Questions about balanced power, Experts please advise!

[DIY_newbie]

I've become interested in all this talk of balanced power. After doing alot of reading I'm quite confused and was hoping someone would clear up a couple of things..

How does balanced power remove/reduce noise in the existing AC that is delivered to my house? I don't understand how this adds anything beyond normal AC filtering?

Assuming that f(x) represents the waveform for the AC power that is being delivered to my home from the power plant.

If g(x) represents the noise that is pickedup by the powerlines before the electricity is delivered to my wall than the total waveform delievired is f(x) + g(x)

Doesn't converting this 120/0 to +60/-60 just give you f(x)/2+g(x)/2 and -f(x)/2 -g(x)/2 on the +60 and -60 V outputs respectivly?...

It would seem that what you really want to end up with is f(x)/2+g(x)/2 and -f(x)/2 + g(x)/2 ... IE, balanced power with all the noise as common mode. But this would require the power to be delivered in a balanced format from the powerstation already.

Now if g2(x) represents the noise picked up after the AC is converted to balanced power than we should have

f(x)/2 + g(x)/2 + g2(x) and -f(x)/2 - g(x)/2 + g2(x) ... So g2(x) should cancle out at the rectifier..

Am I missing something? Is the majority of AC noise pickedup outside the wall on the way to the components?

Thanks inadvance,

--Chris

[ThomasW]

https://web.archive.org/web/20051228063502/http://www.equitech.com/faq/faq.html

[DIY_newbie]

Thomas,

I looked through their faq.. In the "What is balanced power" section it says :

A balanced AC Power system works the same way as a balanced audio circuit but with a higher amplitude. Both balanced audio and balanced AC incorporate phase cancellation or common mode rejection to eliminate noise.


This is the basis of my argument.. Just like balanced interconnects cannot "add" or "remove" anything before they point the signal becomes balanced, I don't think a balanced powersystem can remove any noise that is already on the AC line before it reaches the transformer.. Balanced interconnects only reduce the amount of noise picked up on that actual interconnect. In the same way balanced power will minimize the noise picked up between the balanced transformer and the end equipment.

The way I see it the Transformer only adds isolation and then the inline AC filtering on each socket helps to keep the power clean. If this is the case, wouldn't it be much better to use 4 or 5 of the smaller Avel toroids (6.65A each) and have an individual one on each outlet? That should isolate each piece of equipment from each other?

--Chris

[ThomasW]

My experience with balanced power is that it removes noise before the equipment. And I think you're taking their balanced IC analogy a bit too literally.

Note that Equi=tech's sells big units that are mounted in-wall and designed to power everything in a very large commercial A/V system.

I have some experience with individual transformers since B-P-T used to sell a device with 4 small transformers designed for powering front-end gear. Only problem was it didn't sound as good as a single larger transformer.... go figure. That product is now discontinued.

If you're worried about isolation just use a separate EMI/RFI/ECM filter for each outlet. Note that I have balanced power devices with and without those filters. And I can't honestly say that units containing the filters provide a noticable difference over the transformers that don't have them.

[Dennis H]

The transformer itself will act as a lowpass filter, like a big ol' coil, so a lot of EMI/RFI will get filtered out before it ever gets to the filters on the outlets.

[ThomasW]

I do think it's beneficial to use individual filters on outlets that have 'digital' devices plugged into them. This means DACs, CDP, DVDP and anything that has a digital switching power supply. The goal is to keep them from dumping noise backward into the line.

My experience is that the benefit from additional BP units is cumulative. By this I mean I have every power amp plugged into BP, and every front end device into BP as well. Remove the BP from either the amps, or the front end gear and it's noticable

This is one reason why I think the 'blem' Equi=tech "Q" transformers are such a great deal. They can power several big amps each.....

[DIY_newbie]

If you're worried about isolation just use a separate EMI/RFI/ECM filter for each outlet. Note that I have balanced power devices with and without those filters. And I can't honestly say that units containing the filters provide a noticable difference over the transformers that don't have them.

Suprising I would guess then that the main advantage would come from filtering on the incoming AC line of some type...

