Oddness with U-Turn Orbit noise floor

[gurdyp]

Hi there!

I have a U-Turn Orbit hooked up to a Schitt Mani pre-amp and a Dared tube amplifier. It has a Nagaoka mp110 cartridge on it right now. (I used a cartridge alignment tool and a stylus force gauge to set it up correctly). The Orbit has an acrylic platter, with a cork platter mat. Right now it sits by itself on the top of a bookshelf, with the speakers off to each side (on the floor, not on the bookshelf) and the amps in lower sections of the bookshelf.

The problem I'm noticing is excessive noise when the arm is lowered onto the record — it doesn't matter which record (i.e. brand new, old, etc) — and you hear it very clearly before the music starts, or in quiet parts of the music. When the arm is lifted off the record, there's no hum or noise.

The REALLY strange thing, though, is that when I go to close the dust cover — i.e. I'm holding it with both hands and lowering it — when it gets to half-way down, the sound (loud noise floor) disappears almost completely. As soon as I lower it all the way, though, the noise comes back, even if I'm still holding the dust cover.

Is this a grounding issue? Any idea how to resolve this? So strange!

Thanks for any and all help!

 

[tnsilver]

Doesn't sound like a grounding issue. Can the dust cover be in contact with the RCA terminals anywhere along it's path? Try removing it and re-test.

 

[Hajidub]

A pic of the setup might help, possibly feedback from something else?

 

[Lavane]

I have a Orbit Custom I use in a second system. The tone arms in these aren't grounded. I read a post on another site showing what one person did. Like moving a ground jumper along with adding a bit of foil to add better grounding.
Also this person added a ground wire to the tone arm to that jumper on the PCB.
The person that posted this was complaining about some low level hum coming from the tone arm also. His was the same as mine in that it didn't have the built in phono preamp. Maybe try grounding the tone arm? Mine has a very slight hum that stops when I touch the tone arm.

 

[HPMguy]

Hum on turntables is almost always a ground issue, although lead routing can sometimes induce it.

Static electricity can do weird things too, those coils respond to any electric or magnetic field. We have issues at work with electrochemical instruments giving false readings when large motors on the other side of the wall go on or off.

 

[DavidTT]

OP, send an email or call to U-Turn Customer Service. They are very helpful in diagnosing issues with their turntables and very responsive to inquiries. If hum is an issue they'll help you diagnose and work with you to minimize it. I have an Orbit and they've always been very helpful upon direct contact.