I understand what U-Turn is saying. It is a budget turntable and they don't provide a separate ground. Try wrapping a wire around the outside of the metal part of the RCA plug of the left channel output, get it as tight as you can, then attach the other end to the ground screw of the Moon. If that doesn't work try the reverse. Wrap the wire around the RCA plug left input of the Moon and run a short wire to the Moon ground.
What is the "usual" source of hum between a turntable and phonp-preamp??
I just purchased a U-Turn Basic TT with an acrylic platter and cork mat with an Ortofon 2M Red cartridge. The table is plugged into a Moon Audio LP-110 phono pre-amp. Moon Audio does recommend to isolate the box away from the turntable. I have currently placed it on a 21inch formica platform stand. The hum is most audible in the lead out groove, and between tracks. The sound is very good, BUT I can still hear an undertone of hum when the volume is half way, that is between 55-60 steps on a volume control calibrated from 1-99. The pre-amp is a Conrad Johnson PV-14SE which the Moon phono box is plugged into
I aware that the hum problem can be caused by the phono cable of the turntable ( which is somewhat cheap) or the connect IC which is one of the Canare cables which cost $40.00 to $50.00. It appears well made. The U-Turn TT rep informed me that the left channel input on the table functions as a built in ground. The Moon box has a separate grounding screw which I am not using. Thank you, S.J
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Is the U-Turn new? Can you send it back? Perhaps it is a defect. I would contact the dealer and U-Turn to let them know of the issue. It still seems like a grounding issue to me, one of which their design flaw may have created. The answer to your initial question: Q) What is the "usual" source of hum between a turntable and phono preamp? A) Grounding |
Guys, Thank you for the additional suggestion. Let me quickly summerize what has happened so far.. I finally got a reply from Moon Audio about the hum problem and whether it may be related to LP-110 phono pre-amp. The rep suggested that because the U-Turn unit's ground is built into the left channel of the turntable, the Aux/phono input of the Conrad Johnson PV-14SE may be designed to expect a usual ground wire to come from the phono plugs and be attached to the grounding screw of the LP-110. After asking about the other inputs, he suggested plugging the output cables of the Moon box into AUX 2 input, which is not designed for a ground lead wire which the U-Turn has solved by in the left channel input of the table. I tried it, and it still did not stop or diminish the hum between tracks and the lead out LP grove and also seems now to be somewhat audible playing LP's Next, I replaced the skimpy supplied phono cables with a pair of Audioquest "Coral" ICs which I had owned for 10 years. The pair cost about $45.00 and is definitely budget. Same thing....hum. I then proceeded to swap the Canare IC originally used as the input cable to the CJ pre-amp with the Audioquest Coral IC. Therefore, the Canare IC was used as the phono leads from the turntable, and AQ Coral IC pair as the cable plugged into to the CJ pre-amp's AUX 2 input. Again, no dice, the hum was still there. I thought may be the better made Canare IC was the culprit causing the hum because of poorly shielded RCA plugs. If I had two separate pair of 2-3 meter IC's, I would move the LP-110-phono pre farther away from the audio rack that the CJ pre-amp sits, and below it the BAT VK-200 power amp. I realize the BAT has very large power transformers Lastly, the Moon Audio rep said that if his suggestions did not work, he would arrange with Music Direct who I purchased the LP-110 from, to send me a new one, and I would return my current unit back to MD. That "might" solve the hum problem assuming the Moon phono box is somehow defective. However, U-Turn has a 30 day return policy, and I am at the point of returning it for a refund, and look for a new TT in the $600-700 range including cartridge. In addition, there are a few convenience features missing on the U-Turn TT, I was not aware of at the time of purchase. Everything is preset at the factory like tracking force, anti-skating, even the tone arm comes already balanced. However the counterweight does not have a calibration ring for tracking force adjustment and required getting a track force gauge if I decide to change cartridges. Also the anti-skate supposedly can be reset from its factory default setting, but there is no instruction in the one page manual how to do it. I looked at a ton of tables before purchasing the U-Turn TT The product is cleverly built and is a "real" plug and play TT, but it has limited usable features Maybe, it is true that you get what you pay for.
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Return it and get something else within that price range. Something like this! http://www.needledoctor.com/Rega-Planar-1-Turntable?sc=2&category=353 |
"required getting a track force gauge if I decide to change cartridges" If you aren't willing to invest $11 in a digital stylus forge gauge from eBay and set the force correctly (which takes about a minute) then you really shouldn't be listening to records. Numbers on a counterweight are never accurate enough for any repeatability nor for tuning setup of any quality cartridge. Same thing if you aren't willing to vacuum clean your records and put them in good inner sleeves after cleaning. Good vinyl playback doesn't have to cost a fortune, but it does take more energy than pressing play. Some find the involvement & ritual satisfying tasks. If that doesn't suit you, go hi rez and stick with digital. Cheers, Spencer |
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