The transformer itself will act as a lowpass filter, like a big ol' coil, so a lot of EMI/RFI will get filtered out before it ever gets to the filters on the outlets.

Ahh there's the answer... If the Transformer acts like a low pass filter that would explain why adding balanced power can remove problems picked up in the power grid.. Wouldn't that imply that you would also want some sort high voltage capacitor to shunt the EMI/RFI ?? Basically converting this psuedo-first order filter to second order??

--Chris

[ThomasW]

Wouldn't that imply that you would also want some sort high voltage capacitor to shunt the EMI/RFI ??

Yes that's why you see shunt caps in all the projects I built as well as an example from B-P-T. And that's why I posted those links to threads where these and other projects were discussed.







Image not available

[cdwitmer]

Within their power ratings, are there big differences among balanced power xfmrs?

Obviously, the Equi=Tech blems are the Yokozuna of DIY balanced power transformers, but I'd like to know whether there are significant AUDIBLE and/or FUNCTIONAL differences among the various toroidal transformers used by balanced power DIYers (Equi=Tech, Plitron, Toroid of Maryland, Avel-Lindberg), assuming the transformers are only used within their specified ratings. I suppose I am concerned about each transformer’s: 1) ability to improve the sound quality of audio when AC power conditions are less than ideal, 2) soft-start ability, and 3) freedom from mechanical self-noise. I would be grateful if someone in the know would give their opinions on each of these four brands relative to the others.

I also have another question: as long as I prevent heat buildup, would it be okay to build a false top on my subwoofer cabinet and attach the balanced power transformer and other components directly to the 42mm thick plywood of the cabinet? At its closest point, the back side of the subwoofer motor would be at least 30cm distant from the transformer. Should I also have the components surrounded by metal for shielding?

Many thanks!

Christopher Witmer
Tokyo

[DIY_newbie]

Thanks for all the replys everyone. I've went ahead and placed an order with Equitech for one of the blem units I also ordered 10 isolated ground hospital outlets (Leviton 8310-IG)



ThomasW, How sturdy is the original box it comes in? Would it be possible to paint the original box and make it look proffessional or do I need to change it out for one of the par-metal chassis? Also, I did notice the Caps you put on the output recepticles, I was asking about adding additional filtering on the input of the toroid. I noticed that some companies sell filtered IEC outlets, as well as vishay/dale has an entire line of "AC filtering capacitors"...

Still looking for some EMI/RFI filters but hows this sound so far?

--Chris

[ThomasW]

Christopher & Chris,

With the exception of the Maryland company (BTW they're known from making noisey transformers) I've used all the brands listed. And all do basically the same thing and have the same beneficial impact on the A/V system.

The Equi=tech is pretty much in a league of it's own. It's the quietest under load. It's also inherently soft-starting, the Plitrons are not soft-starting. And given it's very high mass the Equi-tech runs the coolest. The one mounted in my basement is barely warm to the touch under load.

The "Q" 'blem's' are mounted in a stock enameled steel utility box. (go to any home center store and look at breaker boxes in their electrical dept for an example). It can certainly be painted and mounted where ever you want. Note that it weighs in at 80lbs. The steel box does flex and is actually designed to go between studs 16" OC. Since the utility box wasn't designed for a load like the Equi=tech, it is slightly warped by the pressure from the single transformer mounting bolt

If you go with a Par-Metal chassis it will need to be sufficiently braced to support the weight of the transformer. I had to do that for my DIY Plitron tranny and it weighs 1/2 that of the Equi=tech

B-P-T puts shunt/blocking caps on the AC line-input. I decided to put them on the outputs

There are special "X/Y" rated caps available for AC line filters. They're pricey. Their claim to fame is that they don't short out if the cap fails.

Personally I don't see any reason to pay a premium for special filtered outlets when a simple shunt cap will do the same thing.

If you scan the our other BP threads you'll find where I posted a link to some very reasonably priced EMI/RFI filters from a surplus house. I don't remember the link right off hand.

