Balanced vs standard power


Searching for an Isolation Transformer 10 or 15kva. I have the budget for Equitech but I'm sold only on the benefits of isolation and not "yet" on the benefits of balanced power unless one is recording live musicians. My rationale is that most if not all audio components are not designed with balanced power so they may be optimal performers with standard power and lesser performers with balanced power. Until someone does a side by side comparing isolated balanced to isolated standard power we may never know.

I have read the various threads regarding isolation transformers from Equitech 10wq, MGE Topaz etc, and the Euqitech stereophile review. For larger non-balanced options there is Ultra K 600 with K factor correction and triple shielding from the Controlled Power Company. They range from 5 to 25 kva.

I think supersizing Isolation transformers for audio is not well recognized yet because no one has done the necessary review/ comparisons to determine the performance curve of Isolation Transformer size to Audio Performance. Although Isoclean advocates the use of two of their Isolation Transformers for each piece of equipment. Maybe they're trying to tell us something or just sell more transformers. 10 KVA is "plenty" for my system according to Martin at Equitech, but "plenty" is not quantified enough to convince me, so I 'm leaning toward the 15kva on the Ultra K 600 from Controlled Power about $4000 vs Equitech 15 kVA at upwards of $14000.
natan6355
I am a fan of balanced A/C power inot my stuff.
I do not have any graphs, white papers, PhD's blah blah blah.
I just like it better.
I use both a Furman REF 20i and a PS Audio P600 power conditioner. They are balanced output.
I agree with Elizbeth.
I use Signal Isolation transformers wired in ballanced mode. The difference was a much lower noise floor that transmitted into a more spaitial soundstage and more three dimensionality.
A 10kva will be plenty for most systems. I would recommend one 5kva for the source and one 5kva for the amp.
I just want to add that I think that you're thinking very clearly of a high power unit.

I was told by three different audio component manufacturers that, like a power amplifier, the more power, the more headroom for dynamic bursts and an easier handling of the load on the unit.

All three said to allow a 10x power handling capability, and I found that to be true. I started with a 1.8 Kva unit, then a 2.4, then 2.5, then 3.0 and finally a 5.0 Kva unit. I only had two components on mine, and when I finally put the 5.0 Kva, the soundstage opened up and expanded, as well as the decrease in the noise floor and a lot more micro details emerged.

Chuck
Natan6355,

Some information.....
http://www.equitech.com/support/647.html
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This is what I'd look at http://www.solahevidutysales.com/cvs_hardwired_series_power_conditioner.htm for what it is worth. They've been around quite a while, work fine and last a long time.
I have a BPT 20 amp balanced AC transformer the past 3 years. My entire system is plugged into it, everything improved with it`s use,dynamics,sense of scale,much lower noise floor, nuance, inner detail etc.
I have`nt experienced any negative trade offs, none.

The only aspect I would question in your case is the 'super sizing" of the transformer. I don`t believe the added size and expense is necessary. 10x the requirement of your system does`nt seem logical and is simply overkill IMO. It`s the same as having a 300-500 watt amp, when using reasonably efficient speakers, at most listening levels your speakers are only requiring 1-5 watts. Sometimes the headroom arguement is carried to excess(under real world conditions0.

Best of Luck,
Used both balanced and isolation with general purpose step-downs and various others.

http://mysite.verizon.net/vze22yzp/id10.html

For amps in general, never found much benefit for balanced AC. In fact, my Plinius amps are completely indifferent, other than needing a stethoscope to detect any noise, but I still keep them on a 60/60 diet because it doesn't do any harm. My Genesis 1600W bass amp is the only piece plugged direct to "the wall". For class A/B or D amps, even with 10X capacity, a transformer can still be a "speed bump" because those amps recharge capacitors in less than a cycle. Class A amps, with a steady amp draw, are a good load for isolation transformers.

On the other hand, preamps and sources have responded well to balanced AC. In some cases, like the SFL2, which has a power supply larger than many amps, the difference was shocking (sorry, bad pun).

Agree with Zman that multiple smaller isolation transformers are better than one. That is the point of isolation. Do you realize the weight of a 15KVA transformer?

Code issues with distributed (through wall) balanced AC that Equi=Tech has dealt with but that doesn't apply to boxes in room or on the rack.

