[jzono1]

Balanced audio is pretty popular here, for source->amp->headphones. I'm just wondering if balanced mains is effective for improving noise rejection on the way from the power plant to my components.

Here in Norway, mains power is usually balanced, all the way from the power plants. It started with a bogus belief about -115V/+115V being safer than 230V/0V, and they kept doing it.

Lately I've seen stuff like the russandrews mains balancing equipment. Is it just regular snake-oil or is it useful?

Do mains power transformers perform better when fed with balanced mains vs. live/neutral?

 

[Armaegis]

If the idea is to reduce ground loops and DC hum, the problem is still at the consumer end since it is the components and at the end which cause the DC offset.

Granted, I don't know how Norwegian power is "balanced" ("isolated" is probably the proper word here). If there's an isolation transformer at every outlet outlet or breaker, then your chance of ground loops should be reduced.

 

[jzono1]

The safety idea is that 115V to ground isn't as dangerous as 230V to ground.

No, the power is balanced, where you normally have live/neutral, here we have live/live, at 115V and -115V.

 

[jcx]

ART. 647 — SENSITIVE ELECTRONIC EQUIPMENT
An Article covering the wiring requirements for “Technical Power” or “Balanced Power Systems” was added to the 2002 NEC. Technical power is a separately derived, 120V line-to-line, single-phase, 3-wire system with 60V to ground from each ungrounded conductor. Technical power systems reduce objectionable noise in sensitive electronic equipment locations. They are restricted to commercial and industrial occupancies under close supervision by qualified personnel [647.3]. You cannot install them in dwelling units.

Intent: Technical power has been permitted in the NEC since 1996. However, it was located in Art. 530 — Motion Picture and Television Studios and Similar Locations, so its use was limited to these applications. By locating the requirements in a separate Article, its use can be greatly expanded.

equitech has some articles, explanations pushing the idea

Index of Technical Articles About Balanced Power

the above NEC commentary applies to permanent outlets - a free standing power conditioner wouldn't be covered - although it may still have safety consequences


Bill Whitlock's seminar notes covers some of the AC line side causes of the problems as well as the signal level balanced/transformer solutions Jensen supplies

JENSEN TRANSFORMERS, INC. - APPLICATION PAPERS AND SCHEMATICS

 

[Steve Eddy]

Speaking of Bill, I sent him an EMail back on September 17th, 2006 regarding an anomaly I'd noticed in the square wave response of one of their 11P-1 input tranines.

I didn't receive a reply and soon forgot about it.

Then last Sunday, I get an EMail out of the blue from Bill.

It began "I won't even try to explain why this reply is so late (long, long story) ..."

se

 

[Budgie]

I use balanced +60vac/-60vac power, created by transformers, from N. America's typical unbalanced 120vac. Then into pi network noise filters. It works well and no dimmer noise, motor noise, or other junk seems to get past.