Re: Mike on Mics

HARMONICA JOHN	San Diego  PO Box 740613 SD CA 92174 (619)263-6826

God, family, music, fishing, work.	 Can blue men play the whites?

On Wed, 5 Jul 1995, Mike Curtis wrote:

> Harmonica John Wrote
> > I do have one comment though in reference to hi Z cables. The signal has 
> > to have a complete circuit, or you get no signal. In other words, the 
> > music gets pushed down the hot wire, but comes back on the shield.
> Mike wrote
> It depends on our point of reference.  If we open the braid and measure
> current, yes there will be a flow.  But when the ground is opened, it is no
> longer ground.  By definition, ground is at zero.  For unbalanced systems,
> we measure with respect to ground.  Ground is considered to be an
> "unmovable" point of reference, so when viewed from this vantage point, all
> current flow is in the hot conductor.
> If this were not true, any current generated in the shield (i.e. magnetic
> fields, etc.) would be picked up and amplified by the amplifier, as there
> would have to be a complementary current in the center conductor.  But
> because it's ground, this is not the case.
Have you ever picked up radio stations on a cheap guitar cable?
I stick by my point. If you don't believe me, try running signal to your 
amp with just one wire and no ground wire. It won't work. Scientists 
disagree over whether the electrons move +to- or -to+. Some say the 
electrons don't actually move, but nudge each other. 
Also, "ground" is not as unmovable as we would like it to be. This is 
why there are ground loops and 60 cycle hum gets broadcast through your 
speakers. Most older equipment like harp amps use 2 prong power cords and 
reference to chassis ground. People would be electrocuted when they 
played on a wet garage floor, which is earth ground. Then you have the 
ground for your wall electricity which is normally attached to a cold 
water pipe or to a copper rod driven into the earth. There may be a 
difference in that ground potential and the ground potential where your 
lips touch to microphone. A difference in potential is defined as voltage. 
       That is why your mic will ocasionally bite you. Has this ever 
happened to you? I didn't mean to be so long, and again, most people probably 
didn't want to know.


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