If your equipment is not already three wire, adding ground connections to
the components will result in terrible hum problems.

Even equipment which has three wire connections frequently presents a
problem, when used with unbalanced interconnects, leading to the use of
cheater plugs.

Audiophiles frequently have the misperception that hum can be "grounded
away." This is not true, because hum is like flowing water. When it finds
it's level, it stops flowing. Hum is caused by chassis currents which flow
between components on the shield of the interconnects. It originates in the
leakage which arises from all AC transformers, and varies in amount from
component to component.

In consumer equipment, a lot of attention has been lavished to make it
compatible in ungrounded, unbalanced operation. If you start to tinker with
that engineering with improvements inspired by non-EE thinking, bad things
will happen.


"Straycat" wrote in message
y.com...
I bought a box of medical grade ac power cords at the local junk store.
They
are just like the computer and office machine power cords that are very
common, except that there is a sheild on the ac lines in addition to the
normal ground wire. The ground wire itself is on the outside of the sheild
wrap.
I was wondering if it would be useful to install 3 conducter chassis
sockets
on my stuff and use these cords. Right now I have two monster cable power
strips supplying ac which have the grounded outlets. These are plugged
into
a medical grade outlets on a seperate circuit breaker. Another circuit
breaker, on the same side of the main panel, supplies ac power to the
computers, again through monster cable power strips. I mention this
because
the computer systems are sometimes connected to the recording inputs and
outputs of the audio system.
The only problems I have not resolved are that the computer is connected
to
a DSL modem / Router which is connected to the phone line. This phone line
has surge protection, but no sheilding. There is an FM antenna system, but
no cable TV or other static source connected.
There is a low level AC line buzz in the system but it is only audible at
extreme levels of volume setting, well beyond any usable audio level. It
is
not an issue. There is also no other interfereance such as radio tv etc.
Is putting this work into the system a waste of time? Has anyone
experimented with sheilded ac cables and noticed any kinds of effects?

Carl

"Straycat" wrote in message
y.com

I bought a box of medical grade ac power cords at the local junk
store. They are just like the computer and office machine power cords
that are very common, except that there is a sheild on the ac lines
in addition to the normal ground wire. The ground wire itself is on
the outside of the sheild wrap.

I was wondering if it would be useful to install 3 conducter chassis
sockets on my stuff and use these cords.

Sonically this is a study in futility unless you have an environment that is
very noisy, electrically. In that case it would be wise to clean up the
noise sources rather than put band-aid shielded power cords on everything.

Right now I have two monster
cable power strips supplying ac which have the grounded outlets.
These are plugged into a medical grade outlets on a seperate circuit
breaker. Another circuit breaker, on the same side of the main panel,
supplies ac power to the computers, again through monster cable power
strips. I mention this because the computer systems are sometimes
connected to the recording inputs and outputs of the audio system.

Sure and this is almost always done with conventional power cords with no
ill effects.

The only problems I have not resolved are that the computer is
connected to a DSL modem / Router which is connected to the phone
line. This phone line has surge protection, but no sheilding.

Phone lines are twisted unshielded twisted pair, and the twisting of the
pair is adequate in millions of cases.

There
is an FM antenna system, but no cable TV or other static source
connected. There is a low level AC line buzz in the system but it is
only audible at extreme levels of volume setting, well beyond any
usable audio level. It is not an issue. There is also no other
interfereance such as radio tv etc. Is putting this work into the
system a waste of time? Has anyone experimented with sheilded ac
cables and noticed any kinds of effects?

Let's put it this way. If an audio system has no problems with audible noise
pickup through power cords, is experimenting with shielded power cords a
waste of time?
Carl