Buzzing sound from RCA input from PVR to preamp

Paul -- Tue, 02/16/2010 - 13:38

Not sure if this is the place to ask such a question, but wondering if anyone has experienced this type of issue before.
The problem I have is that if I switch to my RCA inputs that connect from Motorola PVR to preamp, with the PVR power turned off, I hear quite a high pitched buzz through the speakers.
I previously had a NAD T753 surround amp and it suffered this problem, and now I have a NAD 2 channel amp and Cambridge Audio 840E preamp and still the same problem. I can leave all components turned off, and in turn switch to all of the other RCA inputs and no buzzing from the speakers, meaning all other sources are quiet when they are powered on or off. I have tried replacing the RCA cables between PVR and Preamp, to no avail.
My concern is that the PVR is creating some noise in the system which may be affecting what I hear from all of my other sources, since the buzzing/noise is there even when the PVR is turned off.
Do I need some type of filter between PVR and preamp? I have tried replacing the power cable on the PVR with a Shunyata Venom AC cable and that did not make any difference.
Thanks in advance,
Paul

Robert Harley -- Fri, 02/19/2010 - 11:43

Is the PVR connected to a cable-TV system through a coaxial connection?

Paul -- Fri, 02/19/2010 - 16:56

Yes it is Robert. Thanks for the response.
Do you know of a solution?
Paul

Paul

Paul -- Fri, 02/19/2010 - 19:32

Hi Robert,
One thing I forgot to mention, that the system is connected as you described with PVR to cable TV system with coaxial cable. I have also tried disconnecting the coaxial cable directly from the wall outlet so that no cable signal is fed into the PVR, and still the same buzzing is the PVR is powered off, and the PVR audio input selected on the preamp. I have also tried different RCA cables from PVR to preamp, to no avail.

Robert Harley -- Fri, 02/19/2010 - 23:56

It sounds to me like the PVR is at fault. I was going to suggest that you use a 75-ohm coaxial in-line transformer to isolate your system from the cable-TV ground, but if disconnecting the cable doesn't help, that's not the problem. I think you need to swap out the DVR.

Paul -- Sat, 02/20/2010 - 03:10

The transformer was a good idea, but as you said since the issue is still there when the coaxial is not connected to the cable outlet there must be another issue. Definitely something to do with the PVR itself, especially since I have 6 other sources and none of them exhibit this problem. I am going to check around a bit more on the web to see if anyone else has had this problem, and if not then consider swapping the unit out. It is under warranty.

Thanks,