RCA cables - I made the decision to simply de-pin the factory harness at the source, flip the wires, and hit everything at once.

Before:

IMG_5761.jpg

After de-pinning, and re-installing with a reverse polarity/phase

IMG_5762.jpg

Bruce Miranda/Mironics cable back in place

IMG_5763.jpg

Fully back together (before carpet and all-weather mat re-installation)

IMG_5764.jpg

I can honestly say the difference is well welcomed - I always thought the bass was a bit "boomy" and fell off down low. Not sure if there is a placebo effect or not, but all of that seems to be remedied.

Sample size is still relatively small, I still need to fiddle with a few settings, and I need to re-run the Kicker Key algorithms. Regardless, I truly feel we're in a better spot now with my system than before I did the change.

Thank you for the recommendation - I never even thought to check polarity/phase!

-DL

[Daaavid]

I come in peace . . . from the B9 sedan side of the forum. I am curious if there will be an improvement for us sedan vs. sportback/wagon owners.

Is the litmus test to simply roll fader front to rear and monitor bass response?

[Lensch09]

I come in peace . . . from the B9 sedan side of the forum. I am curious if there will be an improvement for us sedan vs. sportback/wagon owners.

Is the litmus test to simply roll fader front to rear and monitor bass response?

More or less, yes.

-DL

[djmika]

Daavid - Right. Start there and then if you have questions about what you're hearing, I personally, will do my best to help.

Micah

[t1000bp]

Thanks for the de-pinning instructions. I just did this on my SportBack and definitely bumps harder now.

[chip_]

So can this be done two different ways with the factory sub?

1 - swap the green/black and yellow/Orange on the woofer itself ....see attached pic. From what I read etc green and yellow are wired as positive and black and orange are wired as negative.

OR

2 - repin the harness plug

[Numbahz]

Thank you OP your a savior ! I had upgraded my factory to kicker like most ppl but it's still not lined up and there was so much more bass when tuned to back only (I would often fiddle with songs pretending that's the bass i "should/could" have) now with the simple swapping yellow to orange, orange to yellow _ black to green and green to black ... wow impressive I can FINALLY use the bass control as it aligns purrrrrfectllyy with the sub now ... today is a good day

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[Smac770]

So can this be done two different ways with the factory sub?

1 - swap the green/black and yellow/red on the woofer itself OR

2 - repin the harness plug

It's just wires from amp output terminals to sub voice coil terminals. Swapping them anywhere along the way accomplishes the same result. So yes, either or.

[Lensch09]

It's pretty easy to re-pin the factory harness - Watch this video if you've never re-pinned a connector. Since this is in the interior, there's no "weather sealer." Connector type is also slightly different, but the same in concept.

https://www.youtube.com/watch?v=lrs8-KtJGus

You'll want to buy this tool kit, if you don't already have it or something similar.

https://www.ecstuning.com/b-schwaben...8aAjBgEALw_wcB

Basically, you flip 1,2 and 3,4 (when looking at the connector from left to right). Basically, new wiring looks like this = 2,1,4,3

-DL