USB DAC project with PCM2707 and PCM1794, some feedback wanted

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JEDAC: USB DAC project with PCM2707 and PCM1794, some feedback wanted

I am about to start designing a USB DAC as my vacation project.

This will be based on PCM2707 and PCM1794, and I was thinking to make it totally USB powered. Have TI's charge pump switchers for 5V->3.3V and 5V->-5V. Do you think it is OK to power it that way?

Opamps used will be some of TI's high-end SMD chips, r2r I think and OK from around +-2.7V. But will +-5V be enough headroom?

I also want several identical line outputs (e.g. for desktop speakers, larger livingroom speakers and subwoofer), to get rid of splitter cables. Do you think they need separate buffers or would a series resistor for each be enough separation?
 
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That looks quite like what I will be building, with some differences. I think I will use a normal crystal. Will also only use hole-mount components. Will use single-side board.
Good to have a reference for hooking up the chips anyway.

Seems that one is running the opamps at +-2.5V, is that really enough?
What about the ferrites/inductors, there is no other value than 600-800R... are they necessary?
The reset chip for the PCM1794, according to the datasheet it has power-on reset built-in.
 
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The Pup can drive headphones. People do it all the time. I prefer to use an amp after it. You'd have to ask the designer why he chose +-2.5v.

Most of your technical questions would be better suited to the designer because I'm a mere noob when it comes to designing this stuff. For now I just build it.

Here is a thread where you can ask questions of the designer...
pupDAC Step-by-Step Build Thread
 
I made something similar some years back using: PCM2707, PCM1798, OPA4228 and a TPA6120.
The TPA6120 is supplied by -12V, 12V using TI DC-DC converters.

It was a quick cheap (almost free, all ICs were TI samples) project that worked surprisingly well!
I built it back in 2005 to use with my Laptop for OS travel.
I am still using to this day (gets used every day).

The odd PC/USB-hub doesn't like it due to the large in-rush current on pluggin it in, but these days almost all are ok with it.

Front side:
An externally hosted image should be here but it was not working when we last tested it.


Backside:
An externally hosted image should be here but it was not working when we last tested it.


In its case with 3.5mm jack:
An externally hosted image should be here but it was not working when we last tested it.
 
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