DIY Balanced AC Power Conditioner

[Glen B]

I just recently completed construction of my DIY balanced power AC line conditioner and thought I would post some pics. It employs two separate transformers, one for analog components and the other for digital, each preceded by its own EMI/RFI filter. The two sections share only a common circuit breaker and IEC power inlet.

Parts List:
2,000VA and 250VA balanced isolation transformers.
Qualtek high-current EMI/RFI filters.
Furutech FP15A silver duplex receptacles.
Auricaps.
Pass & Seymour 20A dead -front GFCI switches.
Carlingswitch 20A hydraulic-magnetic breaker.
Schurter 20A IEC inlet.
Par-Metal aluminum & steel chassis.
Mono-crystal and OFC wire.
Miscellaneous hardware.

[jbandpc]

I would like more details on this. Can you post a link or more information on building this?

Thank you!

[Glen B]

I would like more details on this. Can you post a link or more information on building this?

Thank you!

I provided a basic description and parts list. I thought that would be enough for the reasonably knowledegable and experienced do-it-yourselfer. If you are looking for step-by-step details, I don't have any. Following are links to my post on the project at Audio Asylum, rough schematic and other information on balanced power.

The most basic implementation would be a balanced isolation transformer with the primary attached to a power cord plugged into a 120V outlet and the secondary attached to a duplex outlet into which your components are plugged. For safety, a 20A breaker rated for medium or long inrush current should be used on the primary and a ground fault interrupter should be used on the secondary. With a standard household supply, the neutral side is grounded. Balanced power uses two "hots," neither of which is grounded. With equipment connected to balanced power, what would be the normally grounded neutral side is now "hot." Any accidental contact with that now hot side poses a risk of shock.

How elaborate balanced power is implemented depends on the individual. Isolation transformers are great at eliminating low and medium frequency noise but not as effective with high frequencies and could allow such noise to slip through. An EMI/RFI filter placed before the transformer filters high frequency noise beforehand.

If you are not a skilled do-it-yourselfer experienced in working with household electricity, I would advise against attempting such a project. You are still dealing with as much electrical energy as a 15A or 20A household circuit will pass. That is enough to kill yourself or cause a fire if you make a mistake.

Post at Audio Asylum:
http://www.audioasylum.com/audio/twe...es/103826.html

My rough schematic:
http://img.villagephotos.com/p/2003-...ancedpower.jpg

Information on balanced power at Equitech Corp.:
http://www.equitech.com/articles/origin.html

Article on balanced power at Secrets of Home Theater:
http://www.hometheaterhifi.com/volum...er-8-2003.html

[skeptic]

I think your floating secondary is very dangerous. The voltage can drift all over the place with respect to the rest of the household wiring. This can be a real problem if you connect some components to the floating conditioned supply and some to household wiring. You should read applicable sections of NEC article 250 on grounding or get advice from an electrician or your town's building department electrical inspector. Look for specific information about grounded electrodes and grounding neutrals. IMO, what you should do is tie the neutral of the primary and one of the secondar legs together. this will bring the neutral through to the other side and establish the same reference zero voltage point for the conditioned side of the transformer as the rest of the system. BTW, it is illegal to use a circuit breaker or fuse on the neutral leg so be sure it's on the hot side. In case you haven't done it, you need to bring the safety ground through to the ground leads for your receptacles as well. They should be securely bonded. Get advice from expert help if you do not understand this.

[Glen B]

I think your floating secondary is very dangerous. The voltage can drift all over the place with respect to the rest of the household wiring. This can be a real problem if you connect some components to the floating conditioned supply and some to household wiring. You should read applicable sections of NEC article 250 on grounding or get advice from an electrician or your town's building department electrical inspector. Look for specific information about grounded electrodes and grounding neutrals. IMO, what you should do is tie the neutral of the primary and one of the secondar legs together. this will bring the neutral through to the other side and establish the same reference zero voltage point for the conditioned side of the transformer as the rest of the system. BTW, it is illegal to use a circuit breaker or fuse on the neutral leg so be sure it's on the hot side. In case you haven't done it, you need to bring the safety ground through to the ground leads for your receptacles as well. They should be securely bonded. Get advice from expert help if you do not understand this.

