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/tweaks/messages/103826.html

My rough schematic:
http://img.villagephotos.com/p/2003-5/191557/balancedpower.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/volume_10_3/feature-article-isolation-transformer-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.

[SoloScott]

Glen, that looks gorgous!!! Impressive.

BTW, you did take skeptic's criticism pretty rough. "Clark, I haven't seen a beating like that since [someone] put a banana in my pants and let a monkey lose!" -Eddie from one of the Vacation movies :)

[skeptic]

He's from Audio Asylum, it's to be expected. That's how a lot of them are over there. With Jon Risch as the moderator, they're often at each other's throats.

[E-Stat]

He's from Audio Asylum, it's to be expected. That's how a lot of them are over there. With Jon Risch as the moderator, they're often at each other's throats.
That and the fact that with your infinite wisdom, you shot first, insulted your fellow electrical engineer and asked questions later. You "changed your opinion" but never apologized. Some call that arrogance.

rw

[skeptic]

"Some call that arrogance."

In civilized society it is. At Audio Asylum, it's just par for the course. (I wanted him to feel at home here. Making the transition out of the bizzarro world and into ours, it's only natural that he might feel culture shock so a few insults and a little abuse will ease the change.) Besides, E-Stat, what do you want, a signed Magna Carta? I already said I changed my mind when I looked at it. After staying around here for a while, my motto is "Ready, Fire, Aim." (After my threads on "A Love Supreme" it seems many times all I have to do is fill in between the dots.)

[E-Stat]

"Besides, E-Stat, what do you want, a signed Magna Carta?
I can only imagine your response if some guy told you that one of your electrical projects broke code, was dangerous, even illegal and said if you didn't understand any of that, you would help them out. :)

rw

[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?

[ciscokid1970]

He's from Audio Asylum, it's to be expected. That's how a lot of them are over there. With Jon Risch as the moderator, they're often at each other's throats.


Hey skeptic you asked for it...take your beating, eat your crow. It will teach you not to smack someone around before carefully seeing if your arguments have merit.

To quote one of my favorite movies: "Hmm I don't know I could use a good beating, I haven't had one in a while"

The only comment I have on Glen B is that he is brave...I am a EE Yet I have never been comfortable building anything that even has a remote chance of sparking or catching fire.
(When I was 8 I modified a ocillating fan control and it sparked and knocked me flat, memorable).
His design looks sound but I perfer to shell out $80 for a good Triplite AC filter surge protector.

Peace, Love and Audio for all
Ciscokid1970

[Glen B]

He's from Audio Asylum, it's to be expected. That's how a lot of them are over there. With Jon Risch as the moderator, they're often at each other's throats.

I haven't visited AR in some time so that is why I am now responding. Hey, you caught me on a bad day. In hindsight, my response could have been "more diplomatic." I really wouldn't say people are at each other's throats at AA. Actually, there was a time when you could say that such was the case here at AR. I find things more quiet and civilized here now.

Peace.

[Glen B]

Hey skeptic you asked for it...take your beating, eat your crow. It will teach you not to smack someone around before carefully seeing if your arguments have merit.

To quote one of my favorite movies: "Hmm I don't know I could use a good beating, I haven't had one in a while"

The only comment I have on Glen B is that he is brave...I am a EE Yet I have never been comfortable building anything that even has a remote chance of sparking or catching fire.
(When I was 8 I modified a ocillating fan control and it sparked and knocked me flat, memorable).
His design looks sound but I perfer to shell out $80 for a good Triplite AC filter surge protector.

Peace, Love and Audio for all
Ciscokid1970

The only parts of concern are the Auricaps. A number of companies are using them as differential filters in their products, most notably Balanced Power Technologies. I am not alone in my bravado.

[poneal]

charge to build me one?

[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.

[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.

[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

[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.

[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

[Glen B]

How important are the filters you used (corcoms ) ?
The RFI/EMI filters provide some increased noise reduction, and inter-component isolation when used on the secondary side, though they are not an absolute necessity. As a downside, during my extensive listening sessions, I found the filters to cause a loss of detail and transparency. I stopped using them as you will see in my updated pics. I tried both Qualtek and Corcom and the results were the same with both. You may find otherwise. Listen for yourself.


Do I need a circuit breaker ? Yes, circuit breaker or time delay fuse (type MDL) rated according to the size of transformer used.


