VPI Prime ground loop

[reeldeal67]

So, let me preface by stating that I have had many turntables hooked up to my receiver and have never had a grounding issue. Also, I have never had any issues with the cartridges that I roll through my system. I have had the occasional loose cartridge connection, and this is usually right where I go if I have a hum. Issue solved.
I got a raise at work and thought I would treat myself to a better turntable. I had narrowed down the search to two decks within my price range. The Michell Gyrodec and the VPI Prime 3D 10.5". I wanted to buy domestic, so I went with the used VPI. It had great reviews and people saying it is detailed, musical, black and it is going to be their forever table. Sounded great. Until I got it, and it has a grounding issue. When I went online with the issue it turns out there are a lot of people out there with the same problem with VPI. After reading thread after thread on multiple forums. Nobody out there seems to have a definitive answer to the problem. Not only that but, VPI seems to get a lot of people contacting them about brand new and used decks that have this same issue. Worst part is, they don't seem to care. VPI directs you to your dealer and they both give you all the same information that doesn't seem to fix anybody's problem. I didn't purchase my deck new, so I didn't expect a dealer to give a rats rear about me, but I called one anyway. The story I got was that this is a known issue, its common. However, it is not the norm, but you should count your blessings if you get a perfect VPI. I was astounded that VPI could have such quality control/engineering issues and remain in business. Needless to say, if I had come across the derogatory threads before I bought, I would NOT have purchased a VPI.
I have made sure the cartridge connections are secure. Upon reading a post about a VPI ground issue, I sanded the paint off of the needle that the uni-pivot rides on. However, this did not fix my issue as it did theirs. I removed some paint from under the screws on the junction box and disassembled the base and cleaned all connections and made sure everything was put back together securely. I then reflowed all solder connections in the junction box. The left RCA was virtually impossible to get a cable on and off of it. I replaced it with an exact replica. I changed my cables and ground wire. I have operated each channel independently and get the same issue. When I pinch the wire bundle coming from the tonearm to the junction, the hum increases. If I touch any metal on, the base, junction box or grounding lug the hum decreases significantly. Virtually goes away completely. The loop is even affected by me touching the volume knob on my receiver. Nothing I did had any negative affects. Perhaps, it got better to a minute degree.
Needless to say I am not going to risk messing up my receiver. So I guess I have a 50lb paperweight.
If anybody has any suggestions, short of having the tonearm rewired. Please let me know. Thanks

 

[DennisH]

I have owned three VPI turntables and never had a grounding issue. I currently own the Prime. VPI customer service has always been responsive to my questions and service. Did you contact VPI directly or are you reporting what others have said about VPI online?
My VPI Prime is grounded to my phono preamp, not to my integrated amp. Also all of my system is connected to a power conditioner that is plugged into a single outlet. I have read others have had ground loop problems when multiple outlets were used.

 

[Gregadd]

the little pins that come out of the arm tube can be over expanded. Check to see if any of them are loose. If so get a pair needle nose pliers and carefully remove it. Even more carefully squeezer just a little then replace it Repeat if necesary. Most hum is caused by loose or frayed wires.
You can also experiment with different wall outlets.

 

[Kingrex]

reeldeal67, why don't you use a dead soft silver or other small gauge "solid" copper wire and go from ground screw of the plinth to the phono pre, junction box etc. Play around. I get questions about ground issues all the time. 90% of the time its not a ground issue. It's RF modulating into the phono via the cartridge, arm wire, connecting cable, phono stage etc. and phone pre is amplifying it. If you can touch the TT and a grounded object and kill the hum, you have a true ground issue. All ground issues can be solved. You don't have a boat anchor. You just need to figure out where the diverted signal is passing through.

 

[Gregadd]

I should also add VPI will solve your problem. Just call them every morning until you get the right person.

 

[Kingrex]

Think along these lines when experimenting. A ground loop is many times solved by breaking a connection. A cheater plug. Its not "usually" fixed by adding a connection. You want to find a place where a connection may have been added. Like maybe the wires in the tone arm are somehow grounding at the 5 pin din. Or shorted somewhere in the tube. Solder bleed between contacts. Are you using a different input in the phono pre. A cartridge to phono pre is a pretty simple path. Its 4 to 5 wires.

 

[audio.bill]

the little pins that come out of the arm tube can be over expanded. Check to see if any of them are loose. If so get a pair needle nose pliers and carefully remove it. Even more carefully squeezer just a little then replace it Repeat if necesary. Most hum is caused by loose or frayed wires.
You can also experiment with different wall outlets. View attachment 108056

Just a tip... when trying to tighten the pin connectors insert a round wooden toothpick before gently crimping. Without that it's very easy to crunch them which can then require replacement. The difference between the connector being loose or snug on the cartridge pins only requires a very slight compression.

