1 (edited by Doco 2023-12-06 13:57:51)

Topic: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

I have a first revision ADI-2 DAC that is connected to my PC via TOSLINK. I use it with headphones connected to the Phones output. The source is set to Optical for all outputs.

After a bit of silence from my PC, the DAC shows me that it switches from "SP o." to "INT" as its input. This is even with no other input but the TOSLINK connected. Then occasionally both the level meter and spectrum (for Phones, the output that I am using) that a short, potentially very loud (I have seen close to 0 dBFS) pop is played back, primarily (but not exclusively) in the left channel. However, I don't actually hear anything on my headphones, when these pops should be quite audible.

To me it looks like there are multiple things going wrong:

  • The input seemingly "switches" to INT, even though I specifically tell the DAC that I only want Optical as input. However, the input does not actually switch to INT: When I connect another device via USB and play back audio, I hear nothing, because the actual input is still SP o. This is bad because the display of the DAC tells me I am listening to USB when I am actually listening to optical.

  • For some reason, with no input feeding any audio signal to the DAC, audio seems to be detected.

  • The incorrectly detected audio is then not actually played back. Three wrongs make a right? It appears the signal might just be a glitch in the meter and spectrum.

This is happening on USB 81/DSP 59, but I also observed it on 80/55.

Edit: When I set the input to USB, no pops are detected.

Re: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

What you see is the switching of the clock source, not of the input (there is no "INT" input), because the ADI is not receiving a valid signal from your PC. Can you test another SPDIF source like a CD player?

Regards
Daniel Fuchs
RME

Re: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

Right, clock source, not input. I presume the TOSLINK output goes to completely blank with not even a clock signal then.

Unfortunately, this PC is the only SPDIF source I have easily available. Is there anything else I could try to help debug this?

Re: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

You'd have to somehow determine whether the PC is sending a valid signal... Difficult if no other SPDIF gear is available... Have you tried another cable?

Regards
Daniel Fuchs
RME

Re: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

Thanks for pointing me towards the SPDIF device. Changing the driver from the Microsoft provided one to one from the device manufacturer changed the behavior and the output signal no longer goes blank after a while, which also stops the pops from being detected. The DAC never was the issue, it just showed me that it existed in the first place.

Re: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

You could try to disable power saving on the pci bus and maybe usb bus in the windows power settings. Could be that when audio is not used the device is switched off.
It is in the advanced power settings.

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632

Re: ADI-2 DAC "plays back" garbage sound on silent TOSLINK input

vinark wrote:

You could try to disable power saving on the pci bus and maybe usb bus in the windows power settings. Could be that when audio is not used the device is switched off.
It is in the advanced power settings.

I actually looked at the power information in the device manager before I changed the drivers, but it was the same state at all times. Now that there are no more issues with the new drivers, it was probably just drivers behaving badly in a really subtle way that is hard to detect without having digital meters hooked up.