Tuesday, October 30, 2007


SPDIF is "crap". Really! It is simple but to have low-jitter at the DAC it requires quite complex circuit (PLL w/ FIFO). Ideal: slave transport w/ very good clock, get I2S directly and reclock at DAC requires tweaking CD player. No go... but USB is quite a good solution. Digital from computer (where I have lots of music; also it can provide more accurate bit stream since it does not require real-time reading from CD), PCM2707 (not very low jitter), using external Tentlabs 12Mhz low jitter clock. Nice.
The USB board is DDDAC1753 mkII. See picutre(s).

USB board output I2S but I need AD1865 compatible format (18-bit, MSB, standard). I do not like using a digital filter like DF1704, since I will have to oversample to 96Mhz. So I built (PCB in construction) a circuit using shift registers and flip-flops. I learned Eagle (and Eagle 3d).

Note: I also take a loot at gates jitter (and also CPLD, FPGA) and found out that HC is good enough (having not bad PS).


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