Have a perplexing problem. one board is fine. All the dip switchs are correctly set for each board for their respective channel. Spdif switch is on for the board recieving the SPDIF signal, switch off for the board taking the ground and D1 signals from the SPDIF board. Voltages on the Tridents are (and were set to before initial use) 5.25 volts. All LED's on borh boards (all 6 Tridents and both AVCC's) are lit as should be (no flickering, just steady state. When a live SPDIF signal is fed, boath boards' "lock" LED is lit as well. From all outward signs the boards look like they are working. On the left board, the out of phase output of the right is joined - to + and + to - for summing (as the docs say the opposite channel is anti phase). The same arraingement for the right board with the left out of phase + and - is connected to - and +. Everything is per book.

Problem is there is no output on one of the boards. I have spent all afternoon going through the process of elimination and re-re-re checking all connections and solder joints (for cold joints & solder bridges) All looks fine and am fully confident I have not missed anything. Yet the problem still persists to the one board having to output.

The only thing I have not checked, and from this end is not possible is the firmware versions on each board. I originally recieved both boards the same time early last year. A month ago when I finally dedicated time to build my DAC, I discoverd one board was missing it's firmware chip. Russ sent one out to me (Thanks Russ1), so I am thinking something may be wrong in firmware-land?

Anyways, I am very perplexed and getting a bit frustrated with this.

BTW.... I have triple checked both channels of the output stage I am using... Featrex Transformers followed by a tube outputstage (CCS loaded 6N6P anode follower). I tried swapping the known good Buffalo 2 board to each channel, and each output section ( both left and right channels) work (and test) perfectly.

The problem comes down to the one Buffalo 2 Board.

I have looked over the threads here in the Twisted Pair support forum and back over at the DIY forum, lots of good info, but unfortunaley after reading them over and looking at my issue with the one board, there is no solution posted.

Russ, Brian, I need your help here.

Thanks

Jeff Davison
note...Power supplies are in an external chassis.

Edited by user Thursday, February 23, 2012 2:25:50 PM(UTC)  | Reason: Not specified

Jeff,

I would opt to use the Volumite with the firmware chip for dual mono operation instead of a chip for each of the boards. One processor makes 1/2 the noise that 2 would make if you think about it.

Also, once it is up and running, try your set up without the tube stage (unless this is your preamp). One of the major benefits of using a transformer for the I/V is to get rid of a noisy active stage whatever type of stage this may be.

Also, don't wire your board grounds like you have done. Terminate the SPDIF shield at the GDN on the right channel dac and then run a pair of wires from DI and GDN of this dac to D1 and GDN on the left channel dac.

Cheers
David

PS, could you show close ups of the individual dac boards? It is difficult to see if your dip switch settings are correct.

Edited by user Thursday, February 23, 2012 11:54:46 PM(UTC)  | Reason: Not specified

I understand. I do use the Volumite even though I have a preamp. I just set the Volumite's output to max and bury the unit inside the box (ie no provision to adjust the volume externally). If Brian can't get the two chips for you, PM me and I will send you the two that I am not using.

Edited by user Friday, February 24, 2012 12:08:30 AM(UTC)  | Reason: Not specified