[mythtv-users] Eliminating a ground loop/hum

[Owen Mehegan]

I have a new Myth system that I've just built. I'm using an MSI PM8M- 
V motherboard, with its on-board audio (Via VT8233/A/8235/8237 AC97)  
for everything. The system is connected to a Sony 34" CRT TV using  
DVI/HDMI cable. Audio is routed as follows:

cable box -> myth box -> tv -> Sony home theater receiver/speakers

All of that is done via basic RCA cables. My problem is that I have  
an intermittent 60hz hum in the audio. I hear it whether I'm watching  
TV or just in the Myth interface. Playing with various mixer volumes  
doesn't make it go away, in the sense that I can't null it out  
without having the whole system's volume down too low to hear  
anything. I have everything plugged into one power strip/wall outlet,  
and the outlet has three prongs; whether it's really properly  
grounded or not is anyone's guess. I tried unplugging various  
unrelated components (Xbox, cable box, cable modem/router) and got no  
change.

So, any suggestions on what I should do to clean up this audio? Maybe  
buy a better sound card? (And use spdif out while I'm at it? My  
receiver can handle it, though it's a pain in the ass from a  
"management of the available inputs" perspective.) What if I bought a  
UPS and plugged everything into that? I've seen suggestions of "home  
theater" magical grounding thingys... if you think one of those would  
help, a link to a specific product would be sweet. Thanks!

--
owen at nerdnetworks.org (Owen B. Mehegan)
'Therefore, since brevity is the soul of wit,
And tediousness the limbs and outward flourishes,
I will be brief.'
   --William Shakespeare

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