Exposed tonearm cable source of hum??

Sure, it's possible that some hum could be induced there. However, the hum is coming from somewhere, in order for it to be induced on that cable. The wires themselves are not causing the hum, they are just picking it up. Unless there is a wiring problem or dirty connectors.

One thing about your description, is that you seem to state that the loop is somehow separate from the rest of the internal tonearm wiring. This is very unusual. I have never seen a tonearm wired so that the loop is not a continuous section of wire that includes the tonearm wiring. How do you know that the hum is not coming from the internal tonearm wiring? Is there some kind of plug that the loop plugs into at the tonearm, and you can isolate it from the internal tonearm wiring? If so, that may be part of your problem. There should be no breaks in the tonearm wiring from the cartridge clips, all the way to the final RCA plugs. Any breaks cause signal loss, and if they get dirty or have some oxidation can cause this hum.

Something sounds very unusual about this circumstance. What is it? If you have made modifications, tell us so we can properly determine the problem.

Other than that, I would look at trying to eliminate the source of the hum. As Ron said, it is likely a stray hum field from some of your equipment or power cords. If all else fails, get a different tonearm.

Is step-up transformer switchable in Rowland?
You might have enough gain without it.
Well, if not still you can check hum not using a step-up trans.
Also you can borrow or buy cheap another phonostage to realy check if hum percists.
You may also try to disconnect the ground connector that might create a ground loop in your components starting from your analogue.

Hello Raquel:

This may be a repete of something you have already tried, but here goes.

My analog front end was picking-up a hum that drove me crazy for a couple of days. Like yours, everything "downstream" of the tonearm and cart. was dead quiet.

Mine was cured by moving my digital components away from the analog. That is, my turntable is on the top of the rack, the interconnect runs sideways to another rack where the phonopre and step-up transformer are located, then back to the rack to the preamp. Directly below the TT (on the rack)is my CD transport, with the DAC below that, the preamp below that, and finally, the power filters on the bottom. The amp is located below the phonopre and the step-up transformer on the second rack. It makes some of the IC's visible (running between the racks) but I no longer have a hum.

Good luck, Dave.

I'm using VDH black beauty with Graham 1.5T on a VPI table.
I was using Counterpoint SA-2 step-up with Marantz 7c and now switched to Counterpoint SA-5000.
I had hum issue before but due to bad grounding from the phono cable (loose connection) It could be that your ground for the phono is loose somewhere.

I had a bad hum from a VPI PLC power line conditioner until I relocated it away from the turntable and preamps. The SDS is OK.

It should seem that five or six inches of unshielded cable wouldn't pick up that much AC interference unless there were a really big source of interference nearby. Could there be a high voltage line in the wall behind the turntable? Doesn't sound like it if you've had this problem in two different apartments. What about the turntable motor (God forbid)? Is there still hum when it is unplugged? Presumably you've observed the hum when the motor hasn't been running.

Perhaps one of your plugs is improperly wired, e.g., the plug on the end of the exposed cable that goes into the junction box and/or the junction box itself. Is there some way to plug your arm cable into your interconnect, bypassing the junction box? (This may require some kind of adaptor.) Laborious though it may be, consider connecting your cartridge directly to the phono preamp with another set of leads (maybe cheapos from Radio Shack) that don't go through the tonearm at all. Of course, you couldn't play a record, but you can still see if there is hum while the arm sits on its rest. This test would isolate the cabling between the cartridge and the junction box, as well as your interconnect.

If all this results in a reaffirmation that the exposed wire needs to be shielded, try getting some shielding material (webbing) from Radio Shack to wrap the cable, and think about how to ground it. Perhaps the manufacturer could recommend a way to do this without interfering with the mobility of the tonearm. Good luck.