Amplifier: grounding, how to

This is about a headphone amplifier I am building.

I try to figure out how to go about grounding. I find some information
on the web to be slightly contradicting or incomplete. I hope someone
can help me out here...

So for the purpose of minimizing interference, hum, or possibly loops
or oscillations, these are some guidelines I follow:

- I use proper star grounding for the power supply
- The amplifier circuit will have a similar star grounding
- The metal case or anything metal that can be touched must be
connected to mains ground for safety
- Signal ground must be connected to power supply ground.
- Signal ground must be connected to case against interferences (RF or
hum from outside)
- Input signal lines must be connected to signal ground; wires in case
are shielded
- Wires going from inputs going to the amplifier circuit are shielded.
L and R (stereo) are separate wires and at both sides the shield is
connected (i.e. to the star grounding at circuit side)

I am unsure where signal ground connections must be made to the case
(inputs, outputs, potmeters?) Or only at one place, or *only* from the
power supply star grounding perhaps?

Are signal wire shields required to be connected to the case?

.

Relevant Pages

  • Re: Amplifier: grounding, how to
    ... I use proper star grounding for the power supply ... Signal ground must be connected to power supply ground. ... L and R are separate wires and at both sides the shield is ... I am unsure where signal ground connections must be made to the case ...
    (sci.electronics.design)
  • Re: Amplifier: grounding, how to
    ... Signal ground must be connected to power supply ground. ... Wires going from inputs going to the amplifier circuit are shielded. ... L and R are separate wires and at both sides the shield is ... I am unsure where signal ground connections must be made to the case ...
    (sci.electronics.design)
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