Topic: 8 Channel USB sound device for LaserBoy

[johannesgj]

nice piece of hardware pefect build!!!

[James]

This might be useful!


This is the back of the USB SND8 sound card typically used to make a LaserBoy DAC.


Laser signals are in magenta. The yellow L & R is left and right audio. These do not need to be tapped before the audio output decoupling caps. It's better to just use the associated jack for standard stereo audio out.

[James]

For some reason, the last two USB-SND8 boards I modified have the first 2 channels (front left and right aka X and Y) reversed!

No big deal. Just flip the channels in the amp board wiring. But I thought I should report this!

You might find this or not.

James. 

[James]

I have also noticed that when using this card with the Raspberry Pi and presumably any other ALSA Linux system, the side and rear channels are transposed. In other words, channels 5 and 6 are swapped with channels 7 and 8!

I know there is a way to change the ALSA sound device routing to make ALSA order the channels the same way as Windows, but I don't have that figured out yet.

In the mean time, I just swapped the wires.

James.