Audio Background Noise Problems Anybody?, Noisy audio on my Emac G4 700 mhz Options

[abaco]

Emac Audio Problem

My brandnew Emac 700mhz has a good amount background noise in its audio output making it unusable for professional recording applications like Cubase.

The high pitched sound changes loudness and frequency depending on the position of the mouse on the screen so it seems that maybe there's some stray voltage coming in from another sub system (graphics perhaps?)

I went and bought a professional USB audio adapter from Edirol ($250) hoping that may fix the problem. It brought the noise level down at least by 3 times but the same ever changing noise is still there in the background. It seems to also transmit itself somehow through my MIDI devices as well and then show back up on the MIDI device's audio output.

It looks like a design flaw to me. Maybe some components that should have been shielded better on the motherboard. I need help. This computer turns out to be unusable for any kind of music recording. My old iMac has none of these problems and is totally noise free even with just the built in 1/8" audio output.

Any advice how to fix this? I don't want to have to buy another computer.

Thanks,
Alan Steward
abaco@go2mypage.com

[Fusion Head]

This reply comes a bit late, sorry - I have just discovered this forum. Regarding audio noise problems... I am using a G4 MDD DP 867 machine, and was using an Emagic EMI 6|2 interface (now using a new MOTU 828 MkII). I cannot say what is the source of the noise problems, but it is likely grounding issues inside the Mac... but I found a solution.

I did everything to try and kill this digital video "hash" noise when I connected my mixer, but nothing worked (common grounding point, lifting grounds on one end of audio cables, using separate power supply for EMI, etc.)

As a last resort, I then researched and found a VERY cool product: the Hum Eliminator by EBTECH. This thing killed the noise completely by essentially isolating the grounds between each piece of equipment... no ground loops! You can get it in 2 channel and 8 channel versions, through most major online music stores like audiomidi.com. Price per channel is very reasonable given the quality of this product.

This won't solve internal noise problems in the Mac, or your fan noise (I am still working on that one!) but this thing rocks for killing ground interface problems.