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[This is a long post, but it may be helpful to others that may have to deal with similar problems....]
I upgraded from a Denon AVR-2700 receiver to the Outlaw Audio 755 amplifier+Rotel RSP-1068 in that order, in two steps, about 6 months apart. When the Outlaw amplifer showed up with it's 3 prong grounded plug, my journey into the depths of ground loops started. I had a noticeable 60Hz hum, but it was a low level hum from my listening position. When the RSP-1068 arrived, things went from bad to worse. All the discussion about RSP-1068 humming in this forum had me really worried.
Step 1 was to really find the problem and it wasn't too hard. I disconnected my DirecTV satellite feed from my Sony SAT-HD200 and all hum disappeared. Verified that the same thing happened when I disconnected the component video connectors to the TV and the monitor-out connection from the RSP-1068. Interestingly enough, when I reconnected the monitor-out connection, a very small hum was heard...so low you need your ear near a speaker to hear it. When I then reconnected my DVD player connection, my old friend the hum was back in full force. Took a good look at my satellite installation and discovered that it wasn't grounded correctly. Got DirecTV out to correct the problem and it got a bit better, so there's more going on here than satellite system grounding.
Checked the electrical outlets for ground and polarity using a reasonably priced outlet checker and, of course, everything was fine. I also discovered that the electrician that added this wiring really listened to me when I was finishing my basement for my home theater. All the wall outlets in the home theater area or on a separate circuit, so the lighting and my bar fridge are isolated on their own circuit. Never had an ocassion to check it before.
I moved my rack around while checking things and when I pushed it back into place, the hum was worse...really worse. Pulled the rack out and looked at the mass of cabling (separates plus a DVD/SACD universal player lead to way too many interconnects) and started moving things around. I re-ran all the video connections to pull them away from everything else as far as possible, rebunched excess power cord lengths, and cleaned everything up as much as possible. Pushed the rack back in and things were much, much better. I was now down to a low level hum that required your ear to get within a foot of a speaker to really hear. So, I was close, and once again, when I had removed the video connections between the system and the TV, the hum had completely vanished....still something going on with the satellite system.
A friend of mind reminded me to try and tie the chassis grounds of the component with the ground plug (amplifier) to the component that introduced the hum (Sony satellite receiver). I took a 10 gauge wire and touched it to a cabinet screw of the amplifer and a screw on the satellite receiver. The hum faded away and was gone. While retesting, I discovered that touching the wire to any part of the metal case of the satellite receiver removed the hum. So, it appears the satellite receiver itself has some grounding issues.
The final solution was pretty simple. I went to the hardware store, bought a package of 14-16 gauge spade connectors (right size to fit under the chassis screws of the amp and satellite receiver) and a piece of 14 gauge wire. Cut the wire to length, crimped on two spade connectors, connected one end to an amplifier screw and the other to a satellite receiver chassis screw and the hum is gone. I'll have to look at replacing the Sony satellite receiver down the road and I have to figure out if Sony will replace it or fix it under warranty. Sony warranty service doesn't have the best reputation.
Now I can enjoy my system. I am very impressed with the clarity the RSP-1068 brings to DD/DTS material. A big step-up from using my old trusty Denon as a pre/pro. I had to do several tweaks to get things right. Using a CD of test-tones with signals from 100Hz to 20Hz in 5 Hz increments (got the tones at Secrets of Home Theater website), I discovered I needed to change my subwoofer crossover frequency (move it up to a higher frequency) and phase to best blend the 1068 into the system. The phase adjustment seemed counter-intuitive, but it did require moving from 0 degrees to 45 degress to get the best blend below the cross-over I set of 60Hz between the subwoofer and my main/surround speakers.
So, for all of you struggling with ground loop problems, I wish you luck. The first time you introduce a component into your system with a 3-prong plug (like a separate amplifier) may uncover a host of issues, so it might not be that new pre/pro that's the problem.
I upgraded from a Denon AVR-2700 receiver to the Outlaw Audio 755 amplifier+Rotel RSP-1068 in that order, in two steps, about 6 months apart. When the Outlaw amplifer showed up with it's 3 prong grounded plug, my journey into the depths of ground loops started. I had a noticeable 60Hz hum, but it was a low level hum from my listening position. When the RSP-1068 arrived, things went from bad to worse. All the discussion about RSP-1068 humming in this forum had me really worried.
Step 1 was to really find the problem and it wasn't too hard. I disconnected my DirecTV satellite feed from my Sony SAT-HD200 and all hum disappeared. Verified that the same thing happened when I disconnected the component video connectors to the TV and the monitor-out connection from the RSP-1068. Interestingly enough, when I reconnected the monitor-out connection, a very small hum was heard...so low you need your ear near a speaker to hear it. When I then reconnected my DVD player connection, my old friend the hum was back in full force. Took a good look at my satellite installation and discovered that it wasn't grounded correctly. Got DirecTV out to correct the problem and it got a bit better, so there's more going on here than satellite system grounding.
Checked the electrical outlets for ground and polarity using a reasonably priced outlet checker and, of course, everything was fine. I also discovered that the electrician that added this wiring really listened to me when I was finishing my basement for my home theater. All the wall outlets in the home theater area or on a separate circuit, so the lighting and my bar fridge are isolated on their own circuit. Never had an ocassion to check it before.
I moved my rack around while checking things and when I pushed it back into place, the hum was worse...really worse. Pulled the rack out and looked at the mass of cabling (separates plus a DVD/SACD universal player lead to way too many interconnects) and started moving things around. I re-ran all the video connections to pull them away from everything else as far as possible, rebunched excess power cord lengths, and cleaned everything up as much as possible. Pushed the rack back in and things were much, much better. I was now down to a low level hum that required your ear to get within a foot of a speaker to really hear. So, I was close, and once again, when I had removed the video connections between the system and the TV, the hum had completely vanished....still something going on with the satellite system.
A friend of mind reminded me to try and tie the chassis grounds of the component with the ground plug (amplifier) to the component that introduced the hum (Sony satellite receiver). I took a 10 gauge wire and touched it to a cabinet screw of the amplifer and a screw on the satellite receiver. The hum faded away and was gone. While retesting, I discovered that touching the wire to any part of the metal case of the satellite receiver removed the hum. So, it appears the satellite receiver itself has some grounding issues.
The final solution was pretty simple. I went to the hardware store, bought a package of 14-16 gauge spade connectors (right size to fit under the chassis screws of the amp and satellite receiver) and a piece of 14 gauge wire. Cut the wire to length, crimped on two spade connectors, connected one end to an amplifier screw and the other to a satellite receiver chassis screw and the hum is gone. I'll have to look at replacing the Sony satellite receiver down the road and I have to figure out if Sony will replace it or fix it under warranty. Sony warranty service doesn't have the best reputation.
Now I can enjoy my system. I am very impressed with the clarity the RSP-1068 brings to DD/DTS material. A big step-up from using my old trusty Denon as a pre/pro. I had to do several tweaks to get things right. Using a CD of test-tones with signals from 100Hz to 20Hz in 5 Hz increments (got the tones at Secrets of Home Theater website), I discovered I needed to change my subwoofer crossover frequency (move it up to a higher frequency) and phase to best blend the 1068 into the system. The phase adjustment seemed counter-intuitive, but it did require moving from 0 degrees to 45 degress to get the best blend below the cross-over I set of 60Hz between the subwoofer and my main/surround speakers.
So, for all of you struggling with ground loop problems, I wish you luck. The first time you introduce a component into your system with a 3-prong plug (like a separate amplifier) may uncover a host of issues, so it might not be that new pre/pro that's the problem.
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