[avivsworld]

Hi, I've been running XBMC on an acer aspire for a few months, and yesterday I bought a new TV and connected everything up, and it just developed this strange audio problem.

Basically how it's set up is I have a pioneer reciever (no hdmi ports, just an audio one) and the TV is plugged in with a coaxial cable, and it runs on the "tv" channel of the amp.
The XBMC pc doesn't have a hdmi out, so it's connected to the tv with a dvi-hdmi connector, and there's a simple 3.5mm - RCA cable connecting it to the analog "CD" channel of the amp.
Now, this is only when the XBMC comp is on, the amp is on the CD channel and the coaxial cable is plugged in - it starts putting out some weird feedback, kinda sounds like... i don't know, a frequency generator outputting a square wave. Like, I can take out and put in the coaxial cable while the pc is running and the noise will stop and start as it makes a connection.

This stops as soon as the coaxial cable is unplugged, even though it's running on a different channel. The feedback doesn't happen when the amp is on the tv channel, and it doesn't make this noise with any other analog audio, so I'm pretty sure it's not the amp. I've tried a few different coaxial cables in case they had varying impedance, but again, no difference.

I've screwed around with a few values in the settings and alsamixer, but hasn't made a difference.

Anyone have any idea what the hell is going on?

[Wozza_au]

Hi
Did a quick google and found this
http://forums.audioholics.com/forums/amp...-d711.html
not sure if its your issue, but as per the post you may have a ground loop...
try plugging one ot the devices into another power point (will depend on how your house is wired if this will work or not)
Maybe post this in the general help section, as I think its more of a setup issue rather than a linux one and you may get more replies
Cheers
Wozza

[avivsworld]

Yeah, that's pretty much the same thing that's happening to me.
However, I just changed over to a new powerboard and plugged it into a different outlet - still nothing.

Interestingly, I found that it makes the noise if I plug the coaxial cable from the tv into ANY port in the back of the receiver (like, analog in/out, subwoofer preout,video in/out, anything), which just makes no sense to me.

Can I it be moved or should I just re-create it?

[avivsworld]

Also just out of curiosity I plugged the TV into a different room with an extension cord - noise would stop when the TV was unplugged, but as soon as it was plugged in it made the same noises.
Also tried the same plugging the amp and pc into different rooms - it was only different with the pc, in that it was a slightly higher pitch/more distorted.

[Wozza_au]

Yeah, that's pretty much the same thing that's happening to me.
However, I just changed over to a new powerboard and plugged it into a different outlet - still nothing.

Interestingly, I found that it makes the noise if I plug the coaxial cable from the tv into ANY port in the back of the receiver (like, analog in/out, subwoofer preout,video in/out, anything), which just makes no sense to me.

Can I it be moved or should I just re-create it?

Just recreate it
as its coaxial from the tv.... Id try plugging the TV via an extension lead some where else in the house..from the ground loop wiki

"Ground loop issues with television coaxial cable can also affect any connected audio devices such as a receiver. Even if all of the audio and video equipment in, for example, a home theater system is plugged into the same power outlet, and thus all share the same ground, the coaxial cable entering the TV is sometimes grounded to a different point than that of the house's electrical ground by the cable company. The potential of this ground is likely to differ slightly from the potential of the house's ground, so a ground loop occurs, causing undesirable mains hum in the system's speakers. A cheap way to resolve this problem is a 75-ohm coax combiner/splitter and a matching Transformer. The 75-ohm coax combiner/splitter converts the impedance from 75 ohms to 300 ohms and the matching transformer converts the impedance from 300 ohms to 75 ohms. Both parts connected together will act as a "poor man's" isolation transformer."

Cheers
Wozza

Doh you posted as I was typing ....Im slow on the keyboard