 

[Gregadd]

if you have them off you might want to scuff them a little with an Emory board or some fine sandpaper. A contact cleaner may be sufficient.

 

[hongkongfoufou]

I have this problem with my VPI Classic 3. I resolved it with a Nordost Qkore6.
Perhaps, you can try a ground system less expensive.

 

[DeadWax]

For diagnostic purposes, have you tried lifting the ground, first on the table, and then each of your other components on the same circuit? At least this may isolate which component is creating the loop.

 

[bhjazz]

Another Prime owner here and I have had no issues with ground or ground noise. the table has worked exceptionally well. I am the original owner, though. I have swapped a few cartridges in and out with no issue. I am using a Nordost Frey 2 cable.

I'll admit to having some issues getting a hold of the right person at VPI. What a shame. I have far better luck finding answers in forums and such. I miss the VPI forum!

Two things in your post stuck out to me.

"The left RCA was virtually impossible to get a cable on and off of it."
"When I pinch the wire bundle coming from the tonearm to the junction, the hum increases."

I don't know who or where you purchased the table from but I suspect that the previous owner may have been hard on your table. Why either of these happened is a mystery.

Regardless of that, if this were my problem I would approach the problem from the very beginning. Remove the cartridge, keep the cart pins from touching each other, then test. Then connect only the grounds to the cart (blue and green) and test, etc. You could also disconnect/connect the lemo to the junction box and test. Work your way towards your receiver and try to isolate the cause.

Don't rule out that the cartridge itself is not the problem.

Good luck and keep us posted.

 

[Brf]

90% of the time, the hum is caused by an improper tonearm cable shielding, therefore, allowing for potential RFI/EMI contamination. The VPI tonearm/cartridge wires are enclosed in a copper tube within the 3D printed arm wand. The copper tube is attached by a small wire to the tonearm’s metal female bearing cup. For the copper tube shield to effectively drain unwanted energy from the delicate tonearm wires, electrical continuity must be maintained from the copper tube, female bearing cup, male pivot spike, vta platform, rca junction box, ground lug.and then to the phono stage’s chassis ground. If any of these connections are compromised, RFI/EMI can be picked up the tonearm wires and amplified. The fact that the hum/noise changes when you touch the arm tube or tonearm wires, points to a shielding issue ( your body is providing a ground access).

You can check for continuity by removing the plug on top of the tonearm bearing bell which will give you access to the female bearing. Place a continuity probe into the hole and the other probe and the ground lug.

In some instance you will have continuity but still have hum/noise. In these instances, it’s best to move the table away from other components that might be the source of the RFI/EMI energy.

 

[mtemur]

Connect a wire between receiver’s ground and headshell’s metal part. If this eliminates hum just as when you touch the headshell then you have a discontinuity problem on ground wiring. If not then your receiver has a problem on grounding or ground loop.

 

[inquisitivej]

I recently purchased a used VPI Scoutmaster, my first ever turntable. I have a nice ground loop buzz (higher frequency, tweeter more so than mid or bass it seems). It happens only on this source (turntable) and increases / decreases with volume setting. It happens equally on both channels. I read the thread above.

Symptoms:
- When at proper listening volume there is a very audible and annoying buzz. Did I mention annoying?
- When I get my hand near or touching the tonearm cable to the junction box the volume of the buzz increases dramatically.
- If I touch the tonearm and not the cable the buzz reduces dramatically, still there, but almost low enough I could live with it. As soon as I release it the buzz is back

From what I read above I did some continuity tests with my voltmeter. I expected a short or exposed wire inside the tonearm was going to be it. However, when I unplug the tonearm connector from the junction box and test continuity between any part of the tonearm and the 4 pins inside the connector I get no continuity tone. zero. When I test from the tonearm bearing spike and the ground on the junction box, I get continuity. when I test through the hole at the top of the tonearm hub down to the female part of the bearing inside the tonearm, I get continuity. When I test from the female connectors for the tonearm cable (inside the junction box) I get continuity from what appears to be the "blue" and "green" female ports, no continuity from the other two ports (is this expected/correct??). When I test from the grounding post on the junction box to the tonearm base (the metal below the spike bearing, where the tonearm rest and queuing lifter are) I get continuity.

If I plug the tonearm connector in, I get continuity from the grounding post on the junction box to each of the green and blue connectors that go on to the cartridge. There is no continuity from the ground post and the screws for the cartridge because I have plastic washers on the screws and the cartridge itself appears to be plastic (nagaoka MP150), so wouldn't do anything anyway.

I have a grounding wire running from the grounding post to my Linn Magic DSM/3. I also have nice Transparent audio cables connecting to the Linn from the VPI.

I don't know what to do at this point. Can someone here give me a little nudge in the right direction please? I'm a digital+streaming "lifer" since the late 80's and only recently heard how well a great vinyl system, great recording, and great pressing can be!! This damn grounding buzz is killing me!

Thanks in advance!