Turntable Grounding - Sondek & Naim

[Bad Parameter]

I’m spending time in an old family house riding out the pandemic, found and hooked up a cousin’s old 70s stereo, Nikko integrated, patched up Dynaco A25s, added my computer & cheap dac, and now my Sondek. All have two prong plugs and the house I know has bad grounding, as they all seem to around here (provincial Italy) and I can feel a potential on the Nikko’s metal faceplate and on the Linn’s top-plate, pretty good one too. I sprayed out the Nikko set the bias and offset and one day soon it’ll get a recap and a new three prong cord.

My Linn is from 1978, recently, expertly, rebuilt and restored, I was convinced to junk the grommet cooking, soot producing, curtain burner Valhalla for an old Basik supply, old red button, and an old but new 50Hz motor. Sounds just glorious, big, warm, blooming sound and looks retro snazzy with its smoke grey dustcover and big red lighted pushbutton. Humans were meant to push Big Red Buttons. Screw the Valhalla, even though I had recently rebuilt it.

Question, TT has a two prong plug, is it best to change it to a three prong? Should the TT's metal parts, subchassis etc. be grounded at the mains and also ground to the preamp through the tonearm’s grounding wire? Not worrying about safety I would have grounded it already especially with the hot Nikko, I'm asking about when it goes back into my Naim system. There should the TT's mains float, just one ground through the arm cable to the 102/Hicap/250 with the Hicap as the Naim specified star grounding point? In other words, avoid a possible ground loop btwn the TT and Hicap’s mains grounds?

 

[Craig B]

I'd be having a qualified sparky (scintillante?) go over the house mains before so much as turning on a light, let alone plugging any kit in.

 

[Vinny]

Horror of a two pin system apart, using a Linn armboard, the tonearm is electrically insulated from the rest of the LP12 iron-mongery by the armboard itself. However, my LP12 is in no way standard, so you'd need to look where things have been earthed - for instance, a lead may well exist between any bolt on the tonearm mount, and the metal sub-chassis.

In a normal 3 pin system, connecting and disconnecting non-power-lead earths can do no harm in trying to eliminate earh loops, but in a 2 pin system.............

 

[Bad Parameter]

for instance, a lead may well exist between any bolt on the tonearm mount, and the metal sub-chassis.

It does. Which is why I'm wondering if adding a mains ground would cause a loop with the preamp connection and the Hicap's mains ground - it would be a double ground. Granted the 250 has a mains ground so no idea where it's all going, how it's being bused, inside the Naim boxes I just follow what they recommend.

I don't really care about the present temporary set up in the old house with the Nikko system. If the Nikko was grounded as it will be one day the TT even if floating couldn't have a potential on the top plate.

I'm curious what's best with the Naim system. Do most people's Sondeks in a Naim set up have a grounded mains? The new Linns must by law, right? Mine is sounding so good right now I really don't want to futz with it. I don't have a Linn workstand, I hate doing the two chair thing.

I'd be having a qualified sparky (scintillante?) go over the house mains before so much as turning on a light, let alone plugging any kit in.

It needs an earth rod IMO but cousins own it now and trying to sell it. It was fine for the old folks, couple lightbulbs, TV, water heater. Their life was work and sleep not much sitting around spinning LPs.

 

[Vinny]

Logically, an extra earth from tonearm back to an active pre', you'd expect that to form a loop somehow, on a 3 pin system.

In terms of current UK regulations, any and all mains-powered appliances must be either double insulated, or be fitted with an earth.

I suspect that that would make quite a bit of old kit illegal, unless modified. New kit, and by new, that stretches back quite some way, will be one or the other but the huge majority of hifi kit will have an earth.

Water heater and no earth..............................................

 

[Copperjacket]

Make sure you wear rubber Wellies at all times.

 

[Bad Parameter]

Water heater and no earth..............................................

I'm aware of that. Already blew its display during a bad lighting storm, that cost more than driving a ground rod into the ground would have. House GFI trips during any lighting storm too. Tell it to my cousins.

Make sure you wear rubber Wellies at all times.

Especially in the shower!

 

[Vinny]

An earth is no protection from lightning if it strikes close enough.
It is over 25 years ago, but a very close strike melted a telephone answering machine - the tiny cassette was fused into the innards, and also fried a phono stage, where I lived at the time. Plenty of other things were plugged in, but just those two died.