Hello Howard. Can you ask Colin please what is star earthing and does he / will he using it in his new designs? Ta muchly J.N Peterson
Dear J.N.Peterson star earthing should be used in all analog designs, that is a single zero or earth for every component on the circuit board and normally not shared with any others. Since zero or earth is the reference point no earth current or signal should be induced into another as this, in most cases, causes hum and buzz and general current noise. Once this noise is include or added to the reference then it is not a reference anymore.
I defer to Colin on the star-earthing, but I would add that star-earthing is important as is its implementation on a pcb, i.e. how the tracks are laid out.