Mr White's "Opus", designing a simple balanced DAC

[pinkmouse]

Found this on Epanorama:

The transformer must have good coupling factor, so the transformer core must be a toroidal core made of high permiability material. The prototype described in the magazine uses Philips Type TN13/7.5/5-3E25 core which has permiability rating (yt) of 4500. THe primary and secondary windongs consisted of 6 turns of 0.5 mm diameter enamelled copper wire laid on opposite sides of toroid. The transformer used in this prototype was described to have a bandwidth raged from 50 kHz to 17 MHz, which is more than adequate for an S/PDIF link

[Russ White]

Here is what I am leaning toward right now:

http://rocky.digikey.com/WebLib/Newa...ata/S22160.pdf

Should work fine. Any thoughts?

[Russ White]

Scratch that.... it looks like the S22083 is a better part, it has lower leakage inductance which seems to be the critical spec.

http://rocky.digikey.com/WebLib/Newa...ata/S22083.pdf



Now to finish the PCB.

[pinkmouse]

Any progress to report Russ?

[motherone]

You've got me interested to see your progress as well, Russ. I'd be keen on trying out one of the Wolfson chips on a real DAC (the only experience I've had with them so far is on computer sound cards).

Keep up the good work!

[Russ White]

My hope is to order a few prototype PCBs next week. It won't be long now.

Would anyone be upset if I omitted the TORX input?

Thanks for the ijnterest.

Cheers!
Russ

[promitheus]

Hey Russ.
I like the idea of this DAC.
I really would like to see what the result is.
Keep us informed.

[hifimaker]

Originally posted by Russ White
My hope is to order a few prototype PCBs next week. It won't be long now.

Would anyone be upset if I omitted the TORX input?

Thanks for the ijnterest.

Cheers!
Russ

An optical connection would be great, since my PCMCIA sound card has only an optical output, others many be in the same situation. Also the optical connection eliminates any chances of computer PSU noise getting into the DAC.

-David

[pinkmouse]

How about making the input side a seperate module, so you can choose which type you want?

[Russ White]

Here is the current circuit.

Some notes:

1) I am not sure if I need R9 or not, and if I do if I have the correct value.

2) I have set the WM8740 to reset with the CS8416, which aoocurs on power up after the digital voltage reach 3.3V.

3) Both the digital side of the WM8740 and the CS8516 are running on a singal 3.3V digital supply. The analog side of the WM8740 should be 5V.

4) I will add a legend for al the jumpers and what they do.

Cheers!
Russ