VPI Prime Hum - Lemo connector

[djk123]

Hi: I have a VPI prime with hum at higher volume. I grounded the lemo connector today and the hum stopped. Any ideas why this would happen?

 

[KevinB]

Would love to know the details of what you did, been chasing a hum in my VPI Classic Signature with no success.

love to see pics.

 

[djk123]

I can get some pics later, but basically I noticed the hum stopped if I touched the connector so I wrapped some speaker wire around it and then connected the other end to a screw on the outlet cover. Very unscientific, but it worked!

 

[KevinB]

Thanks.
I have tried similar without success but always interested in how you did it.
Thanks again.

 

[Vintagear]

@djk123 @KevinB - as you know ground hums can be system dependent so my solution may not work for you. I would suggest running a ground wire from the motor assembly to the ground lug on the VPI junction box. This way the tonearm and the motor are both grounded to the same point. Then from there (as usual) ground to your phono/pre-amp. That configuration worked perfectly for me.


One of the red twisted wires below (I didn't have any black wire on hand) goes to the motor and the other goes to the phono pre (also twisted around the L&R phono cables not seen in picture). The black wire dropping from the ground lug goes to the tonearm. The deck is dead silent.

 

[KevinB]

@djk123 @KevinB - as you know ground hums can be system dependent so my solution may not work for you. I would suggest running a ground wire from the motor assembly to the ground lug on the VPI junction box. This way the tonearm and the motor are both grounded to the same point. Then from there (as usual) ground to your phono/pre-amp. That configuration worked perfectly for me.

Thanks. VPI suggested the same unfortunately had no affect.

I have chased numerous paths. The hum is tolerable, but for the price of these tables it is disappointing. One should not have to fix a hum issue that I know is the table itself.

Appreciate the recommendations and support.

Kevin

 

[Vintagear]

Thanks. VPI suggested the same unfortunately had no affect.

I have chased numerous paths. The hum is tolerable, but for the price of these tables it is disappointing. One should not have to fix a hum issue that I know is the table itself.

Appreciate the recommendations and support.

Kevin

If you have a uni-pivot use a multi-meter to check to be sure that you have continuity from the tonearm to the ground lug. If the spike tip is not making a clean contact with the female bell of the tonearm you can get hum.

Since I have a SAMA I'm not sure if my motor ground point will work on the Classic which has an integrated motor mount. You may need to be able to get to the chassis of where that motor is mounted. Also, be 100% sure that your phono cables are very, very well shielded (my previous cables allowed noise to get through).

If you're using a speed controller it can also add a layer of complexity when trying to isolate a hum.

Don't give up!