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colinmusic
Oct 3, 2008, 09:52 AM
i bet this is a common problem. Apple os 10 goes out via usb to edirol ua 25 audio interface and then phono leads go out from edirol into home hi-fi and passive speakers to use as a monitor. There's a terrible hum coming from the speakers. Any idea what can be done?

thanks colin



Killyp
Oct 3, 2008, 04:03 PM
Does it do it on all the amp's sources?

colinmusic
Oct 3, 2008, 04:25 PM
Does it do it on all the amp's sources?

the answer is NO. Only on the mac. I have a PC connected to the same amp and this is noise-free.

My local music shop told me to remove the earth from the amp plug.

is this a possible cure?

thanks for the interest

colin

Killyp
Oct 4, 2008, 01:17 AM
Sounds as though you've got a ground loop. Yes, removing the earth from the amp would fix this but I really wouldn't do it personally. The amp is earthed for a reason.

Have a look at this (http://www.angelfire.com/electronic/funwithtubes/Eliminating_Ground_Loops.html) link. Fixing ground loops isn't the simplest task in the world, but it's doable.