There's also the running cost. Although they're quite efficient under load, they have an "idle" or exciting current (typically 10% of capacity). Although larger transformers have a lower percentage of exciting current, it's always more.

Gotta disagree with Jeff about the Sola CVS (and MCR) regulated transformers. They are great for their intended purpose but they're noisy and don't respond well to dynamic loads. The CVS series provides less isolation and noise reduction.

Prefer standard EI core transformers rather than toroidal for this purpose even though toroids make for better packaging. Enough online and archived discussions about this already.

Saw a NIB Signal DU-10 on Ebay for about $1200 (retail) and there's pages full of 5, 7.5 and 10 KVA GP step-downs (240V required) under $500. Doesn't sound like cost is an issue for you. Just gotta say... there's good power and better power but ain't no such thing as audiophile power.
Good info Ngjockey. I just picked up a Signal DU-5 on ebay. I'm going to use it wired in balanced mode for my amp (Almarro 318B). I've got a Signal DU-2 for my source.

The Signal DU series is a great isolation transformer. Wired in balance, it droped the noise floor substantially.
If anyone buys one off of ebay, PM me and I'll send you the wiring diagram for Isolation or balanced.

The DU-2 (2KVA) is plenty for sourse components in balanced mode. The DU-5 (5KVA) is plenty for high current amps in balanced mode.

If you check out my virtual system, you can get an idea on the box I've made to hide it. I used a Porter port for the outlet and a Furutech IEC for the inlet.
You don't have to use an IEC for the inlet, but it leave the option for rolling PC's.
Ngjockey - Am assuming you are referring to mechanical noise / 60 hz hum, which is a good point regardless of vendor choice. I.E. something to look out for.
I'm not sure why you think an oversized sola ('oversized' per other posts) would not provide excellent stability under dynamic load conditions?
Wish it were that simple but there's more to those than just a transformer. As part of the ferroresonant design, they are partially saturated at all times. Along the same lines, in regulating voltage, amperage can suffer. So... with a dynamic load, they have to be oversized to a larger factor . While the CVT series has better amperage stability and tighter regulation, they're more like autoformers so noise reduction is one third of the MCR and a true isolation transformer.

Don't get me wrong, for decades they have been the 'king of the hill' as far as fast, reliable regulation and only recent, advanced electronic tap switchers can compete for the throne. They're also heavier and expensive, except for that used, $20, 1000W MCR portable I bought once.
Ngjockey - Thanks for the response.
I understand that the sola is not just a transformer:).
I'm curious about how incoming line harmonics would compare between a system with electronic tap switchers vs a sola system, maybe not an issue unless the o.p. went with multiple smaller units that could potentially be 'talking' to each other or had other sensitive non-stereo electronics on the same ac line. Perhaps not an issue at all but since the topic is about getting very nit picky with incoming ac it may be a nit worth picking.

Oh, for what it is worth I've never seen $20.00 per unit but I think you can find them reconditioned for about 50% price fairly regularly.
No response necessary unless the mood strikes you. Just pondering.
I'm curious about how incoming line harmonics would compare between a system with electronic tap switchers vs a sola system, maybe not an issue unless the o.p. went with multiple smaller units that could potentially be 'talking' to each other or had other sensitive non-stereo electronics on the same ac line.
11-04-11: Jeff_jones

Jeff_jones,

Most of the odd harmonics found on the AC mains of our homes is from nonlinear loads connected to the mains within our homes. The home computer being one of the worst.

>http://www.pge.com/includes/docs/pdfs/mybusiness/customerservice/energystatus/powerquality/harmonics.pdf


>http://www.emersonnetworkpower.co.in/KnowledgeCenter/Whitepapers/K-FactorTransformer.pdf


Natan6355 is looking at a K rated 15 KVA transformer.

K rated transformers
>http://www.powertransformer.us/transformerarticles/transformerkfactorrating.htm


JMHO a 15 KVA transformer is overkill. He will have to feed that beast with #3 copper wire connected to a 2 pole 80 amp breaker, minimum, (125% of primary FLA). (240V single phase.)

Because there will be next to nothing of a connected load more than likely it will be mechanically noisy and very inefficient.....

