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

[wigginjs]

The major design point however, is that it can output I2S direct to the DAC without using SPDIF.

Why is this so important? My understanding of why everyone hates S/PDIF so much is because of jitter introduced by poor clocks. So, it would see to me anyway, if you have a soundcard with S/PDIF output you are really comparing the clock included with the USB interface with the one included with your soundcard. I have sort of a cursory understanding of a lot of these topics so I'm looking for an opportunity to learn. Someone please correct me if my statements are inaccurate.

[Russ White]

m0tion, you questions are perfectly good ones, and I am afraid I cannot answer them all(yet).

I2S generally has much less jitter than SPDIF.

What you should remember is that the single USB module you are talking about may not be in the scope of what you want. But I have good news! Opus very likely still supports exactly what you want to do. You could easily take the clock and SPDIF from you sound card and use it as input to the DAC using one of the two SPDIF modules. OR, you could easily design our own SPDIF module and feed the I2S(or whatever) to the DAC module.

Cheers!
Russ

[BrianDonegan]

Dac/USB/Ballsie stack, along with LCPS and new Dual supply for Ballsie.

[fierce_freak]

Beautiful work!

[pabbi1]

What is the dimension of the dual supply board? Is it also driven off the toroid? Would the one toroid be sufficient to run a dual and LCPS?

Since the LCPS has vreg, could I run it off my 25+25 40VA toroid?

[BrianDonegan]

They are both regulated, so yes, you could.

You could not run both supplies off a single trafo, however, as the LCPS is two seperate supplies, and the Dual supply will connect two of your secondaries as a 0V (GND).

[MegaMe]

Originally posted by BrianDonegan
Dac/USB/Ballsie stack, along with LCPS and new Dual supply for Ballsie.

That looks far to tempting to ignore.

So any comparisons between USB and spdif coming?
It would be good to know if the pcm-2707 module works as well as the rest of the dac or if it lets the team down... (especially as its usb powered)

[BrianDonegan]

Testing USB (S/PDIF Out) -> WM8804 Receiver -> DAC -> Ballsie (not connected)...

[Russ White]

Originally posted by MegaMe
It would be good to know if the pcm-2707 module works as well as the rest of the dac or if it lets the team down... (especially as its usb powered)

When used as intended (just I2S out) the fact that it is bus powered should make no difference at all.

Cheers!
Russ

[BrianDonegan]

esting USB (S/PDIF Out) -> WM8804 Receiver -> DAC -> Ballsie (not connected)...

This setup was really just to test the USB S/PDIF out mode. If used in this config, I would use the USB I2S out => Receiver I2S In (dejitter) => DAC (I2S)

[EDIT] Actually, not sure if it's possible to do this (I2S in and out at the same time). Will test it tonight.