Bose sound system

Archived from groups: rec.audio.tech (More info?)

Does anyone know a patent no. or other technical information
explaining how this sound system works? I mean the system
with the little cube speakers where you can't tell where the
sound is coming from.

Just curious,
Andy

Archived from groups: rec.audio.tech (More info?)

In article <2tioncF1vp2okU1@uni-berlin.de>, Andy <spam@hotmail.com>
wrote:

> Does anyone know a patent no. or other technical information
> explaining how this sound system works? I mean the system
> with the little cube speakers where you can't tell where the
> sound is coming from.
>
> Just curious,
> Andy

They probably mess with the phase of the left and right channels. Bose
uses extremely low grade building materials then compensates for some of
that using custom filters in the electronics.

There's old trick that was often called "Stereo Wide" on boomboxes of
the 80s. It's essentially crossed negative feedback between the two
channels with various filters varying the amount and phase by frequency.
Tuning it to sound good is tricky but once you've got that, it costs not
even $1 in electronic parts. At best is sounds good, at worst it causes
headaches.

Stereo Wide can be implemented in passive components too! The simplest
case looks like:

Amp Left ---------------------->
Speaker Left
Amp GND ----+--+---+---+ +--->
| | | | |
| R C L |
| | | | |
Amp GND ----+ +---+---+---+--->
Speaker Right
Amp Right ---------------------->


L passes through <200 Hz
C passes through >8 KHz
R controls mono pass-through