Balanced AC power?

[tedmich]

BALANCED POWER SUPPLY



the review ends with:
"Goertz Audio’s BP1000 balanced symmetrical power supply is an apparently simple product with a unique design, all wrapped up in a small, unassuming package that will simply disappear into your system"

for $433

Looks like a huge 20lb toroidal transformer, is ass-ymetric AC power a big problem?

[Enzo]

I don't know what these guys are doing, but from what I recall, balanced power means having a CT to ground. Common household wiring has a 120v hot and a neutral bonded to ground. In balanced they put a CT to ground, so there are now two hots of 60v each. Does it really do anything useful? Beats me. As with any audiophile stuff, there will be some people praising it to heaven with a night and day experience.

[Leo_Gnardo]

Some audiophools claim balanced power is a superior way to supply AC to your hi fi system. Who knows, maybe they're on to something.

Good story: ShowPower supplied power for the 1987 Bowie tour I worked on. We started in Europe and I mentioned it would be a good idea to have a stable AC supply for stage. Next thing I knew SP's boss John Campion wheeled in a huge 800 lb constant-voltage transformer mounted on a big steel frame with extra heavy wheels to match. It did hold stage voltage to plus or minus three volts BUT its output was balanced. 60 VAC to ground from hot and antiphase 60 VAC from the line we usually have as neutral. "No worries" said John and everything ran just fine for 87 shows around Europe, North America, Australia and New Zealand.

Medium story. Running backline for a band at Midem festival 1998 in Cannes. French PA company supplied 120V to stage with a big autoformer, a good 100 pound chunk of iron and copper. Voltage read perfect from ground to neutral, but these guys gave us the upper "leg" of the autoformer. 120VAC from hot to neutral, and 120V from neutral to ground. OOPS. Neutral wasn't neutral. Band brought their own AC strips from the USA, bought from Radio Shack. No USA style plug strips available in Europe, you gots to bring your own, that's the way it is. The Shack plug strips had built in "safety feature" that would not pass power to the outlets if it read over a certain small voltage between neutral and ground. So I cracked open those plug strips, and bypassed the "safety feature." After this, measured with a meter between gear & microphones, no deadly voltage found. On with the show and no shocks, no smoke, no busted gear, WHEW, got thru that one.

Not so good story: Trying to do a show at BB King's club in New York City, February 2004. House sound man says the place was wired up by an Israeli physicist with - balanced power - to minimize hum and whatever else it might miraculously do. He must have done more than that, because all the "house" gear ran great, but all the "guest" gear hummed like crazy. Show went on two hours late after swapping out the band's monitor mix system for the club's and of course none of the monitor mixes were right all thru the show. Talk about some PO'd rock stars. This being the "showcase" appearance and after that screwup, not a single promoter bit. End. of. tour. after one show. Also scrapped trying to multitrack record the band that night. I told the in house guy, you don't need an Israeli physicist, you need a New York City (UNION) electrician.

Balanced AC power maybe isn't the "blue sky solution" to everything. And if you have equipment that objects to a neutral that's not at or near ground potential, from plug strips on up, it can spell trouble.

[Tom Phillips]

Ballanced AC power systems have been around for ~20 years. My understanding has been that it can be an advantage as an integrated system but you can get into trouble when you mix in equipment connected to a standard line supply system. I thought that special permitting was required. The product in post #1 is the first I have seen of a small balanced AC power unit.

There is a lot of information including several white papers at Equi=Tech "The Pioner of Balanced Power" . I have read their literature on & off for several years. It's very interesting but I have never utilized balanced power.

Cheers,
Tom

[Leo_Gnardo]

The product in post #1 is the first I have seen of a small balanced AC power unit.

There's also the effect of "cleaning up" the AC by passing it thru a transformer, tends to filter hi frequency noise and correct misshapen waveforms to something more like an ideal sine wave. That could be half the battle. Plus whatever other line conditioning gadgets they may have included in the package.

I don't see where the power transformers in any of the usual audio gear would care whether their input comes from a balanced or unbalanced source. Gear that's powered by switching supplies, I have insufficient knowledge to make a guess. Balanced or not, the same current travels in the hot and neutral, or hot and antiphase hot so I don't see how one would "throw" a noise field more or less than the other. Balanced mic & interconnect I understand just fine. Balanced power, I guess I can read the company literature but then again, they are going to tell whatever story they need to, to convince people to buy their product. Is this a solution in search of a problem? Lots of that going around.

[S2udio]

Looks like a torodial tx in a plastic box to me.....
More audiophile BS
true Balanced mains power does not really exist.....unless you tap the centre for a "Safety" earth connection,
As in a building site mains transformer , amazes me the myth and misinformation that surrounds this subject.
Another opening for the marketing scammers.

