A4 B5 stock amp mystery bare wires?

[SmoothAssault]

When I bought my A4 I noticed that the rear speakers sounded **** (in fact maybe only one of them was even working at all), so I had a little look at them and found a chunk of metal with a couple of BARE wires coming out of it and it had a little blue connector plugged into it. I have since learned that this is supposed to be an amp!? I found this picture of it that someone posted in another thread...

(What a beast!!)


What I'd like to know is what the green and black wires are supposed to be connected to? Hopefully once soldered to something, this will fix my dodgy speakers.

Also, on the pasenger side in the boot where the tool kit is stored, what is supposed to be in the space under the tool kit? Cause whatever is supposed to be there; isn't =[

Can any one help?

Thanks.

 

[SimonN]

I'm not sure about the green and black wires but I can tell you about the space under the tool kit.....

It's where the CD changer goes.... I presume you don't have one then! Me neither .

Simon

 

[SmoothAssault]

I'd thought it was that, don't really need one when you can fit about 400 songs on a single mp3 CD. =]

Thanks.

Could any one have a look and tell me what the green and black wires are supposed to be connected to?

 

[SimonN]

Right, I quick climb into the boot of my car and I think I have an answer for you !

The green and black wires are connected to the left speaker itself. The picture in your post is of the "amp", which connects to the wiring of the car through the plug on the right hand side. The left speaker itself connects to the green and black wires. I'm guessing that two of the wires in the plug are outputs from the amp and go to the right hand speaker.

I'm no expert, but I have the same car as you and a decent multi-meter so give us a shout if there's anything else you need to know!!

Good luck,
Simon

 

[SmoothAssault]

Thanks again, I'll go have a play with it now and see what happens.

 

[SmoothAssault]

Ok, had a rummage around in my boot, holding a torch in my mouth to see what I was doing... I connected the 'amp' to the blue connector, started up the CD player and touched the wires onto the speaker and it worked!! My soldering iron is at uni, so I'll have to wait a few weeks to finish that off properly.

I did notice however, that the right hand rear speaker still wasn't working. I took off it's plastic cover and wiggled it's connecting wires around and it did produce some audio, but very quiet. So I think I've got a dodgy wire somewhere in the bowles of the audio system. =[

Unless someone has a good idea of where I can pin point the problem, I think my answer will be to get an after market amp, power that straight from the battery, and hook it up to my Alpine HU (I'm pretty sure it has the right outputs on the back). Then put in some good quality speaker cable from the amp to my rears. Will probably be worth putting in some good quality speakers while I'm at it.

Sigh, all this is really going to eat in to my "New wheels and tyres" fund. =[ I hope I can fix the stock stuff and save myself 100 odd quid.

 

[SimonN]

Glad you're "getting there" !

It's dark and cold outside right now, but I'll have another look tomorrow. I'm pretty sure that the right hand speaker is simply wired to the blue plug that goes into the amp and that's the most likely cause of the problem. It's unlikely to be a wiring fault within the car, far more likely to be at one of the two ends i.e. the amp/speaker or head unit. Should be easy enough to run a bit of wire from the plug to the speaker to test it...

Alternatively, it could be that the amp or speaker itself is goosed.

Are you using the factory head unit?

Simon

 

[SmoothAssault]

No, I had an Alpine HU fitted as soon as I bought the car, here's a 'not so great' pic:

In my car the blue plug is on the left (passenger side) and this is also the side where the amp is mounted. Connecting the blue plug to the amp makes the right hand speaker produce some very quiet audio, and once the green and black wires are connected to the left speaker, the left speaker works perfectly.

The right speaker appears to get it's audio signal from the blue plug, as it doesn't work unless the plug is connected to the amp. I'm hoping that if I take the parcel shelf apart, and have a good look at how the right speaker is connected to the plug I can work out how to fix everything.

Does anyone have a good tutorial of how to take the parcel shelf apart? My haynes manual doesn't have any pictures and without pictures I find following the instructions quite difficult (I'm dyslexic).

Thanks again for your help.

 

[AndyMac]

Why on earth are you even bothering with the crappy Audi amp?
Just run some new speaker wire from the Alpine HU to the rear deck and by pass it. It only has 2 x 20w, so even if you get it working properly it will be completely obliterated by the 2 x 45-60w going to the fronts from the Alpine's internal amp.

 

[SmoothAssault]

I just don't like the fact that something that should work; doesn't. But you do have a good point. My head unit has a 4x 50W amplifier. What would you suggest regarding hooking it up to my rear speakers?

Thanks.

 

[AndyMac]

Just buy a male & female ISO speaker harness (£2.99 each from Maplins or Halfrauds) this will allow you to connect to the HU without chopping the Audi front speaker harness. Then run some new cable from the HU back to the rears and connect directly to the speakers.

 

[SmoothAssault]

I tested the speakers yesterday, the right/driver side one was ******. Only the tweeter was working. The left one worked but it sounded rubbish. So they've been removed. Once I'd manage to remove the top section of the shelf with the grills, I could see they were in a very bad way. They actually look a bit mouldy and very discoloured, no wonder they didn't sound very good...



I am still a bit confused as to why I need to run new wires from the HU. Is the original wiring not already using the HU's amplifier? If I dropped some new speakers in and hooked them up to the original wiring, would they not just be amplified by both the HU amplifier and the little audi amp?

I plan on hiding an after market amp in the space where the stock CD changer was supposed to be. That will connect the the HU with RCA leads, and new speaker wire will be run up to the shelf speakers; totally avoiding all stock wiring. If the benefits of dodging the audi amp aren't that great, then I think I'll just wait till I have the after market one.

After building the install in my old (now burnt out) punto, I swear by Vibe Audio products, and I'll be fitting 100% Vibe products in the A4. Starting with some beefy coaxial shelf speakers, then a 'blackbox I' amp. But I really, really, really wanna get the 18's on before I start ******* away money on the ICE.

 

[AndyMac]

The stock wiring is effectively RCA leads, feeding the Audi amp with a low level signal and remote on. That is why you have to run new cable as you can't use this for hi level speaker output. All Audi stock HU's only have an internal amp for the front speakers, whereas all aftermarket units can run fronts & rears off their internal amp.
If you just drop new speakers in and connect them to the existing wiring then they won't work unless you extract the Audi amp from the duff speakers and connect it up to the new speakers. Much easier to just run new speaker cable and do the job properly, as said before the stock amp is only 2 x 20w and shyte, so no idea why you still want to use it.

 

[SmoothAssault]

Just because connecting the audi amp to the new speakers would save me having to pull my head unit out, buying the adapter and pulling up all the plastic to run the wires to the speakers.

How I'm looking at it is; I wouldn't be using the audi amp for it's amplifing capabilities, I agree with you; it sucks. But I would connect it to the new speakers just because doing that is easier than running new wires from the HU. So as long as I'm not going to have any adverse effects from powering my speakers through the HU amp, and the the little audi amp, surely that is the easiest thing to do?

Or am I way off the mark here? haha

 

[AndyMac]

I'd say running new cable would take less time and be far superior. You don't have to pull all the trim, speaker cable can just be tucked under the trim. If the Alpine has it's own loom then you don't even need any adapters, you can just cut the Alpine loom and connect the rears.
For the sake of 30 minutes, this will give you much better results and won't compromise your new speakers.
Also remember you'll need adapter rings for the new units as the stock ones use a wierd profile, so you'll need to go shopping in any case.

 

[SmoothAssault]

Ok, thanks for all the advice.

I'll let you know how I get on once I have the new speakers =]

Happy New Year :icon_thumright: