Chasing 60 hz hum

Thanks, Jim.

I've never been able to figure out how to navigate through long threads at AA in an efficient non-confusing manner :-), and in trying to do so in the thread you linked to I just encountered a lot of disagreement and arguing.

In any event, my point is that while good sounding equipment can certainly be designed and built without making circuit ground and safety ground common, the fact is that many designs do have them in common. And I would expect that modifying an EXISTING design to isolate the two grounds from each other might not be simple to do, and may have adverse sonic effects.

Best regards,
-- Al

I've never been able to figure out how to navigate through long threads at AA in an efficient non-confusing manner :-),
11-09-11: Almarg

LOL..... That's why it's called the Asylum....

Try this, it might be a little easier....

http://www.audioasylum.com/cgi/t.mpl?f=amp&m=156311
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Thanks again, Jim. I read through the entire thread, which unfortunately fails to reach consensus, due as I see it to personality conflicts getting in the way of what could have been very constructive exchanges. Which is particularly unfortunate considering the impressive backgrounds of several of the participants.

In the end, I'm left with the feeling that simply double-insulating the ac wiring and isolating safety ground from chassis could very well be a solution that can be directly applied to most if not all designs without sonic penalty, but the thread would seem to leave at least a little bit of doubt about that.

Best regards,
-- Al

Ralph, isn't that very commonly done intentionally, notwithstanding the fact that it creates the ground loop issue you are describing? And if so, wouldn't a fix (a)be likely to be hard to implement, and (b)be likely to degrade the integrity of the internal grounding scheme that was intended in the design, thereby affecting sonics?

Al, if something like that is done with intention, it can only be out of ignorance, like the kind that existed (and was excusable) 40 years ago. Nowadays you can't get away with it!

On top of that, it **compromises** the sound rather than improving it. Another way of looking at that is that audio components really don't like to be grounded on account of noise in the AC ground and also because of ground loops. If, OTOH, the ground *floats* at AC ground potential, the noise issue is gone and so is the ground loop issue.

Years ago I was of the opinion that a preamp is the place where the chassis and circuit ground being the same was acceptable (this is the way most pro-audio systems are done, although instead of the preamp we are talking about the mixer), but have come to realize that if some other part of the system has incompetent grounding, then the preamp is unfairly implicated. On top of that, if proper grounding technique is observed, you will notice right away that the noise floor is improved (for example, less hiss in a phono circuit) and of course there will be no need for exotic and possibly dangerous external grounding schemes.

Greetings,
In a lot of cases the 60Hz hum is not necessarily do to equipment miss wiring. It can be caused by a number of different problems.
In some cases it can be the wiring in your house. An example would be that when the Romex cable was installed and was clamped down to the J-Box the Hot, Neut. or Gnd wires could have crossed over each other at the clamp point. If this happens one of the wires could have compromised the insulation of the other wire and is causing a hum.
When I was doing a re-model of my kitchen I pinched the ground wire over the Hot wire (insulation broke on Hot lead), this in turn caused a direct short and the breaker did trip. If the wire just partially compromised the insulation this could cause a bleed through to the other wire.
A 60Hz HUM drives all us music listeners crazy.
To track down these type of problems will take a lot of time if you do the work yourself. To pay someone to do this would cost a lot of money.
I do plan to pull all my J-boxes (light fixtures & outlets) apart someday to see if this is one of the problems with the HUM.
Thanks for the advice about getting rid of the cheater plug and to just disconnect the ground wire.
I'm also purchasing a MIT conditioner for my front end equipment. I will eventually find were the HUM is coming from and fix it, it will just take time and effort.
Respectfully,
Joe Nies