[km6xz]

For some applications like a measurements lab or a studio balanced power is measurably and probably audibly quieters in the resulting output of devices running on it. But a road sound system is the last place noise would be a major issue. Based on the last few concerts I attended, noise was an improvement. Isolated power would be helpful in a touring rig regardless of where the ground return is. After investing in the Equi-Tech system noise floors dropped, in both the lab test gear and recording studio so I am a big proponent it for it in signal chains that can justify the cost with increased billing. Never for a home stereo, touring system etc since it is expensive for a proper instillation and equipment. The studio ran balanced power at the output of the ferroresonant regulating transformers. Most people install regulating transformers in a conventional unbalanced but isolated configuration and even that helps since the hi-Q of the resonate transform suppresses harmonics and noise at frequencies removed from 60hz[50hz for the rest of the world].
As an isolation transformer along, the plug in device pictured in the first post could be a safety benefit but I doubt it would improve any sound system, particularly not a high gain guitar amp that has far more sources of noise to contend with such as pickups self-generated noise in high gain stages that would still be noisy if run on batteries 50 miles from the nearest power line.
If this unit is needed in a typical musician system, I would think fixing the problem directly, instead of filtering or balancing power, would be the preferred first step. There is no plug and play magic pill to solve most of the problems that people assume will eliminate noise.

[J M Fahey]

FWIW I had some sort of "balanced power" in my old home/lab , over 30 years ago.
In Argentina we have always used 220V but means to send that to homes changed with system build date and contractors.
Never saw DC systems, although it seems they were available up to the 1920s .
Next "improvement" was 220V AC and one British contractor wired homes with 2 x 110V AC lines, in series and with the center tap grounded.
European type 2 round leg plugs, not keyed, they can be inserted both ways.
*Maybe* the idea was user safety ... or simply they used some surplus "USA type" stuff (transformers, switchboards, etc.) to save money.
Fact is that it was *horrible* , no real ground (2 pin plugs, remember?), all amps buzzed in some degree.
Oh well.

By the way, we now use star 3 x 380VAC everywhere, which gives 220V phase to ground.

[km6xz]

It is only a balanced system if the current in both legs are the same and phase opposite so the load has to be balances as well. With AC using 2 120 legs running into a home or office building, those legs are never with the same power factor and phase is not opposite when reactive loads might be tied to one but resistive loads on the other. Homes are good example, light switches are usually on one phase and outlets on another. Incandescent bulbs are resistive loads and the vacuum cleaner is not. So true balanced power systems are local to the load, where nothing else ties into it. Anything that could unbalance it cancels the beneficial effects. There is the safety aspect, reaching into a live, 60volts-to-ground circuit is not the threat to life or limb that conventional sources are.

[tedmich]

[50hz for the rest of the world]

there is 60Hz power a few other places, I believe, including the odd and unfortunate situation in Japan with 50Hz and 60Hz power coexisting!
Japan's incompatible power grids | The Japan Times

[Leo_Gnardo]

there is 60Hz power a few other places, I believe, including the odd and unfortunate situation in Japan with 50Hz and 60Hz power coexisting!

Done some music touring there. Used a rented Hammond B3 and Leslie built for 60 Hz, and the PA company brought a little "cycle converter" that we dialed up for the other when playing in non compatible areas.

It's gonna take about a bazillion yen to get those systems all on the same frequency. If ever. I tried opening the link, no dice. edit: got it now, good reading & thanx for the link. Interesting that there are a few 50/60 conversion stations. Must be some huge motor-generators. Which parts 50 & which 60, read the link.

Similar situation in Brazil, some areas are 50, others 60 Hz.

Rarely seen but still existing, 25 Hz power. Apparently some remote areas in Canada have this. Not good to run anything with a normal transformer. Must be fun to have the lights wavering in intensity.

I've heard some parts of Greenwich Village in NYC had DC power up 'til the mid 60's. Good thing this got fixed!

[tedmich]

heres anopther write up:
Japan?s two incompatible power grids make disaster recovery harder | Observations, Scientific American Blog Network

never had to run 400Hz on an aircraft carrier Leo? I once found a case of beautiful cast aluminum Rotron blowers, kept them for a while before realizing they here 400Hz...

[olddawg]

Generally the east coast of Japan is 60 Hz, and west coast 50 Hz. I may have that reversed, it's been a while. Done some music touring there. Used a rented Hammond B3 and Leslie built for one line frequency, and the PA company brought a little "cycle converter" that we dialed up for the other when playing in non compatible areas.

