Becker "MB Sound System" amp analysis

[compu_85]

A good trip to the junkyard netted me a newish replacement amp for my 1991 350SDL's audio system (the label on top says it was produced in 1996, it came from an 89 car).



MB Claimed this setup was 25 watts per channel, for a total of 200w. Considering the physical size of the amps I was doubtful. So I took this one apart to see what makes it tick.





A fairly simple device. The 4 chips mounted flat on the board are preamp / compressors, ST tda7232.
http://www.datasheetarchive.com/pdf-...SA-634896.html

The 8 mosfet's are ST BUZ71FI.
http://www.datasheetarchive.com/pdf-...SA-561210.html
The datasheet says they are rated at 17 amps continuous, with a quick pulse of 68(!).

So I guess this thing really could put out that much power. The heatsinking really leaves a lot to be desired though, there's no thermal compound anywhere, you can see how tiny the internal heatsink is, and that just contacts the non-finned case to dissipate heat.

The construction of the cabling to the amps is quite good though, the line level inputs run in a cable with 2 layers of copper shielding

Overall the system preforms well in my car, but deep bass notes get really flabby. It's almost like it's overdriving the speakers.

-Jason