Re: More on cheater plugs


"Bret Ludwig" <bretldwig@xxxxxxxxx> wrote in message
news:1143046565.848881.78300@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Years ago most all military equipment had AC plugs that had a ground
prong that flipped over so you could use it as a two prong plug or a
three prong one. These were briefly sold at a jacked up price through
audiophile channels, and not since.

The lowest noise connection is ALWAYS when there is ONE, and only one,
connection to a good low impedance ground in the system.
Neutral-"earthy"-AND safety ground schemes are de facto ground loops in
and of themselves.

I have seen systems where the owner removed the neutral rather than
the ground connection and relied on the ground for return, or provided
his own via plumbing and/or a driven stake. It's illegal and when done
by the inept could burn down the house, But his stereo was quiet.
Oldtimers did these kind of things all the time and as long as no one
else fooled with things they usually got away with it. Needless to say
there were no guffers on those lines.

The safe, sensible solution? Two hots for POWER and a good ground. All
houses built since WWII have balanced 220 power. Properly using that is
the quietest power you are going to get and with no tweako crap
involved-which is why the high end ignores it.

IOW, "balanced power".
I'm not sure if this is a complete panacea for systems which have unbalanced
interconnects. Please take a look at the following gedanken experiment, and
see if you can poke a hole in it:

1. Consider two components, say, an amp, and a preamp, with unbalanced
interconnects, that have their 3rd wire safety pins connected to each other,
BUT, for the sake of this gedanken experiment, the 3rd wire safeties are not
actually attached to an external ground.

2. There is a closed loop path for electrons. An electron can start at the
preamp output, pass through the interconnect to the amplifier, out the 3rd
wire of the amp, back in the 3rd wire of the preamp, and through the
interconnect again. Thus, there is a classical closed loop.

3. From Maxwell's equations, Int{E dot dl} around the loop = d/dt { Phi } =
d/dt { Int B*dA } where A is the area of the loop.

Thus, the electromotive potential induced in the closed loop is caused by
the time rate of change of the total flux in the loop, which, assuming that
the hifi is awash in the omnipresent 60 Hz field, is roughly proportional to
the size of the loop. From the above, it can be seen that the "hum loop" is
not an effect which is caused inherently by attachment to an external
ground, but by the creation of a current loop completed by the 3rd wire
safety grounds.

Now, there are all kinds of modes, capacitive and inductive couplings, that
can produce additional hum, so the above reasoning does not say that
balanced power will not be beneficial. But the above phenomena, the
classical "ground loop" is operative even if the system is connected to a
perfectly balanced source of power. It therefore seems to me that balanced
power is probably most useful for systems that are already quite close to
optimal, such those using well balanced differential inputs/balanced
interconnects, so that the residual hum is caused by other modes.


.

Relevant Pages

  • Re: More on cheater plugs
    ... interconnects, that have their 3rd wire safety pins connected to each other, ... BUT, for the sake of this gedanken experiment, the 3rd wire safeties are not ... There is a closed loop path for electrons. ... In such an environment balanced power would matter less. ...
    (rec.audio.opinion)
  • Re: More on cheater plugs
    ... interconnects, that have their 3rd wire safety pins connected to each ... BUT, for the sake of this gedanken experiment, the 3rd wire safeties are ... There is a closed loop path for electrons. ... In such an environment balanced power would matter less. ...
    (rec.audio.opinion)
  • Re: More on cheater plugs
    ... with unbalanced interconnects, that have their 3rd ... wire safety pins connected to each other, ... There is a closed loop path for electrons. ... Bulgin plugs are debatably better. ...
    (rec.audio.opinion)
  • Re: More on cheater plugs
    ... with unbalanced interconnects, that have their 3rd ... wire safety pins connected to each other, ... There is a closed loop path for electrons. ... Bulgin plugs are debatably better. ...
    (rec.audio.opinion)
  • Re: Ground Busses
    ... Someone suggested I write an article on power and grounding techniques ... be no need to worry about power and ground topologies or wire routing. ... By definition, every circuit forms ... strong field from a transformer or choke) exists in the loop, ...
    (rec.audio.tubes)