Simple grounding question

[Mark Amundson]

J. Larry Hendry wrote:
> .... I am rewiring the power supply outputs to a star configuration
> to reduce noise.
> 
> My question concerns the connection (if any) between AC earth and signal
> ground.  In this system, earth was not connected at the inputs of the power
> supply.  The supplies are connected to 120 VAC via two wire 120V hot and
> neutral.  The power supply outputs are mainly +9v, -9v and ground.  I am
> connecting these voltages to the modules in a star configuration.  So the
> "ground" output of the power supply is connected to each module.  However,
> neither the modules or the power supply have any earth connection.
> 
> Any suggestions?  Should I isolate the signal grounds to earth?  Should the
> ground output at the PS be connected to earth?  Any guidance would be
> appreciated.  I am a newbie at this analog low voltage stuff.Larry Hendry

You could tie your ground to a "earth" or "ground" connection for the
peace of mind of safety. There is the possiblility that a ground loop
may occur though, when used with other equipment connected your modular
synth that also have a conection to ground. One way to help break these
loops is use about a 100 ohm resistor between supply ground and safety
ground. This allows the supply to stay close to zero volts on the AC
wiring.

Mark Amundson,