Checking the AC polarity of your amplifier

1.) Get a simple volt/ohm meter.
2.) Detach interconnects and speaker cables from the amp.
3.) Attach a *bi-polar cheater plug to the three-prong
plug on the amplifier power cord.
4.) Set the VOM to AC volts with an approximate range
of 0-100 VAC.
5.) Remove the trim plate from the wall outlet.
6.) Plug the amplifier power cord (with cheater plug
attached) into the wall socket. Do not turn on the
amplifier.
7.) Using the VOM, measure the voltage between a point on
the amplifier chassis (a bare metal spot like a
chassis screw or some unpainted part of the chassis)
and the galvanized metal mounting frame of the duplex
wall outlet. Note the reading.
8.) Remove the plug from the wall socket, rotate it 180
degrees and re-insert it into the socket. (The plug
blades are now in new slots) Measure the voltage again
as you did in #7.
9.) Whichever plug **position gave you the lowest reading
on th VOM is the way you want to plug in the amp (or
any other device you may wish to measure, into the
wall socket.

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* A bi-polar cheater plug is a cheater plug (three prongs in, two prongs out) which has had the wider (neutral) blade filed down so it will fit the narrow outlet slot when you turn it over 180 degrees in step 8. You can't buy them, you have to make them.

** If you want to ground your amp (using all three prongs) but the best position (as determined above) leaves you with the ground prong out of line with the hole in the wall outlet, get a cheater plug with a green wire coming out of it. File down the wide blade so you can plug the power cord into the wall in the most desireable orientation you determined in step 9, and then wire the little spade connector on the cheater plug to the screw that holds the trim plate onto the wall outlet (you may have to use a longer screw).

Robbyg, Stuartbranson, Tbg:

Robbyg: The reason one makes the measurements with the component off, and all input/output connections detached is because what your trying to determine is how all the component's various circuits "grounds" combine and where that total is positioned electrically -- i.e is it closer to the "hot" blade of the power cord or the "neutral" blade of the power cord. Depending which way the blades of your equipment's power cord are oriented relative to the real "Hot" and "Neutral" of the electrical service in your wall, you'll get a bigger potential difference or "leak" in one position or the other. The position with the smallest leak will give you the least hum in your system when the component is finally turned on.

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Stuartbranson: You little devil!! Of course you could, but what about when you start to get oldtimers disease like me, and forget what you did where. Or what if someone buys your house and can't understand why they keep getting shocks from their vacuum cleaner!!

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Tbg: Soooo....you like a little electrical stimulation once in a while, do you?! "Higher leakage voltage" indeed! Listen: Audiophiles are a dying breed, so please be careful, we need you. If you find yourself craving higher and higher leakage voltages, please, email one of us before it's too late, your body fries your computer and you lose all contact with the outside world!

Neil

Tbg, I wish you would expand on your 3/1 comment, which I found very interesting. Exactly what could be some of the problems that might arise if balanced power were used inappropriately?

For everyone's info, and for what it's worth vis-a-vis our discussion about mixing balanced and unbalanced power:

I had about an hour and a half conversation with Brent Jackson (who is the CEO, chief engineer, etc) of ExactPower on this subject to see what he'd say (especially since I use both of his units, the EP regenerator and the SP balanced unit -- and do so only because I'm in an apartment now. When I had a house it was dedicated circuits with high-speed diodes on the breakers for surge protection and that was it!)

Anyway, his recommendation for using both units together was to put the EP regenerator at the speaker/amp end and plug in the amp, both (CLS) speakers, the subwoofer, and (using a longer 12 ga. PC) the SP balanced power unit, which I have near the source devices.

First I listened with all ground pins connected. It was pretty quiet except the sub which had some barely perceptable 60 ~ hum. So I started putting ground lifters on the devices plugged into the regenerator. That got any residual noise/hum, so I haven't messed with polarity yet on those devices (but you know I will ;-)