Please list all your equipment so we can have a go at a solution. Add any power conditioners or cheater plugs, etc.
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My equipment list is as follows;
Michell Orbe/Graham 2/Ruby 2 attached to a Naim 52 (K) and a Naim 250 amp. Digital sources are a Arcam transport and DAC as well as a Magnum tuner attached to a roof antenna. Phono Cables consist of either Harmonic Technology or Graham and non phono are Naim or some Kimber.
What I can say at this point is that when the arm is on the Orbe and I touch (with a wire) either the springs, the arm board, spindle, I get the pops. So at this point I am assuming that there is continuity between the arm and the Orbe. If I remove the Graham from the Orbe it still has the problems. The arm cable has no ground wire at the DIN to attach to the Orbe's sub chassis ground screw like a Linn arm cable. If I run a wire from the Orbe's grounding screw to the preamp ground post nothing changes.
Not having another arm to try, Saturday, I borrowed a Linn Basik arm from a local Dlr. and hooked it up to the preamp, and have the same problem! I have it mounted on a wood block cause I cannot mount it on the Orbe. The same problem, touching metal to metal causes pops. I think it rules the Graham out as the source. I hooked the Linns extra ground wire located at the DIN plug to the 52's ground post and nothing changed. I even ran a wire from a cold water pipe in my crawl space and attached it to the above mentioned Linn ground wire and it did not help. I have run an extra wire to the preamp ground to the base of the Graham and it does not help. Only grounding it to myself helps!
The fact that a second Naim preamp of the same model I brought in a while back and tried did similair things says its not my individual preamp.
I have tried cheater plugs on all items mentioned, using in different conmbinations, removed all sources but the preamp and amp and nothing helps.
I know that Naim uses a star grounding approach, is there something going on between the Naim gear and my house AC that may be causing this? The only thing left will be to bring home some non-Naim gear to see if the same problem takes place.
Thanks for your suggestions I look forward to more.
I'm dying here! This is a bugger!
Sorry for jumping in late so late, but I've lived thru some strange grounding problems, too, and have some different ideas to try.
Since you have dedicated lines, we can assume that there is ground at the outlet. Having never seen Naim gear, have you checked that the 3 prong plug wiring is all attached within the case, or could the ground be "floating" in the Naim?
You have had a ground lead connected to the Orbe with no effect. Have you tried grounding the Orbe and the Graham at the same time, first to each other and then both to the preamp? (Even though there isn't a screw on the arm post, temporarily you could use a cable tie, rubber band or "twistie" just to keep it on there, making contact.
A preamp of mine had a low level hum problem due, somehow, to the brass feet digging in to the metal rack. I had to ground my rack to the preamp! Hum gone! I never would have believed it.
Have you unplugged your AC to the turntable to test any difference in hum? The fact that you can feel a small bit of current in the arm makes me wonder if the turntable/motor wiring is completely insulated from the rest of the base (metal, I'm guessing). Or if you have the outboard power supply, if there might be some sort of leakage that the gain in the phono stage is picking up on.
Thanks for the input. I have checked the two dedicated outlets for proper grounding and they are fine. The Naim gear comes three pronged and I am pretty sure its not floated, plus when I float it there is a difference in noise through the phono stage. I have grounded the Graham to the Orbe and the Orbe to the Naim, as well as; the AC ground at outlet, the cold water pipe under house and the AC bar ground post outside. No good. As far as the Orbe motor, it seems inert in this whole thing as I cannot get it to "pop" with the metal-metal touch test and I have unplugged the power supply to it as well with no differences noted. The Orbe motor wiring is far away from the subchassis and since the motor itself is in a stand alone base, though near to the sub-chassis, it is not seeming to be the culprit.
Thanks for the suggestions. I'll take any I can get!