Project Details

This project entails making a special connection cable for a windows PC and downloading and running a simple remote control windows program.

The program allows the PC to send mode commands to the BOSE bass unit simulating the original BOSE CD/RADIO head unit.

Once the bass module is powered up and in the correct mode, audio from the PC's sound card via it's stereo Analogue or Digital interface (TOSLINK/Coax) outputs can be played using the bass module and  2, 3 or 5 small satellite speakers.

The satellite speakers can be any reasonable small bookshelf speaker with eight ohm impedance. These speakers do not require good low end bass performance as the bass module provides these frequencies. They only need to go down to around 200 hertz (cycles).

To use the inbuilt Dolby 5.1 decoder you have to use the Digital input connection (usually via optical TOSLINK on most modern PC's), although the Bose signal processor does a fairly reasonable simulation job with only an analogue stereo input if it's set to 5 speaker surround sound mode.

All six AM-25/30 audio amplifiers run in "Class G" mode. This is class AB mode with additional circuitry to allow the amplifiers to run at half maximum DC rail voltage at normal listening levels. This ensures the amplifier hardware runs efficiently and stays cool when used at normal volume.

Look on the other project pages for other ways to use the AM-25/30 that bypass the DSP boards if you want to use it in that way.

Surround sound speaker characteristics

The AM-25/30 DSP filters all frequencies above 200 Hz (cycles) to the five speaker amplifiers (L,R,C,SL,SR). The speakers originally supplied with the AM-25/30 were very small single 2 inch (5.5 cm) cone speaker cubes.  I have heard these BOSE Lifestyle systems in the past and the cube speakers don't sound very good to my ears, the response at higher frequencies is not good if you look at the response curves in the technical manuals in the download area of this site.

So the bass response of these surround speakers does not need to be good below 200 Hz. You could use any small bookshelf or  even PC  type speakers on the five outputs of the AM-25/30.

I did not buy any of the BOSE cube speakers and instead used five KEF HTS1001.2 "egg" type speakers. These sound really good on the AM-25/30's five channels and cost me £50 ($65) from eBay. I have been listening to them almost daily for about three years for several hours of the day and they don't give me any "listeners fatigue" like some cheap audio systems.

However any reasonable small eight ohm speaker should be OK, I have tried several small pairs of speakers taken from mini HI-FI systems, with the AM-25/30 in 2 speaker stereo mode and they have also sounded good.

Click on the link to PC amplifier project page for more details on how to connect and use the AM-25/30 module with a PC for 2.1, 3.1 and 5.1 audio.