Audio DAC power supply design

[DrBudz]

Hi friends,

Currently I am designing USB & SPDIF audio DAC.
I have some doubt about power supply design.

I have attached schematics of the supply. As you can see it is +/-12V symmetrical. It supplies analog and digital parts of the device.
Both analog and digital part have their own LDO's and FE beads with PI filter for decoupling.

I need your help to select right values for the components in schematics, and to correct the design if necessary.

Any advice is appreciated.

Thanks!

 

[crutschow]

One thing very important is to keep the analog and digital grounds separate expect for one point (single-point ground). This could be at R1. Separate ground lines should be run to there for all the analog power supply and circuit connections, and all the digital power supply and circuit connections. Do not connect them together as you show on the schematic.

Alternately that single point could be at the DAC if the DAC has both analog and digital ground pins.

Are you building a PCB for this?

 

[DrBudz]

Yes, I will build a separate PCB for this. It will have 2 connectors on output(like on schematic) - one for digital part of audio dac, and one for analog part.
DAC board will have both analog and digital ground pins.

What do you think about capacitor values? How can I calculate them?
I am afraid of 50Hz noise from power supply. Is this enough to filter it?

 

[crutschow]

The capacitor values depend upon the current output of the power supplies.

What is the AC voltage?

 

[DrBudz]

AC voltage is 12V. I could determine max current on the output required by audio DAC, but how to calculate capacitance?