There are two generations of the amplifier in the Bose Mercedes W140 S-Class and C140 CL-Class Coupe.
First generation Bose Mercedes W140 Amplifier
The 1st generation of the W140 amplifier, found in the 1992-1993 S-Class, has 6-channels output and is placed in the trunk, under rear deck, above the wheel. Total power output is advertised at 275W. There are 7 amplifier modules inside, three of these amplifier boards being powered by the TDA7256 chip.
The TDA7256 is a class AB fully protected bridge power amplifier, designed for car radio applications. The high current capability allows to drive low impedance loads (up to 2 Ohm). The differential inputs availability makes it particularly suitable for boosters and active loudspeakers applications.
Channel outputs are as follows:
Front Speakers – full range
Rear Door speakers – high pass
Rear Deck speakers – low pass
Mirror mounted speaker – high pass
Second generation Bose Mercedes W140 amplifier
The 2nd generation amplifier, found between 1994-1999, is smaller and is located in the left side of the trunk, right above wheel well.
Bose Mercedes W140 / C140 / V140 Speakers
W140 is the short S-Class, V140 is the long version and C140 is the CL Coupe.
There are a total of 11 speakers on the Mercedes-Benz W140 S-Class:
2 Front doors, 11.4 cm low-mid-range speakers, in a ported enclosure
2 Front doors, 7.6 cm tweeter
2 Rear doors, 9 cm wide-range speakers
4 Rear shelf, 16.5 cm woofers, using trunk as an infinite baffle