Loud Hum from DNA 0.5

Also, I should clarify that the hum is loud enough to make the amp useless. And regarding the preout noise, prior to repair, there was no hum and prior to the DNA 0.5, the Rotel amp produced no hum.

Hi Taylormade2 -

Sorry to hear about the problem with your DNA-0.5. I have no idea what work was done on your amp, but it seems possible that the factory updated the Earth / main-board ground path while doing the repair work. This would normally be a good thing, but it may have gone awry in your particular setup.

If the amp were "broken," I would expect to hear noise constantly, even with no input cables connected. You say that the noise disappears if you remove the interconnect cables, and this suggests a ground loop. Try "floating" the earth ground connection on the amp by using an AC "cheater" plug (3-to-2 connection adaptor). These are available at your local hardware store. In addition, if you have any kind of an audio connection to a cable TV video system, disconnect it. If the hum disappears, you have been dealing with a ground loop. For a more complete explanation, go here: http://www.altavistaaudio.com/hum.html

Good luck!

Best regards,

Steve McCormack
www.SMcAudio.com

I tried disconnecting everything from the receiver other than the DNA and the hum is still present. The AV receiver only has a 2 prong plug. I can try getting the converter for the DNA to see if that solves the problem.

In reading over the counter point article, the DNA is the only component with 3 prongs. The DVD player, AV receiver and TV/Cable box only have 2. Even with the cable tv disconnected from the wall, the hum persists.

I stand corrected! Thank you so much Steve! I had disconnected the cable tv from the back of the cable box but when I pushed it back on its shelf, the cable was still in slight contact with the connector. I realized that if I removed the coax cable away from the cable box, the hum disappeared. Looks like I need to get a cable TV ground.