Make 8 time-sharing parallel DACs

At the end of 2008, I designed an 8-parallel DAC (see post: http://bbs.hifidiy.net/viewthrea ... highlight=%2Bcdream), but I always felt that there were many places that needed to be improved, so I thought about improving it into a complete machine.
After more than a year of brewing and experimenting, after drawing the PCB became cross-eyed, after thinking about the program became a nightmare that I almost couldn't wake up, after the board transformer was rotten to the intestines, after discovering the board BUG kicked my head, and after the case was opened, I improved the original parallel structure, rewrote the parallel driver, output the left and right channels independently, used a low-pass circuit with better balance, and added a single-chip controller to the entire system...

Finally... I was able to see her beautiful figure, my improved 8-chip time-sharing parallel DAC (the whole board diagram: the basic structure is WM8805 (digital reception) + CPLD (data processing) + WM8740x8 (digital-to-analog conversion) + single-chip microcomputer control)

Rear view: All boards can be seen from this angle

Input signals include BNC optical fiber COAX, I2S, balanced; output signals are balanced single-ended;

Front view:

(Soft start of switch, manual signal selection, output mute control, parallel mode, balanced/single-ended output control, because of the introduction of single-chip control system, it can be easily achieved automatically) [page]

Detect input signal (long press the signal line selection button to automatically enter the signal detection mode), automatically save the current settings, delay startup, etc.
Data processing part:

MCU control part:

In order to minimize the noise interference of the microcontroller control system to the DAC, the control connection between the microcontroller and the DAC part is all coupled with optical coupling:

DAC part:
left and right channels are independent boards, one DAC contains signals of two channels. After digital processing, it is made to output data of only one channel, and then the two output signals are connected in parallel, that is, one DAC chip is a 2-parallel connection. There are 4 DACs in total, which is 8-parallel connection. The timing is also an 8-time sharing architecture. After one DAC outputs, DAC No. 1 works, followed by DAC No. 3, and finally DAC No. 4, completing the 8-time sharing timing.

Two DAC boards:

The power supply soft start module also includes power supply filtering

Finished image:

The sound of the machine is significantly improved compared to the previous 8-way sound, because the separation of the left and right channels is very good, and the three-dimensional sense of the sound is very strong. After the improved analog calculation part and low-pass part, the problem of the previous 8-parallel sound being too hard has been greatly improved. Now it listens to the sound, which maintains the characteristics of the 8-parallel sound with high density, rich details and fast speed, and is not lacking in flexibility. It should get better if it continues to burn in for a while.