I have an ESI PCI card in the PCIX slot #4 (133 MHZ) of my G5 2.7. As I listen to the output of audio in Logic Pro I hear a " beeping" sound coming through my speakers, obviously when music is not playing. I also hear funky noise artifacts like "swishing" when I move my mouse. I had heard these sounds at a time when I was troubleshooting the computer using only the MAC 1/8 inch inputs and outputs. The Apple folks said "Ground loops, beeps, hum" were not present in their outputs but due to problems with electric interference and ground loops occurring after audio leaves their computer. And they had support papers out to tell folks how to deal with it. It involved buying transformers and fitting them in the audio cable chain to "lessen" the noises. These noises were quite loud and bothersome but not recorded, only heard.
I've double checked - my audio preference input and output, in MAC is set to ESI Julia card. The same is true for my Logic Pro audio driver. Latency is set to 128.
Darned if don't I hear the same noises, but softer and less intrusive, in the output of my ESI PCI card. Are these normal to PCI cards? Will a firewire device such as the Apogee Ensemble deliver these weird noises?
I think you hear in fact (at least) CPU activity. It should disaear or at least diminish if you disable NAP on the processor (energy saving mecanism buit-in the CPU). To do so, grab your install OS X DVD, dive into the Xcode developer tools and install /mac OS X install DVD/Xcode tools/Packages/CHUD.pkg
You'll have a new prefpanel named Processor with a NAP check box. Disable NAP and see.
Note the latest CHUD version is freely available in the Apple Developer Connection website (free registration)
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