# No sound from rear speakers



## Essexblue (Dec 14, 2017)

I bought my Audi TT back in December. It has the bose sound system but no sound comes out of the rear speakers.

I have tried fade and balance on the head unit but make no difference to the rear.

Are there any issues involving this or is it likely the orginal head unit was replaced at some point and then refitted at point of sale?


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## Wak (May 6, 2002)

Assuming coupe!

If you have fade front to rear then the stereo isn't coded for Bose entirely correctly , hopefully it comes up BOSE when you turn it on?

Bose in a coupe is Front Channel only driving all 7 speakers

Fading to the rear will just turn all 7 speakers off!

The sound equalisation is preset and hence fade all to front , turn volume up and stick your head near a rear speaker you should hear something but it is meant to be "fill in" sound much lower volume than the front door main speakers.

In a roadster the rear is used to drive a central Sub woofer (8 speaker setup)


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## Essexblue (Dec 14, 2017)

Hi WAK

Just been out and double checked and there is no noise at all from the rear speakers with the volume cranked up.

Yes it is the coupe and BOSE appears when the head unit is switched on.


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## Wak (May 6, 2002)

Could be an amp failure or if it previously has aftermarket kit that's been removed

When owners de-mod a vehicle some are not as bothered when refitting things for a sale.

Needs further investigation sadly


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## Wak (May 6, 2002)

Do your door cards have Bose on them? 
If you had a non Bose car with a Bose coded headunit that may give you this situation but I don't know if Bose coding effects the line and speaker outs on the headunit


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## pcbbc (Sep 4, 2009)

Wak said:


> Do your door cards have Bose on them?
> If you had a non Bose car with a Bose coded headunit that may give you this situation but I don't know if Bose coding effects the line and speaker outs on the headunit


No indication of which OEM headunit the OP has...
However all the pinouts of the Chorus II and Concert II that I have seen only ever have speaker outs labelled for front speakers; never the rears?
They do have a full set of front and rear line outs to drive an amp, but as we know the BOSE amp is front channels only (except Roadster as mentioned, where rear channels drive sub).
For this reason my assumption has always been that a non-BOSE setup either does not have rear speakers, or rears are driven in parallel from front speaker outs? Can anyone confirm?


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## LesRSV (Jul 5, 2017)

pcbbc said:


> For this reason my assumption has always been that a non-BOSE setup either does not have rear speakers, or rears are driven in parallel from front speaker outs? Can anyone confirm?


Hi pcbbc,I can confirm that on my non bose concert head unit,the rear speakers work independantly from the front when turned to"fader"


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## pcbbc (Sep 4, 2009)

LesRSV said:


> Hi pcbbc,I can confirm that on my non bose concert head unit,the rear speakers work independantly from the front when turned to"fader"


Thanks Les.

Strange then that the Concert II doesn't show the rears on the label (put I presume they are the "vacant" pins on either side of the fronts):


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## LesRSV (Jul 5, 2017)

pcbbc said:


> Strange then that the Concert II doesn't show the rears on the label (put I presume they are the "vacant" pins on either side of the fronts):


Hi,stole this from wak's site,pic clearly shows no pins for rear speakers,very odd. Don't know if chorus and concert are the same :?: the mystery goes on


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## pcbbc (Sep 4, 2009)

LesRSV said:


> Hi,stole this from wak's site,pic clearly shows no pins for rear speakers,very odd. Don't know if chorus and concert are the same :?:


Same. I had a Chorus.


LesRSV said:


> the mystery goes on


According to this post headunit drives fronts and separate amp for rears.

Seems plausible, but surprised I've never heard this before.  Mind you I have BOSE, so only really familiar with that setup.