A power utility pole transformer in older residential neighborhoods that feed 4 or more homes is only a 25 KVA transformer on avg. Pad mounts a 50 KVA on avg.
.
Interesting question about the harmonics. Personally have doubts about any kind of harmonic filtration below 1 KHz for any passive technology, not including regeneration, but I'm not an expert and ferroresonance has it's mysteries. Don't have an oscilloscope to do any testing either.

Shared this link before with the caveats of the author affiliation and date.
http://www.contractorsav.com/article/2006/11/07/ac-power
Here are the links I posted above.
http://www.pge.com/includes/docs/pdfs/mybusiness/customerservice/energystatus/powerquality/harmonics.pdf

http://www.emersonnetworkpower.co.in/KnowledgeCenter/Whitepapers/K-FactorTransformer.pdf

http://www.powertransformer.us/transformerarticles/transformerkfactorrating.htm
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I'm interested in balanced power, and I have a question I hope you guys might now. I have two amps that I like to run together, but the hum like crazy when both are plugged. I know the issue is because one, or both, are not wired in common mode.

I have been reading some papers on the Equitech web site about this issue and they claim balanced power will solve this problem with no equipment changes needed. Not that I dispute their claim, but I'm having a hard time understanding how it would clean up the ground circuit after current has entered from down stream. What do you guys think? Would balanced power connections safely isolate these amps?
I think I get it, but see what you guys think about this. My two amps hum because they reference ground at a slightly different potential, and that creates a small current between them when they are on the same circuit. The balanced connections assure that all components plugged into it reference the same ground so there would be no potential between the amps.

Yes? No? Smoking crack? :-)
Dan_ed

Just curious have you ever checked the two amps for the proper AC polarity orientation?
http://www.boundforsound.com/tweak.htm

Ground loop hum.
http://www.jensen-transformers.com/an/an004.pdf
11-06-11: Dan_ed
I think I get it, but see what you guys think about this. My two amps hum because they reference ground at a slightly different potential, and that creates a small current between them when they are on the same circuit. The balanced connections assure that all components plugged into it reference the same ground so there would be no potential between the amps.
Hi Dan,

See the second paragraph of page 2 of this Jensen paper. A key factor in how much hum reduction would result is the stray capacitance within each component between each of the two ac input lines and chassis, particularly stray capacitance in the power transformers of the components, and how similar or dissimilar those stray capacitances happen to be. So while I would expect there to be SOME improvement, the amount of improvement figures to not have a great deal of predictability.

Best regards,
-- Al
Jea48, I run them from the same wall outlet. So I have 2, really three with the SS bass amp, grounded devices on the same circuit. It is the best case, but I still get potential between any two of the amps. Individually, they are dead silent. I do suspect the issue is zero reference between the two, tube amps.

Hi Al. Thanks for tuning in cuz I'm just about over my head. :-) The Jesen paper is very good reference. Only difference is I think this is on the ac lines. Maybe I'm misinterpreting things. From my experiments, I get this hum regardless of interconnections between the amp inputs. Just having one of the other amps plugged in but not turned on or connected in any other way is enough to cause the hum. Still, it is cheap enough to try the audio isolators on the inputs. That may help convince me if more power side treatment will work or not.
I took some measurements from each amp using the ground tab on a cheater plug with nothing turned on, just plugged in. I'm seeing 16 vac on the ground tab from one tube amp and 14 vac on the ground tab with the other tube amp. The SS amp shows no potential. I didn't bother measuring the ac current.
Just having one of the other amps plugged in but not turned on or connected in any other way is enough to cause the hum.
Wow! That's different!

When the amp that is not connected to anything except power is turned on, does the hum get better, worse, or stay the same, compared to when it is turned off?

A possible explanation that occurs to me is that, referring to Figure 1 of the Jensen paper that Jim and I both linked to (great minds think alike :-)), when you plug in the unused amp, and it is in the turned off state, you are placing CPS4 (as defined in Figure 1) of the unused amp in parallel with CPS4 of the amp or amps that is/are being used. That would worsen Vy (as shown in Figure 2) for the amp(s) that is/are in use, thereby worsening the ground loop situation between the amp(s) being used and the preamp or whatever is driving it or them.

If the amount of hum decreases when the unused amp is turned on, it would add credibility to that theory, because doing so would place CPS3 of the amps in parallel, as well as CPS4, which would to some degree reduce the effects of the increase in CPS4.

I presume, btw, that the preamp to amp interconnections are unbalanced, as I would expect these kinds of effects to be much less significant with balanced interconnections.

