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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
alpha_gt
155 posts
 
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? 
sunnyjim OP
927 posts
 

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 


alpha_gt
155 posts
 
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. 
sunnyjim OP
927 posts
 
alpha-gt,   Thank you for the advice and the TT recommendations; they are all good.    S.J.
alpha_gt
155 posts
 
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! 
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