Is it better to use multiple transf.? I find multiple transformers preferable to a single transformer with EMI/RFI filters as mentioned above. The multiple transformers IMO provide maximum component isolation without the sonic downside, though at much greater cost. Good transformers are not cheap.

[twekr]

Thank you again,

Do you think a 20 A breaker is okay for a 2000VA unit ?

I am going to try the silica sand to dampen the vibration and noise of the transformer .

Therefore the filters are not a must correct Glen ?

Should I still use the .47 uF caps on the prim and second

Do we use a resistor across to drain the caps ?

Can we use Solen caps or any hi voltage NP caps instead ?

I noticed that Audience units sell upgraded Teflon packages for an extra $1000 on their units
Do you think it will give a sonic difference ?

Cheers

[Glen B]

Do you think a 20A breaker is okay for a 2000VA unit ? Yes, I recommend a Potter & Brumfield 20A hydraulic-magnetic breaker, available from.Digi-Key, their part # PB593-ND.


I am going to try the silica sand to dampen the vibration and noise of the transformer . May not be good idea. How do you plan to accomplish this ? If you pack the transformer in any material other than potting compound, you may increase it operating temperature. A good quality transformer should not be noisy in the first place. To minimize noise transfer to the chassis, try extra padding underneath. I also recommend sound dampening material on all inside surfaces of the chassis. Make sure the material has flame retardant properties.


Therefore the filters are not a must correct Glen ? They're optional. YMMV. Experiment.


Should I still use the .47 uF caps on the prim and second. Also optional. Experiment.


Do we use a resistor across to drain the caps ? No. Why ?


Can we use Solen caps or any hi voltage NP caps instead ? There is an issue of Auricaps not being UL listed for use across the AC line, although the manufacturer "suggests" its okay. Same issue with Solen and other "audiophile" brands. I've been using Auricaps for over 5 years without incident. Wima X- rated film caps will work fine in this application.


I noticed that Audience units sell upgraded Teflon packages for an extra $1000 on their units
Do you think it will give a sonic difference ? I have not tried the teflon caps and can't comment. I'm sure they're fine caps but I would rather spend $1,000 to make improvements elsewhere, like in better outlets.

[blackraven]

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

http://brickwall.thomasnet.com/item/industrial-surge-protectors/panel-mount-unit/pwp20?&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?forum=tweaks&n=42249&highlight=filter+isolation+transformer+Jon+Risch

I have uploaded my schematic drawing of the Jon Risch filter that is on the primary.
http://forums.audioreview.com/attachment.php?attachmentid=6761&stc=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?forum=tweaks&n=42249&highlight=filter+isolation+transformer+Jon+Risch

I have uploaded my schematic drawing of the Jon Risch filter that is on the primary.
http://forums.audioreview.com/attachment.php?attachmentid=6761&stc=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.

[Glen B]

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?forum=tweaks&n=42249&highlight=filter+isolation+transformer+Jon+Risch

I have uploaded my schematic drawing of the Jon Risch filter that is on the primary.
http://forums.audioreview.com/attachment.php?attachmentid=6761&stc=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!

The Equi=Tech article is not saying that filters on the secondary are "required". The discussion linked to is only discussing reactive currents and using capacitors to show the relationship of those currents. Caps on the secondary are useful as simple differential filters, and the simplest method of decoupling outlets, but are not an absolute necessity.

A single noise filter such as the Jon Risch is most useful ahead of the balanced isolation transformer, as Jon has it in the PDF schematic above. You should also make sure to isolate your preamp AC from your digital equipment. Caps across the outlets IMO are a minimum. Separate Jon Risch filters on the secondary, feeding the preamp and digital components is second best. The ultimate IMO would be separate isolation transformers for your preamp and digital/TV. Go back and re-read Jon's responses on AA where he recommends that "in theory, using isolated filters on each separate digital component would provide some benefit".

As an alternative to using Jon Risch filters on the secondary, you could experiment with packaged EMI/RFI filters like Corcoms. Just note that I've done extensive experimentation with various Corcom and Qualtek filters and to my ears, they had a noticeable negative effect on the sound when switched into the electrical path. They should be fine with TV. YMMV.

Glen

[bengel]

The Equi=Tech article is not saying that filters on the secondary are "required". The discussion linked to is only discussing reactive currents and using capacitors to show the relationship of those currents. Caps on the secondary are useful as simple differential filters, and the simplest method of decoupling outlets, but are not an absolute necessity.

