I created a test audio board for a T4 project that isn't acting exactly as expected.
This test board is modeled after Paul's OSH Park CS42448 multichannel TDM board. I followed the passive input and output schematics in the CS42448 manual and like the OSH Park board used a 10uF X5R in place of the schematic's polarized 10uF.
Overall it functions as anticipated with the exception that the audio is higpassed. This proved adequate for developing the board's software and I am starting on the layout for a full version with active input and output filters and power supply. The passive test board will no longer be used, but before moving forward I feel compelled to understand what I did wrong in the existing board so I don't make whatever stupid mistake that caused this again.
The passive board configured with a passthrough sketch and tested with REW using a loopback-calibrated external sound card produces the following response:
The board's inputs are laid out like so:
Not shown are the to 2700pF capacitors snuggled up next to the CS42448.
The outputs:
Thanks!
This test board is modeled after Paul's OSH Park CS42448 multichannel TDM board. I followed the passive input and output schematics in the CS42448 manual and like the OSH Park board used a 10uF X5R in place of the schematic's polarized 10uF.
Overall it functions as anticipated with the exception that the audio is higpassed. This proved adequate for developing the board's software and I am starting on the layout for a full version with active input and output filters and power supply. The passive test board will no longer be used, but before moving forward I feel compelled to understand what I did wrong in the existing board so I don't make whatever stupid mistake that caused this again.
The passive board configured with a passthrough sketch and tested with REW using a loopback-calibrated external sound card produces the following response:
The board's inputs are laid out like so:
Not shown are the to 2700pF capacitors snuggled up next to the CS42448.
The outputs:
Thanks!