I recently changed PCs and have run into some digital noise issues. When the PC does stuff (resize windows, mouse over buttons, etc) I can hear a burst of digital noise. If i don't move the mouse over stuff and there's not much cpu use happening, the noise vanishes. It's either occurring, or not, and it's quite loud when it does.
I've reduced the problem to my PC, a firepod soundcard connected via firewire to the PC, a yamaha mg124cx mixer, and a NAD C326BEE amplifier. By plugging headphones into all the outputs on the soundcard, I do not hear any noise, despite the fact that I can still hear it in the mains. I don't hear the problem in the mixers headphones out either. I can turn all the mixer sliders to zero and the problem persists. If I disconnect the last patch cable from the soundcard to the mixer, the problem goes away. It doesn't matter what this cable is connected to, it can run from an out on the soundcard to an aux out on the mixer, or in to a strip which is not getting routed and with the slider down. If I leave the soundcard connected to the mixer, and disconnect the firewire cable then the problem also goes away.
All devices are connected to grounded electrical strips, apart from the soundcard which is only connected to the mixer and pc via firewire. I thought ground loops were more of a constant deep buzz, not this intermittent high pitched bzzz of digital noise. I've removed unnecessary pci cards, usb hubs, etc. If the problem IS a ground loop near the soundcard, why is the noise not heard on the mixer headphone outs, but IS heard on the amp once the amp is connected to the mixer (with the master fully down)? I also took the cables runnign from the mixer master outs to the amp inputs, and connected from from a stereo IN on the mixer to the amp IN. The problem re-occured. This leads me to think it is NOT an issue with the audio path at all.
Worth mentioning perhaps is that the amplifier is also connected to some home theater gear, wifi routers and other crap, but I haven't disconnected that yet since it's very difficult to reach. However, those devices have always been there. The problem has only appeared since I installed the new PC.
I'd appreciate some tips on what to try next!
I've reduced the problem to my PC, a firepod soundcard connected via firewire to the PC, a yamaha mg124cx mixer, and a NAD C326BEE amplifier. By plugging headphones into all the outputs on the soundcard, I do not hear any noise, despite the fact that I can still hear it in the mains. I don't hear the problem in the mixers headphones out either. I can turn all the mixer sliders to zero and the problem persists. If I disconnect the last patch cable from the soundcard to the mixer, the problem goes away. It doesn't matter what this cable is connected to, it can run from an out on the soundcard to an aux out on the mixer, or in to a strip which is not getting routed and with the slider down. If I leave the soundcard connected to the mixer, and disconnect the firewire cable then the problem also goes away.
All devices are connected to grounded electrical strips, apart from the soundcard which is only connected to the mixer and pc via firewire. I thought ground loops were more of a constant deep buzz, not this intermittent high pitched bzzz of digital noise. I've removed unnecessary pci cards, usb hubs, etc. If the problem IS a ground loop near the soundcard, why is the noise not heard on the mixer headphone outs, but IS heard on the amp once the amp is connected to the mixer (with the master fully down)? I also took the cables runnign from the mixer master outs to the amp inputs, and connected from from a stereo IN on the mixer to the amp IN. The problem re-occured. This leads me to think it is NOT an issue with the audio path at all.
Worth mentioning perhaps is that the amplifier is also connected to some home theater gear, wifi routers and other crap, but I haven't disconnected that yet since it's very difficult to reach. However, those devices have always been there. The problem has only appeared since I installed the new PC.
I'd appreciate some tips on what to try next!