Perplexed ! ?

B

b.falvey

Member
Hiss problems and general electric buzz problems. Playing outside on a flatbed truck, I had a buzz through my Pa so bad it blew my breaker on my guitar amp. Fix: Some guy on a WW11 Harley drove up (Time frame 1985) and asked me the problem. He then took a Horseshoe stake and pounded it in the ground, took a thick wire or a metal coat hanger and hooked it to the generator. Hospitals and many studios all use a third AC ground as does anyplace with a lot of sensitive electronic equipment but making sure your house has a good basic AC ground is also very good for elimimating unwanted buzz. I also always used a 12v batterys instead of pluging my foot pedals into the AC your out there when in an environment your not sure of. Take or leave it! My name is Bob, by the way and hello to everyone.
 
There is no argument about having a well grounded house supply, both from a safety as well as an audio noise point of view. The situation is rather more 'problematic' in the field.
Generators do not, it seems, usually tie one side of the supply to earth and the chassis as is the case with house mains. Such a 'floating' supply is inherently safe as copping one side of it will only give a bit of a 'tingle' due to capacitive leakage. Even if an amp chassis say went faulty, short to chassis there would be no shock hazard since there is no ground path. For a 110V supply a centre tap taken to earth is perhaps the best compromise as 'worse case' 55V is unlikely to kill (but don't bet on it!) Over here, 120 above earth is of course still very lethal.

Hospital and other 'scientific' mains supplies are 'balanced' using a 1:1 isolating transformer with a centre tapped secondary which is grounded. These are not however safe in EU at least because fusing is generally only in the 'live' line and a service guys may not be aware that there is 120V still on the 'neutral' line.

Dave.
 
Hello to Dave, The AC field generater buzz blew the fuse on my amp. Never happened to me before playing outside . . . and never forgot th
e hum through the PA untill the AC field generater was grounded . . .
 
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