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## PlasticMac (Apr 25, 2017)

On a non Bose/Chorus 2 (CD Changer + Cassette in my case), the rear speakers are driven from an amplifier under the rear seat. The 12 volts supply to the amp, and the audio signals get there via the CD Changer cable, that plugs into the Chorus, (LR, RR, 12V & COM, you can see them on the label photo shown in previous replys).
I just fitted a Bluetooth adapter to my Chorus, and initially had the same problem, no rear speaker output, which I eventually worked out, was down to the fact that I had not correctly fitted the adapter cable from the CD Changer cable loom to the CD Changer connector on the Chorus, hence the outputs from the Chorus never got to the rear amp etc.
The same situation will arise when an aftermarket head unit is fitted, unless you fit an adapter cable between the CD Changer loom and an output on the new head unit that will provide left and right speaker outputs signals, +12V and GND, suitable for the under seat amp. These must be specifically for the rear speakers in order that the head unit Front/Rear Fader works.
Failing such an output on your new head unit, you'd have to run new cables and power the speakers direct from the head unit rear speaker output, by-passing the amp. If you retain the amp, it'll need +12V and GND (COM), which you'd have to pick up from the head unit supply. The amp can only handle low signal levels, not speaker power outputs. High input levels will kill the amp.
Hope this helps someone, as it took me hours to work out last week!


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## PlasticMac (Apr 25, 2017)

This pic shows the rear speaker amplifier outputs on the Chorus, LR, RR, COM, 12V. The same connector has front speaker amp outputs, LF & RF. This may be for the Bose amp, but can't be sure, as mines non Bose.


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## pcbbc (Sep 4, 2009)

PlasticMac said:


> This pic shows the rear speaker amplifier outputs on the Chorus, LR, RR, COM, 12V. The same connector has front speaker amp outputs, LF & RF. This may be for the Bose amp, but can't be sure, as mines non Bose.


Great information PlasticMac.

Yes, lineouts and switched power for BOSE.
Although note that in Coupé BOSE uses front line outs only, and while Roadster also uses rear line outs they drive sub only (as discussed previously).


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## Wak (May 6, 2002)

You've made good points and makes sense

Non-Bose have an amp to drive rear speakers hence front only is needed for fronts 
Rear line out is used for the amp (built into left rear speaker )


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## LesRSV (Jul 5, 2017)

PlasticMac said:


> and the audio signals get there via the CD Changer cable


Hi, not wishing to muddy the water,but what if there is no CD changer fitted ? have I missed something ?


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## PlasticMac (Apr 25, 2017)

The CD Changer loom will be there anyway, because it doesn't just do the CD Changer function, but supports the rear speaker amp, which is always there. The loom supports options even if they are not fitted to your car.


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## LesRSV (Jul 5, 2017)

PlasticMac said:


> The CD Changer loom will be there anyway, because it doesn't just do the CD Changer function, but supports the rear speaker amp, which is always there. The loom supports options even if they are not fitted to your car.


Hi,got you now, just had a look in the rear of mine and low and behold,there can just be seen the plug of a cd changer cable poking out from depths,might have to buy a changer now,mind you I only have 1 cd :lol: 
well done that man.


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## SPECSMAN (Oct 11, 2016)

Bose/non-Bose, with or without aftermarket head units, if we are being honest, all sound $hite. 

I would like the time and inclination to strip out all the (almost 20 years old) junk and replace and rewire the whole thing.

My thing about originality would probably stop me.

Speaker technology has improved considerably, you don't need auto-changers and tapedecks, and it's nice to have hands-free calls and music streaming. (not that I would make or receive calls whilst driving; when I am driving, I drive)

Add to this the external amplifier(s), then the weight saving would be worthwhile.

It has been mentioned before, but the door card covers a quarter of the cone, when you remove the grille, so attention is required in this direction too.

Has anyone done this? Care to share?

Specsman 8)


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## spacekatgal (Jan 12, 2018)

Others have said this, but I want to back them up. The BOSE amplifier has a separate accessory wire to turn on than the head unit. Just add it to the accessory wire from your aftermarket stereo.

