toslink optical connection has intermittent hum

[crazypete]

Hi all,

 

This issue was originally posted in the windows 7 forums but no one had an answer (toslink optical connection has intermittent hum - Windows 7 Help Forums).

 

I have an odd problem. I have my pc audio connected to my stereo via the optical out. I am getting an intermittent humming noise (sorta like a ground loop hum but of course that is impossible for optical). My optical out goes to a minisharc and then to the amps. I've checked the toslink cable (switched it out) but it couldn't really be that anyway.

 

Now, this noise is independent of the volume level I set in windows, BUT if I mute windows audio it stops. It appears connected to various applications, like chrome and media monkey, IE, etc because if I go into the realtek digital output settings (where you see master volume and the volume for various apps like chrome, etc) and I mute them one at a time, it will go away when it hits the right one. It also goes away on its own for no reason Ii can fathom. It is always the same volume regardless (unless I turn my stereo volume up). I've disabled the AMD audio devices (HDMI out) for what it is worth.

 

It appears that apps are outputting an intermittent low level noise for some unknown reason at unknown times. Does anyone have any explanation/ fixes for this? It is pretty annoying.

 

Thanks,

 

Pete

 

Driver Packaging Version 14.301.1001-140915a-176154C

Catalyst Version 14.9

2D Driver Version 8.01.01.1423

Direct3D Version 9.14.10.01061

OpenGL Version 6.14.10.13084

Mantle Driver Version 9.1.10.0034

Mantle API Version 94209

AMD Catalyst Control Center Version 2014.0915.1813.30937

AMD Audio Driver Version 7.12.0.7719

[EuroDriver]

Can you describe the minisharc model, what it does, the nature of the connection from minisharc to the DAC, DAC model and how DAC is connected to amps. Also the nature of the power supply to the DAC. also describe the amps you have, and how they are powered and type of interconnect to your DAC.

 

On the PC end of things, what sort of power supply, which mobo, and which sound card, or does your mono have optical out ?

[crazypete]

As far as I know there is only one minisharc model: miniSHARC Kit | MiniDSP.

It is a DSP, which I'm using as a crossover, splitting my stereo digital signal to 4 digital outputs, which (via I2S) connect to 2 curryman DACs (Curryman DAC (ES9023) | MiniDSP). The power supply for the minisharc and DACs is (http://www.mouser.com/ds/2/323/55245-197346.pdf). The amps are a 20 year base level sony and a EP4000 with fan mod.

 

The MB is the MSI Z97-G45 Gaming, using the optical out on the board.

 

Now my assumption in all of this is that the power supplies, DACs etc are not the problem, since the sound originates from the PC. If the sound was introduced later in the series (like the DACs) closing a program or muting windows sound should have no effect. The fact that it does tells me that there is an actual digital output from the opt out on the MB that corresponds to this sound. Is this correct?

 

 

 

Thanks for the help.

 

Pete