[DIY_newbie]

Thomas,

Thanks for the quick reply. I'll probably use individual EMI/RFI filters on each outlet and a shunt capacitor across the output terminals like you did. I got a pretty sweet deal on those Leviton 8310 outlets.. If anyone else is looking their going for $3.99 on ebay, $3.85 shipping for the first one, $0.45 each additional.. So I got all 10 for around $47, and they retail for $12 each

I started looking at EMI/RFI filters and honestly got lost in all the different types, ratings, leakage currents... I think I ended up more confused than educated from looking Any suggestions on models to look for?

--Chris

[ThomasW]

That's a good deal on the receptacles where did you buy them?

Here's the low-buck filter link.

https://web.archive.org/web/20061113135808/http://www.excesssolutions.com/cgi-bin/category/11700

Don't get all fixated on the specifics of the filters. Just buy the amperage rating you want.

BTW, we discussed filters in this thread.

https://www.htguide.com/forum/showthread.php?t=12758&highlight=EMI%2FRfi+filter s

If you really want to get fancy, put a single 20A filter on the AC line input and individual ones on the outputs rated to the specific ampere rating you intend to plug into that specific receptacle. If in doubt about the ampere rating for the outlet buy filters with a higher than needed rating.

[Glen B]

Thomas,

Thanks for the quick reply. I'll probably use individual EMI/RFI filters on each outlet and a shunt capacitor across the output terminals like you did.
--Chris

If you use individual EMI/RFI filters on each outlet, you really don't need differential caps as well. The latter will be redundant because the EMI/RFI filters already have differential caps in the circuitry. In balanced power units from BPT et al, there are caps across each AC outlet because there is only a single EMI/RFI filter feeding a bank of outlets.

EMI/RFI Filter Circuit:

[DIY_newbie]

Here's the link to the outlets for anyone interested :

Link not available

I haven't received them yet so I can't comment on delivery etc...

I'm sending a money order tomorrow so I'll keep you guys posted..

Thanks for the link to the filters, I'll start looking again

FYI: PE is having a sale on Hospital grade 3 prong and IEC plugs ($8, and 17$ respectivly)

--Chris

[Glen B]

Here's the link to the outlets for anyone interested :

Link not available

I haven't received them yet so I can't comment on delivery etc...

I'm sending a money order tomorrow so I'll keep you guys posted..

Thanks for the link to the filters, I'll start looking again

FYI: PE is having a sale on Hospital grade 3 prong and IEC plugs ($8, and 17$ respectivly)

--Chris

Note:
In some circles, Leviton receptacles have been noted to start out sounding good only to have the character of the sound change over time. Do what you want with this information. :roll:

[DIY_newbie]

Note:
In some circles, Leviton receptacles have been noted to start out sounding good only to have the character of the sound change over time. Do what you want with this information. :roll:

Well myself being an engineer I really look at the technical side of things.. The only real reason an AC outlet can "start to sound bad" is if the quality of the contacts degrade. Most AC outlets, including leviton, have brass contacts which over time will corrode, pit, and start to make worse and worse electrical contact. The 8300 series is nickle plated brass. Nickle plating resists corroding EXTREMLY well. Also, all the hospital rated outlets have to apply positive clamping pressure and have to do this for a ridiculously high number of insertions and removals. (I think its on the order of several 1000) .. Those two things combined should guarantee reliable electrical contact for a long time If not, maybe I'll just get 10 more at this price and replace them as they go bad

Regards,

--Chris

[ThomasW]

Okay, moderator's pre-emptive strike.......... before this goes any further lets just say some people hear differences in things like this and others don't. The isn't a tweaks forum, so I won't tolerate never ending debate/flame fest about what's audible and what's not.

People should build stuff using the components they like....and not pass judgement on the components used by others. That creates a win-win situation for everyone.... :wink:

[DIY_newbie]

Thomas, Glen,

I appologize if my comment was taken as the start of a flame war.. It was not meant in that way. I'll delete it or edit it if you would like me to.

I was just explaining why I'm of a cynical nature about things. Being an engineer I want to graph/chart/calculate something to prove to myself I'll see/hear a difference before I start any project.

