Ground Busses
Iain Churches wrote:
My experience with ground buss amps is limited. I have
never been
able to make them quiet enough. I found that the exact
position in
which a wire was placed on the buss was critical, and that
a difference
was audible.It may be there is something lacking in my
implementation
of the buss.
I guess the order in which connections are made along a bus
is significant. If you think of the bus as a resistor, then
a high-current return placed furthest from the ground will
produce a voltage gradient along the bus. If the next
connection is, say, the signal ground from the first gain
stage, that voltage could be significant.
OTOH, if the connections to the bus are made in order of
highest current, the voltages they produce will be
minimised.
But perhaps there is countervailing argument? If a sensitive
connection is close to the ground, then a voltage produced
by a high-current connection further along will be
attenuated. So perhaps the order is important, but it
doesn't matter to which end of the bus the ground is
connected? What you don't want is a high-current connection
and a sensitive connection both distant from ground.
I find a genuine star earth is hard to implement if there
are many ground connections to make. Exactly how do you
fashion a star?
The signal ground must be safe to touch if it is brought out
to exposed external connectors. If a resistance is placed
between the 0V and chassis ground, then it should be a low
enough value and high enough power to ensure that the fuse,
and not the resistor, will blow quickly if the signal ground
becomes live due to some fault. Perhaps some statutory
regulations apply?
Not a "pro", or an "expert", as usual, thankfully.
Ian
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