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

the monitor is the biggest culprit of background noise... especially if recording guitars as the pickups are very sensitive... if recording guitars, keep pickups as far from monitor as possible and face away from monitor. Keep cables and device as far from monitor as possible also... this may help but not totally solve problem.

This post has been edited by Synthetic: Tue 8 Jul 2003, 17:17

One thing you should do that might help is make sure everything is using the same power outlet.. I am not exactly sue I uderstand what your problems is, but either way, this should only help ifanything...BTW i dont knw how experienced you are, but dont monitor the audio when your recording..

u can't expect nothing but a not-good-sound from this output.
(you can't hear your hard drive or else )
but u can get a descent sound.
look for lights also, they can't emits noises
electricity also (i have same problem with ibook, see next topic)

get a firewire output if you wanna do "real" audio recording.

Another thing to consider....
Make sure your devices are properly grounded. If you are using a power strip or surge protector with the ground connector broken off, you are going to have problems. Check the ground connection outside of your house. Coming off of your power box (outside where the meter is) there should be a copper wire that is nailed into the ground (literally). Make sure it goes into the ground quite a ways. If not, pound a longer (copper) rod into the ground and connect the grounding wire to that. The best rought is to ground all your sound devices and computer to a dedicated ground. This may sound silly, but most hiss and other sound anomallies are from poor grounding.

I have had exactly the same problem, having upgraded from a G3 i-Mac to a G4 eMac, and I reckon the main problem is not actually to do with grounding, etc (although this will make things quieter) but with THE FAN. G3 iMac's have a different cooling system and are beautfully quiet, but this damn eMac is a noisy bastard. The fan can also cause electrical interference as well as audio noise.

Like you, I find recording audio (via a mike) virtually impossible - it sounds like there is a hoover in the background! However, I don't seem to have any major problems with audio inputs other than mikes (guitar, etc) now with Midi inputs and VST instruments, using Cubase SX and Reason and an external Midi module.

If you are using an external mixer, try disconnecting the leads one by one, and you might identify a grounding problem when the interference level drops.

Right now I am in search of a quieter fan to replace the inbuilt one. I'll let you know if I find one, and if anyboy can help me in this, please do! Thanks!

by the way, you didn't mention - are you using the latest OS? this definitely helps. Earlier versions had mega-problems with audio.

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.