Easter update

Someone kindly pointed out the eeschema library file was missing from the git repository. I did notice a few weeks back and had committed the file. I obviously did not push the update to the master branch though!. 

Which brings me to board revisions 1.1/2,0. The ADC board revision 1.1 is almost ready to release with correct power pin assignments, I am also working on a newer revisions of the DSP boards with a master SPI connection. There is a new revision of the DAC board with the mating slave SPI connector. This means the ADAU1452 should control the ADAU1966 for faster sample rates without the need for a microcontroller.

I am also revising the PSU and buffer board. This is mostly component spacing and silk screen tweaks. On all boards I have decided to switch to some lower cost regulators in digital supplies. The TPS7A45xx series are quite expensive but I will still use these in the analogue supplies due to their low noise across the audio band.. 

I have also been playing with RightMark Audio Analyser. There seems to be a problem with Intermodulation distortion+noise readings using the SPDIF input on the DSP. THD at lower frequencies is high on the SPDIF input as well. Otherwise the measurements seem to fall in the noise floor of my Xonar U7 soundcard. Some of the noise issues are from low level 50Hz and multiples (a lot actually, all the way up to 500Hz). This is a very crude test so take all results with a pinch of salt, but it is interesting anyway.

Results shown below. First result is the Xonar U7 analogue output connected to the Xonar U7 line input. Second is connecting the Xonar U7 analogue output to the DSP platform ADC analogue input, and the DAC analogue output to the Xonar U7 analogue input. Third is the Xonar U7 SPDIF output connected to the DSP board directly, and the DAC analogue output to the Xonar U7 analogue input