Axiom Home Page Forums General Discussion Home Theater Grounding and hum

They say it's the first thing to go. Now what was the second?...

Scott

Alan,

Do you have any advice on dealing with HTPCs? Fixing the poor ground on the cable tv line has almost eliminated that as a source, but the HTPC is definitely introducing some noise (EMI/RFI I'm sure) into the system. I was going to switch to an optical connection for the audio, but there is also a small of noise being introduced by the HDMI connection from the HTPC. Not really sure what the options are here aside from trying a whole different HTPC such as a laptop based system that uses an isolated ungrounded power supply and runs via DC only internally...

Anyone have any ideas?

At this point the hum is around the <15db level (I'm guesstimating). It's really really low, but the idea that it should be completely silent is driving me nuts.

Also, I doubt it's actually an issue, but in term of interconnects from pre to amp... Should I be using RG-59 or RG-6 coax interconnects here? Do I really need quad shielded RG-6 to go the 2 ft or so? Right now the interconnects don't seem to be introducing any noise. I can verify that by taking out all the sources form the pre and connecting my iPod to the Aux in... everything is dead silent even with my current RG-59 based interconnects.

Foo, on your point about the pre-out connections, RG-59 would nearly always be adequately shielded for a typical home environment, even for considerably longer distances than that. RG-6(which may or may not be more heavily shielded)isn't needed.

Hi Foo,

I'd agree with JohnK on the RG-59 as being entirely adequate and your not needing RG-6.

Your idea of using a laptop with the isolated power supply may be a solution, but frankly I'm not experienced with HDMI/grounding issues using a home theater PC in a system.

Of course we all want dead-silent noise-free systems, but from a practical point of view, without a lot of tedious trouble-shooting, it's almost impossible to entirely eliminate all noise from a system.

I think the goal of achieveing no audible hum/hiss from your listening area when the volume is advanced to a level that would normallly generate very loud sound with CD or movie playback is a worthy one and achievable without becoming obsessively preoccupied with eliminating all audible hiss/hum with your ear next to the speakers and volume control fully advanced.

Regards,

Alan