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Persistent Buzzing When Stylus Makes Contact - Need Help Troubleshooting!

djchaseb

djchaseb

New Member
I've been troubleshooting an issue with my U-Turn Orbit (1st Gen) for a few months now. I've exhausted forum research, U-Turn customer service, and at this point I've done about all I can. Before I give up completely on this turntable I thought maybe some help from the good folks at AudioKarma would be worth a shot. Like I mentioned, it's a first generation U-Turn Orbit I purchased in early 2016. It's the non preamp model, I'm using a simple Technolink TC-750LC preamp which is output to a pair of powered Mackie Monitors. The issue I'm having is the table is dead silent until the stylus makes contact with the record surface. Not just the record though, tapping the stylus, tapping the table, anything to trigger the stylus to start outputting audio will trigger the buzzing. There are no open grounds anywhere in the turntable. I've checked grounds and continuity with my multimeter and everything is as it should be. The tonearm is grounded, and the table is grounded through the left RCA output with a piggy back adapter U-Turn sent me that plugs directly into the outlet ground. I've eliminated it being the preamp, plugging the turntable directly into the powered monitors (although alot lower output), I can still trigger the same buzz. I had an Ortofon 2M silver, thought it was maybe the cartridge itself picking up EMI. I changed to an Audio Technica VM95e and the same thing occurs. The connections at the cartridge are as tight as they can be, very snug and all the way on. I don't think it's a grounding issue because the table is well grounded. I've moved the table into every room of my home, same issue. I've even taken it outside in the middle of the yard to get away from all items / wiring that could cause any interference. I've powered the turntable, preamp, and powered monitors by battery, no change. The only thing that has helped quiet the hum, is literally wrapping my hand around the whole of the tonearm itself. The buzz then gets lower but doesn't go away completely. Again the tonearm has a proper ground. My only guess is that the tonearm is just acting as an antenna and picking up interference and amplifying it. My next option was ordering new shielded tonearm wiring and gutting the original wiring.

Here's a video of the issue:

U-Turn Orbit Buzz

Any ideas or things to try would be appreciated!

Thanks,
Chase
 
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catBot said:
Are there any contacts/relays that short the cartridge while the lift is up?
Click to expand...

None that I am aware of, the U-Turn PCB is very simple, basically just ground pads and the RCA outs. When removing the cartridge and shorting the connectors to their respective grounds the table is again dead silent. Totally stumped here.
 
If it partially goes away when you wrap your hand around the arm, that's a grounding issue. Did you get rid of the grounding adapter? Maybe separate the ground from the signal connections?
 
I would try insulating the cart from the head shell. A thin piece of Delrin, Teflon, or even cork, and use some nylon screws on your cart. You might be getting a ground loop thru your cart ground and the tone arm ground.
 
I used to have a uturn with a grado cart, some similar sound start one day. After a troubleshooting end with two sources, internet router and dining room dimer. Beside that orbits are very simple TT.
Hope its helps.
Andre.
 
I may just be at the noise floor of the turntable, maybe I'm expecting dead silence and it's just not possible. I have shielded RCAs at the turntable and preamp to monitors. The headshell is plastic, I tried attaching a small wire from the body of cartridge to the tonearm which is grounded and there was no difference. The buzzing is definitely lower with the Audio Technica cartridge vs. the Ortofon. I can only really hear it with the monitors cranked at full volume and no music playing. Guess I'll just have to live with it. It's not motor noise or a ground loop. I'm guessing just environmental interference picked up by the cartrige. I know my $50 preamp isn't the greatest, just apprehensive to spend money on another one that may not do any better at filtering the noise. I appreciate everyone's input! Thank you!
 
Ken Boyd said:
I would try insulating the cart from the head shell. A thin piece of Delrin, Teflon, or even cork, and use some nylon screws on your cart. You might be getting a ground loop thru your cart ground and the tone arm ground.
Click to expand...

