ProtoDAC TDA1387 X8 project

[OnkelPH]

Hi
I have enjoyed my protodac for over one and a half year now. No issues. Decided to build my third project together with a c3850 clone front and. The prototype was a success, but l’ve stumbled upon a problem in my attempt to build it in an old NAD cabinet. The main difference between the prototype and this build is the signal output. I’ve  direct wired L/R channel in front of the 5v input instead of using rca jacks. I now struggle with a lot of noise in the left channel. I’ve tried to different boats, the noise is still there, like the left channel is not properly grounded???!! No difference with or without power to the board. Tried to disconnect the output cap., but the noise increased dramatically…. No issues in the right channel…

Picture with the cap disconnected:
   

[hifinet]

What type of noise? Hum? How are the signal wires connected to the c3850?

[OnkelPH]

Found the source. The left channel was connected to chassis through the mounting hole for the stand of…. Really tight space between the mounting holes.

[OnkelPH]

   

Easy to Short the left channel through the stand of mount.

[speedy210]

It looks as though the Innomaker DAC Pro HAT should work (perhaps you can confirm), since it is a master DAC with two crystal oscillators and has a topside GPIO connector. Setup Moode so that it works with the Innomaker DAC. The Innomaker will then reclock the I2S, and the reclocked I2S will pass through to the topside GPIO. Install ProtoDAC to the topside GPIO.

Thank you, I will test it when I get the chance.