Cant even start recording because of mains noise.

G

Gimmehendrix

New member
Hi,

I am running Sonar Producer 7 on a P4 3.2GHz machine. I am unable to record anything however due to a ridiculous amount of residual noise. It appears to be dependant on what screens are being displayed . You can even hear the mouse moving across the screen! I though it was the computer or a combination of the computer and soundcard (MARC 4) . As it happens I have tried out the setup with a replacement laptop and TASCAM 144 USB unit but still same old issue. Its great when I run the laptop on battery but when I plug the adapter back in all hell breaks loose. Have incidently noticed that applications like VB3 FM7 etc run perfectly ok.
Am pulling my hair out over this so any help would be good.
 
Have you tried plugging the laptop power cable into a different power outlet?
Use an extension cord and plug it in to an outlet in a different room that has its own circuit.
Good luck!
Scott.
 
Hi,

I am guessing that you have an earth loop that is completed via the USB cable.

On lap tops the problem is caused by earthed power supplies, you can tell if yours is earthed by seeing if the mains plug has 3 pins, early lap top supplies were not earthed (2 pin). The fix is to buy a double insulated aftermarket power supply (2 pin) for your lap top.

If using a desk top the problem is harder to fix, you need to lift the earth on the audio lines to and from the soundcard, in the case of balanced audio lines you could try to lift the shield, in the case of unbalanced lines of it the shield lifting does not work use an isolation transformer like this.

I have been looking for anyone that makes a USB connection with the earth disconnected but no luck yet.

Cheers

Alan.
 
Gimmehendrix said:
Hi,

I am running Sonar Producer 7 on a P4 3.2GHz machine. I am unable to record anything however due to a ridiculous amount of residual noise. It appears to be dependant on what screens are being displayed . You can even hear the mouse moving across the screen! I though it was the computer or a combination of the computer and soundcard (MARC 4) . As it happens I have tried out the setup with a replacement laptop and TASCAM 144 USB unit but still same old issue. Its great when I run the laptop on battery but when I plug the adapter back in all hell breaks loose. Have incidently noticed that applications like VB3 FM7 etc run perfectly ok.
Am pulling my hair out over this so any help would be good.
Click to expand...

USB wireless mouse?
 
I have this exact same problem... I have three screens; one mega-huge CRT and two 14" LCDs. If any one of the two LCDs is plugged in but not switched on, my amp starts to whine.

I have several USB extensions running quite near my audio cables but they do not seem to cause any trouble.

Here's the funny thing: When I was recording with a mic, we were getting noise on the track. I noticed that when I maximised the playlist screen to one of the LCD monitors, it stopped. Possibly this means it's something to do with the monitor colour frequency but I don't know any more than this. I know this sounds insane, but try changing the colour of your desktop...?! Well, anything's worth a try... Right? That's not a solution, by the way!

Dr. V
 
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