A single noise filter such as the Jon Risch is most useful ahead of the balanced isolation transformer, as Jon has it in the PDF schematic above. You should also make sure to isolate your preamp AC from your digital equipment. Caps across the outlets IMO are a minimum. Separate Jon Risch filters on the secondary, feeding the preamp and digital components is second best. The ultimate IMO would be separate isolation transformers for your preamp and digital/TV. Go back and re-read Jon's responses on AA where he recommends that "in theory, using isolated filters on each separate digital component would provide some benefit".

As an alternative to using Jon Risch filters on the secondary, you could experiment with packaged EMI/RFI filters like Corcoms. Just note that I've done extensive experimentation with various Corcom and Qualtek filters and to my ears, they had a noticeable negative effect on the sound when switched into the electrical path. They should be fine with TV. YMMV.

Glen

So you run the caps straight across both hot legs of the outlet? Or should you run them across each hot leg to ground (i.e. 2 caps per plug). Size matter? Conventional wisdom, bigger capacitance is better, i.e. >2.5 uF?

[Glen B]

So you run the caps straight across both hot legs of the outlet? Or should you run them across each hot leg to ground (i.e. 2 caps per plug). Size matter? Conventional wisdom, bigger capacitance is better, i.e. >2.5 uF?
Connect the caps across the two hot poles of the outlet. No cap to ground. Caps should be around .47uf 250V X-2 rated (for across the AC line usage). Wima .33uf film 250V X-2 rated noise supression caps from Mouser will work fine. You can use one or two pieces across each outlet. The x-rated caps fail open, thus preventing a fire. You don't want to use caps that fail as a short. Too large caps (total value greatar than 1uf) are not necessary. All you will have is unnecessary leakage across the poles. I've been using .47uf 600V Auricaps, for the past 5+ years without incident. These are not marked as x-rated, although the manufacturer's usage notes say they fail open and are safe for AC noise suppression use.

Wima caps: http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMsh%252b1woXyUXj5Km 331xGoRehsQpAmomCk0%3d

[bengel]

Thanks for the insight/advice....

I went with these caps as they were cheaper and easier to mount across the outlets. They are also X2 rated...

http://mouser.com/Search/ProductDetail.aspx?R=F17734472000virtualkey6131000 0virtualkey75-F17734472000

[Glen B]

Thanks for the insight/advice....

I went with these caps as they were cheaper and easier to mount across the outlets. They are also X2 rated...

http://mouser.com/Search/ProductDetail.aspx?R=F17734472000virtualkey6131000 0virtualkey75-F17734472000

Those should be fine. I only mentioned the Wimas because they came highly recommended.

[mbolek]

Glen,

Just stumbled across your posts on your DIY power conditioner. I have several transformers (700VA) and left over Auricaps. You have inspired me to take a stab at building my own.

I also have a PS Audio Soloist and thinking about using it to front end the power conditioner. It should help with filtration and surge suppression.

One question on your build. I noticed only one cap on the primary side of the larger (2KVA) transformer. Did you install caps (primary side) on the smaller transformers.

Your build looks very nice.

Regards,

Marty

[Glen B]

Marty, a single 1uf 600V cap is across the incoming AC, so it benefits all three transformers.

[mbolek]

Marty, a single 1uf 600V cap is across the incoming AC, so it benefits all three transformers.


Thx Glen.

I figured you went with a larger value.

Marty

[zycomatique]

Hi Glenn!

Is there a difference in the sonic result between the standard industrial toroid and the model made by equitech?

Thanks: David

[Dual-500]

Hi Glenn!

Is there a difference in the sonic result between the standard industrial toroid and the model made by equitech?

Thanks: David
I'll leave the final answer to Glenn - but, I would suggest probably not.

[Glen B]

What exactly do you mean by "industrial toroid" ? Any center-tapped transformer, whether E-I type or toroid, that outputs 60V-0-60V (120V-0-120V in countries that use 240V) can be effectively used as a balanced isolation transformer (poor man's isolation tranny). However, its degree of common-mode noise reduction is likely to not be as great as that of a true balanced isolation transformer. In fact, Parts Express sells an Avel-Lindberg toroid rated at 800VA that outputs 60V-0-60V, and can be used as a poor man's balanced power supply for low-powered amps and sources (hint).