Good suggestion, I may try moving some wires around on the PCB that share a common ground.
 
djchaseb said:
...maybe I'm expecting dead silence and it's just not possible.
Click to expand...
It's not possible.
djchaseb said:
I can only really hear it with the monitors cranked at full volume and no music playing.
Click to expand...
All audio systems have a signal-to-noise ratio and it's never infinite, ie, dead silence is never possible, it's a technical impossibility. Generally, turntables have the worst S/N ratio of any source.
As you why the noise starts when the stylus touches the record, that's a bit of a mystery. My guess is that there's a noise gate built in to your active monitors, though that's just a guess and it does seem unusual.
 
rothwellaudio said:
It's not possible.

All audio systems have a signal-to-noise ratio and it's never infinite, ie, dead silence is never possible, it's a technical impossibility. Generally, turntables have the worst S/N ratio of any source.
As you why the noise starts when the stylus touches the record, that's a bit of a mystery. My guess is that there's a noise gate built in to your active monitors, though that's just a guess and it does seem unusual.
Click to expand...
It could be the uturn is too close to thr speakers or it is on a flimsy shelf and it is picking up room modes causing a hum.
Just another possibility
Chris
 
Could the proximity of the speakers to the cartridge be the issue here - magnetic/inductive feedback from insufficient magnetic shielding?
 
djchaseb said:
The issue I'm having is the table is dead silent until the stylus makes contact with the record surface.
Click to expand...
Having watched the video, I didn't notice a change in hum when the stylus touched the record surface. Yes, the turntable is microphonic, but that's to be expected.
Really, I don't think there's a problem. The OP's expectations are unrealistic. This is a turntable, not a CD player.
 
JP said:
What model? Do they have auto-off/standby/mute?
Click to expand...

No that's what I can't figure out, it's just a standard uturn orbit with no onboard preamp. Everything is dead silent until the stylus makes contact, my only guess is that once it stops vibrating it's not sending a signal enough to be amplified. If I set the stylus down on a record, it will buzz for a few seconds then stop. Same occurence when I lightly touch the stylus. At this point I'm just going to not worry much about it. I can only hear it in between songs if I'm relatively close to the monitors. I have OCD with this type of stuff so yeah, that's my own issue haha.
 
djchaseb said:
No that's what I can't figure out, it's just a standard uturn orbit with no onboard preamp. Everything is dead silent until the stylus makes contact, my only guess is that once it stops vibrating it's not sending a signal enough to be amplified. If I set the stylus down on a record, it will buzz for a few seconds then stop. Same occurence when I lightly touch the stylus. At this point I'm just going to not worry much about it. I can only hear it in between songs if I'm relatively close to the monitors. I have OCD with this type of stuff so yeah, that's my own issue haha.
Click to expand...

Ok. I asked what model your Mackie monitors were....
 
rothwellaudio said:
Having watched the video, I didn't notice a change in hum when the stylus touched the record surface. Yes, the turntable is microphonic, but that's to be expected.
Really, I don't think there's a problem. The OP's expectations are unrealistic. This is a turntable, not a CD player.
Click to expand...

Turn the volume up - it's there plain as day, and it cuts in and out which is the odd part. I put markers at the top of the spectrum plot below to show these events. My guess is the signal is right on the cusp of an auto-standby/mute circuit.

Screenshot 2025-03-01 at 8.33.21 AM 2.png
 
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djchaseb said:
Oh, yeah they'e CR5-Xs
Click to expand...

The manual doesn't mention an auto-standby mode, but as they're active with an internal DSP it's not unusual for a DSP to auto-mute if it thinks there is no input signal. If you've an ADC, likely the easiest way to test this is to record from the line out of the phono pre and see if the noise level changes at all. If it doesn't, then it's something with the monitors. Or maybe Mackie support can tell you.

It's not extraordinarily difficult to get a vinyl signal chain to be pretty quiet, but I don't think it's achievable with what you have, and near field is going to add to that challenge. If your recording is at/near full volume on the Mackie's then I probably wouldn't find the level of noise you're getting to be odd. The odd part is that it cuts in and out.
 
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