The DAC4 Project (1999)
- Modular 24/96 Sigma-Delta-DAC
- Plug-in modules for digital input receiver and digital analog converter
- Inherent jitter reduction through sample rate converter and low jitter clock
- Digital input receiver / sample rate converter modules based on Analog Devices® AD1892 or Crystal® CS8420
- Sigma-Delta DAC modules based on Analog Devices® AD1855/AD1854/AD1852, Crystal® CS4390/CS4396, Burr Brown® PCM1716
- Accepts up to 24 bit input data
- 96 kHz maximum sampling rate
- Filtering and balanced output stage using a single discrete opamp module
This DAC project is dedicated to Sigma-Delta-DAC-chips exclusively. Due to the usage of SMD-chips the new type of 32-pin-module used for DIR, DAC and opamps is tiny compared to DAC3 modules: only 40,6 x 25,4 mm.
People are asking me to implement a DAC with the Burr Brown® PCM1704 and DF1704 chips. This is not planned for this project as it doesn’t fit into the scope of using integrated modules for the digital filter and the converter.
The final DAC4 technical design document is released. All circuit descriptions can be found in that document now. I would like to encourage people to review that document and let me know what’s missing or what should be explained better.
The final DAC4 schematics and PCB layouts (Rev. B) are released. Some changes to the original design have been made, e. g. the clock generator is now using a low-jitter integrated crystal oscillator manufactured by Fox Electronics® and a reset pulse generator has been added.
The DAC4 prototype is in use in my system since beginning of November 1999. The photo below shows the main board with a AD1892 DIR/SRC module and a AD1855 DAC module. A pair of discrete opamps DOP03 can also be seen.
The best results in my system I do achieve with the following module combinations:
- CS8420 + AD1852
- AD1892 + CS4396
The PCM1716 and CS4390 DACs cannot reach anywhere near those two combinations whatever the DIR is they are used with.
Download schematics, PCB designs and part lists as PDF files: