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

[Russ White]

Here is how the prototype PCB might look

[ezkcdude]

Why do you have the V outs going through electrolytics, or for that matter, any caps at all?

[Russ White]

The output are going through caps so that the DAC output can be used directly. They are AC coupling caps. If you did not have them the outputs would be at DC potential. If you intend to have coupling caps at some other place(say a filter circuit) you could simply jumper the caps on this PCB. In short the caps are there to block the DC. Pretty much standard on a DAC output.

[ezkcdude]

Oops...I broke a cardinal sin and didn't read the data sheet first. Sorry, about that.

[Russ White]

Also note I will be adding bypass caps for the Vmid pins on the DAC, just had not got around to it yet.

[maxlorenz]

Hi Russ
I missed this thread!
Glad to see your interests are growing
Maybe a high quality active crossover is in your future

When you get tired of your Wolsom DAC, PLEASE consider the following chips form AKM:
*sample rate converter AK4122 and AK 4124.
*DAC chips AK4193, AK 4195 and AK 4196 (the later is new, I don't know if it fits)

I would make an upsampler DAC (all I2S Ins/Outs) myself IF i had the knowledge and could source them. To my ears, there is definitelly an improvement in resolution and lower sound floor when upsampling
(yet I use a NOS DAC also )


Best of lucks!
M

[naz]

Have you thought about adding in a PCM2902 with all surface mount stuff for a USB input? There is a bit of extra space on the board and you might be able to just add it to this board instead of having another board for just the USB. People can just leave off all the parts if they are not looking for that feature. I think it would be about 16 more parts including the USB header. Oh, if I'm babbling or this is contrary to the design goals just ignore me.



-Naz

[Variac]

Lots of interest in usb, well, me too at least!

[hifimaker]

Like USB as well. At least consider adding an optical input, that is relatively easy. It is really nice to have a couple of different input options.

-David

[Russ White]

Hi guys,

Thanks for the input, I will consider adding USB. if it will fit the PCB as I have it sized. Optical input can actually be done with the current PCB, its just some of the components would be off the PCB.

I would really appreciate some input about my schematic. Is the reset scheme OK? I have heard nothing really on that. Does the basic schematic look OK? I want to get some protype PCBs made, but I don't want to waste money on a circuit that has no chance.

Remember this is my first DAC design. I really need lots of eyes looking at this and giving me plenty of hints.

Thanks!

Cheers!
Russ