Best regards,
-- Al
Yes, all unbalanced. I put the two tube amps on cheaters. When they are both off I see about 2.5 vac and that drops to about 1.3 vac when both are switched on. That seems to go along with your theory, Al.

I have also been referencing this paper from Equitech's web site.

Lifting the Grounding Enigma

They seem to be saying that the balanced power approach will do the trick for my situation but I can't reason it out.
Hi Dan,

I read through the Equitech paper, and it strikes me as excellent. However, it also strikes me as not inconsistent with the comments on balanced power in the Jensen paper, which is to say that there would probably be significant hum reduction if you used a balanced power arrangement, but not necessarily a reduction that is fully satisfactory.

From the Jensen paper:
It is also very unlikely that the two capacitances, CPS1 and CPS2 or CPS3 and CPS4, would be exactly matched in any piece of equipment. Mismatch ratios of two to one are common.... Although intuitively attractive, [the balanced power] approach can completely cancel interchassis currents in a system of three or more devices only in the case where each of the devices had such matched capacitances. This would be an extremely rare occurrence.... 10 to 15 dB hum reductions ... would be more routinely achieved.
From the Equitech paper:
If any aspect of the circuit is applied OR LOADED [emphasis added] in an unbalanced manner, noise will appear in the ground.... On the average, 16dB improvement in background noise has been noted.
In other words, any difference between the stray capacitances CPS3 and CPS4 in your particular amplifiers (which is unpredictable) will limit the amount of hum reduction balanced power would provide.

In considering the 10 to 16 db numbers, keep in mind the rule of thumb that a reduction of 10db is subjectively "half as loud."

Best regards,
-- Al
Thanks for your interpretation. I believe I have the "extremely rare" occurrence mentioned in the Jensen paper. :-) I realize this probably won't eliminate all of the hum, but cutting it in half might make it liveable. I'd like to put each of these two amps on their own balanced supply. These are around 60 watt PP amps so I don't need too large of transformers. Maybe a pair of 500va on each. Finding them for an experimenting price might take some looking.
See the second paragraph of page 2 of this Jensen paper. A key factor in how much hum reduction would result is the stray capacitance within each component between each of the two ac input lines and chassis, particularly stray capacitance in the power transformers of the components, and how similar or dissimilar those stray capacitances happen to be. So while I would expect there to be SOME improvement, the amount of improvement figures to not have a great deal of predictability.
11-06-11: Almarg
Al,

My thinking as well.

>>>>>>>

I took some measurements from each amp using the ground tab on a cheater plug with nothing turned on, just plugged in. I'm seeing 16 vac on the ground tab from one tube amp and 14 vac on the ground tab with the other tube amp. The SS amp shows no potential. I didn't bother measuring the ac current.
11-06-11: Dan_ed

Dan_ed,

If you are checking for the proper AC polarity orientation of the primary winding of each amp's power transformer nothing can be connected to the input of the amp/s. Also equipment ground of the amp/s has to float. (Amp is isolated)

The ground cheater you use needs to be the non polarized plug type or you will need to trim down the wider blade so you can reverse the plug in either direction.

The lower measured voltage reading is the correct polarity orientation.

Post back your results.

http://www.audioasylum.com/audio/general/messages/449743.html
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Nothing about the Equitech article implies any kind of panacea. In fact, if it's a ground issue, even separately isolating each amp might not help.

Perhaps Jim or Al can comment on the issue of UL/CSA standards and shunting/grounding as compared to IEC. I gotta step back and listen when those guys are talking.
Perhaps Jim or Al can comment on the issue of UL/CSA standards and shunting/grounding as compared to IEC. I gotta step back and listen when those guys are talking.
Thanks for the compliment, NG, but those kinds of standards are not among my areas of expertise. Jim?

Best regards,
-- Al
Thanks for the help, guys. Jea48, even if I did that it can't be maintained with a three prong connector. Yeah, the best solution would be to pack them off and have them rewired to play together. I hate shipping them as one already has chassis damage from mishandling.
Dan-ed - All connections back to and inside the incoming ac panel have been verified for tightness? Wire routing is according to hoyle, etc.? I suspect that you have checked all the basics but, just in case.