What are you talking about ? Before launching into what I consider to be a condescending diatribe, did you even look at the schematic ? Do you even know the first thing about balanced power ? Its funny that out of the many responses I received when I posted this project at Audio Asylum, no one else found a problem with the implementation.

Now, to respond in fact to your comments:

“I think your floating secondary is very dangerous. the voltage can drift all over the place with respect to the rest of the household wiring.”

The secondary is NOT floating. The center tap is grounded. The power company transformer supplying your home has the same balanced configuration with the center tap grounded at the pole with two 120V hots.

“IMO, what you should do is tie the neutral of the primary and one of the secondary legs together. this will bring the neutral through to the other side and establish the same reference zero voltage point for the conditioned side of the transformer as the rest of the system.”

Wrong. Tying the incoming neutral to one of the secondary legs will unbalance the system and defeat its purpose. The NEC recognizes that with balanced power the two hots are ungrounded and permits this. That’s why the NEC requires a GFCI on the secondary for safety.

“BTW, it is illegal to use a circuit breaker or fuse on the neutral leg so be sure it's on the hot side. In case you haven't done it, you need to bring the safety ground through to the ground leads for your receptacles as well. They should be securely bonded. Get advice from expert help if you do not understand this.”

I have the breaker in the hot line. The center taps of the transformer(s), receptacles, GFCIs and EMI filter cans are all bonded to the incoming ground.

I have been working with electricity for more than 36 years and don’t need advice from you. Read up on balanced power before you make criticisms and assumptions about my knowledge and capabilities. Although my profile says “newbie,” I have been posting at AudioReview in one of its previous incarnations since 1998. I would be happy to provide links to some of my old reviews.

[skeptic]

Pretty touchy GlenB. No I didn't look at your schematic. Now that I have, I've changed my opinion.

[Dual-500]

I just recently completed construction of my DIY balanced power AC line conditioner and thought I would post some pics. It employs two separate transformers, one for analog components and the other for digital, each preceded by its own EMI/RFI filter. The two sections share only a common circuit breaker and IEC power inlet.

Parts List:
2,000VA and 250VA balanced isolation transformers.
Qualtek high-current EMI/RFI filters.
Furutech FP15A silver duplex receptacles.
Auricaps.
Pass & Seymour 20A dead -front GFCI switches.
Carlingswitch 20A hydraulic-magnetic breaker.
Schurter 20A IEC inlet.
Par-Metal aluminum & steel chassis.
Mono-crystal and OFC wire.
Miscellaneous hardware.

Very nice. Please post schematic - if permissible.

What are the surge protection specs?

[Glen B]

Very nice. Please post schematic - if permissible.

What are the surge protection specs?

Sorry, I don't have a schematic. Surge protection is 210 joules. I have had similar levels of protection for the past couple of decades and never had an audio or video component fail. I usually unplug my equipment during electrical storms anyway.

[poneal]

charge to build me one?

[Glen B]

How much would you...charge to build me one?

The raw parts cost alone is $1,200. For that money you could get a brand new BP-2 (1,800VA, $1,100) or BP-2.5 (2,400VA, $1,400) from Balanced Power Technologies. I did my DIY project not to save on the cost of factory-built unit but because I thought I could build one as good as or better with the parts that I like.

Were I to buy a BPT, SMART Devices or other brand unit, I would end up spending several hundred dollars in modifications, replacing parts like the Hubbell, Eagle/Cooper and Leviton devices in their products. IMO, the Furutech FP-15A silver receptacles and Pass & Seymour GFCIs that I use in my project are superior parts. The contacts in the Furutech outlets are the heaviest I have seen of any receptacle to date -- 15 or 20A.

Since my original post, the unit has been rebuilt and is now a "MKII" version with 2kVA Equi=Tech “Q” type transformer for analog and several other changes/improvements. (Some owners of BPT balanced power units claim to hear a slight hum. The Equi=Tech Q transformer is extremely tolerant of DC and severe power line distortion and is absolutely silent, thanks to its massive core). Because this replacement tranny was much larger and heavier than the original (12" diameter, 60 lbs vs. 8" diameter, 35 lbs). I had to switch to a larger chassis but was able to keep the same rear panel.