The purpose of my last post was to give my justification for why I felt that Hospital Grade Isolated Ground outlets were of superior performance to houselhold grade.. Will the outlets really corrode enough to affect the sound or loosen so they don't hold the plug well over the next 3-4 years... Probably not, but the peace of mind knowing that they met hospital regulations was worth the extra $2/outlet

--Chris

[Glen B]

Chris, you've got nothing to apologize for. I hope we get to see some pics when your project is completed.

[DIY_newbie]

Chris, you've got nothing to apologize for. I hope we get to see some pics when your project is completed.

Yeah me too.. Problem is I have like 4 projects goin on at once.. so it may be a while... BTW: I Think the bright orange/red outlets will look pretty sweet

1) FountekJP2.0/PR170 open baffle (waiting on repaired jp2.0 after I blew it up)

2) TC2+ H-baffle bass cabinet to go with the project #1 (waiton on TC2+ drivers)

3) Installing my DLP projector in my new home (waiting on me to actually buy a ladder so I can hang the screen... Kinda hard to buy a ladder when you're only car is 2 seat vette )

4) Balanced power project (I shouldn't have started it but all those threads by ThomasW sorta peaked my curiosity)

--Chris

[DIY_newbie]

I was thinking of putting a couple of these Panel Meters on the top too :twisted:

They're 2.5"x3" each



Image not available

--Chris

[Saurav]

1) FountekJP2.0/PR170 open baffle (waiting on repaired jp2.0 after I blew it up)

2) TC2+ H-baffle bass cabinet to go with the project #1 (waiton on TC2+ drivers)

Is there anything else between the TC2+ and the PR17? If not, what's the XO frequency between them? I want to try a dipole woofer under my PR17s too, but don't know what to try.

[Occam]

Transformer characteristics and balanced power

Transformer characteristics have a large impact on the efficacy of balanced power implementations.

Those characteristics can roughly be divided into 2 areas

1. Characteristics as an isolation transfrormer/filter

Transformers are wonderful at dealing with common mode noise, and in conjuction with capacitors accross the line, X2, which take differential noise and make it more common mode, make wonderful filters. (I avoid Y caps (to ground, for other reasons...).

The bandwidth of a powerconditioning transformer also affets performance, as we're really not interested in passing anything other than 50/60hz. Toroids have very high bandwidth, not ideal, but have substantial benefits with regards to size, radiated field, and economy. Split bobbin EI core, r-core and double-c core transformer offer substantial benefits with regards to bandwidth, but are more expensive, harder to find, and have substantially larger radiated fields.

Another mechanism for noise coupling is the capacitive coupling between primary and secondary. Within a properly implemented toroid balancing transformer, Equitech, BPT, specific Plitrons and Avels, there will be a interwinding shield to minimize this capacitive coupling, substantially lowering coupling and leakage. Same thing applies to overwound EI core transformers, but in the same way, this can be addressed by and interwinding shield. Split bobbin, r-core and double c-cores address this via the physical separation between primary and secondary.
Any transformer specified as 'medical' typically also has an interwinding shield. The Avels obtainable from PartsExpress lack that interwinding shield.

2. Those benefits soley attributed to balanced power-
This has been discussed in other posts and deal primarily with the 'canceling' of leakage noise. Performance is substatially affected by the accuracy of that balacing, with bi-filar winding, whether on a toroid or EI core being ideal.

Its relatively easy to evaluate the specific benefits of both the isolation/filtering, with and without the balancing. You simply put a SPDT, center off, switch on the ground. This allows you to switch between isolation, where you either float the center tap giving floating balanced or bond the ground to one of the output legs giving a classic isolation transformer, or connect the ground to the center tap giving real balanced output. Its quite illuminating to evaluate the benefits of isolation/filtering alone, as well as isolation/filtering with true balancing.
FWIW

[ThomasW]

Paul,

I have a pair of the original Tice PowerBlock/Titan II (2- 60+lb E-lam isolation transformers) These make some improvement in the sound/video, but there's more benefit available using any of the balanced units I have (Plitron/Avel/Equi=tech).

