…And the Musiland 03 USD
Retail: ~1000 RMB [link]
1 ppm frequency stability
Got to wait for Soomal to see what is inside…
Soomal just did that: [link]
The 1ppm clock replaces the 24 MHz clock that feeds the USB controller. The audio-frequency clocks are derived from this clock by the FPGA exactly as before. The new clock brings frequency stability but not necessarily lower jitter because the resultant jitter is still determined by the cumulative jitter of the clock management modules inside the FPGA.
However, there is a new power section consisting of a different LDO regulator (can’t figure out who makes it) and (I think) additional LC filtering?. No doubt this new supply section has lower noise and thus can improve jitter by minimizing power-related jitter inside the FPGA.
Update: The PHKI is an adjustable switching regulator from TI: TSP62200 switching regulator. Thus the use of large inductors. This is certainly an innovation. Switching regulator technology has developed tremendously especially driven by by mobile device industry segment. But I am not sure whether this is better than linear regulators especially the newer breed of ultra low noise regulators. If indeed this configuration is more effective and lower noise to what they were using before, then the jitter performance can be somewhat improved by providing cleaner power to the FPGA.
But, since there is no analog part in this device, it is very likely the I2S lines have been disabled. There are no traces where the I2S lines are located in the other devices. Thus NO I2S lines to tap.
Compare the above photo near C33 (Musiland 03 USD) with the photo below near c34 (Musiland 03 US which has an analog section). Notice that the I2S lines are missing
There is still some more good things: every time Musiland releases a new model, there are improvements to the layout. Notice that in this version that data lines are shielded by ground lines (I marked with blue lines). I believe there are additional improvements in the layout that are not readily apparent.
On the balance, the improvements are positive but I was expecting separate oscillators for the generation of the audio-frequency clocks. I am also not sure about the switching regulators. Seems some of the newer low noise linear regulators would had been a better choice.
For the diy’er, it would be more fun to start with the Musiland MINI and mod the clock and power section.