Tube power supplies & grounding

[Eric]

>I have completed building a power supply for my
tube synth


Beautiful job, Doug! Nice design.

>All filament power supplies are completely
isolated from
>the rest of the circuitry.


Also a good idea--helps reduce induction hum
and allows the supply to float wrt the tube
cathodes.

>The DC common/signal grounding system is set up
as a "star"
>ground, and is not connected to the chassis earth
at any
>point. My question is this: should the chassis/AC
earth
>ground be connected to the DC common/signal
ground
>directly, through a small capacitor, or not at
all

Solid earthing to the chassis, and to the 3rd
earth pin on
the AC power socket, is recommended at all times.
Make it a thick, short wire, and make it a solid
mechanical
contact if possible. A star earth is always good
to have in
any electronics--it's easier to do in tube
circuits with point
to point wiring. This helps reduce hum and RFI, of
course.

Electrical safety is not a problem--working with
hot HV involves
just common sense and care.  You should always use
insuated
tools, and perhaps wear gloves. (And turn off the
power when
making a change!) I would also add 40k 10w bleeder
resistors
across the +160 and -160 supplies, to discharge
the caps
when power is shut off.

Proper grounding is most important, in tube or in
solid-state.

--Eric