Ok I'm not sure if these pictures show you much of anything but here they are. I'm guessing you might want to see the jumpers on the Metronome I'll have to pull the USB module off in a few and take a picture of it. I have to feed my son real quick though so give me 15 min. Let me know if you see anything wrong in these pictures though.

Yes single ended. I connect it directly to my amp.

No didn't do that. I had it working before with just the USB module and DAC. I took a picture of the Metronome so maybe you could check the settings.

Ok it's working now and sounds excellent except when I play music and then turn off the music there is this weird like pulsating static sound coming out for about 15 seconds or so and then it stops.

Ok I'll have to move stuff around when my son goes to bed here soon. Getting hard to mess with it and him pulling stuff off my desk constantly.

Ok modules are all stacked on top of each other now (except the PSU which is inside the box) and the wires are as short as possible and its shielded wire. The same thing still happens. Before I play something completely silent after I play something and then pause it for about 15 seconds or so there is a static like pulsating sound.

Thought I would mention something I found a bit strange. When my computer just a click or something it doesn't happen when a loud sound happens it makes the sound like its resonating or something.... I'm not sure if that makes since. BUt like a loud status sound passes and then its like a wave of noise keeps going for a second. Kind of like noise coming from caps discharging or something I don't know. Any idea's?

Well I have absolutely no clue what it could be. I wired it up just like anyone else does. All the modules are stacked on top of each other. At the bottom are the 2 opus modules on top of those is the Metronome and on top of that the USB module. Power wires are not running right next to the I2S or Analog output wires. I have no clue whats going on here.

No it wasn't happening prior. There was a bit of noise before but I changed the mounting method and this noise that I'm hearing now is not the same. I'll have to give it a try without the Metronome. Might now be tonight though.

Watch out for ground loops in your power supply and signal wiring. You actually should normally have just one ground return per board.. Probably better to daisy chain the digital grounds from board to board and have only one connection back to the supply negative. You want the ground plains of all the boards to be at the same ac potential which implies short (SHORT!)wires between each board. To avoid loops there should not be more than one going back to the psu.

Incidentally for a really low inductance ground conductor braid in heat shrink or teflon tubing is appropriate for the ground connections.

I have a single ground connection to each board, and I ignore all other ground connections except for one to the isolated bnc I use for spdif which goes to the receiver board. Both dac boards grounds are alsp connected to the IVY. (Did not cause a loop problem)My receiver and dac (2) boards are stacked with a single supply ground bussed to all 3 pcb. Should your analog and digital supplies have separate grounds I found it best to bring both grounds to just 1 board and then buss a single ground to the rest. Ground loops are one of the potential downsides to modularity - you just have to be aware that the possibility exists and avoid it if possible.

You may need to experiment to find the right grounding strategy.

My cod based dac is totally silent, and sounds great, but it took some tinkering to get it that way. My dac is not very representative of the standard board set because I built bare boards of the IVY and 2 CODs and made minor modifications. I'm also using my own psu design which is entirely different from the TPA supplies. (And transformer based balanced to unbalanced outputs driven directly by THS4131.)

Edited by user Monday, April 21, 2008 9:06:50 PM(UTC)  | Reason: Not specified