MY DAI
Isolated Data Acquisition Front End for High SNR Recording
General Description ... ...
It's interesting to record the sound of nature, like singing of bird, rain dropping, and thunder. On hearing these sound, our soul feels released, especially for people who lives in big city.

We always use portable MD as recorder. But the internal ADC for a normal MD is not good enough. Its SNR should be in the range of 80 to 85 dB. That's not so quiet when recording at night in the forest.

So it's necessary to use an individual data converter with higher SNR as front end and connect to the MD using optical cable. Most MD recorder has a optical line in port.

Or, alternatively, use a USB to optical converter ... ...

The heart of the converter board is a Crystal CS5331 18bit stereo ADC chip. The companion chips are the preamplifier, SPDIF transceiver and some glue logic.

The PCB should be carefully routed for superb SNR performance. Special care should be taken for the ground traces.

Here are some brief measurement charts of the performance ... ...