Another buzz issue


Hi All, I recently updated my preamp to a Marantz AV7706. The Marantz has a 2 prong plug and after extensive trial and error have determined the hum must be a grounding issue. I have separate amps on all channels (a total of 4 amps with 3-prong plugs and a Marantz, 6 channel amp powering 3 pair of overhead fronts, sides and overhead rears for (ATMOS) configuration that, like the preamp, has a 2 prong plug. I don’t want to put cheater plugs on ALL of my 3 prong plugs so was wondering if/how it’s possible to “ground” - or convert - the 2 prong plugs to 3 prong? FWIW - I have a dedicated circuit for the HT/sound system, almost everything is plugged into a Furman AC “conditioner” and all plugged into the same circuit. There are NO coax runs. I’m sure there is another thread on this topic somewhere but am looking for guidance. Also, all the interconnects are in shielded, RCA (my 4 old Hafler 9300’s don’t take XLR). To rule out the cables I put in some old AQ shielded cables with no luck. I will also mention that there are a few auxiliary components (subwoofer, Amazon cube and and Apple TV that are plugged into a Panamax which is plugged into the same outlet/circuit - I just don’t have any more outlets available on the Furman. I have tried to troubleshoot this for over a year and have had 2 installers come out with no luck. At first I thought there was a problem with the Marantz but swapped it out for a new one (same model) so doubt that’s the issue.

whiterockman

Success!!! Thanks for the suggestions. The solution turned out as follows: I had all my amps plugged into a Furman surge protector and the TV and some other ancillary products plugged into a Panamax, both of which were plugged into a dedicated circuit outlet. I eliminated the Panamax and bought a 12 gauge power tap at Home Depot. I plugged this into the Furman and gave me enough outlets to plug everything into the Furman. I then put cheater plugs on ALL 3 prong devices and unplugged the Panamax. That did the trick! Definitely trail and error was involved but this turned out to be the solution! Why the Hell manufactures make ungrounded products - I’m looking at you Marantz! - I’ll never know. Either all components should be grounded or not! Anyway, after over a year the problem was solved and my system never sounded better as the buzz masked all the fine detail and “air” around the instruments! I’m not happy I have high-dollar aftermarket power cords interfaced to a .99 cent cheater plug but oh well. I figure if something electrical goes wrong it will hit the Furman as opposed to the (now ungrounded) equipment plugged into it…

whiterockman

... I then put cheater plugs on ALL 3 prong devices and unplugged the Panamax. That did the trick! Definitely trail and error was involved but this turned out to be the solution ...

The goal is to get all safety grounds at the same potential. Defeating the safety grounds altogether is not really a solution, although it can be a useful diagnostic tool.

 

But how do you do that??? I don’t want it to be a permanent solution either but I am no engineer and haven’t the slightest clue how to get “all safety grounds at the same potential”…