How to ground a high-end Turntable

[*Robes]

Hi Everyone, 1st post here as a DIY-er,

I need to run a ground wire from the bottom spindle of my turntable (TT) platter to dissipate electrical static charge. The very top most aspect of the spindle assembly is the record spindle which protrudes through the TT platter (the revolving portion holding the record) and sticks through the vinyl record hole. This short record spindle terminates about 1/2 inch into the upper platter. The platter itself is 20 lbs of solid aluminum.

Below the short record spindle is the vertical stainless steel (SS) rod shaft of the spindle bearing, a separate item in line with the record spindle above it. The top of the SS rod shaft has a SS ball bearing that seats into the upper female bearing (a sapphire plate) directly in line under the record hole spindle.The SS spindle bearing rod/shaft is held within the platter by an aluminum bearing housing and inner brass bearing retainer (race). This upper portion of the bearing housing is a circular concentric layer from outside inward: Aluminum platter, aluminum housing (inserted into the aluminum platter), brass race within housing, and SS spindle shaft, within the brass race.

The bottom of the SS spindle rod/shaft seats (held motionless) into an aluminum housing (no brass race retainer here) that passes through the plinth (the plinth is composed of layered metals: steel & aluminum, and wood acting as the main structural base of the TT) and held in place by a SS nut at the bottom of the plinth. The SS spindle rod/shaft seats (bottoms out) about 1/2 way through the lower aluminum housing in the plinth.

The lower aluminum housing is 1” in diameter and held in place by the SS hex nut. There is a SS 3/8” bolt that is taped into the center of the termination of the aluminum housing on the bottom of the plinth. The SS nut can be removed with the bolt in place. This bolt is meant to be a site to connect a ground wire.

My questions arise from how no one on the TT forums question wrapping a copper wire around this bolt and terminating the wire to the stereo systems ground source.

I understand that there is a process of galvanic action occurring here that no one addresses. Is it insignificant?

We have essentially aluminum that needs to be grounded, a bearing shaft of SS inside a brass retainer in the upper aluminum housing only. The SS bearing shaft then terminates into a aluminum.

Can I use a copper tinned terminal loop to the SS ground bolt on the lower aluminum housing? Do I then use copper or SS wire from the terminal loop to ground source? Can my ground source be a copper or SS grounding rod?

What about soldering the wire to the terminal loop, anything special needed here as in solder and type of metal loop?

I have tried to upload 4 pics for added clarity:
#1= Upper platter female bearing (contains sapphire plate) view from bottom of platter.
#2= Top portion of lower aluminum bearing housing from topside of plinth, SS rod/shaft removed to side.
#3= Bottom portion of lower aluminum bearing housing, seen from bottom of plinth
#4= As #3 with SS hex nut & bolt securing housing

Thanks for any help in answering these questions about grounding my turntable, and sorry for the length-
*Robes

 

[Lucien Nunes]

Unless the bearing is filled with salt water, there should be no measurable galvanic action, and in any case that is a localised effect that is more or less independent of the method of grounding since the metal parts concerned are already in intimate contact with each other.

The ground connection is mainly to provide a low-impedance sink for AC current capacitively coupled to the turntable from ground-referenced external sources such as domestic wiring, plus triboelectric static charges. Small DC thermoelectric and electrochemical potentials have no impact on this function, therefore it is not important what metals are used in the ground connection.

The connection should be made to the ground reference that the rest of the system is using, typically the equipment ground conductor of the circuit powering it. The TT ground must be the same one as the phono preamp uses and by extension the rest of the equipment, otherwise the difference in ground potentials can capacitively couple hum into the cartridge and leads.The grounds must not form a loop enclosing physical area (e.g. TT ground to amplifier, to outlet and back to TT via different route) to avoid circulating AC (hum) being induced. A pure star topology is ideal. Unless you have a specific problem with a noisy or elevated ground at your panel, I strongly recommend sticking to this as the ground source.

Bringing in a separate ground from a rod just for the audio system can be dangerous, as it will not be part of the equipotential zone of the electrical system. In the event of a fault in wiring or appliances, not specifically the audio equipment, the EGCs in your installation can vary in potential and cause the non-interconnected audio ground and equipment to become a shock hazard. Even absent a fault, it can differ in potential by both AC and DC voltages (the latter because a rod is in (real) damp ground containing electrolytes) and may be more trouble than it is worth.

 

[DPG]

Lucien offers excellent advice above, as always. The key thing being that your turntable needs grounding to your pre-amp ground.

Which reminds me, I need to sort out why the arm on my Planar 3 keeps tracking badly.

 

[Lucien Nunes]

Check your arm setup. It should look like this:

Note the grounding:

 

[*Robes]

The connection should be made to the ground reference that the rest of the system is using, typically the equipment ground conductor of the circuit powering it. The TT ground must be the same one as the phono preamp uses and by extension the rest of the equipment, A pure star topology is ideal.

Thanks so much for the reply and thorough explanation. To think I thought a separate grounding rod would be the best way to ground the TT, and alone. Sounds like I have no need to be concerned with galvanic events or anything more then just using a copper wire to the bolt at end of spindle and run it to my preamp and amp ground. I was wondering, what is "A pure star topology", I never heard of that -

Anyhow many thanks for clearing this up for me, most appreciated- Robes

 

[*Robes]

Check your arm setup. It should look like this:
View attachment 87407

Note the grounding:View attachment 87408

Remarkably similar tonearm and exactly the same wire and attachment site I'll be using !! ?

 

[DPG]

Remarkably similar tonearm and exactly the same wire and attachment site I'll be using !! ?

What turntable are you using?

 

[Lucien Nunes]

star topology

Everything that needs grounding connected separately to a single star point, with no other connections between them. This avoids circulating currents being induced, and prevents the impedance of one ground conductor carrying current impressing a voltage on anything else.

 

[*Robes]

What turntable are you using?

I have a walnut VPI Prime as seen here in a number of pics: VPI Prime Turntable & JMW-10 3D Tonearm (Walnut) - https://elusivedisc.com/vpi-prime-turntable-jmw-10-3d-tonearm-walnut/

 

[DPG]

I have a walnut VPI Prime as seen here in a number of pics: VPI Prime Turntable & JMW-10 3D Tonearm (Walnut) - https://elusivedisc.com/vpi-prime-turntable-jmw-10-3d-tonearm-walnut/

Nice looking deck.