I was checking out what is available for converting the BOSE to a line level.
"Clean Sweep" being the most common and SCOCHE "LOCs" another.
The LOC's use transformers (cheap ones at that) and the distortion is unbearable.
The Clean Sweep is complicated and expensive ($200+) and like the LOC's, connects to the speaker outs.
The audio from the head unit is differential (for noise) and needs to be converted to single ended.
There are only two (right and left) audio lines from the head unit with the BOSE amplifier doing all the tone and volume control (more on this) via class II to the amp.
I was turned on to a Burr Brown IC that is specific for this ($1.25!).
It required very few external parts (about 6 at less then $3.00) and two small switching power supplies ($4.00@).
The reason for the power supplies is the chip requires +/- 15 volts or 30 volts center tapped.
So, for less then $30.00 I have a convertor that kicks ass over LOC's and the CleanSweep.
The drawback is I have no control over tone or volume, just a line level pair of LOW DISTORTION audio signals (which is all I wanted in the first place).
This is no big deal as I use the Mac Mini for all audio control.
With the FREE software I have a 31 band eq(!) to adjust, so "dialing in" the sound is much better.
Here are pics of the "proof of concept".
I had to make a connector to plug into the BOSE connector as I didn't want to splice into wires.
"Clean Sweep" being the most common and SCOCHE "LOCs" another.
The LOC's use transformers (cheap ones at that) and the distortion is unbearable.
The Clean Sweep is complicated and expensive ($200+) and like the LOC's, connects to the speaker outs.
The audio from the head unit is differential (for noise) and needs to be converted to single ended.
There are only two (right and left) audio lines from the head unit with the BOSE amplifier doing all the tone and volume control (more on this) via class II to the amp.
I was turned on to a Burr Brown IC that is specific for this ($1.25!).
It required very few external parts (about 6 at less then $3.00) and two small switching power supplies ($4.00@).
The reason for the power supplies is the chip requires +/- 15 volts or 30 volts center tapped.
So, for less then $30.00 I have a convertor that kicks ass over LOC's and the CleanSweep.
The drawback is I have no control over tone or volume, just a line level pair of LOW DISTORTION audio signals (which is all I wanted in the first place).
This is no big deal as I use the Mac Mini for all audio control.
With the FREE software I have a 31 band eq(!) to adjust, so "dialing in" the sound is much better.
Here are pics of the "proof of concept".
I had to make a connector to plug into the BOSE connector as I didn't want to splice into wires.