# why dont you have to use a ground lead for speaker wire?



## PITTM

i still am trying to understand the way the signals move and whatnot and i dont get why speaker cables dont need to be grounded. when i put banana plugs on my wires i thought i would have to ground them to, but since i didnt i was a little curious as to why not.

 rj


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## rickcr42

[size=large]*NO !*[/size]

 ground the output of your power amp and watch the magic smoke come out ! 
	

	
	
		
		

		
			





 (you could blow it up if it uses a floating output stage)

 Speaker cables have a plus and minus for phasing purposes and the minus is not a ground connection but simply an indicator for proper speaker phasing.

 Even amps that have a common "ground" output stage will suffer if you connect it to another ground because it will set up a huge ground loop


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## rickcr42

to expand on the "why don't you need to ground the speaker wire".
 the amp is already grounded internally and if it uses a three prong cord this can be in two places if the input jacks are not isolated (not good usually)

 The third prong of the AC cord is actually connected to a true earth ground and is your house ground.The reason it is called a "true earth ground" is bcause the connection is actually made into the earth at a depth below your local frost line.It is when you have multiple system paths to this common point that you get into trouble.

 "system Ground" is made by the equipment interconnections where each interconnect wire attaches _signal _ ground from chassis A (say a preamp or cd player) to chassis B (the amp or receiver).Without this ground connection you would have no signal because it has no reference point for the audio signal to be positive or negative againsty so is in effect zero.

 where all this gets screwy is when you have gear with some tru earth AC plgs,some isolated and some connected to ground input/output jacks,a cable or satellite system with its own earth grounding rod (another path to earth) and even if two non insulated metal chassis touch each other (makes a second circuit ground/signal ground).

 anytime you have multiple ground paths to the same thing you have created a ground loop and this means noise an/or hum.As in most things simple is best and overcomplicating the simple is a recipe' for disaster unless you fully understand signal flow paths and GROUND is also a signal.

 glad you asked ?


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## jefemeister

It's basically best to think of your speaker as a resistor. The two leads going to it are simply the signal and return lines going throug the resistor. The grounding happens at the amplifier.


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## gerG

A subtle variation on this theme. When bi-amping speakers, be very sure that the driver grounds are not tied together internally. Connecting the speaker "ground" of 2 amps together can do bad things to audio integrity, and to your nerves, as it turns out.


 gerG


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## jpelg

Quote:


  Originally Posted by *jefemeister* 
_It's basically best to think of your speaker as a resistor. The two leads going to it are simply the signal and return lines going throug the resistor. The grounding happens at the amplifier._

 

So, does this apply to headphone cabling too? I've seen headphone cabling schematics referring to "ground" - what does that mean there?

 How does this work with headphone cables that "share ground" (usually single-sided headphone cables)?

 If i wanted to power a pair of headphones directly from speaker taps, do I need two wires for each channel or not?

 I'm confused, but very curious.


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## rickcr42

Quote:


 So, does this apply to headphone cabling too? I've seen headphone cabling schematics referring to "ground" - what does that mean there? 
 

same thing.you are terminating the output with a resistive load (the ohmage of the headphoners) though being electro-mechanical there is an inductive/capactance element too.

  Quote:


 How does this work with headphone cables that "share ground" (usually single-sided headphone cables)?

 If i wanted to power a pair of headphones directly from speaker taps, do I need two wires for each channel or not? 
 

With a _balanced bridge _ power amplifier you can not be used with any speaker switch or other device on the output with a shared ground (such as a Hafler Dynaquad device ) or you will destroy the output stage by shorting the left and right channel "-" terminals.These terminals are NOT grounds but totally separate ampliifers used to amplify the negative phase of the signal instead of referncing the "hot" output to a ground as in a normal power amp..To use headphones with a true balanced bridge power amp you need either an isolation network that loads each negative terminal and sythesizes a "psuedo ground" (can be simple resistors if the value is high enough) or true balanced connections.

 hope this helps a bit


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