The weirdest hum issue I've had (2 arcam alpha 10's, 1 would hum whenever plugged in the other 1 never hummed, nothing else plugged in to the same circuit showed any sign of a problem) went away for good when I tightened all neutral connections at my incoming breaker panel. At least I assume it was due to a neutral connection because no other connections seemed suspect. Arcam's tech said on the phone that it was an ongoing frustration for him at the time, some units would hum at customers site but not hum in shop, some units would not hum.

Thanks for the help, guys. Jea48, even if I did that it can't be maintained with a three prong connector. Yeah, the best solution would be to pack them off and have them rewired to play together. I hate shipping them as one already has chassis damage from mishandling.
11-07-11: Dan_ed
Dan the polarity orientation check is only a test to make sure the manufacture of the amp checked for proper polarity orientation of the primary winding of the transformer before it was wired to the circuit.

If the test shows one of the amps power transformers has reversed polarity the next step is to check the power cord, if detachable IEC connection, and make sure the polarity of the cord is correct. Especially in the case of an aftermarket non UL or CSA listed power cord.

Next step if the power cord/s checks ok and the problem is the amp I would then try a real word test of the system and check for the ground loop hum.

Remove the ground cheater on the good amp. For the test the amp that needs the polarity reversed install the ground cheater into the wall outlet that gives the lowest voltage reading of the two.

Next connect the ground of the cheater to earth ground. (equipment ground at the wall outlet).

Turn system on and check for hum. IF hum is gone then the next step is to correct the problem.
The correct procedure is to reverse the primary leads connection inside the amp. Who better to do the job than the manufacture. Good chance he will only charge you for shipping.

You could also take the amp to a reputable repair tech.

There is no guarantee the hum problem is caused by a polarity reversed orientation. The test will require a little of your time and hopefully find the problem.

Or you could just buy a Jensen isolator for one or both ics.
Contact Jensen, bet they would be glad to help.
Jim
Perhaps Jim or Al can comment on the issue of UL/CSA standards and shunting/grounding as compared to IEC.
Ngjockey

Ngjockey,

Could you please expand on your question.

I am no expert on UL, just know the basics.

UL like NEC code is bare minimum safety standards.
And in the case of Dan's hum problem as long as the amps are safe to use UL or NEC could care less how they sound.

In fact, if memory serves me right, any current leakage below 5ma is acceptable.
.
The cost of the jensens and the fact that they will impact the sound doesn't make that an attractive long-term solution. I guess I'll just byte the bullet and send these off to get fixed the right the way. Can't blame a guy for trying to find an easier solution, but in the long run, there is only one way to fix this correctly.

I know my guy can fix this since he's been marketing his own monoblocks for a year now. He'll be shocked I'm finally sending these amps to him since he's been after me for a while now. :-)
For the record, I just noticed what appears to be a boo boo in the paper by Mr. Whitlock of Jensen Transformers.

In figure 2, which I referred to earlier, the formulas for Vx and Vy should have CPS1 and CPS3 in their numerators, respectively, rather than CPS2 and CPS4. That follows from the fact that the voltage divider effect between the two capacitances in each component will be dependent on the reactance of the capacitors (1/(2piFC)), not on the capacitance values themselves.

Therefore I retract my previous theory about CPS4 of the unused amplifier causing Vy, and hence the hum level, to worsen.

Best regards,
-- Al
Sorry, misled again.

UL101 and IEC 60335/60990 are more consistent than I was told. IEC is specific about class and such but generally leakage limited from 0.5mA. Difference is that IEC specifies true RMS reading.

Still, that's per appliance.
... limited TO 0.5mA ...
While I see the benefits of having one large primary isolation transformer for separating your main audio line from the rest of the house and regional power. but, you still have noise generated and kicked back into the line by individual audio components, especially those with switching power supplies.

So, you may want to isolate individual components from each other. Obviously, amps need much larger transformers than sources.

I bought six surplus commercial/industrial Topaz 2.4kVA Ultra-Isolator Transformers. It was actually a 240V, 3-phase, setup that I simply separated into individual units and re-wired for balanced power operation.

Anyway, it is amazing how much line noise you don't notice until it is gone.
11-07-11: Ngjockey
Sorry, misled again.

UL101 and IEC 60335/60990 are more consistent than I was told. IEC is specific about class and such but generally leakage limited from 0.5mA. Difference is that IEC specifies true RMS reading.

