I need some information on Audi OEM and BOSE version headunits (Concert I tape/radio)

[A4 stu]

Hi - hope someone can help?

This thread relates to my 98 B5 A4 saloon which is fitted with the standard non-Bose concert tape/radio, no cd changer and the active rear speakers.

Basically I am trying to determine the difference between any built in EQ (if any) between the standard Audi Concert tape radio and the BOSE version. I am led to believe the BOSE version is the same unit but simply re-programmed through VAG-COM to work differently.

As a bit of an experiment I plan to install a connects2 ipod adapter through the the factory CD changer input, upgrade the speakers, add an amplifier and maybe add a subwoofer as well.


I can easily use the rear speaker output which is already low voltage output and then convert the front speaker high level output to low level, to feed the relevant amp(s).

But - am I better of sourcing a Bose programmed unit before I do so?


I have been trying to determine if aside from the on-screen 'BOSE' display and voltage outputs (ie I believe all four speaker output is non amplified and low level on the BOSE version) if the Audi and Bose versions have any preset EQ curves built in.


Many people suggest that the BOSE programmed units have a 'flat' output which in my mind will be better to feed an amp. It seems the BOSE amp does all the equalisation and I dont plan to use the BOSE amp!


I have also read the standard Audi versions have a sort of low volume 'loudness' function which diminishes as the volume is turned up? I can't verify either of these facts but it would seem a waste of time to go to all this work if the bass diminishes as the volume increases!


Getting the unit reprogrammed should be a dealer option but if I pay to have it done and it doesnt work or sound better then I'm going to have to pay to have it put back! My dealership have said they have never reprogrammed a Concert head unit and don't know how to do it. I was asked to get a guide from the Internet and they would book the car in for one hour at a charge of £80 plus vat and hope they could get it done within the hour - no thanks!


These BOSE versions command a high price on eBay so trying to pick up a cheap second unit to experiment with isn't an option either.

I have read that on some Bose head units there is a Bose pin out which if earthed will set the radio to Bose mode?

Has anyone done his or can anyone tell me if the sound quality from the concert after amplification is worth the effort?

I have some experience fitting head units, speakers and amps etc so willing to have a crack at pretty much everything. Fitting a spangly new head unit is the easy option but for this car I really like the idea of a stealth/oem look.

Thank you for reading

Stu.

 

[AndyMac]

The Bose EQ is indeed flat, so essentially the Bass & Treble will then do very little
Non Bose EQ is a normal smiley face EQ - Bass & Treble work properly
Bose mode is select by earthing the Bose pin on the back of any Audi HU
There is absolutely no difference between a Bose HU and non Bose HU. The only thing you can do via VCDS/VAGCOM is turnoff the internal front speaker amp and select the Bose welcome when you first turn the unit on, neither of which change the EQ or the sound quality. Most people switch off the Bose EQ, rather than switch it on to improve the sound. With some Audi HU's you can adjust the EQ curve via VCDS but it is a real hit or miss activity experimenting with different codes. TBH you'd be better off installing a decent aftermarket HU and if you want to retin the stock look then try and source an old Becker GP

You can get reasonable sound from the stock HU with aftermarket amping, you will need the BLAU RCA (PC3-11) adapter which plugs into the stock HU and provides front & rear RCA's and remote on. All Audi HU's have front & rear pre-outs available, just not on standard RCA connections.
You will need adapters to fit aftermarket speakers

 

[A4 stu]

Thank you.


Which is the bose pin on the concert I?

Will earthing this pin give me the low level front output as well or is this already there?

Stu

 

[AndyMac]

No front and rear pre-outs are active regardless

 

[A4 stu]

Thank you - much appreciated. Does this pin need a separate earthing point or can it simply be connected to one of the head units earth cables?

My plan is to activate this Bose mode and set up an amp to drive the components I have fitted in the front doors and see how it sounds before I spend too much time on this and add more kit.

Stu.

 

[AndyMac]

Any earth will do, earth is earth
Really don't understand why you want to do this, it sounds shyte in Bose mode with the Bose setup, it'll sound dreadful with aftermarket kit, but you'll soon find that out for yourself. Flat EQ is all well and good in your living room with no bass/treble cancelling background noise, but in a car it's a terrible idea

 

[A4 stu]

Cheers for the advice Andy i do appreciate it. I just wanted to check the Bose pin didnt need a particular earthing point to prevent any type of ground loop.

As for the EQ, I want to hear the difference between Audi and Bose. It may well be that I EQ the sound after it leaves the HU, but I have a variery of amps and speakers to play with all with different sound characteristics.

I prefer to start with a flat EQ and see where it needs improving.

Anyway thanks again.

Now onto the sub!

I have seen the sub box you do for the A3 and its an impressive design and idea. Any idea if anyone has done anything similar for the A4 - the B5 saloon version specifically?

EDIT - On checking the wiring diagram at the rear of my radio I can see some differences than the one you posted including the fuse size.

- the pin you have identified as Bose and labelled Bose on the diagram is labelled 'GA' on my radio
- the one above it is labelled 'mute' and not 'alarm gnd' as your diagram
- the one above 'K' is not blank is is labelled 's'
- the one labelled 'ant con' on you diagram has a symbol that looks like the letter 'Y' with a head/neck if that makes sense?
- the one above it is not blank as per the diagram it is showing thea symbol that looks like a sun with the number 1 to the right of it.

I am not able to post a pic at the mo from this computer but will try later if needs.

Edit2!

Here is a link to an image identical to the wiring block image on my radio:

http://elsegra.com/Car pinouts/Audi_datoteke/concert_4b0035186b_1.jpg

I have taken the block connectors out to see how many pins have the wires connected. I have looked at the wirring blocks that go into the rear of the radio and in the top block connector by the fuse (the one that deals with the power/earth etc) there are two pins where I have no wires connecter.

They are labelled 'mute' and the one that loos like a 'Y' next to the positive + (labelled ant con on your diagram)

On some other google images of Audi OEM radios it is again the one on my radio that is labelled 'GA' that is labelled 'Bose'. I have a wire going to the GA pin.


Stu

 

[AndyMac]

Yes GA is the GALA speed sensitive volume wire, this is used on non Bose systems to adjust the volume with speed. Bose use a different system called AudioPilot, which leaves that pin free to set the EQ, eathing the GA pin will put the HU into a flat EQ but obviously you will lose the Gala facility as a result

 

[A4 stu]

Ah I understand now. Thank you again much appreciated.
Stu.

 

[Final 3Green Land]

Is there a way to turn off the diminishing loudness function so it retains the loudness at all volume levels?

This is the only thing which p*sses me off when the volume is increased, the bass dies to a tinny wishy washy noise...




Is it worth retro fitting the Bose system in the car, speakers amps et al and junking the Audi non Bose fitment?

Mines a A4 B5 Avant...