[efzauner]

Spent some time over the holidays on this... Opening up the Audio20 unit on my 2005 C240 to see where I can tap in.. Eureka. I now have 4 RCA outputs!
I had to split up the pdfs to get under the max file limit.

The pdfs also have links to the datasheets for the PA and the DSP chip.


Jan 3rd 2010:
Edited page 3 adding comments on scaping off coating to make pads ready for soldering
Edited page 5-6 to add maximum output measurements.

and NO... I won't do this for anyone. Its kinda risky with the tiny soldering needed and the cost of failure is high.

 

[bbwannabe]

way cool. thumbs up!

question: will your output be distorted/cutoff at any level between vol.0 to vol.max? the vol here refers to the audio 20 vol.

 

[efzauner]

way cool. thumbs up!

question: will your output be distorted/cutoff at any level between vol.0 to vol.max? the vol here refers to the audio 20 vol.

Good question.. and I just measured it
The RCA out will put out about 450mV rms maximum. At which point the power out from the PA is at 6v rms undistorted into one 4 ohm load (as seen by eye on my scope)
I tested from 60 hz to about 3 khz.
That gives 9 watts undistorted before power limiting. I would not be surprised if dynamic output is higher. But at this point the 450mv is sufficient to drive my Rockford Fosgate PAs.
I will add it to the pdf sometime.

 

[bbwannabe]

haha sounds great.

you should make a easy to solder in kit for the rest of us.

could be a somewhat profitable hobby.

there is just a shear number of audio 20 users out there who would want this.

 

[efzauner]

haha sounds great.

you should make a easy to solder in kit for the rest of us.

could be a somewhat profitable hobby.

there is just a shear number of audio 20 users out there who would want this.

Profitable ? what maybe I could sell a few dozen... even at $100 profit that is not alot of money. My feeling is that most MB owners make some sort of buy vs diy tradoff and if the DIY cost in time gets too high then purchasing makes sense. At this point it starts to make sense to buy an new HU with all the bells and whistles, bluetooth, sat, and steering wheel controls.

I was hoping to get a MOST fiber optic to rca out adaptor but my calls and emails to that electronics company that makes lots of MB adaptors have not been answered.

 

[Strictly4Boosting]

looks great ! ... i was thinkin of doin the same thing , there are converters out there that you can grab the interior speaker wiring instead of coming from the radio out to the speakers u cut the wires and run it from the radio to a converter from the converter it has rca to the interior amp and then from there to the speakers .... on the subs u can do the same thing but u use the rear speakers , i had good success with other car radios but the only thing was fine tuning had to be all done from the amps , and on the sub it was very hard to control because of the converter

 

[efzauner]

Yes there are speaker to line level converters. I have used them but I wanted to avoid the PA to get better sound quality. Level converters should work ok for subs as long as you dont clip and of course if you vary front to back fading your sub will also change levels. My RCA outs will also do that unfortunately. I will mostlikely tie the sub to the fronts, that way if I fade to rear then the sub will fade too.

and I dont recommend cutting any in car wiring. Get a harness and a reverse harness and use that to connect into your car wiring. Many Power Amps have speaker level inputs also.
I have installed all new wiring to the doors.. I will post a build soon.
I intended this thread to be only about the rca outs, not a general car audio build thread. There are plenty of those.

 

[Bambam90]

Hi, how can I get hold of the pdfs? Im unable to download since the site handles the files as images?