It's gonna take about a bazillion yen to get those systems all on the same frequency. If ever. I tried opening the link, no dice.

Similar situation in Brazil, some areas are 50, others 60 Hz.

Rarely seen but still existing, 25 Hz power. Apparently some remote areas in Canada have this. Not good to run anything with a normal transformer. Must be fun to have the lights wavering in intensity.

I've heard some parts of Greenwich Village in NYC had DC power up 'til the mid 60's. Good thing this got fixed!

When I was repairing consumer electronics, one of the ways we could identify black market units for warranty repair issues was the 50hz designation on the back of the unit. In most cases the units worked fine with the occasional PT failure. Smps have alleviated line voltage comparability problems somewhat nowadays.

[Leo_Gnardo]

never had to run 400Hz on an aircraft carrier Leo? I once found a case of beautiful cast aluminum Rotron blowers, kept them for a while before realizing they here 400Hz.

Aircraft like to run 400 Hz too. Never had the pleasure of being on an aircraft carrier. I should visit the one parked in NYC
sometime. Is a 400 Hz supply common to all naval vessels / equipment?

Did you ever try one of those motors on 120VAC just to see what would happen?

[km6xz]

60 Hz power usually does fine with 50 hz transformers but not the other way around. A lot more core losses and heat are the result from running 60hz transformers on lower frequency mains. Some core are large enough for it, some are not.
I have a Carvin bass amp here that a guy brought right from eBay purchase after it blew fuses when turned on using a large step down transformer. The 800 w amp has a large toroid and it will not run at more than 90 volts in 50hz as current increase quickly as the mains voltage is increased. The amp is fine, so is the transformer. Using a power amp with step up transformer and 60 hz sine wave driving it, all worked fine with low idle current and no heating of the transformer but dropping the frequency to 55hz doubled the line current and 50 hz doubled it again on idle so I did not have enough power to try any further. Conventional laminated cores have the same problem but less so.

I loved getting surplus 400 hz gear when I was a kid since I could carry it on my bicycle from the McClellan Air base surplus disposal auctions. I saved up my money and would peddle the 4 miles and bid on anything that looked interesting that I could get home as a 10-year old on a bike or pulling a wagon. The 400hz stuff was so much lighter that I could get more interesting transmitters and receivers or test gear for my $1 to $5 bid. By the time I was 11-12, I could see any military module or subassembly and tell what it came from as the next larger assembly. Same with test gear of the time.

I had my own high voltage power supplies so those DC dynamotor or vibrator supplies just got ripped out anyway. Motor regenerators were available as were dynamotors but they were noisy and pulled a lot of current from 14 or 28 volts. Vibrator power supplies were quieter but vibrators were limited in current to about 4 amps switching current. For younger people vibrators were not woman's sex toys but important methods of generating higher voltages from battery power in your parents or grandparents era. They were an identical precursor to the SMPS, chopping DC at a high frequency and using a relatively small transformer to get higher AC that was then rectified for B+, C- etc. Dynamotors were used for higher power, up to 1000 watts. They were self contained low voltage DC motors driving in integrated high voltage DC output generator,

When I got my own plane, years later, a Piper Arrow, I was happy to learn that what I had learned as a kid still applied to the wiring and power. I completely restored the plane myself except for paint which I contracted out for a very non-traditional artistic design but I did everything else myself from electronics to mechanics with a neighbor(closest neighbor was a 1/2 mile) who was a A&P signed it all off or told what I did wrong. General aviation had based the whole industry on 1930s technology and very few advances until things like cheap GPS became available in the early 90s. If electronics had advanced at the same rate we would be marveling at galena crystal radios now instead of the high tech that any school kid can afford. It is too bad that no one seems to know how anything works anymore, everyone is totally dependent on systems they do not understand. That is the first time in history when people did not know enough to stay alive without depending on external systems and money. If the next war involves cyber attacks on power and communications(absolutely guaranteed to be the main tools to paralyse the opposing sides) the only people to remain will be in primitive societies living in complete ignorance of modern dependent life of developed countries. Look around and see what you have that will aid you when power , and communications goes down. No food, no gas can be pumped or paid for, no internet so no commerse, gas heat or access to money in banks, no transportation, no control of systems that everything else depends on. There are majority of stores which can't ring up a manual sale. It will be a desperate time for hundreds of millions of people in developed societies who can't fend for themselves. Rural people think they are exempt but they are just as or more dependent and do not realize it. We see daily how ill-prepared corporations and governments are to protect communications and vital services that depend on data communications and single fault point systems. Those "hackers" invading systems apparently at will might be only probing or practicing.