Transformers from companies like Equi=Tech, Plitron and Toroid Corp. of Maryland feature bi-filar windings, and one or two electrostatic shields between the primary and secondary windings, features which may be lacking in other products, and which contribute to increased noise reduction.

Plitron transformers are built around "NBT" (narrow band) and "LONO" (low noise) technology, which further improve performance (read more on the Plitron website). Equi=Tech "Q" type transformers have massive cores, feature low inrush current, and substantial immunity to saturation by power line DC offset, a phenomenon which causes audible mechanical transformer buzz.

Does this translate into a sonic difference? While it is a subjective matter, the greater common mode noise reduction of a true balanced isolation transformer is likely to result in lower system noise floor, and improved sonics. I have tried products from the three above-named manufacturers and found performance differences among them, but that is a discussion probably best left to another thread.

[sugarpop233]

There have been a number of threads on AK and other places on balanced power conditioners, and the benefits they can bring in reducing the noise floor in an A/V setup. So, I started building one and wanted to share some of the details. It is not complete yet, but I will wire it all up hopefully over the next couple of weeks.

What can balanced power do for you? It can be a little, a lot or nothing at all. It depends on how clean the ac input is to begin with. A good isolation transformer can bring much of the same benefits that a balanced power conditioner can bring – namely, reduction in the common mode noise that might be riding on the power lines. But I suppose a balanced power conditioner can be used to extract the last bit of performance from your system.

[lag0a]

I've read a Topaz Isolation transformer with a 0.0005 pf rating can have a common mode noise reduction of -146 db. The pf rating seems to determine the noise reduction. How low can you go with common mode noise reduction to reach the noise floor or until it is inaudible to the human ear? Can you get -300 common mode noise reduction? I don't know if it has any differential mode noise reduction. I think what people need to look for is the curve on a graph of the common mode and differential mode noise reduction within a range of frequencies if possible. The problem is I don't know how these frequency ranges affect digital and analog gear separately. Also how do these transformers affect the sine wave?

[Glen B]

What can balanced power do for you? It can be a little, a lot or nothing at all. It depends on how clean the ac input is to begin with. A good isolation transformer can bring much of the same benefits that a balanced power conditioner can bring – namely, reduction in the common mode noise that might be riding on the power lines. But I suppose a balanced power conditioner can be used to extract the last bit of performance from your system.<O:p</O:p
<O:p</O:p

I concur.

<O:p</O:p

[Glen B]

I've read a Topaz Isolation transformer with a 0.0005 pf rating can have a common mode noise reduction of -146 db. The pf rating seems to determine the noise reduction. How low can you go with common mode noise reduction to reach the noise floor or until it is inaudible to the human ear? Can you get -300 common mode noise reduction? I don't know if it has any differential mode noise reduction. I think what people need to look for is the curve on a graph of the common mode and differential mode noise reduction within a range of frequencies if possible. The problem is I don't know how these frequency ranges affect digital and analog gear separately. Also how do these transformers affect the sine wave?

The pf rating appears to be the capacitance figure between primary and secondary. You would want capacitance to be as low as possible so as not to couple differential HF noise, which can pass from primary to secondary, and may need to be filtered if this occurs. This can be accomplished before or after the transformer. Many of the audiophile isolation transformer products employ some additional form of noise filtration.

I like to use caps across the primary line and secondaries for this purpose. I’ve tried several of the popular box filters and did not like their effects on the sound. Although on paper, these products operate outside the human hearing range, to my ears, when in the circuit, they imparted an undesirable veiling and loss of detail, like if a blanket was thrown over the speakers.
</O:p
How your system sounds with a particular transformer may be more important than raw noise reduction specs. Also, there is only so much noise reduction that can be achieved. For one thing, an isolation transformer (or any kind of line conditioner/filter) will not remove thermal noise (a.k.a. Johnson-Nyquist noise). It is interesting to note that the audiophile products have noise reduction figures in the range of -80dB. An isolation transformer should not affect the sinewave, after all it is just a transformer.

[Dual-500]

There have been a number of threads on AK and other places on balanced power conditioners, and the benefits they can bring in reducing the noise floor in an A/V setup. So, I started building one and wanted to share some of the details. It is not complete yet, but I will wire it all up hopefully over the next couple of weeks.