Other changes/improvements:

1. Used higher temperature rated wire in some places.
2. Improved/revised wire routing and connection points.
3. Replaced uninsulated faston connectors with insulated ones.
4. Replaced steel transformer mounting hardware with bronze.
5. Added vibration-damping materials to chassis inside surfaces and top cover.
6. Discontinued use of EMI/RFI filter on input of large tranny (per recommendation by manufacturer). Filter was causing loss of detail.
7. Switched EMI/RFI filter on input of small tranny from Qualtek brand to Corcom.

Updated inside pics:

[Rycher]

Dude, that is sweet!! Very, very nice.

[Glen B]

After almost 5 years, here's my latest upgrade and rebuild that now has three isolation transformers. Now, instead of punching holes in the rear panel myself, with rotary and nibbler tools, I furnished a cutout drawing to the chassis manufacturer, Par-Metal Corp., and had them do the hole punching at the factory for a flat $30 charge. The rear panel has a cleaner, more "professional" look than my previous efforts.

New version: http://img.villagephotos.com/p/2003-5/191557/2083672

Previous versions: http://img.villagephotos.com/p/2003-5/191557/1741050

[atomicAdam]

Glen B - that is super pimp!

I wish I was knowledgeable about EE - it is so interesting but I hate math so much.

[Feanor]

After almost 5 years, here's my latest upgrade and rebuild that now has three isolation transformers. Now, instead of punching holes in the rear panel myself, with rotary and nibbler tools, I furnished a cutout drawing to the chassis manufacturer, Par-Metal Corp., and had them do the hole punching at the factory for a flat $30 charge. The rear panel has a cleaner, more "professional" look than my previous efforts.

New version: http://img.villagephotos.com/p/2003-5/191557/2083672

Previous versions: http://img.villagephotos.com/p/2003-5/191557/1741050

Thanks for sharing, Glen. Unfortunately I'm not an electronics DIY, or I'd be all over it.

[nightflier]

I just recently completed construction of my DIY balanced power AC line conditioner and thought I would post some pics. It employs two separate transformers, one for analog components and the other for digital, each preceded by its own EMI/RFI filter. The two sections share only a common circuit breaker and IEC power inlet.

Very impressive indeed. To isolate the digital from the analog, I've been using to power systems (one Monster and the other Furman). Probably nothing like what you've built, but it works for now. I also don't have an EE...

At the risk of getting pimp-slapped like an AA newbie, any thoughts on adding one or more LEDs to the front? Granted, my Monster's light show is quite the eye-sore, but just for piece of mind, it's nice to know that at least your power center is on and working properly.

[Glen B]

Glen B - that is super pimp!

I wish I was knowledgeable about EE - it is so interesting but I hate math so much.

There are a lot of non-EEs doing some serious DIY work. Just pay a visit to diyAudio forum and the Lab at Audio Circle.

Very impressive indeed. To isolate the digital from the analog, I've been using to power systems (one Monster and the other Furman). Probably nothing like what you've built, but it works for now. I also don't have an EE.

At the risk of getting pimp-slapped like an AA newbie, any thoughts on adding one or more LEDs to the front? Granted, my Monster's light show is quite the eye-sore, but just for piece of mind, it's nice to know that at least your power center is on and working properly.

Look at picture #4 in post # 20, and also in the photo gallery at the first link. I have a blue LED on the front panel.

[NV001]

Great work, Glen. I just came across your posting - the project is impressive. Tried to access the schematic, but the link seems to be broken. Could you repost? Thanks!

J

[Glen B]

Great work, Glen. I just came across your posting - the project is impressive. Tried to access the schematic, but the link seems to be broken. Could you repost? Thanks!

J

Here is a basic schematic showing a single isolation transformer. Across the primary is an optional varistor for surge protection (Digi-Key part # P7324-ND / Panasonic part # ERZ-V20R241) and 0.47uf caps across the primary and secondary. I use 600V rated Auricaps. X rated caps are normally used in applications across the AC mains. Ther has been dbate about the use of Auricaps. The manufacturer, Audience lists AC line use in their application notes. I have been using them for the past 5 years without incident.

[Feanor]

Here is a basic schematic showing a single isolation transformer. Across the primary is an optional varistor for surge protection (Digi-Key part # P7324-ND / Panasonic part # ERZ-V20R241) and 0.47uf caps across the primary and secondary. I use 600V rated Auricaps. X rated caps are normally used in applications across the AC mains. Ther has been dbate about the use of Auricaps. The manufacturer, Audience lists AC line use in their application notes. I have been using them for the past 5 years without incident.