I keep the Tice unit in the most critical circuit, because it's a multi-tap unit that adjusts the AC voltage level. My house voltage chronically runs higher than 120V

[Glen B]

I keep the Tice unit in the most critical circuit, because it's a multi-tap unit that adjusts the AC voltage level. My house voltage chronically runs higher than 120V

How bad does your voltage get ?

[ThomasW]

125-127vac

[Occam]

Paul,
I have a pair of the original Tice PowerBlock/Titan II (2- 60+lb E-lam isolation transformers) These make some improvement in the sound/video, but there's more benefit available using any of the balanced units I have (Plitron/Avel/Equi=tech).

Thomas,

If your point is that balancing is preferable to just isolation, we're in complete agreement. My last comment was specifically an easy way to empirically verify that assertion. Comparing a Tice EI core isolation transformer to a toroid balancing transformer simply leaves too many variables to draw any conclusions as you're comparing apples to fried clams.
While it is well and good to defer to the opinions of those you trust, when the opportunity presents itself to easily check it out for oneself (what can be easier than inserting a spdt switch?), its always an illumminating experience, or as my intellectual hero said -
"When you come to a fork in the road, take it."

Regards,
Paul

[cdwitmer]

I have two more questions, if anyone doesn't mind enlightening me further.

First, is capacitive coupling between the primary and secondary windings in Avel Y23 transformers (due to the lack of an interwinding shield) likely to make a noticable difference in the performance as a balanced power transformer? Would a certain set of conditions have to apply before the difference became noticeable? (I get the impression from what Paul wrote above that common mode noise could be carried over to the secondary side by capacitive coupling.)

My second question is, would anyone care to comment on this statement by Bill Whitlock of Jensen Transformers? --

"Balanced power, or more properly symmetrical power, is a seductively appealing concept illustrated in Figure 28. However, its proponents mistakenly assume that each piece of equipment has precisely matched capacitances from each leg of the power line to chassis in their explanation of how it "cancels" ground noise. Of course, if this were true, capacitive noise currents from each 60-volt leg would then be of equal magnitude and opposite polarity, and would completely cancel each other. But this assumption isn‘t true for the overwhelming majority of real-world equipment, where ratios of capacitances C1:C2 or C3:C4 are often 3:1 or 4:1. It's unlikely that equipment manufacturers will ever adopt costly power transformers having capacitively balanced windings or RFI filters having precision capacitors. Even balanced power proponents admit that actual noise reduction is usually less than 10 dB and rarely exceeds 15 dB. For audio, a 10 dB improvement will rarely make the difference between unacceptable and acceptable system performance. In fact, many of the benefits ascribed to balanced power and other conditioning are due to simply plugging all system equipment into the same outlet strip or dedicated branch circuit. Whenever possible, this is always a good idea!"

Actually, it seems to me that a 10dB improvement is nothing to sneeze at, but does he have a valid point here?

Thanks!
Christopher Witmer (Tokyo)

[Glen B]

I have two more questions, if anyone doesn't mind enlightening me further.

First, is capacitive coupling between the primary and secondary windings in Avel Y23 transformers (due to the lack of an interwinding shield) likely to make a noticable difference in the performance as a balanced power transformer? Would a certain set of conditions have to apply before the difference became noticeable? (I get the impression from what Paul wrote above that common mode noise could be carried over to the secondary side by capacitive coupling.)

My second question is, would anyone care to comment on this statement by Bill Whitlock of Jensen Transformers? --

"Balanced power, or more properly symmetrical power, is a seductively appealing concept illustrated in Figure 28. However, its proponents mistakenly assume that each piece of equipment has precisely matched capacitances from each leg of the power line to chassis in their explanation of how it "cancels" ground noise. Of course, if this were true, capacitive noise currents from each 60-volt leg would then be of equal magnitude and opposite polarity, and would completely cancel each other. But this assumption isn‘t true for the overwhelming majority of real-world equipment, where ratios of capacitances C1:C2 or C3:C4 are often 3:1 or 4:1. It's unlikely that equipment manufacturers will ever adopt costly power transformers having capacitively balanced windings or RFI filters having precision capacitors. Even balanced power proponents admit that actual noise reduction is usually less than 10 dB and rarely exceeds 15 dB. For audio, a 10 dB improvement will rarely make the difference between unacceptable and acceptable system performance. In fact, many of the benefits ascribed to balanced power and other conditioning are due to simply plugging all system equipment into the same outlet strip or dedicated branch circuit. Whenever possible, this is always a good idea!"

