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Here's the deal..................

75.161.156.90

In Reply to: RE: My equipment doesn't hum, even on my bud's 102db speakers. (nt) posted by twystd on June 25, 2009 at 13:10:47

If you have a power amp with a 3 prong plug and a pre-amp with a 3 prong plug you have a ground loop. Whether your hearing is good enough to hear it or it doesn't bug you is another topic.

I have 104 db Klipshorn/Altec speakers, and I can hear hum on them without the grounds lifted. I have studied this problem for 5 years and unless you use isolation transformers (which are not cheap and may compromise other parts of your system) lifting the ground is the ONLY way to totally eliminate the problem. If there was a cheaper more effective way to completely eliminate ground loop hum, I would have done it long ago. Other than using a passive pre-amp (which I own, but doesn't sound as good)

The other bottom line is an Electrical Inspector will tell you that a circuit with GFCI protection and a 3 prong device with the ground lifted is a safer situation than a non GFCI circuit with a 3 prong plug intact. So before you chastise a lifted ground with GFCI protection, please lobby everyone to install GFCI protection on their stereo circuits. I am not sure why lifting the ground raises hackles on people like it does, but it certainly does!

If we really wanted to be completely safe we wouldn't want to use electricity at all. Or even think about driving a car! Let's keep lifting a ground in perspective.

Cut-Throat

Follow Ups:

Way to go insult my hearing ability, rather to look into possible problems with your equipment. - twystd 14:33:05 06/25/09 (3)
Do you really think all of us that don't have ground loop problems, are just putting up with it, or have defective hearing?? I guess your equipment is the summit of perfection, and if it has problem so does everyone else's.....jeeze!

You've talked to an electrical inspector that has proved the Peter Principle, that you get promoted to your own level of incompetency. It depends if the fault happened while I was in physical contact with the device, then a GFCI would be best, as it would trip before a fuse would blow, or circuit breaker would throw. However if the fault happened while the device was operating, but I wasn't in physical contact, I'd prefer the three wire system, as it would trip as soon as the fault happened, without me providing the path to ground, and suffering the 6ma shock.

Without the three wire system, a device under fault just sets at it's faulty electrical potential, until presented with a path to ground, and that could be you. This is why the three wire system was adopted in the first place. With the GFCI, hopefully you'd be exposed to only the theoretical 6ma short duration shock, and you don't have a pacemaker, underlying heart condition, or your three year old didn't stick his tongue on it!;-)

twystd
- RE: Way to go insult my hearing ability, rather to look into possible problems with your equipment. - tube wrangler 10:54:34 06/26/09 (1)
  Not only is the 3-prong system necessary for safety-- the GFCI units SOUND BAD...... very bad.
  
  In a practical system, we're going to have 3-prong wiring on every component.
  
  It is up to the installer to arrange all of these 3-prong connections AND WIRING LENGTHS and PLACEMENTS so that ground-loop problems are minimized.
  
  Equipment is not safe, nor is it necessarily going to sound "better" with grounds "lifted".
  
  Keep the grounds, and learn how to use them properly.
  
  ---Dennis---
  - RE: Way to go insult my hearing ability, rather to look into possible problems with your equipment. - Dave Davenport 14:44:14 06/26/09 (0)
    Hi Dennis,
    
    "Keep the grounds, and learn how to use them properly."
    
    AMEN....
    
    Dave
- The facts are that a GFCI is still safer than a 3 wire system...............nt - Cut-Throat 14:38:30 06/25/09 (0)
  nt
  
  Cut-Throat

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