Sent from my iPhone using Tapatalk Pro


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## Smaler10 (Oct 7, 2017)

Hi everyone, confused ..... having read all of the above discussion about various connection wizardry, can I ask, why the standard concert head unit plus multi changer CD are not connect as standard to the rear two speakers and sub as supplied from build? My wife has recently acquired a 2000 Roadster Quattro, in mint condition,which was previously owned by an older lady who had kept all bills etc and would I assume never have messed about under any seats or certainly not behind any rear speakers. So why do the said rear two speakers and sub not work. Why would Audi fit speakers in rear that are an option to have working from new ?


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## pcbbc (Sep 4, 2009)

Smaler10 said:


> Why would Audi fit speakers in rear that are an option to have working from new ?


Is it BOSE or non-BOSE?

For BOSE Roadster rear speakers and sub should have been connected from new. If they weren't it was a build error that went unnoticed by Audi QC!








Don't know enough about the non-BOSE Roadster speaker setup to say. Did it even have rears/sub?


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## silkman (Jul 29, 2004)

@Specsman take a look on my radio build thread.
http://www.ttforum.co.uk/forum/viewtopic.php?f=2&t=1745586

I did the work around September but had the pics and just now found the time to post on the forum. Mind you, the speakers are shite and I discovered yesterday that on mine now the rears also don't work :x despite having a proper autoleads adapter. I remember they definitely worked when I put everything together. Maybe 4x50 fried them.

Made an impulse buy the other day which i know I'm gonna regret :lol: :lol: :lol:

Haven't fitted them yet. Front and rear cheapo alpines for about 100eur


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## PlasticMac (Apr 25, 2017)

Hi Smaler10. Copied this text from an old post (Acks to MrBrown):

"Re: 2003 225 Roadster- no Bose
27 Jan 2016, 20:25

The "non-Bose" Roadster (well at least in my 03) has a central sub with an amp mounted on the back of it. This amp drives the sub AND the rear quarter speakers. There's a good write-up here

http://mk1tt.montebellopark.com/subwoofer.html"

From that post, it sounds, (excuse pun), to me, like the rear amp is the place to start. I'd check 12V supply at the amp first, then each speaker. To do that, dab an ordinary battery, AA or similar across the two wires that go to the actual drive unit, if it's OK, you will hear a blip as the DC battery moves the cone, Let us know how it goes.


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## Smaler10 (Oct 7, 2017)

Thanks for the responses lads. Very useful. Firstly it is a non Bose, as in "standard Audi". Yes I can see through the speaker grills that all three rear speakers are fitted but no sound. On the concert head unit the fader control does allow rear fade but all this does is fade the door speakers down to nothing. Im having a few minor troubles with this 18 year old car that is only really a weekend toy for the wife. Is spends most of its life laid up under a small cover. I haven't really had the time to get stuck in, other than fixing the drivers door switch (window drop/interior light), passenger door window switch pushed into door handle (nightmare), Haldex earthing strap rusted off, rear window heat wires broken (convertible roof), oh and now the thermostat stuck open, it only runs at 60c thus not returning more than 24/ gall. 
Thanks lads


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## BS3_TT (Feb 25, 2018)

Hi - first post so bear with me please! And no doubt a question asked a million times but can't find a definitive answer...

I have installed a Pioneer MVH-S300BT in my 2000 (W) mk1 TT - non Bose stereo, using Harness Adaptor PC9-401, and PC5-90 aerial adapter... but... no sound from rear speakers.

I know I have to add the blue wire to something... have tried directly off the remote wire from new HU but no joy.

A (idiot proof) description of what to do here would be greatly appreciated!


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## pcbbc (Sep 4, 2009)

BS3_TT said:


> I know I have to add the blue wire to something... have tried directly off the remote wire from new HU but no joy.
> 
> A (idiot proof) description of what to do here would be greatly appreciated!


