Originally Posted by proid
Yes, it's a mini O2, can you explain why you suggest to ground like that? In fact i build all 3 version and ver1 sound much better than both ver2 or ver3
Keep the return currents from the headphone away from the amplification circuitry, and the input source, and feed it to the "battery source" to sink the currents immediately. You could also make the ground plane smaller and use smaller slices to feed the opamps, same idea about "isolation". A larger "well" for the input side. I'm not sure if NwAvGuy did it that way, you can look at his docs. I believe it has pictures of the ground planes.
Edit: Also, star ground. I wouldn't use it for a PCB. For point to point wiring, yes. In star ground, you have nodes of ground potential. The same idea. For PCB, you use planes. Your first version looks better, but you need a bigger "wire" to return. You also didn't have power caps in the first one, and you should tie the input ground directly to the plane with the volume knob. It would probably be better to move the input jack next to the pot. It'll require a different layout.
Edited by holland - 7/3/13 at 9:40pm