Thanks a lot, Glen.

Sorry 'bout my ignorance, but I'm curious. In general, are there component designs that don't tolerate balance power input?

Regarding the schematic ...

• Are the 60V output taps opposite phase?
• Are the caps both across these 60 taps and the input 120V/0V leads the 0.47 uF caps you refer to.

[Glen B]

In general, are there component designs that don't tolerate balance power input?

No specific designs -- as with all other types of power conditioning devices, once in a while you will find components that don't work well sonically with balanced power.

Are the 60V output taps opposite phase?

Yes, just like household 240V (120V-0-120V).

Are the caps both across these 60 taps and the input 120V/0V leads the 0.47 uF caps you refer to.

Yes.

[twekr]

Thank you for sharing this with us Glen

Could you send me a pm with few answers please?

How important are the filters you used (corcoms ) ?

Do I need a circuit breaker ?

Is it better to use multiple transf.?

thank you for your help

[blackraven]

I'm thinking about buying one of these and having it installed

http://brickwall.thomasnet.com/item/...p20?&forward=1

[usbmusic]

Thanks for sharing, I have been looking to something like that for a while. The only concern I have is working with main voltage

[bengel]

Hi,

I know this thread is a little stale but I thought I would take a shot...

I am about to build a balanced power supply. Basically it is only going to power digital stuff like my preamp, dvd/blu ray etc.... plus my TV (which I guess is analog). My amplifer will not be plugged into this.

My plan is use the EMI/RF filter designed by Jon Risch however I cannot not seem to find a good answer as to where to place the filter. Either before ON the primary or after on the secondary.

From the article at Equitech, having filters on the seconday seems to be "required" as it provides a pathway for reactive currents to flow to ground.
http://www.equitech.com/articles/origin.html (see figure 2)

I read other places to put it before - on the primary and just wire the secondary taps "directly" to the outlets.

Then I read Jon Risch saying do a hybrid.... which puts the inductors and 1 bypass (across both 60 hot wires). http://db.audioasylum.com/cgi/m.mpl?...rmer+Jon+Risch

I have uploaded my schematic drawing of the Jon Risch filter that is on the primary.
http://forums.audioreview.com/attach...1&d=1268107554

Just wondering if anyone could offer any clarification on this. The equitech diagram (figure 2) makes the most sense to me as it is providing a pathway for reactive (noise) currents to ground.


Thanks!

[Feanor]

Hi,

I know this thread is a little stale but I thought I would take a shot...

I am about to build a balanced power supply. Basically it is only going to power digital stuff like my preamp, dvd/blu ray etc.... plus my TV (which I guess is analog). My amplifer will not be plugged into this.

My plan is use the EMI/RF filter designed by Jon Risch however I cannot not seem to find a good answer as to where to place the filter. Either before ON the primary or after on the secondary.

From the article at Equitech, having filters on the seconday seems to be "required" as it provides a pathway for reactive currents to flow to ground.
http://www.equitech.com/articles/origin.html (see figure 2)

I read other places to put it before - on the primary and just wire the secondary taps "directly" to the outlets.

Then I read Jon Risch saying do a hybrid.... which puts the inductors and 1 bypass (across both 60 hot wires). http://db.audioasylum.com/cgi/m.mpl?...rmer+Jon+Risch

I have uploaded my schematic drawing of the Jon Risch filter that is on the primary.
http://forums.audioreview.com/attach...1&d=1268107554

Just wondering if anyone could offer any clarification on this. The equitech diagram (figure 2) makes the most sense to me as it is providing a pathway for reactive (noise) currents to ground.

Thanks!

Welcome to AR Forums, Bengel.

Sorry, I don't think I answer your question, (but see below). I think you might do better with such questions over at DIYaudio where there are more technophiles than around here.

Maybe my eyes (or brain) misleads me but in JR's Audio Asylum reference it almost looks like the PS there is not a balanced supply: the outputs are labeled "H" and "N", not "+" and "-" as you would expect from a balanced supply -- of course it might just be a typo. However that being the case, I wouldn't risk putting a capacitor across the + and - taps on balanced supply.

Thanks for the schematic you supplied which is very interesting. It's tempting to me to consider such a project in the future.