I have a Supermicro C2SEA board which sports the Realtek ALC888 (HD 7.1 channel audio).
I keep getting a computer-sounding background noise (quite lowlevel in audibility but is easily faintly noticed during pauses in sound). It sometimes happens when I move the mouse around the screen. And, it sometimes happens when the HD drive is accessing data and when the network chip (on the motherboard also) is transceiving via CAT6 a large amount of data.
Could this be an issue with an improper ground? Or, could this be an issue with the PC's power supply? Supermicro does not make bad boards.
I do know that lowlevel noise can happen in automobiles, why, and how to fix it. But, never had this before in a computer.
And, this has been the case for years (the board is from 2007 I believe). I have been using an E-MU 1820m system or ESI Waveterminal 192X card to get around the problem.
For testing, it would be cool if someone could tell me how to "shield" the PSU from the motherboard or make a tiny shield around the Realtek chip to temporarily see if that helped (Faraday cage, right?).
Thanks!
I keep getting a computer-sounding background noise (quite lowlevel in audibility but is easily faintly noticed during pauses in sound). It sometimes happens when I move the mouse around the screen. And, it sometimes happens when the HD drive is accessing data and when the network chip (on the motherboard also) is transceiving via CAT6 a large amount of data.
Could this be an issue with an improper ground? Or, could this be an issue with the PC's power supply? Supermicro does not make bad boards.
I do know that lowlevel noise can happen in automobiles, why, and how to fix it. But, never had this before in a computer.
And, this has been the case for years (the board is from 2007 I believe). I have been using an E-MU 1820m system or ESI Waveterminal 192X card to get around the problem.
For testing, it would be cool if someone could tell me how to "shield" the PSU from the motherboard or make a tiny shield around the Realtek chip to temporarily see if that helped (Faraday cage, right?).
Thanks!
I don't believe its feasible that shielding will do any good because this problem is unlikely to be due to radiated noise. There are probably a couple of issues here - common mode noise and common ground impedance coupling. Both of which are caused by interference currents flowing in ground conductors. If you could get a ground connection (for the audio output) right on the ALC888 IC you might fix up the second of these issues. The first is tougher to solve - going to a linear PSU for the computer will most likely help.
This is not a problem that can be actually resolved. The only way to see of the board is the culprit or not is to replace the power supply.
The last time I encountered this issue, even that did not helps as the board's onboard filtering was inducing a massive amount of junk into the PCI slot power inlets and the power line for the onboard audio. Only replacing the board solved the issue,
It's not a question of supermicro making bad boards. It's just not intended to be used for any serious audio work, just system sounds. You're art least lucky that the pci slots are getting decent power.
The last time I encountered this issue, even that did not helps as the board's onboard filtering was inducing a massive amount of junk into the PCI slot power inlets and the power line for the onboard audio. Only replacing the board solved the issue,
It's not a question of supermicro making bad boards. It's just not intended to be used for any serious audio work, just system sounds. You're art least lucky that the pci slots are getting decent power.
Issues like this tend to be topological in nature - and include components not mentioned in the OP, like what's connected on the output with what kind of cable. In this case the onboard audio is the only one not using balanced output - my gut feeling says it's a plain ol' ground loop. In a scenario with a typical PC and pro audio gear interfaced with a typical aftermarket unbalanced to balanced cable, this is entirely expected ("broken by design", you could say).
Solder up an unbalanced to balanced cable like Jensen Transformers' Bill Whitlock suggests (i.e. similar to Rane Note 110 #17, but with shield connecting to ground at the output end and possibly left unconnected at the receiving end, just in case you've got a pin 1 problem), and things should much improve. It gets even better f you can find out output impedance, in which case you could add a matching resistor between ground and cold (black cable) on the output end for better impedance balance.
Note that there are onboard audio implementations with the ground loop built right into the board (well, bad luck then) - or worse, appearing depending on mounting. Welcome to the wonderful world of open systems, where components may work fine on their own but all hell breaks loose when they are combined.
Solder up an unbalanced to balanced cable like Jensen Transformers' Bill Whitlock suggests (i.e. similar to Rane Note 110 #17, but with shield connecting to ground at the output end and possibly left unconnected at the receiving end, just in case you've got a pin 1 problem), and things should much improve. It gets even better f you can find out output impedance, in which case you could add a matching resistor between ground and cold (black cable) on the output end for better impedance balance.
Note that there are onboard audio implementations with the ground loop built right into the board (well, bad luck then) - or worse, appearing depending on mounting. Welcome to the wonderful world of open systems, where components may work fine on their own but all hell breaks loose when they are combined.
Or a line-level isolation transformer, rather (a classic DI box has a non-unity turns ratio, like 10:1). Something like a Behringer HD400 (unbalanced in one side, balanced out the other) is a proven fix for people who don't feel like soldering. I just assumed that soldering wouldn't deter people here.use a di-box.
It is a ground loop. Specifically the return current from the motherboard to the power supply, which is tens of amps of dirty DC modulated with "computer sounding" noises, passes along the same ground wires that go between the ground terminal of your audio output and the ground pin of the PC's mains connector.
The best solution (that I'm aware of) is a DI box or isolation transformer as others have suggested. A USB DAC may not fix the problem, as the USB ports are subject to the same ground loop and the DAC doesn't provide isolation.
The best solution (that I'm aware of) is a DI box or isolation transformer as others have suggested. A USB DAC may not fix the problem, as the USB ports are subject to the same ground loop and the DAC doesn't provide isolation.
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