Actually, it seems to me that a 10dB improvement is nothing to sneeze at, but does he have a valid point here?

Thanks!
Christopher Witmer (Tokyo)

The performance of a transformer like the Avel that does not have an electrostatic shield is clearly not going to be as good as one that does have a shield. You should be going into the project with the understanding that it is a budget (and fun) project and you SHOULD expect a tradeoff in using a transformer that was not designed to be used as an isolation tranny.

With regard to Bill Whitlock's statement, I would say take it for what it is, an opinion. Many of us using balanced isolation transformers ranging from the budget DIY projects to the BPT, Equi=Tech and other similar products have found some noticeable improvement in our systems and that is what's important. The fact that YOU can hear a difference is what matters.

As was suggested in another thread regarding EMI/RFI filter choices, please don't over-analyze the project. Just build and enjoy. Any significant noise reduction is better than nothing. As you so rightly observed, a 10dB improvement is nothing to sneeze at. I will defer to others to give a more in-depth technical analysis.

[cdwitmer]

Thanks, Glen -- very much. If I was in the USA I would have stopped asking questions and built something by now, but in my case all the components have to cross the Pacific Ocean to reach me (read: major shipping expenses), so I want to look carefully before I leap. Actually, I can also buy components locally, but my research tells me that even with shipping I still come out ahead by buying overseas. In fact, I would love to go with a pair of the Equi=Tech Trannie in a Box blems without hesitation if it was only somehow possible to send them from the USA via surface mail, which has a maximum weight cap of 70 lbs. . . . is there any way to "disassemble" those units to a point where the toroidal transformer itself can be packaged to squeak under the post office's 70 lb. limit? (I could also use a private freight forwarder but by the time I pay someone to bring them through Japanese customs the money involved gets to be rather outrageous.)

-- Christopher Witmer (Tokyo)

[JoshK]

Christopher,

I would suggest you first look to transformers available locally, even if they are not large behemoths like those found on Equi=tech's site. Paul and I have found exceptional results with a balanced/isolated/filtered design using smaller transformers on source equipment. The results where actually astonishing and much greater than anticipated. It was also a fairly inexpensive experiment. If you can find a surplus center that sells some balanced transformers (w/ shield, etc) cheaply then pick one up, experiment and if you like what you hear then you can order a big boy here in the states and ship. Less to loose.

[ThomasW]

Christopher,

I think the weight is an issue best taken up with Equ=Tech. Unfortunately I think the trannys themselves are very close to 70lbs.

The other option is the Plitron. The raw 'Secrets OF HT' tranny is approx 35 lbs

[Glen B]

I would love to go with a pair of the Equi=Tech Trannie in a Box blems without hesitation if it was only somehow possible to send them from the USA via surface mail, which has a maximum weight cap of 70 lbs. . . . is there any way to "disassemble" those units to a point where the toroidal transformer itself can be packaged to squeak under the post office's 70 lb. limit?

The 2kVA Equi=Tech tranny removed from the box is approximately 60lbs. measured on my digital bathroom scale. The transformer is attached to the box with a single bolt in the center, so yes it is easy to disassemble.

[ThomasW]

That's good news Glen.

Surround it by 6" of heavy duty foam and Christopher should be under the 70 lb limit... :wink:

[DIY_newbie]

A quick update on my project:

Equitech transformer arrived, nicely double packed. This thing is a beast, the pictures thomas posted don't do it justice..

