I have (as I suppose many do) hooked my HD PVR (TIVO for our American
friends) to my stereo so that the sound will be of quality to match the
picture.

For the record - Apt-Holman Preamp, Bryston amp, Polk RTA12b speakers. All
have always worked perfectly, and still do, aside from this issue.

A nasty hum has made itself evident recently. The hum clearly has its
source in the TV cable. It sounds very much like a 60-cycle AC hum, but
where would a ground loop happen? It pervades the entire system, no matter
what the input selector on the preamp is turned to. There is no apparent
change or lessening of the hum regardless of which audio channels are
connected.

The two different cable guys that have had a go at it have pronounced
themselves helpless. They were actually there to deal with video issues,
not audio ones. The video issues are still unresolved so they're coming
back again tomorrow.

Does anybody have any experience with this kind of thing? Anything that I
could suggest to the cable guys to try, that might fix this thing?

Is there a box that I could get a Radio Shack (or whatever it calls itself
these days) that would do the trick?

Any help or advice greatly appreciated.

Best,
Greg.
--
Greg Grainger grainger(at)vex.net

'What a world of gammon and spinach it is, though, ain't it?'
- Miss Mowcher


--

On 8 Apr 2006 21:31:22 GMT, (Greg Grainger) wrote:

Does anybody have any experience with this kind of thing? Anything that I
could suggest to the cable guys to try, that might fix this thing?

Is there a box that I could get a Radio Shack (or whatever it calls itself
these days) that would do the trick?

Any help or advice greatly appreciated.
Hi Greg:
Check Parts Express at:
http://www.partsexpress.com/pe/pshow...TOKEN=26525905
Or from Radio Shack get two 300 Ohm to 75 Ohm bauns, connect the
300 Ohm terminals together, connect your cable to one 75 Ohm terminal
and your TV to the other 75 Ohm terminal. This will break the ground
loop.
The hum is caused by different ground potentials between the
cable company and your electric company.
This has been a common problem since cable companies started
business, you'd think they would have a solution by now. My neighbor
got a $15 refund from his cable company to buy the device listed above
at Parts Express and it works fine.


...

-=Bill Eckle=-

Vanity Web Page at:
http://www.wmeckle.com


--

"Greg Grainger" wrote in message
...
I have (as I suppose many do) hooked my HD PVR (TIVO for our American
friends) to my stereo so that the sound will be of quality to match the
picture.

For the record - Apt-Holman Preamp, Bryston amp, Polk RTA12b speakers. All
have always worked perfectly, and still do, aside from this issue.

A nasty hum has made itself evident recently. The hum clearly has its
source in the TV cable. It sounds very much like a 60-cycle AC hum, but
where would a ground loop happen? It pervades the entire system, no matter
what the input selector on the preamp is turned to. There is no apparent
change or lessening of the hum regardless of which audio channels are
connected.

The two different cable guys that have had a go at it have pronounced
themselves helpless. They were actually there to deal with video issues,
not audio ones. The video issues are still unresolved so they're coming
back again tomorrow.

Does anybody have any experience with this kind of thing? Anything that I
could suggest to the cable guys to try, that might fix this thing?

Is there a box that I could get a Radio Shack (or whatever it calls itself
these days) that would do the trick?

Any help or advice greatly appreciated.


It is most likely a TV-Electrical System ground loop that is not uncommon on
cable systems. If so, an isolation transformer on the cable input will
solve the problems. Radio Shack may have these (probably do, although they
may have to order it in) but you can also get them elsewhere. I ordered
mine directly from Jensen - part number VRD-1FF - which cost $60 and works
with analog or digital cable systems but not satellite. Worked like a charm
to eliminate a problem identical to yours.

The Jensen link:
http://www.jensen-transformers.com/prices.html#vrd1ff

Good luck.

Harry



--

Greg Grainger wrote:
I have (as I suppose many do) hooked my HD PVR (TIVO for our American
friends) to my stereo so that the sound will be of quality to match the
picture.

For the record - Apt-Holman Preamp, Bryston amp, Polk RTA12b speakers. All
have always worked perfectly, and still do, aside from this issue.

A nasty hum has made itself evident recently. The hum clearly has its
source in the TV cable. It sounds very much like a 60-cycle AC hum, but
where would a ground loop happen? It pervades the entire system, no matter
what the input selector on the preamp is turned to. There is no apparent
change or lessening of the hum regardless of which audio channels are
connected.

