"infamis" wrote ...
What does it really mean to be grounded?

Depends on what you mean by "ground". See "mc"s posts
for several good descriptions of what the various meanings
of the word "ground" are.

I guess I'm confused there. In all the books I've read, grounded
means it's connected to a metal rod stuck inside the earth's crust.

You don't really believe that. Else you would be asking why
your RCA and mini-jacks didnt have a wire running to a ground
rod. And there you have two different meanings of the word
"ground": a) a connection "to the earth's crust", and b) a common
point of reference and shielding (i.e. most consumer electronic
equipment).

That makes me think that the circuit is:

audio_generating_source - conductor wire A - destination
device - conductor wire B

You seem to have a good grasp of what it takes to make a complete
"circuit". Did you look up the other dictionary definitions of the
word "circuit"?

- earth.

But you seem to repeatedly go wrong when you think that
"ground" has some sort of magical properties. In your circuit
above, any one point can be connected to ground without
changing the functionality of the circuit.


When I think it needs to be:

audio_generating_source - conductor wire A - destination
device - conductor wire B - audio_generating_source

Obviously you can't stick another metal rod in the earth
& connect it back to the audio_generating_source.

Sure you can. The "earth's crust" is a conductor just as a
piece of copper wire is. It is not quite as good as copper
wire, but megawatts of power are transmitted all over the
planet using the earth's crust as the return path of the circuit.

The power that runs the computer you are reading this on
is likely transmitted through the ground (on the return path
of the high-voltage side). When you see a single wire on
the power poles with taps going into the transformers, note
that the other side of the transformer is connected to a
ground wire. The electricity comes from the generator,
through the single wire along the poles, into the transformer
(the "destination"), and then returns through the earth's
crust back to the generator.

One of the meanings of "ground" is "the earth's crust".
And that "ground" is a *conductor*.

OK...are you saying that when (a) is +12V, if (b) was not
connected to ground it should be -12V. But if it is connected
to ground, it may be -14V?

No. When the signal is at "+12V", ALL the circuit is at +12V.
A few milliseconds later it might be -12V, and then ALL the
circuit will be -12V.

Furthermore, voltage doesn't exist in space. It cannot be
"measured" without some point of reference.

Your analogy is flawed, but if we accept it anyway, in your
scenario if (a) is +12 and (b) is -12, and then you grounded
(b) for example, (a) would be +24 and (b) would be zero.

That means that ground was adding 2 volts? Or that the
whole audio signal is offset 2 Volts above the X axis...
like a DC correction?

* Conductors DO NOT generate signals.
Understand that.

OK, so which is it? Do you *really* understand that
conductors do not generate signals, or do you believe
that connecting something to ground is "adding 2 volts"?
I don't know how to reply to you when even you don't
know what you believe (or not)?

OK, they why ground? Maybe I just don't get the whole
point of grounding if it makes no difference on the audio
signal once they are differenced against each other.

To answer that, you must be VERY SPECIFIC about what
you mean by "ground". Select one...

1) "ground" means the "crust of the earth"
2) "ground" means a common point of reference in an
electronic device, typically the metal chassis or case.

If you mean (1), then people ground things to...
a) to reduce interference through the air (as from a radio/
TV station).
b) to make potentially dangerous power safer. All mains
power in the civilized world is conected to ground at
one point for this reason.
c) to provide a safe path for lightning so that their electronic
stuff doesn't get zapped.

If you mean (2), then people ground things to...
a) to use a convienent return path for power and signals.
For example, the outside of your RCA jacks or mini-phone
plugs, etc. Or virtually everything in your car.
b) to provide a common reference point for various
pieces of equipment.
c) to "shield" things from interference, similar to (1)a)
above.

This is a very simplistic and even *******ized explanation
and can be blasted by many people here at a higher technical
level of discussion. But I am trying to couch it in terms of
your apparent understanding/confusion, and your examples.