Grounding on Power cords

Glen McLeod -- Fri, 09/10/2010 - 09:07

I just had a conversation with Nordost, where we discussed grounding techniques. They don't suggest using a 3-2 adapter to lift the ground on any components. This made me curious, as, when older units had a polarized plug, the way to get the correct orientation was to use a 3 to 2 adaptor to get the correct orientation (or use a Namiki Direction Finder). I'm using their Q-Base unit, by the way.

Now that plugs are all polarized, I'd like to know if others still use a 3 to 2 adaptor or plug directly into the wall. Guys? Girls? Others?

Steven Stone -- Fri, 09/10/2010 - 15:12

The 3 to 2 adapter is my friend. I can't begin to tell you how many times I've used a "cheater plug" to solve a hum problems by floating grounds so only one component is grounded so you have a star-grounding configuration.

Steven Stone
Contributor to The Absolute Sound, EnjoytheMusic.com, Vintage Guitar Magazine, and other fine publications

wayne325 -- Sun, 09/12/2010 - 15:26

Ummmmmm.
Steven, I hate to burst your bubble but you didn't solve any problems by using a cheater plug. All you did was create another potentially larger one that you perceive as fixing the problem because it caused a SYMPTOM of a problem to go away.
By using the cheater, you've merely lifted the ground so as to get rid of the ground currents that were causing hum in your system. Thereby also rendering your equipment unsafe should a fault occur.
Finally, you do not know that you have a star grounding system as a result of lifting your ground. In order to determine that, you would have to know the ground connections inside your equipment. Furthermore, even if you do have what you think you have, it is dependent on low current capacity audio cables to carry deadly currents around your system should a fault occur.
Your advice is particularly bad in that you are foisting upon unsuspecting readers a "solution" which at its worst can lead to people getting killed. I think it's also illegal.
To answer the original poster... I use polarized plugs in all my (home built) equipment (phono pre, pre, power amps, and DAC) which uses balanced circuits and of course balanced connections. My system is DEAD quiet unless your ear is basically beside the speaker drivers. My DAC uses transformers intended for DS3 signals for electrical isolation.
There was a GREAT article on equipment grounding I found on the diyaudio site a couple weeks ago which would help all with their grounding issues.

Steven Stone -- Sun, 09/12/2010 - 15:33

Can't burst my bubble, I've been doing this for 30 years sucessfully. My systems (three now, MANY over the years) have had hum problems solved by lifting grounds.

Illegal? Not in this universe.

I could call your solution crimially expensive overkill worthy of only a serious audio neurotic, but I won't...

There's more than one way to most things in audio.

Steven Stone
Contributor to The Absolute Sound, EnjoytheMusic.com, Vintage Guitar Magazine, and other fine publications

wayne325 -- Mon, 09/13/2010 - 08:09

Glad to hear you've had no equipment failures in 30 years. Your logic however, if I'm to unnderstand that what you really mean is along the lines of "I've never had a problem for 30 years and that is proof that what I'm doing is OK" is fundamentally flawed. In order to prove that your system is safe, you'd have to have it enter a fault condition, and then see what happens.

The fact remains, you have not solved your problem. You have simply masked its symptom. If you call that "success", my hat's off to you.

I found it odd that somone who spends more an a power cord probably than I spent on my entire system is calling a 3-conductor cord that's $5 from Digikey "criminally expensive overkill".

As to the legality, here's some text from the very first reference I opened after googling "ground lift nec":

(NEC is the National Electric Code for those who don't know)

I could go into the NEC and find the clause that says it's not allowed to lift the ground but clearly my time would be wasted so I'm not going to bother.

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Fort check that you have made the cabling between equipments properly. Proper audio cable connection methods are essential in getting humm free system. Rane technical note Sound System Interconnection is a very good source for information how the audio wiring between equipments should be connected. This is a well worth to read article.

Breaking of ground loop can be done in many ways, some which are better and some are less good.

Dangerous method: break the mains ground connections
Logically you could think, you could eliminate ground loops by disconnecting the power-cord ground pins on all your gear. Some people might try to break the ground connection by cutting the grounding pin in the connector, using cheater plug, cutting the ground wire in equipment, taping over the grounding connector etc.

Do not do this. Removing the ground connection isn't right. It is against electrical safety regulations and potentially very dangerous. Removing ground connection can defeat the actions of your noise filter or spike protectors inside the equipments. If the ground connection is cut then a fault in the isulation inside equipment will cause dangerous voltages to the equipment case instead of burning a fuse. Removing the ground connection from the equipments which have it is dangerous, against electronic safety regulations and you risk damaging your equipment. Running without a power ground will not automatically electrocute you but will make this much more propable if something goes wrong in your system.

NEVER use a three wire to two wire adapter on ANY piece of audio gear where a human can POSSIBLY come into contact with it. You're asking for a nice 120v "signal" thru someone's body. Yes it MIGHT eliminate the hum, but there's a MUCH safer way to do the same thing.