The two different cable guys that have had a go at it have pronounced
themselves helpless. They were actually there to deal with video issues,
not audio ones. The video issues are still unresolved so they're coming
back again tomorrow.

Does anybody have any experience with this kind of thing? Anything that I
could suggest to the cable guys to try, that might fix this thing?

Is there a box that I could get a Radio Shack (or whatever it calls itself
these days) that would do the trick?

Any help or advice greatly appreciated.

Best,
Greg.
You don't say whether you have analog or digital cable. Go here
http://www.jensen-transformers.com/iso_vid.html for a solution that will
work with both. If you don't have digital, a cheaper solution can be
found here http://www.dplay.com/tutorial/cablehum.html which uses a
couple of parts found at Radio Shack for under $10.00. I use the Jensen
in my system and it works like a charm, although the Cable TV people
don't think it is their problem. Go figure. HTH


--

Greg Grainger wrote:
I have (as I suppose many do) hooked my HD PVR (TIVO for our American
friends) to my stereo so that the sound will be of quality to match the
picture.

For the record - Apt-Holman Preamp, Bryston amp, Polk RTA12b speakers. All
have always worked perfectly, and still do, aside from this issue.

A nasty hum has made itself evident recently. The hum clearly has its
source in the TV cable. It sounds very much like a 60-cycle AC hum, but
where would a ground loop happen? It pervades the entire system, no matter
what the input selector on the preamp is turned to. There is no apparent
change or lessening of the hum regardless of which audio channels are
connected.

The two different cable guys that have had a go at it have pronounced
themselves helpless. They were actually there to deal with video issues,
not audio ones. The video issues are still unresolved so they're coming
back again tomorrow.

Does anybody have any experience with this kind of thing? Anything that I
could suggest to the cable guys to try, that might fix this thing?

Is there a box that I could get a Radio Shack (or whatever it calls itself
these days) that would do the trick?

Any help or advice greatly appreciated.

Best,
Greg.

The problem is caused by differences in potentials between the cable
ground and the ground in your audio system. Make sure that the cable
feed is grounded to the house ground where the cable enters your house.
Typically, you should be able to connect the cable ground to a grounding
screw in your electrical service (breaker) panel.


--

I had the same problem as you and it was driving me nuts. It was NOT caused
by cable TV, which I verified by yanking the coax from the system to no
improvement.

I was told that the noise stemmed from differing ground potentials in some
of my 3-pronged components. I unplugged everything from the mains, and then
plugged in the 3-pronged components one by one to see which ones caused the
noise. They turned out to be my Fanfare tuner and Escient music server.
Interestingly, the Velodyne subwoofer, an obvious suspect, was not a
problem.

The solution was a great and indispensable product called Hum X by Ebtech
Audio (http://www.ebtechaudio.com/new.html). It's a simple plug that you
place between the component and the wall socket/power conditioner. Unlike
cheater plugs, a couple of which I had been previously using, the Hum X
maintains a safe ground. It's expensive ($90), but the damn thing works.
Best $180 I ever spent. My system is dead quiet now.



--

Greg Grainger wrote:
I have (as I suppose many do) hooked my HD PVR (TIVO for our American
friends) to my stereo so that the sound will be of quality to match the
picture.

For the record - Apt-Holman Preamp, Bryston amp, Polk RTA12b speakers. All
have always worked perfectly, and still do, aside from this issue.

A nasty hum has made itself evident recently. The hum clearly has its
source in the TV cable. It sounds very much like a 60-cycle AC hum, but
where would a ground loop happen? It pervades the entire system, no matter
what the input selector on the preamp is turned to. There is no apparent
change or lessening of the hum regardless of which audio channels are
connected.

The two different cable guys that have had a go at it have pronounced
themselves helpless. They were actually there to deal with video issues,
not audio ones. The video issues are still unresolved so they're coming
back again tomorrow.

Does anybody have any experience with this kind of thing? Anything that I
could suggest to the cable guys to try, that might fix this thing?

Is there a box that I could get a Radio Shack (or whatever it calls itself
these days) that would do the trick?

Any help or advice greatly appreciated.

Best,
Greg.


A) GROUND your cable TV cable to a solid ground - usually a cold water
pipe. And/or ground it's shield to your AC ground from the mains (second
best) and see where that gets you.

B) If that fails or is insufficient then you need a 1:1 RF isolation
transformer between the cable TV coax and everything else. That means
that at least on one side of the transformer the "ground" is not
connected to the ground of the other...

_-_-bear


--