Squeeto

<center><img src="http://pictureposter.audiworld.com/125817/sony.jpg"></center><p>
This looks better and you can set the leds to red!

cpj002

Ty,
You are unlikely to find any after market amplifier that will drive the Bose speakers, as some of the drive units have an unusually low impedance (1 ohm). Also, the simple crossover circuit you posted will not match the multi element tuning that the Bose amp has, custom configured for the A8 (ie a Bose amp from another Audi will not sound the same).
The Bose amps can be repaired - are you sure it is the amp?

Squeeto

<center><img src="http://pictureposter.audiworld.com/125817/bose.jpg"></center><p>
The Line Ins from the deck to the amp are clean.
I have no schematics or pin outs to the amp but I do have pin outs for the deck. Line outs are pins 1,2,4,5 on the 20 pin (small gauge in cable, green white grey yellow).

The scope shows:
-lower is pin6 input to ic 134499 which drives the quad fets.
-upper is to the speaker

The rear speakers (only the rears) thump heavily at about 3 hertz. As you can see the 134499 amp is being fed this thump. Is is originating from the equalizer section.

Ok without schematics, I am not going further. Besides, there is a sizeable inaudible hum on the rears. At 1 ohm or less, maybe this is why speakers are burning up for people.

If there is a chance of torching the car, maybe it is time to upgrade the speakers\deck anyway.

I did try a few grounds to make sure that I wasn't injecting this hum.


How about a car wiring diagram? You have one?

S.

Squeeto

I have read that the bose amp is class D and the hum might be typical for this system. I have the thumping speakers disconnected and they might be part of the filtering for the hum.

cpj002

<center><img src="http://pictureposter.audiworld.com/83025/a8_1998_radio_bose_wiring.jpg"></center><p>Ty,

Here is the Radio, amp and speaker wiring diagram from the A8 service manual (1998). There should be no hum from the amp, just a low level hiss.
If you are getting loud thumps from the speakers the amp is bad. You should not be able to measure any appreciable DC voltage across any of the speakers.
I cannot provide you with a schematic for the amp (proprietary), but can probably fix it if you don't want to use any of the online sources of repair.

Paul

Squeeto

Thank you Paul for the info.

I may consider swapping out the woofers and installing that Sony with the usb. I need to find out if the mid and tweeters are also in the range of 1 to 2 ohms, if they are, I may change my mind.
It is the wifes car. This weekend we will go to the audio shops for fun anyway and take in the hype and bs.

I'll let you know if we decide to fix the bose.

S.