1. Did rears work before you removed old unit?
2. Assuming they did, is there +12v on the remote wire when new headunit is on?
3. If not, disconnect blue wire and temporarily connect to 12v from elsewhere (e.g. headunit supply) as a test. Do not leave like this though, or you will get a flat battery.


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## BS3_TT (Feb 25, 2018)

Thanks for the reply! Yes they worked before removing old unit.

I'm struggling here with even knowing what the remote wire is! I've literally plugged it all in and have the blue wire left to attach on the aerial adapter.

Have read; _On the red plug of the speaker adapter, there may be a blue cable with a bullet on the end. Connect this to the blue cable of the back of the stereo (switched feed/power aerial)
_
The blue cable from my stereo goes into the block so sure there's some cutting / joining involved but want to be sure before I start. if I do the above I still need to connect the aerial adapter blue wire... assume that will be here?


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## pcbbc (Sep 4, 2009)

BS3_TT said:


> Have read; _On the red plug of the speaker adapter, there may be a blue cable with a bullet on the end. Connect this to the blue cable of the back of the stereo (switched feed/power aerial)
> _
> The blue cable from my stereo goes into the block so sure there's some cutting / joining involved but want to be sure before I start. if I do the above I still need to connect the aerial adapter blue wire... assume that will be here?


Switched feed goes hot (+12v) when the headunit is on. Usually it is used as a signal to turn on related equipment, e.g. an amplifier, or drive a powered aerial up and down (on older cars where it was stowed as an anti-vandalism measure).

In your setup it will need to power *both* the amp for the rear speakers and the signal amp for the aerial adapter. So yes, splicing required.

But you seemed to indicate that rears were not working, and that blue wire for amp is already attached? This is why I said check for 12v on blue coming out of the new headunit when switched on. If there is not 12v there, the amp is never going to work.

If you want a definitive answer, post clear pictures and descriptions of pin outs of both old and new units. Post details of which pin/pins the blue wires are currently connected to. Otherwise it is very hard to offer advice when you are not intimately familiar with the specific headunit and harness, and have no idea what work has been done so far...


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## BS3_TT (Feb 25, 2018)

Really appreciate your help (and patience) - have fixed. The harness had an additional blue and white wire separate to the block... attached that to remote on stereo and blue wire from aerial adapter and hey presto!

Learning quickly with Audi... as with the ignition and live being the wrong way round they insist on doing things slightly differently!


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## PlasticMac (Apr 25, 2017)

Hi, the cable loom that was plugged into the Chorus radio, but now is plugged unto the PC9-401 adapter, takes the switched +12 volts and Comm (along with left and right audio) to the rear of the car, to supply the rear speaker amp, and the antenna amp in the tailgate. The blue fly lead from the PC9-401 adapter needs to be attached to a switched 12 supply to provide this power now the Chorus is gone. I think the blue wire, from the antenna adapter does not need to be connected (but should be insulated to prevent a short circuit), as the existing antenna amp, in the tailgate, already has the 12 Volt supply it needs. If it didn't your radio would not get any signal, so no stations would be received. So just connect the blue wire from tbe PC9-401 to the switched 12 Volt at your new radio. Hope this helps, but if not, a couple of pics will be needed. Don't worry, we'll get there!


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## pcbbc (Sep 4, 2009)

PlasticMac said:


> I think the blue wire, from the antenna adapter does not need to be connected (but should be insulated to prevent a short circuit), as the existing antenna amp, in the tailgate, already has the 12 Volt supply it needs. If it didn't your radio would not get any signal, so no stations would be received.


My understanding is it's an antenna *power adapter*, not an *amplifier*. The OEM head units supply power back to the tailgate amplifier by applying a DC offset on the aerial lead. There isn't a separate dedicated power feed to the tailgate amplifier.

You can have a similar setup for a home TV aerial with a masthead amp, and also your sat disk sends power (and other stuff) up the cable to the LNB (a signal selector/amplifier) in exactly the same way. It's a very common technique for providing power to antenna located amplifier without requiring extra wires.

