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

  

sunnyjim
You need to run a ground wire from the ground of the turntable to the Moon Box grounding screw.
+1 what dill says. Generally a hum from turntable is a grounding issue.

To Dill and jmcgrogan2,    U-turn indicates that the turntable uses has a ground built in the left channel RCA input. There is NO ground screw ON THE BACK OF THE TABLE WHERE THE RCA CABLES ARE PLUGGED IN. 

Let me know if you have any other suggestions. I tried to contact Moon Audio, but got no response so far  I will also contact  U-Turn  customer service about the problem.    Thanks,  SJ 

 

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. 
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.    

 


 

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

To sbank, I just knew the comment about the stylus force gauge was going to incur flak from some members.  However: 

I can and would easily purchase the $14 Shure Force gauge

If numbers on tracking force  tonearm  counterweights are  inaccurate and unnecessary why do so many TT manufacturers provide a calibration ring with counterweight or etched on it..

I do clean my records before each play with a Mobile Fidelity Liquid and brush, and then when the LP is dry, use a Hunt record brush to finish off.

I place my records in MF treated  inner sleeves to prevent deterioration of the vinyl, scratches and dust

I cannot afford a vacuum record machine, but am considering the Spin-Clean "Starter Kit" for record care at $79.00

I mentioned in previous analog related threads, I only play LP's 20% of the time.

So,  I am not the lazy analog slug as SBANK suggests.

Lastly, to all members, let me ask: would the new Project RPM-3 with Sumiko BP-2 MC  be a worthy upgrade from U-Turn TT as described above??   There is internet audio vendor offering a mint demo at a 30% discount from the retail of $999.00

Thanks to all who have responded so far.   SJ 


@sunnyjim I certainly don't intend to insult you and never called you or anybody else a slug. I'm not here to make enemies. Your last post implies that you are less undaunted by the steps needed to get decent analog sound than I had realized. So I am glad to understand that now.

I applaud your effort with the LP cleaning brush, but feel that the Spin Clean would be a great deal more effective! 

There's nothing wrong per se with the Shure gauge and I used one for many years, but for even less money the digital ones on eBay(they all look like the same one but with different names(mine is Neoteck NTK002) is easier to use, more accurate and also safer in terms of less chance of damaging your cantilever/stylus. Every time I use it, I think that I should have changed out the Shure for this sooner.  Cheers,
Spencer
Without playing a record, but platter spinning, move the arm from its post to the spindle, and back. Does the hum increase as the needle gets closer to the spindle? And quiets down as it gets back to the rest post? If so, I've had this problem before. It's feedback from the motor. On a low priced table I had, Project Debut. At moderate volumes I could demonstrate this effect, the small motor is unshielded and under the platter, too close to the cartridge. And the closer the needle gets to it, the more hum I heard. It really wasn't that bad, only heard it as you say, in between songs, so I lived with it until I upgraded to a nicer 'table. Not much can be done about it, just an inexpensive 'table design. If it's that objectionable then perhaps you should invest a bit more money into a nicer 'table? Or a good deal on a used table? 

To sbank,  Thank you for the reply and recommendations for the stylus force gauge. I will check them out.  P.S. I tend at times to over state my case  See below my response to alpha_gt about the hum problem

To alpha_gt,   I spoke to Ben Carter at U-Turn turntables. He walked me through the following procedure which seems similar to what you suggested.  I put on a LP and played the selection at a higher than normal volume, and the hum was audible. He then told me to shut off the motor, leaving the stylus still on the record. He ask if there was any hum, I said NONE, even when I turned the volume to step 69 on the CJ pre-amp whose volume control is scale from 1-99.  He concluded that the problem was  the turntable motor and not the Moon LP110 phono pre-amp, or the connecting cables from the table to the box. He offered that I could return it and a replacement of the same TT as ordered would  be sent out, or I could just return it for  a full refund.  

Even with the hum being audible, the sound was very good and surprisingly dynamic for a budget table. I am not a big fan of the Ortofon 2M RED  cartridge which was one of  the cartridges offered as part of the customized package price, and, I would eventually replace with a Denon DL-110  high output MC which U-Turn claims mates well with my table, and its tonearm which is standard throughout their line. . 

However,  I am torn between returning it and as you rightfully suggested, spending more money for a better TT  The other tables I have very recently considered is the Project RPM-3 with the Sumiko BP-2 MC for $999.00, and Project's 1Xpression TT with a  Ortofon 2M Silver cartridge (at $999.00) which supposedly stands between the 2M Red and 2M Blue  There are a few of the RPM-3 tables around with the less expensive Sumiko "Pearl" cartridge, on sale at $599.00 by Audio Adviser  which has 3 left.

 I can opt for the replacement and hope the new one is free of hum. If so , i can always sell it, if I later decide to upgrade.  Thanks, SJ 


At a little higher price is the VPI Nomad, at $995, if you shop around you can find the Clearaudio Concept for $1200 or so, many of used ones out there. My son in law has the Music Hall Ikura, which he is very fond of for less than $1200. And I bought my Scout used for $1100. Some of those have cartridges and some don't. There are Rega's and Projects in that price range as well, I'm not familiar with. And I've always fancied the Marantz TT-15 at $1500. 

Im guessing that a replacement 'table may not hum like the last one, but it will still hum a little. Motor placement is too close to the needle toward the spindal, no way around it. I vote to get your money back and save up for the next level up. Many fine gems to be had in the $1000 to $1500 range. You'll be glad you skipped all the hassle later. 
alpha-gt,   Thank you for the advice and the TT recommendations; they are all good.    S.J.
You're welcome Sunnyjim, let's just say I've been there and done that. For every major upgrade I've made to my system over the years, I always hesitate, and worry about the money. But I find that the money is soon forgotten but the pleasure of ownership lasts a long time, and I wonder why I waited or hesitated.  I took the long road up to where I am now with my analog setup, and looking back I wish I had the foresight and guts to pull the trigger and jump up to where I am now in the first place. I guess that could be said at any level? But, the differences between entry level and the $1500 level is massive! No small thing! So much so that I may never jump to the next level? Perhaps I'll get a better cartridge or preamp one day? But for now I am extremely happy and got more than I ever expected. And don't forget that you'll eventually want a good RCM! 

To alpha-gt

Makes good sense.  About three months ago, I upgraded to a separate power amp, the BAT VK-200( 100RMS).  I owned at the time a Rogue Sphinx integrated amp  whose pre-amp out I was used to connect the BAT amp  I looked a long time for an amp, when I decided to go separates again, and even longer for  a pre-amp.

I wanted to find a BAT pre-amp, but settled on a Conrad Johnson PV-14LSE.  They are a terrific combo and exceed the sound the Rogue IA by at least 30 percent ( if that statistics means anything) However, I am hearing more music from my CD's with almost every thing better from bottom to top.   The Rogue integrated was very good unit with an excellent phono stage. But, the BAT/ CJ combo are in another league of sound quality and presentation....   Thanks, SJ