Grover Gardner wrote:
I know some you guys have experience building DACs so I'm looking for suggestions.
My friend there in DC, Jim, and I both ordered the Doge 7 DAC about two months ago. They are supposedly redesigning them and they were selling the old model at a steep discount. Jim's works fine, but mine developed distortion in the right channel after about a week. There are two boards in the case, one for the DAC circuitry and one for the tubed output stage. The headphone output bypasses the tube stage and the distortion shows up there so I'm pretty sure the tube stage is not the problem.
The chip is an ES9038. I contacted the sales rep about the problem and after some back and forth he said they would just send me a new DAC board to drop in. That was three weeks ago and I am not getting any response now. ;-( For the moment I've got a $1000 doorstop. I'm keeping my fingers crossed that I'll hear back from them, but if I don't I was trying to figure out how to salvage the unit. Is there an ES9038 DIY DAC I could drop in and connect to the tube output stage, or maybe something using a different chip? The DAC board doesn't employ opamps but goes directly to the 6-tube output stage.
Could I send the board to someone to diagnose without shipping the whole unit? (It's very well-built and heavy.) The board has two harness clips for the outputs to the tube stage so it's easy to disconnect. Or does anyone know a good repair person who could take a look at the whole unit, if it comes to that?
I'm going to poke around some more and see if there's anything obvious, like a loose solder joint or something.
If I don't hear back soon I'll open a PayPal dispute and see what happens, but in the meantime I was just trying to think of what to do with this lovely, not-working thing. It sure sounded nice while it worked.
The issue here is if -- and that is a big if -- you can find someone that can trouble-shoot at a board level. And only if they the have entire unit to run diagnostics. They would need a 100-mHz. scope (at least) and the various chips' application information (and/or handbook) to determine the fault. if you find that person we would all like to know who it is.