Leviton 8310 isolated ground outlets arrived. They came nicely packed in a 10 count box. Brand new and never been opened just as described.. I highly recommend purchasing from Herb at the link I posted earlier if you need some nice oulets

Meter panels arrived. A little "cheaper" build quality than I would have liked but for this purpose will work just fine. I tested the 150V AC meter in an outlet, reads 125V on the line and rock steady. I tried testing the 15A meter but did not give it sufficient load, ended up with an EXPLODED meter, two vaporized wires, and black soot all over my hands ... I think I got off lucky though...

Filters are still in the mail, should arrive by UPS on monday.

Internal wiring will be 10gauge red/black for the "hot" wires, and 16gauge green for the ground line.

I still need to find an IEC jack and rocker switch to power the sucker.. Any ideas? PE is backordered on IEC jacks until 6/1

--Chris

[ThomasW]

www.apexjr.com has these in their 'new arrivals' section

[Glen B]

I still need to find an IEC jack and rocker switch to power the sucker.. Any ideas? PE is backordered on IEC jacks until 6/1

--Chris

Digikey Corp.

May I recommend ?

Schurter 20A IEC inlet, Digikey part #486-1015-ND.

http://dkc3.digikey.com/PDF/T052/0898.pdf

and

Carling M Series rocker switch breaker, Digikey part #432-1041-ND.

http://dkc3.digikey.com/PDF/T052/1182.pdf

[ToddAnisman]

Just wanted to add my .02 here....scanned the thread and didn't see this addressed...

the biggest problem in a home electrical environment is not so much the ground as it is the Neutral. electricians will share the neutral across many different circuits, regardless of where it may be attached, thus causing severe contamination of the line. The neutrals job is to return unused power to ground; there could be massive amounts of noise, hash, voltage etc in your neutral, and this will cause more noise problems than anything else. a Balanced power system has no neutral; and thus this is the reason it is superior from a noise perspective.

That being said, it is possible to wire around the problem, generally for less money than an equi=tech rig. (although I love BP...). The simple fix is to Homerun your Hots, Neutrals, and grounds for every outlet. This is serious wiring, but works really, really well. sometimes it's not practical, but for those who don't have th resources for a BP tranny, maybe a solution....

OK, hope this doesn't confuse anyone...

-Todd A.

[Glen B]

Just wanted to add my .02 here....scanned the thread and didn't see this addressed...

the biggest problem in a home electrical environment is not so much the ground as it is the Neutral. electricians will share the neutral across many different circuits, regardless of where it may be attached, thus causing severe contamination of the line. The neutrals job is to return unused power to ground; there could be massive amounts of noise, hash, voltage etc in your neutral, and this will cause more noise problems than anything else. a Balanced power system has no neutral; and thus this is the reason it is superior from a noise perspective.

That being said, it is possible to wire around the problem, generally for less money than an equi=tech rig. (although I love BP...). The simple fix is to Homerun your Hots, Neutrals, and grounds for every outlet. This is serious wiring, but works really, really well. sometimes it's not practical, but for those who don't have th resources for a BP tranny, maybe a solution....

OK, hope this doesn't confuse anyone...

-Todd A.

Not discussed in the thread but a well known issue -- circuits with daisy chained receptacles versus dedicated lines.

[Occam]

Cheap 'n Cheerful Balancing Power Conditioner

Christopher,

Given your difficulty in sourcing transformers specifically made for symmetrical power in Japan, I'd suggest the following cheap 'n cheerful experiment -
I believe there is a surplus electronics market in Tokyo, the 'Abracadabra'(sp) where you should be able to find dual primary transformers. Here in the States, I use these from BGMicro -

http://www.bgmicro.com/prodinfo.asp?sid=06961458333333332041281925&prodid=PWR1164&page=4&cri=PWR&stype=2

