Not your usual grounding question . . .

[acheld]

So I promised a hi-fi tube pre-amp build to a family member.  The one condition I was given is that it will be an entirely wood cabinet/chassis.

The circuit will utilize a star ground.  My question is how to connect the circuit ground to the earthing ground from the plug. Does it even need an earth?  Normally of course you'd earth the chassis and reference your star ground to the chassis.  But with the chassis being non-conductive, that doesn't make sense.  Would I elevate the circuit ground, and reference that to earth via the plug? 

Also, the phono pre-amp will need to be grounded to the turntable.  I'm guessing that will be through the circuit ground, or should that go straight to earth?

[kagliostro]

If I were asked for such a thing I'll avoid to use a wood chassis, I'll use a metal chassis covered with wood

To try to have less problems connecting ground between the preamp and other components (Turntable and others), use this configuration

https://sound-au.com/earthing.htm



this trick is used also by VOX in the AC30CC2 (and may be other amps)

Here look to pic 15.16 and 15.17

http://www.valvewizard.co.uk/Grounding.pdf

Franco

[Merlin]

If you do use wood you'll almost certainly want some kind of foil lining or earthing plate, just to keep out hum. Connect your mains earth to the star ground, and separately to the foil.

[acheld]

These are great ideas!   Much appreciated.

I do have some copper foil used for guitar construction.  That should work.  He'll never know. . .

Normally I use a wood covered metal box with an aluminum top plate, but that was not on the menu.