Still, that's per appliance.

Ngjockey,

Big difference between 5ma and 0.5ma!
So much for my memory concerning UL standards.
IEC 60335-1 Standards.
.
Somewhere between a decimal place and half a heart attack.
Somewhere between a decimal place and half a heart attack.
11-09-11: Ngjockey

LOL, though actually 5ma of AC current passing through the heart will not kill or cause heart damage. At least NEC code doesn't think so.

5ma is the maximum amount of leakage current,("consisting of possible resistive and capacitive leakage currents"), for the audible alarm to sound for a Line Isolation Monitor for an AC Power Isolation System found in Health Care facilities in; OR, Cath Labs, and ER rooms where electrical monitoring equipment and such may be connected to a patient. (Also required ma meter. Green light for normal, red light for alarm condition.)
2011 NEC 517.160 (B) (1) (2) (3)
Notice I said alarm, the power is not interrupted.
Though I would assume the doctor or techs in the room would disconnect the medical equipment from the patient in a timely manner or at least monitor the milliamp meter.... Don't know the answer to that one...

Also per NEC a GFCI is supposed to trip open around 5ma of current when detected between the hot to earth ground/earth grounded object. (GFCI senses more than just the hot to earth ground for its operation).

The problem with UL they only test new appliances as far as I know of. New at normal operating temperatures.
Not necessary the case in the real world.
As you know heat will degrade the insulting resistive covering the conductors of motors and transformer windings. Over heating, excessive overheating, caused from ambient temperatures or over working of the appliance can cause a break down of the insulation and result in more leakage or worse case a short.

http://hypertextbook.com/facts/2000/JackHsu.shtml

Jea48 THANK YOU! GOOD LORD, why don't we just hook a dedicated line from a substation. There is no doubt that this 15KVA is an overkill idea. I used to work with dc current 60-1,200 amps. requiring less than 1/4 voltage drop. For that kind of specification, we sometimes used cables as big as you'r wrist!(750kcml). I don't doubt that they engineered these battery circuits for very specific purposes. So when I see consumers buying bigger is better thinking, I know that there is an uneducated/greedy salesman lurking in the shadows. Yes, there is a great need for clean power, and balanced power is very effective for cancelation of noise. Yes, there is a need for adequate reserve, but don't you think that a DECENT piece of equipment(such as Levinson) considers that in their design? No doubt you should have low impedance, and the best(read tight) connections required. Yes can analyze this to death, but in the end, your ears are to be the judge and not some hype/misinformation.
Thanks for all the advice.
I am still leaning toward 15 kva Isol trans due to the size of my system. I have a dedicated 100 amp service from the electric company transformer feeding a dedicated 9 circuit/ 80 amp isoclean breaker panel. This service shares the same power meter with 2 other 100 amp services feeding my 2 household breaker panels.

I have 3 systems fed by the isoclean breaker panel which includes hometheater with projector, processor, large multichannel amp, 3 powered subs, multiple sources, housewide music distribution with 1 large multichannel amp and 1 large stereo amp and multiple sources, and finally 2 channel system with 1 amp, 4 powered subs, digital, vinyl, reel to reel sources, main preamp and phono preamp. Also several large plasma screens.

In the future I anticipate more computer based sources and processors, more amplifiers and more screens and possibly a 4th system.

during the summer and fall I usually have 2 systems working simultaneously. Winter and spring usually 1 system at a time. On rare occasions all 3 are going.

All electric services come in through my garage which is the location of my isoclean breaker panel. The 450lb ultra k will be installed in the garage immediately adjacent to the panel. This location is completely isolated physically from all systems.
I will say that, in a way, I envy your overkill of this power system. Most people seem to think that a plug in surge protector will do the job. The way that you have implemented the devices, i.e. not having them close to the HT/audio systems, is absolutely correct. I can't tell you how many times I have owned devices that made more physical noise than the electrical noise that they were trying to eliminate in the first place!
I took my situation as far as I could by having the secondary feed to the house replaced, as well as having three other houses replace theirs too. We all fed off of the same transformer. Then I replaced an old panel with a decent Square D panel. Then I ran a 10 Ga. dedicated line to the audio system. And finally, I use a BPT balanced device that uses 8 different secondary windings to help isolate one section from the other. Did it help, you bet. I am eager to see what positive effects that your method adds.
Well, I finally had Controlled Power co's Ultra K 600 isolation transformer (15 kva with triple shield and k 13 factor correction ) installed in front of the Isoclean Zero Ohm breaker panel. I have pics but unsure how to upload them here. The benefits were discernible immediately and performance continues to improve at 100 hrs currently.

