2. analog
  3. 1054175497

Exposed tonearm cable source of hum??

I run a 0.65 mv. output van den Hul Frog through a tonearm that features a looping, exposed (in the sense of lacking any real shielding) tonearm cable such as are found on some linear tracking arms, VPI arms, etc. (brand of tonearm to remain nameless so as to keep passions to a minimum). The tonearm cable becomes shielded after the "loop" and runs to a Rowland Cadence phono stage that features a built-in step-up transformer, i.e., I have a lot of gain. I have had a consistent hum with this set up in two different apartments. After consulting with the manufacturers and trying nearly every conceivable fix, I narrowed the problem down to the cartridge / exposed-loop portion of the tonearm cable which is the sole source of the hum (everything beyond the "loop" going in the direction of the speakers is dead quiet). Because the cartridge leads are connected properly, my guess is that it is the five or so inches of looping tonearm cable that is introducing what is a quite audible hum.

Does anyone out there know if such exposed tonearm cable "loops" are indeed known to be sources of hum? If yes, is there a fix (I can't imagine what that would be) beyond switching to a different tonearm cable design (which would mean, practically speaking, going to a different arm)? I have been listening to a lot of chamber music recently and the hum is starting to really bother me.

Thanks in advance.
raquel

Showing 1 response by consttraveler

consttraveler
250 posts
 
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.
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