Can this DAC Board be Powered via USB?

[spaceman5]

Hi


I was searching eBay for PCM1794, and found this nice DAC board,
which apparently is named "1794 Pro":

Assembled SA9023+PCM1794 Decoder Board DAC Kit Decoder DAC Sound Card | eBay


Does anyone know if using the "AC In" connector is mandatory,
or the board can be powered via USB without needing to add an AC Power Supply?


Thank you

 

[phofman]

The board uses dual 5V AC, generating symmetric power supply. You would need a 5V -> -5V convertor for USB voltage plus USB 5V is way noisier than output of the onboard regulator.

The seller says 10W. USB port fetches by standard 5V * 500mA = 2.5W.

Now you know the answer to your question

 

[spaceman5]

Thank you very much phofman,
definitely solves it

The reason for more power is because the DAC is older?
A DAC without a power amplifier should not need so much W...

 

[sgrossklass]

Power wise, I'd say we're looking at well under a watt there, depending on how high the analog supplies are (presumably anywhere from +/-5 to +/- 8 V - not sure why the regulator footprints seem to be suggesting 7815 + 780x, looks like a regular split supply job to me). They're using 5532 opamps, which generally require a minimum +/-5 V supply. While a number of audio opamps will run to 5 V or even below, their voltage swing at low supplies may be less than stellar.

You could run a circuit like this from USB power, but it would require step-up converters - this board uses all conventional linear regulators.

 

[spaceman5]

Wow, great identification of all components..
I see.

OK I think I will (sadly) not buy this DAC, due to the AC Power requirements..

 

[phofman]

E.g. this DAC Khadas Tone Board Hi-Res Audio Development Board for Music Fanatics is a good example of symmetrical supply generation from USB (schematics included - good for inspiration) while keeping excellent params Review and Measurements of WesionTEK Khadas Tone Board DAC | Audio Science Review (ASR) Forum .