General Overview

I want to try  stop these and other used devices from being dumped in the rubbish tip as still OK to use.

Recycle and do your bit to stop the relentless production of new electronics devices when they are not required, and help save the planet!

The digital bass box AM-25P or AM-30P MK2 is a powered speaker system with the following features:

-SPDIF digital signal input (this input must be used for Dolby AC-3 - Digital 5.1 digital input).
 -the ability to decode Dolby Digital™ digital AC-3 bitstreams.
 -all audio signal processing preformed with DSP's

 -5 x 20 watt RMS amplifiers (50 watt RMS max peak) these amplifiers use the TDA7294 chips.

 -1 x 80 watt RMS amplifier  (100 watt RMS max peak) this is a discreate servo amplifier.

The bass amplifier can be reduced to about half of the peak power that would normally be required in a system like this because the BOSE designers used a 6th order bandpass enclosure which gives about a 3db improvement in output level compared with a simple bass reflex cabinet.

There are two Printed circuits in the bass cabinet one for digital circuits one for the six analogue Power amplifiers.

The power supply is a transformer based 360 watt 110/220 volt A.C to 17v & 34v D.C and follows the rule of thumb for class AB amplifiers i.e. to specify a P.S.U with about twice the required full power output of the device.

Go to the download page to get copies of user, service manuals and schematic diagrams for full information on these BOSE AM-25/30 modules in PDF format.

Sketch showing the PCB mounted components and their relationships.

There is a 13 pin DIN socket on the bottom rear of the bass module which takes all the input and return signals. Looking DOWN on the socket here are the connections:-