I am using a Lenovo S20 PC with a Asus Xonar DGX soundcard. My problem consists of RF noise this is a oscillating static sound. The only thing I have done is to ground the 2 chassis of the amplifier and the PC together which has no effect whatsoever. I have no florescent lighting near the units.
I was wondering if this is a common issue and if so is there an easy correction for it. P/S. The home where the unit is used is a wood and brick structure however it does have steel roofing installed, might this be a contributing factor? Thanks, Dave
I was wondering if this is a common issue and if so is there an easy correction for it. P/S. The home where the unit is used is a wood and brick structure however it does have steel roofing installed, might this be a contributing factor? Thanks, Dave
What is the amplifier and what else is connected through it? I suspect a ground loop, though then the grounding should have made a difference assuming it was sufficiently heavy (much higher gauge than the PE connections).
Is the noise also heard in headphones on the same output? If not - must be a ground loop. Is this the back output, or have you reconnected the front panel to the DGX and are using that output? If so, try the other.
Does the same noise also occur through onboard audio? If not, would the DGX happen to be installed next to a powerful graphics card?
Is the noise also heard in headphones on the same output? If not - must be a ground loop. Is this the back output, or have you reconnected the front panel to the DGX and are using that output? If so, try the other.
Does the same noise also occur through onboard audio? If not, would the DGX happen to be installed next to a powerful graphics card?
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I experienced this problem at one time - one amp produced a bunch of noise when connected to a computer audio interface and another amp was silent. Both used non-grounded US plugs. I was able to find the schematics for both amps and the noiseless one included RF filtering at the input and the noisy one did not.
You can pretty easily add this yourself. Insert, in series, a 1k resistor on the signal lead at the amp end of your interconnect (assuming unbalanced here), and after that insert a 1nF cap (NP0 type is OK, or audio quality) between the signal wire and input signal return of the unbalanced interconnect. Other R and C values will work, too. That will have a corner frequency of 160kHz and should low pass filter the audio enough to clean up the noise. My guess is that swiching noise from the computer is getting demodulated in the amp's input stage down into the audio band, producing the odd noises.
You can pretty easily add this yourself. Insert, in series, a 1k resistor on the signal lead at the amp end of your interconnect (assuming unbalanced here), and after that insert a 1nF cap (NP0 type is OK, or audio quality) between the signal wire and input signal return of the unbalanced interconnect. Other R and C values will work, too. That will have a corner frequency of 160kHz and should low pass filter the audio enough to clean up the noise. My guess is that swiching noise from the computer is getting demodulated in the amp's input stage down into the audio band, producing the odd noises.
OP, I had this same problem with my Ausus Xonar ST years ago.
Make sure that all "recording" devices are disabled in your "sound" settings. This fixed it for me.
Make sure that all "recording" devices are disabled in your "sound" settings. This fixed it for me.
Turning on and off the devices with the soundcard software does indeed make a difference however they were all off to start with, thanks for the tip, something else to keep in mind.
I purchased this PC used from a off lease program which I don't think it was ever used, very little if any. This was from a commercial graphics application, There are no onboard video or sound built into the motherboard everything is customer optional.
The video card I don't think is what would be considered extremely powerful it is a Nvidia Quadro 400, the soundcard I added myself and I have space them as far apart as possible. Holding different types of materials between them shielding them from each other doesn't seem to have any noticeable affect.
I have experimented with grounding various components and what has produced results has been to ground the mounting bracket of the soundcard directly to the amplifier cabinet which is earth grounded this has not completely eliminated the issue but has reduced it by what I would approximate as 50%. So this does appear to be a ground issue.
I am certain that the amplifier itself has nothing to do with this, someone asked what the amp is. It is a do-it-yourself version of a Naim140. If I hook up any other source CD player etc. there is no such noise. It is almost as if there is a poor ground from the card going into the PCIe slot, but physically moving the card in its PCIe slot also has no effect. Enclosed are a couple of pictures showing layout inside the computer. Thanks for the help, Dave
The video card I don't think is what would be considered extremely powerful it is a Nvidia Quadro 400, the soundcard I added myself and I have space them as far apart as possible. Holding different types of materials between them shielding them from each other doesn't seem to have any noticeable affect.
I have experimented with grounding various components and what has produced results has been to ground the mounting bracket of the soundcard directly to the amplifier cabinet which is earth grounded this has not completely eliminated the issue but has reduced it by what I would approximate as 50%. So this does appear to be a ground issue.
I am certain that the amplifier itself has nothing to do with this, someone asked what the amp is. It is a do-it-yourself version of a Naim140. If I hook up any other source CD player etc. there is no such noise. It is almost as if there is a poor ground from the card going into the PCIe slot, but physically moving the card in its PCIe slot also has no effect. Enclosed are a couple of pictures showing layout inside the computer. Thanks for the help, Dave
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We have a winner!
You've got unbalanced audio running between two IEC Class I (safety earthed) devices. That's just about guaranteed to give problems.
You will need to either
a) modify your amp so it becomes a Class II (double insulated) device (adequate insulation of wiring, shield winding in the power transformer would be good to reduce capacitive coupling there), like most hi-fi gear is.
or
b) employ an isolation transformer ("ground loop breaker") of adequate quality.
RE: RF noise from PC through amplifier. UP DATE
I replaced the sound card with one of a earlier ventage Creative Sound Blaster Audigy 2 ZS. No Noise!!! This older card has somewhat less pre amplifacition than the Asus card but it is silent, and is also a 24 bit decoder, I will switch in and out of PCI slots to see if this is a motherboard issue or the card its self.
I replaced the sound card with one of a earlier ventage Creative Sound Blaster Audigy 2 ZS. No Noise!!! This older card has somewhat less pre amplifacition than the Asus card but it is silent, and is also a 24 bit decoder, I will switch in and out of PCI slots to see if this is a motherboard issue or the card its self.
This is certainly peculiar. I can only guess that the 2ZS has different / better ground routing. A PCI slot also has a fair few more ground connections than a PCIe x1 to begin with...
Like I said, normally you'd be expecting problems in a setup like yours.
The Asus card is PCIe and the Creative card is PCI. The Asus card has been a problem from onset, I have returned the orginal due to a poping issue in one channel. The software has trouble, I have to go in and manipulate controls, one channel will just drop for no reason, etc. I am going to put the Asus card in a different computer to confirm my thoughts on the issue.
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