Hello everyone,
I have the dreaded ground hum in this setup (Supernait in the AV mode for the main speakers). I have an Oehlbach Powerstation 909 that supplies the power for all components.
And I have read posts here and in other forums for hours about this.
The issue is resolved with a ground loop isolator which I got on Amazon for 20EUR. However the sound quality is abysmal, especially in the lower frequency area. Really unbearable.
So I know the problem and now I would like to ask here
Should I spend $$$ for a high-end ground isolator? Which are you using?
Or can I tackle the root problem somehow?
The Marantz only has a two-pronged power connection and maybe I can add some ground connection here? I read some suggestions but frankly could not understand what specifically needs to be done.
AFAIK the Marantz Cinema range only grounds signal to chassis and chassis does not go to earth. If you have a Naim digital source (like a CD player or streamer), that can also handle the signal ground provided the ground switch is set to “chassis” instead of “floating”. If you have no Naim digital source, then you will have to do as @bruss suggested and manually link up the signal ground back to either the SN2 or via a dedicated signal grounding device.
The advice here is correct. I had this same problem with a Marantz AV surround amp and a SN3. Was resolved by grounding as advised here. I recall trying various combinations till I got it to work.
Buy a cheap phono to phono lead off Amazon. Pull it apart to give you a single cable. Lop off one plug..strip back insulation to reveal shielding mesh. Get a spare mains plug and connect the shielding mesh to the earth pin. Cut the signal wire short and do not connect to anything.
Plug into free mains socket and the phono into a spare RCA plug on your Marantz.
I do have a Naim DAC-V1 and and a Naim CD5i connected. The Marantz even provides a “Signal GND” screw beside the (unsed) phone RCA inputs. The DAC grounding is set to “Chassis”.
Just to be clear, what would be the cleanest way to connect the devices?
The SN2 is connected via DIN cable, so the RCA output is unused.
If I create an RCA cable that connects the outer RCA connector to the “Signal Ground” of the Marantz, would that work?
Unfortunately the answer with grounding isn’t a definitive answer. You will need to experiment. I would first ensure that among the CD5i and DACv1, that only one has the ground switch set to Chassis. Naim configure it so that a single Naim source should provide the signal ground reference for the whole system.
Then you might try a ground wire via the Marantz to the signal ground screw terminal on the SN2.
Rememebr to only make one change at a time and then test before making the next change. @Neilb1906 suggestion has certainly worked for a lot of users. But I would try other things first. dongling the return direct to mains is actually a good way of causing the problem you have if you don’t have it already in many cases. You might even find an RCA screw terminal (literally an RCA plug that goes nowhere and has a ground screw terminal on it) between Marantz and ground terminal on the SN2 works.
The goal is to make sure the signal ground has one and only one path to earth. As the Marantz doesn’t have it, connecting it to the SN2 somehow upset the balance somehow.
Thank you, just a brief update:
The CD, DAC (both connected via DIN) and Phono (RCA) inputs do not cause any issues. They are dead silent and a pleasure to listen to. I switched the DAC to “Floating” just in case. Did not change anything.
I did connect the Ground screw of the Marantz with Ground of the SN2 with no change at all. Same hum as before.
I will now butcher a main plug and reanimate my soldering skills.
I resolved this issue with a common $35 ground loop isolation interconnect between the two amps. RCA at both ends. You need two if you want full tape-loop two-way playback.