Oversizing did not hurt performance or create excessive noise as mentioned in this thread, and the results i am getting are nothing short of exhilarating. Unfortunately, I can't comment if its better than 10 kva or 5 kva since I don't have these on hand. However, since the size of the exterior of these units are very similar and the weight varies by roughly 150 lbs from lowest to highest and the cost variation is not significant, 15kva @$3700 vs 10kva @$2900 vs 5kva @2700, I would say opting to oversize is a no brainer.
I am convinced that whether you live in the city, or in the country as I do,
whether your sharing the grid with multiple neighbors,or just a few as I am, that an isolation transformer is one of those audio purchases that is so satisfying that the monetary investment becomes a pleasure rather
than a burden. Honestly, I think some would pay a lot more than $3650 to get this kind of performance upgrade. But Controlled power has no idea of this, yet. And I'm sure some savvy audio dealer may eventually get them
to tweak their design with audio applications in mind.

So while the balanced vs standard power debate rages on, I am thrilled with my current set up.
Natan6355,
Hello and congratulations on your sucessful implementation of the balanced power (BP) transformer. Is the size overkill? I `d say yes (for home audio components) but absoluttely harmless(and hey, it`s what you wanted).Your results don`t surprise me but are what one would expect.

As I wrote earlier in this thread my experience with a BP transformer (in use 3 years) has been a completely positive move 'without any downside'. The improvement was immediate and substantial, and when I tried putting the components back into the wall outlets(dedicated 20 amp service) the decline in sound is undeniable. I don`t understand what is 'debatable' about balanced AC power at this point.
Thanks for the follow-up. Would like to see that more often.
I, also, recently joined the BP ranks. I’m using a Signal DU-10 transformer wired for balanced power with electronics that can potentially draw a max. of 3400kVA. My findings with BP are similar to that of Zmanastroomy & Charles1dad. By adding a 220uf capacitor to the secondary side of the transformer, this made a HUGE improvement to the sound. The improvement with the added capacitance is far more impressive than BP alone, which was already a significant upgrade. The down side with the added capacitance the trannie generates more heat and noise.
By adding a 220uf capacitor to the secondary side of the transformer,
03-10-12: Norm

Norm,

A word of caution when adding capacitance in an AC circuit.
Two things that can happen.

(1) The capacitor can raise the output voltage.

(2) Too much capacitance causes the voltage to lead the current causing a leading power factor. Result is a low power factor.... That can cause overheating of the secondary winding of the transformer.
.
Jim -- Good points, but in no. 2 shouldn't "lead" be "lag"?

Re the 220uf, that corresponds to an impedance (capacitive reactance) of 12 ohms at 60 Hz. That will certainly pull a lot of current through the transformer, but I suppose it's within reason given the 10 kVA rating of the DU-10, and the 3.4 kVA load. Assuming the breakers and wiring can handle it all, of course!

Best regards,
-- Al
Good points, but in no. 2 shouldn't "lead" be "lag"?
03-10-12: Almarg

Al,

You are correct....

Should read
Too much capacitance causes the voltage to "lag" the current causing a leading power factor. Result is a low power factor....

Re the 220uf, that corresponds to an impedance (capacitive reactance) of 12 ohms at 60 Hz. That will certainly pull a lot of current through the transformer, but I suppose it's within reason given the 10 kVA rating of the DU-10, and the 3.4 kVA load. Assuming the breakers and wiring can handle it all, of course!

Norm has the transformer configured for balanced power. That cuts the KVA rating of the xfmr in half.
The xfmr maximum continuous FLA rating is 5 KVA.

Jim
Thx Jea. You are correct. By adding capacitance to the secondary side this did raise the output voltage to approx. 1v. However, input voltage is still 2V higher than output voltage.

Hi Al,

Would you please elaborate how increasing the capacitance to the secondary side of the transformer may cause voltage to "lag"? Also, how much additional current is the transformer "pulling" by adding 220uf.

Best reagrds,

Norm