As you have an aftermarket unit, it doesn't do that. This adapter is simply there to do the "injection" of the 12v DC offset for you.

So without it, you may get some reception, but it won't be amplified as the amp has no power. Regardless there should be no harm in powering it and seeing if reception is improved or not.

Regardless - The OPs original post is about his rear speakers not working. That's not going to be in any way related to the aerial adapter blue wire not being connected! Something wrong with the other blue wire for the BOSE enable - maybe! OP needs to check for 12v on blue wire coming out on switched feed of headunit, and check where it is going.


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## PlasticMac (Apr 25, 2017)

Hi, since the radio worked, lack of sound from rear speakers being the only problem, there must have been power to the antenna amp, without a power supply (ie blue wire from antenna adapter) from the antenna adapter. The antenna amp in my TT (2005 Mk1 Coupe) does not get it's 12 Volts via the antenna cable. The old Chorus head unit didn't have that capability. I'd avoid sticking 12 Volts up the antenna cable. As Corporal Jones said many times, "they don't like it up'em"


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## BS3_TT (Feb 25, 2018)

Thanks - all seems to be working... will know for sure tomorrow if I get out to a flat battery! Supposed to plug and play (to an extent) so figure the least splicing the better!


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## gerontius (Aug 27, 2016)

My 2001 coupe is non-Bose and the rear speakers have not worked since I changed the head unit to a Sony.
I've just stripped out the rear side panels with a view to directly wiring the rear speakers to the Sony head unit but first I just want to check the power to the rear amp (which is mounted on the back of the left rear speaker. )

Those rear side plastic panels are a right pain to remove 

Do we have a diagram showing which is the +12 & which is ground to the amp ?


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## PlasticMac (Apr 25, 2017)

We do:


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## gerontius (Aug 27, 2016)

PlasticMac said:


> We do:


Thanks Mac,
But I don't think that shows the amp like mine, which is mounted on the back of the left rear speaker - it's only got a 9 pin plug.

After a bit of work this eve, I found I do have a 12v power feed to my rear amp, on the red/white wire and the usual brown for ground.
In fact, my rear speakers do work, but the audio level is significantly lower than the fronts. I can correct this with the fader adjustment on my Sony head unit (mex 5100) but it doesn't seem like a good long term fix.

I'm thinking I could easily fix this by disconnecting the rear amp and feeding the rear speakers direct from the head unit output. I'm only reluctant as it'd be more difficult if I wanted to revert to standard.
Cheers
John


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## PlasticMac (Apr 25, 2017)

Yes, dis the rear amp altogether, and run 4 cores from the new HU rear speaker outputs (check the new HU pin outs), direct to the rear speaker coils (having removed the connector from the now redundant amp). I'd run a temporary 4 core, to get it working, then tidy up, once you're happy. Run 4 core under carpet/door frame capping. 4 core flat cable taped to floor is least obtrusive. I think the rear amp was fitted only to allow the same loom to be used for Bose and non Bose, not for sound quality, as it's not a very special amp. Mac.


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## gerontius (Aug 27, 2016)

Thanks Mac,

All done, rears cables directly to the head unit rear outputs, works much better, I should have done this 2 years ago when I changed the head unit.
The old rear amp, mounted on the back of the left rear speaker, I have removed, pictured below. I think this amp did still work and was powered up with the head unit, the problem was that the line-out level from the head unit was too low to feed this amp. (and the set up was unnecessarily complicated.


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## PlasticMac (Apr 25, 2017)

Glad it's sorted. I plan to do the same, been putting it off, in the name of originality, but, a new HU beckons. Fancy the new Kenwood, single din, with a display, and camera input, so will fit a reverse camera. Not sure about the antenna, for FM and DAB. Guess I'll have to bypass the antenna amp in the tailgate, and fit a powered FM/DAB splitter somewhere. Not keen on stick on screen antenna. Mac


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