Please help me debug a channel problem

So, tonight, the right channel went out on my stereo while playing my tuner which is connected to a DAC. I switched to streaming to the DAC and the channel stayed out.

I am running a recently repaired Gryphon Colosseum and a new to me Gryphon Pandora.

My heart sank thinking it was the amp.

So, I switched the inputs on the back of the Colosseum and restarted the system. After a while, the other channel stopped working.

Now, I think something upstream has a problem.

Both my Accuphase T-1000 tuner and my streaming from a Mac Mini connect to an Aqua Formula DAC.

Next, I switched to the phono section on the preamp and have not had a channel cut out while playing a record.

How do I narrow the problem down to the preamp or the DAC?

I can use analog out from the tuner into a different input on the preamp to see if the channel still drops.

I have a CD player that is connected to a different input on the preamp so I am playing CDs to see if the channel drops. This does not seem to drop a channel.

Any advice? Thanks!

jadedavid said:

I would try the analog out from the tuner next.
If that works and doesn't drop out then the problem would appear to be in the DAC, seeing as how the TT and the CD player are not having any problems into the preamp.
One further trial would be to hook up the CD player to the input that is dropping out. This would let you know if that input is having a problem.

Click to expand...

That’s a great idea. I need to rule out the preamp.

Well, I hooked the tuner into a balanced input on the preamp and moved the CD player to the DAC’s input on the preamp, thereby taking the DAC out of the signal chain.

So far, playing the radio or the CD player has not resulted in a channel dropping out. It has been over an hour.

If I cannot get a channel to drop without the DAC, I guess I will have to conclude that something is wrong with the DAC. I’m surprised, as I thought the DAC would be the least likely component to fail.

I have written to Aqua to ask how I can get the Formula DAC serviced.

It almost seems heat related because both channels work for about fifteen minutes before one cuts out.

Are there any other tests I should try?

Both my Mac Mini and the digital out from my Accuphase T-1000 cut out when connected to the DAC.

I have ordered a USB to optical output so I can connect my Mac Mini to the optical input for the DAC on the Accuphase DP-65V cd player.

So, support at Aqua said I should switch the XLR output cables on the Formula DAC to see if the channel drop moved.

Yesterday, I ran the Mac Mini into the DAC for hours with XLR cables both ways and a channel did not drop. I did open up the DAC to check that the upgradeable board is tight and it was.

I’m at a bit of a loss why a channel did not drop as it happened to me three times.

I guess I’ll have to keep an eye on it and see if it happens again.

jadedavid said:

Maybe it didn't like the music you were playing.

My system refuses to play country music.

Hope it doesn't mess up again.

Click to expand...

Haha.

Actually, I want it to mess up again because I feel something must be wrong.

Well, this morning while playing the radio, which is connected into the preamp and not the DAC, the right channel dropped.

So, it appears that the problem is not the DAC.

I have switched the input cables on the back of the amp to see if the channel drop will moved to the other channel.

Right now, both channels are playing fine after I shut down everything and restarted.

Sigh.