maybe this is stupid but how is it a signal and voltage travel together

[blearyeyes]

Although to be more precise, rather than "to ground" what you need is a return path for the electrons, literally.

That's why you need 2 wires for everything.
Using the metallic chassis as return path and calling it "ground" is just to simplify the concept and layout, but that's what it actually is.

I get it.
Thanks Juan.

[blearyeyes]

The ground being the return path, is that because guitars use an unbalanced wire with only a hot and a ground?

I noticed in the amp I am working on the dc power has a plus and minus and a ground so a balanced circuit?

So how does that all work together?

[Enzo]

perhaps if you think of it as common rather than ground. After all, you can have a 9v battery circuit amplifier you plug your guitar into and it drives a little speaker or headphones. Nothing is connected to ground or earth, but what we might call ground inside it is its "common."

Every circuit needs a complete path there and back for any signal. That is why it is called a "circuit" from the same word as circle. An unbalanced guitar cord has a wire down the center and a grounded shield around it as the return. A balanced microphone cable has two signal leads of opposite polarities. Neither is grounded or commoned in that balanced line, one goes out and the other returns.

A balanced signal circuit has two paths through it of opposing polarities. A split power supply is not the same thing. If you have ICs running on +15 and -15, then the signal path is referenced to the zero volts between those extremes. If you have a circuit running on one 9v battery, then your signal path inside through any ICs would be referenced to 4.5v, and move plus or minus from there. Both those are probably unbalanced, since there is only a single signal path.

Acoustical energy, voltage, it is important to understand the distinction between signal and voltage. Signal is the information. VOltage is just a dimension.

I can start with a signal: sound coming out my mouth. MY wife often gripes about the amount of signal I generate. Let
s say I speak a sentence, "Turn off the water.". I say it into a microphone, which translates the acounstic energy into a varying voltage signal. We amplify that signal, and someone hears it in headphones in another room. That translates the signal back into acoustic energy. That person then types the words on a sheet of paper, and drops it in a slot to the floor below. Now the signal is in written form. The person in the lower room, reads the sentence, and then grabs a couple flags, and climbs to the roof and waves the flags to send the sentence in semaphore. The signal is now in the form of flag patterns. On the hill across the valley, someone sees the flag semaphore signal and passes it along with a bright light using Morse Code to a ship in the harbor.. My sentence signal is now in pulses of light. The ship is stationed next to a large flood gate. Someone on the brtidge sees the Morse Code flashes and writes down the sentence. The signal is now traslated back into written form. He hands that to the officer of the deck, who picks up the ships PA mic and says into it. "Turn off the water." The signal there just passed from written to acoustic to electronic. Out on the deck of the ship, a loudspeaker blares"turn off the water." SO the deck crew grabs a large valve wheel and closes the flood gate. The signal has made it to the valve.

None of those forms were the result of something physically passing all the way through the system. Only the signal did that. The various manifestations of it stayed in their respective sub-systems.

Maybe a simpler version is that desk toy with the row of steel balls hanging on strings. Pull the end one away and let it go and it slaps into the end of the row. The ball on the othe end then pops away into tspace, only to fall back and send the signal back where it came from. The oleft end ball never travels to the right e4nd, or vice versa. IN fact the balls between the ends never move. Only the signal passes through. Just as the electrons in the guitar pickup do not go through the amp and come out the speaker wires.

[eschertron]

It's crazy. Humans have harnessed electrons and use them to make music.

I just watched a TED talk (TED.com?) "David Byrne: How Architecture Helped Music Evolve" that addresses how our environment, recording technology and otherwise, forces musicians and composers to adapt to their surroundings. Kind of a thoughtful link between the physical and the mystical.

[blearyeyes]

I have the app for Ted talks on my iPad. I love the people that give their talks. I'll look that up.

[blearyeyes]

I looked it up and watched it. Awesome insight. Thanks.

[blearyeyes]

Good one Enzo.

I agree and think you made a great analogy.

Typewriters are transducers.