Background hum with digital coax connect??

D

dfburrell

Audiophyte
I'm mystified - hope someone out there can shed some light! I'm working to connect my home theatre system, and cannot seem to come up with the right combination to make all go well.

Right now, I have connects as follows:

Cable Box > TV (through HDMI)
Cable Box Audio > Receiver (through Digital Optical)

DVD Video > TV (through component cable)
DVD Audio > Receiver (through digital coax)

Problem is, every time I connect the Digital Coax from the DVD to the Receiver, I get an annoying background Hum on my speakers - almost as though I'm getting feedback noise. Disconnect the digital coax, and all is fine. I tried a second dvd player with the following video connects to see if it made a difference:

DVD Video > Receiver > TV (through S-Video)
DVD Video > TV (through S-Video)

and still encountered the problem of background noise when connecting the digital coax...

Is my digital coax just "bad", or is there some other configuration I should be trying to work out to get clean sound?

Any help is appreciated.

(note: neither receiver nor DVD have HDMI inputs; receiver is an Onkyo receiver with one digital optical input and two digital coax inputs - i tried both coax inputs with the same result)
 
Warpdrv

Warpdrv

Audioholic Ninja
What are you using for cables for connecting audio and video... Brand..?

If they are really cheap, they can be introducing a ground loop.

Ground loops are very common with cable boxes, but not often on a DVD player... I would think its a bad cable...

I thought I had good enough RCA cables from my receiver to my new AMP but a hum/buzz was there, ordered new heavy shielding cables from BlueJeans Cable, and that solved my problem...

If your using optical for your audio, then its probably the video side thats giving you an issue.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
I'm mystified - hope someone out there can shed some light! I'm working to connect my home theatre system, and cannot seem to come up with the right combination to make all go well.

Right now, I have connects as follows:

Cable Box > TV (through HDMI)
Cable Box Audio > Receiver (through Digital Optical)

DVD Video > TV (through component cable)
DVD Audio > Receiver (through digital coax)

Problem is, every time I connect the Digital Coax from the DVD to the Receiver, I get an annoying background Hum on my speakers - almost as though I'm getting feedback noise. Disconnect the digital coax, and all is fine. I tried a second dvd player with the following video connects to see if it made a difference:

DVD Video > Receiver > TV (through S-Video)
DVD Video > TV (through S-Video)

and still encountered the problem of background noise when connecting the digital coax...

Is my digital coax just "bad", or is there some other configuration I should be trying to work out to get clean sound?

Any help is appreciated.

(note: neither receiver nor DVD have HDMI inputs; receiver is an Onkyo receiver with one digital optical input and two digital coax inputs - i tried both coax inputs with the same result)
While you have this hum and with the DVD connected to the TV, remove the video cable from the cable box to the TV and tell us what happens. Also, may want to just remove the cable TV feed from the wall to the cable box for starters and simpler. There are ground isolators for that line, about $10, that will solve your issue, if these experiments eliminates the hum.

I bet the hum goes silent.:D

Ground loops are usually caused by the cable TV box. The optical isolates that ground so the HDMI is the only other path.
 
D

dfburrell

Audiophyte
HDMI was the culprit

So suggestions proved rather useful - ground loop (something I was previously unaware of) was finding its outlet through the HDMI cable from the cable box to the TV. Used component video cables, and the background hum disappeared. Good for a short-term solution, and am planning on getting a ground isolator to be able to re-introduce the HDMI cables into the mix.

Thanks to all I now have clean sound through my newly acquired KEFs!:D
 

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