What can balanced power do for you? It can be a little, a lot or nothing at all. It depends on how clean the ac input is to begin with. A good isolation transformer can bring much of the same benefits that a balanced power conditioner can bring – namely, reduction in the common mode noise that might be riding on the power lines. But I suppose a balanced power conditioner can be used to extract the last bit of performance from your system.
I use a 220v to 110v step down isolation transformer with it's own #8 awg copper ground. Keep it simple.

[lag0a]

Has anyone been able to compare the performance of the Avel Y236905 to an Equitech 1kva? How come the Avel weighs about 14 lbs. while the Equitech Son of Q Jr. 1kva weighs 48 lbs. (not sure what % is not the transformer? Does the Avel Y236905 produce any hum or audible noise, and how efficient is it because Equitech claims 97% efficiency?

[Glen B]

Has anyone been able to compare the performance of the Avel Y236905 to an Equitech 1kva? How come the Avel weighs about 14 lbs. while the Equitech Son of Q Jr. 1kva weighs 48 lbs. (not sure what % is not the transformer? Does the Avel Y236905 produce any hum or audible noise, and how efficient is it because Equitech claims 97% efficiency?

The transformer in the Equi=Tech Son of Q should be around 30lbs, which is about 1/3 larger than other manufacturers' toroids of similar VA rating. The cores of all Q type transformers are oversized, which helps to maintain power factor, regardless of the load, and also helps them be resistant to saturation by DC on the power line. In the case of the Son of Q, that massive core is responsible for the vast difference in weight between it and the Avel. Following is a link to a thread on cheap DIY balanced power that employs the same 800VA Avel unit. The builder shares his impressions near the end of the thread.

HTGuide Forum - Cheap DIY balanced power device (http://www.htguide.com/forum/showthread.php4?t=8227&page=1&pp=50)

[ursus262]

Hello, Glen

I use Balanced Power on my system using an off the shelf transformer with pleasing results. I bought mine from Airlink Transformers in the UK. I would like to ask a couple of questions if I may:

1. I notice that noise filtering components operate across both legs, instead of down to earth. I assume that this is to prevent filtered noise polluting the earth and, hence, finding its way back into the balanced system. Am I correct in this assumption?

2. I notice from the schematic that the centre tap of the secondary winding is referenced to ground (earth). Whilst this is inherently a wise thing to do, is there not a risk that earth noise could find its way into the secondary winding, or up into the audio system through the earth pin?

Many thanks

Dave

[Glen B]

1. I notice that noise filtering components operate across both legs, instead of down to earth. I assume that this is to prevent filtered noise polluting the earth and, hence, finding its way back into the balanced system. Am I correct in this assumption?
Dave
The caps across the two hot legs are differential filters.



2. I notice from the schematic that the centre tap of the secondary winding is referenced to ground (earth). Whilst this is inherently a wise thing to do, is there not a risk that earth noise could find its way into the secondary winding, or up into the audio system through the earth pin?
No, the center-tap is at "0V" potential, and the balanced configuration is inherently noise-cancelling in its design. The following article will give you an idea of how noise currents flow in unbalanced and balanced AC systems.

Balanced Power: The Next Generation (http://www.equitech.com/articles/bpng.html)

[ursus262]

That was a really good read. Thank you so much for that. I does help to be reminded of basic AC theory from time to time as I hadn't dealt with it since my days as an engineering apprentice.

The other thing worthy of note, is the presence of DC on the mains supply. When using a balanced transformer, this manifests itself as a rattling noise coming from the transformer housing as the cores saturate in the transformer itself. This can also degrade sound quality and is also filtered out by the isolation that the transformer can provide.

With my system, this noise comes and goes - as if someone in our neighbourhood is using an appliance which causes this to happen. In fact, our washing machine and dishwasher both do this when they are switched on

[Glen B]

I've tried a number of different isolation transformer brands and had experience with DC on the mains. The 2,000VA transformer in my first post in this thread buzzed like a gas powered chainsaw in time with the agitation of the household washing machine anytime it was running. Equi=Tech Q type and Plitron LO-NO transformers are designed to be quite immune to DC. Simple DC blocking circuitry will solve that core saturation issue and noise. I've built a number of DC blockers for people that either totally eliminated transformer buzzing or reduced it to a tolerable level (see post dated 8/4/09 at link below). PM me if interested in circuit details.

AudiogoN Forums: Do all toroidal transformers hum? (http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1247693407&openflup&23&4#23)


http://i994.photobucket.com/albums/af67/mr_classe/DC%20blocker/DC_blocker.jpg

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