These are 175va split bobbin with dual primaries and secondaries for $9 each. I take 2 and wire both the primaries and secondaries in series and hook them up in an anti-missionary configuration, secondary to secondary, with a big honking 15uf motor run, polyprop in oil cap (<$4 NOS) accross those secondaries. Feed the 115v AC (or 100v AC in Japan) into the series wired primaries at one end, and get balanced power at the other end, after grounding the center tap of the series connected primaries at the output end. As we're constrained by the current capacity of the primaries, we derate these transformers to 1/2va, i.e. around 90watts, sufficient for most any single source component.
This is basically an extension of Jon Risch's QS&D iso trans with added balancing. Split bobbin trannies minimize capacitive coupling by physically separating the pri/sec, the balance is excellent at they typically wind the dual pri/sec bi-filar windings (not for the technical benefits, it just cheaper to do so) and the oversized cap (the optimal varies according to the trannies) provides massive filtering of differential noise without raising issues of current leakage as its galvanically isolated. Its so cheap, if you can find the components surplus, that its quite simple to provide each source component with its own cheap 'n cheerful balancing conditioner. I don't use any IECs or outlets, but simply cut a Volex 17605 in half and make a combination powercord/balancing conditioner, a boa constrictor digesting a cappibara. IMO, as well as some others, it works very well. Not as easy to do with power amps.....
FWIW

[cdwitmer]

Occam, that’s a razor-sharp idea! Although with the particular unit you selected, are you not limited to a maximum output voltage of 30V? Or can you end up with 120V output through a particular wiring scheme?

I just found a signal transformer that may be available to me locally with the winding arrangement shown in the diagram. Is this diagram telling me that I can boost from Japanese 100V to 115V with balanced output from the secondary side? -- because that would be ideal for my American-made power amps. (This signal transformer is plenty big enough to handle the load.)

Thanks!

Christopher Witmer (Tokyo)

[JoshK]

Chris,

Paul (Occam) and I were experimenting together (he lives in the general vicinity of myself) with this design. Paul is ultimately the ideas guy, but to answer your question, no, you end up with 120V in this case because you are using 2 transformers, one steps down to 30V, to which you put a cap across the live to neutral and then the other tranny is ass backwards and steps back up to 120V. It limits the total current this solution can deliver, but it is more than sufficient for a source or preamp.

I don't know what the policy of this forum is as far as pointing to other forums, but if you go onto audiocircle.com and browse in "the lab" you will see a thread detailing this scheme as well as some nicely drawn schematics that Paul provided.

[JoshK]

Oh, btw, the results were quite profound, and I did put in a dedicated line. We tried both before and after the dedicated line. In both cases it offered definite improvement over the wall and over an isolation transformer solution I had. I am very pleased with the results, and for the price to mock up one it is cheap to try it out yourself. It is also cheap enough to build one for each front end component. It doesn't solve filtering for your amps though, that is where the Equi=tech comes in.

[Occam]

Christopher,

Looks like you found a SignalTransformer HPI. Which model? They run HPI-12 thru HPI-35, which would give the VA rating.....just multiply those 2 digits by 100 and it tells you the VA rating (which you'll still have to derate by 50% for balanced symetrical use). These are classic interwinding shielded transformers, built like a brick shithouse.

You can use a single HPI alone to give you balanced power. Remember the primary and secondary voltages represent a ratio of voltage adjustment. If you wire the 'inside' 0 and 115 volt wires of the primaries together and feed your power to the 100v and 'bottom' 0 tap, and ground the center tap of the secondaries (the 'inside' 0 and 115v taps of the secondary) along with the interwinding shield, you'll get about 107v AC balanced, 100 x (230/215) [ignoring the transformer's 'regulation'] Not the 115V AC you'd ideally like, but closer, and a good compromise for running both American and Japanese voltage configured components.

I'd still put a big polyprop in oil motor run cap accross the outputs. This, in conjunction with the powertransformers in the components themselves will give you filtering of differential noise, but is also going to give you passive power factor correction. This is a technique touted by both Furman and Audience in their newer products -

http://www.google.com/search?hl=en&lr=&q=power+factor+correction&btnG=Search

Dunno which value, and you'll have to experiment, but given the size of these transformers, I'd start with 20uf and work upwards. The Japanese ASC motors run caps are excellent caps, better than the American manufactured versions. Use a 330volt or higher voltage rated caps.

Congrats! an excellent find.