Eliminating hum

Based on my own personal experience, hum can also be picked up as airborne EMF from a nearby amplifier. In my case, what I had spent hours configuring and re-configuring, as suggested by Tjassoc, was not an AC ground loop at all, but EMF picked up by my IC connecting the phono stage and pre-amp. Simple aluminum foil around the IC remediated the problem. This issue can be very tricky, as my own experience attests to. Good luck.

Goodness I have used cheaters my whole 37 years of audio life. Most of us have and it will at least help you understand if it is a ground loop issue.

I must be lucky:). I have never, ever heard of any incident in real life to be honest Agoners.

Al, most amps are grounded at the first reservoir cap in the power supply etc...

This topic comes up all the time on many threads and it always makes me think " who has ever, ever been harmed by using a cheater on an amp or preamp?"

If a power cord would have a short to the chassis would'nt that trip a
breaker in the home? I think the most cautious of us would say never use
them as there is certainly a possibility of shock if all the conditions are
aligned perfectly. It is also reasonable to say many things we do every day
are far more risky. Things like riding a bike, taking a walk, ice fishing, etc...

I did just read this ...............

"In the professional audio and video fields, the cheater plug has been
identified as a serious safety problem. Its casual use as a method for
avoiding ground loops in analog audio and video signals (to eliminate hums
and buzzes) is dangerous.[4] Bill Whitlock, president of Jensen
Transformers, writes, "never, ever use devices such as 3 to 2-prong AC
plug adapters, a.k.a. 'ground lifters', to solve a noise problem!"[4] Whitlock
relates how an electrical fault in one device that is connected to its
electricity source through an ungrounded cheater plug will result in
dangerous, high current flowing through audio or video cables. Whitlo

01-03-15: Grannyring
If a power cord would have a short to the chassis would'nt that trip a breaker in the home?

Hi Bill,

The purpose of the AC safety ground connection (which is what a cheater plug defeats) is to make that happen. Since equipment having 3-prong power plugs connects AC safety ground (the cyclindrical third prong) to chassis, a short between AC "hot" and chassis will cause a very large current to flow through the circuit breaker, resulting in the circuit breaker tripping.

If the AC safety ground connection is defeated with a cheater and that kind of a fault occurs, what is likely to happen is that the 120 volts will cause a current to flow through the shield and/or the return conductor of an interconnect cable to another component, and through that component's AC safety ground back to the service panel. However, depending on the design of the grounding configuration within each of the components a significant impedance, perhaps 10 or 20 ohms or more, will often exist (and should exist, if the equipment is well designed) between the circuit ground and the chassis ground/AC safety ground of each of the components. Chances are good that that resistance will be high enough to reduce the current flow to an amount that is too small to cause the breaker to trip.

In that situation what is likely to happen is that the interconnect cable will get very hot, creating the possibility that it might either go up in flames or ignite whatever it may be in contact with, such as a carpet. And of course the chassis would present a shock hazard to anyone who touched it.

Al, most amps are grounded at the first reservoir cap in the power supply etc...

That doesn't change what I have said, as that involves the amp's circuit ground, not AC safety ground.

BTW, I should add to my earlier mention of ways in which AC "hot" can become shorted to chassis the possibility of a short developing in the power transformer of a component.

... it will at least help you understand if it is a ground loop issue.

Agreed. Using a cheater plug temporarily as a diagnostic tool can be useful, and entail negligible risk.

It is also reasonable to say many things we do every day are far more risky. Things like riding a bike, taking a walk, ice fishing, etc...

Agreed. But it is each individual's call. My point, though, is that a statement that using a cheater is "completely safe" is misleading and incorrect.

Best regards,
-- Al

Thanks Al. I did just read this.....seems we have some cases of electrocution on record. We Aphiles should be aware.

" In the professional audio and video fields, the cheater plug has been identified as a serious safety problem. Its casual use as a method for avoiding ground loops in analog audio and video signals (to eliminate hums and buzzes) is dangerous.[4] Bill Whitlock, president of Jensen Transformers, writes, "never, ever use devices such as 3 to 2-prong AC plug adapters, a.k.a. 'ground lifters', to solve a noise problem!"[4] Whitlock relates how an electrical fault in one device that is connected to its electricity source through an ungrounded cheater plug will result in dangerous, high current flowing through audio or video cables. Whitlock notes that in 1997, consumer audio and video equipment electrocuted nine people.[4]