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In Reply to: How to Spec a Dedicated AC Line? posted by Omera_T on April 2, 2007 at 04:49:46:
Hi
Don’t fool with power systems unless you know exactly what and why about what you’re attempting.
Here is a link to one article that goes into what is involved.http://www.middleatlantic.com/pdf/PowerWhitePaper3_07.pdf
Essentially all of the problems associated with wall outlet power noise and unbalance, that sometimes are even real, can be squashed with an isolation transformer.
Many of these transformers have low pass filtering and spike suppression, some, the kind called resonant transformers (like Sola makes) regulate the voltage and put out a constant Voltage sine wave too even with a distorted input. These devices do tend to make airborne noise so they should be located in another room, not in the listening room..
Large computer systems used to be real sensitive to power supply variations, the best place to look would be for a power isolator that was removed from service.For example, here is a 500 Watt unit that is on e-bay.
http://cgi.ebay.com/SOLA-POWER-LINE-CONDITIONER-500-VA-63-23-150-8-NIB_W0QQitemZ320096243423QQcategoryZ42881QQrdZ1QQcmdZViewItemAnd a 2KW unit
http://cgi.ebay.com/SOLA-POWER-LINE-CONDITIONER-500-VA-63-23-150-8-NIB_W0QQitemZ320096243423QQcategoryZ42881QQrdZ1QQcmdZViewItemUnderstand, these ARE NOT a UPS supply, they just regulate / isolate and clean up house AC for sensitive electronic equipment.
Skip the exotic wire unless you already have it, it makes no electrical difference at 60Hz. Use conduit or armoredflex cable (BX around here).
Best,
Follow Ups:
Hi.Isolation transformer ia not a cure-all.
A PROPERLY design-built isolation transformer can effectively stop the harmful surges riding the powerlines from damaging the sensitive electronic equipment load.
We need high temp multi-varnished magnet wires, high dielectric interwinding insulation sheet instead of cheapie Kraft papers, etc etc to prevent surges arc-overs.
Another very important feature is the interwinding electrostsatic shielding to drain away common-mode lightning surges.
But unfortunately many isolation powerline transformers commonly cheat away by using copper or even aluminum foil wraps. Why can the huge lightning surge currents be drained away in split seconds via such skinny so called shield ??
Properly built isolation transformers should use heavy gauge copper flat ribbon bars as shield to drain away the hugh current surges effectively.
Another neglected factor is effective loading of the isolation transformer in case of HF noise surge across common-mode lines (live/neutral & ground). Without effective loading, the transformer windings ring bigtime at their resonance frquencies & boost up the incoming noise peaks instead of isolating them !!!
Therefore it is imperial to have effective LC powerline RF noise filter DOWNSTREAM of the transformer to damp down the resonance spikes.
Again not all powerline filters are built equal to do the job.
This is another story to tell.c-J
Feroresonant transformers did not sound as good as over-sized E-I core transformers in my own testing.( See: http://www.geocities.com/jonrisch/catch2.htm )
In fact, of all of the ferroresonant transformers I tested, including a couple of Sola brand units, NONE of them sounded very good on an audio system.
What works on a computer (with it's switching power supply) or on one of the older style mainframes (which had incredibly beefy power supplies in one sense, but without enough AC line protection from surges, spikes and EMI), doesn't necessarily work well for an audio system.
I found this to be true for surge suppressors as well, (see: http://www.geocities.com/jonrisch/surge.htm) the cheap ceramic caps, the low capacity inductor cores, etc., all conspire to reduce performance under extreme conditions.
What about a ferroresoant transformer could cause such a sonic problem?
It could be any one of a number of things:
The resonant beahvior could be extending the duration of line transients or 'events', this could then create a background of noise to blur the playback performance.
The resonating cap could be of poor quality in terms of audio power usage, again, instead of shortening line events and transients, increasing their length, smearing them out in time.The saturated portion of the circuit could be adversely affecting peak current delivery.
The extra windings would increase the output impedance, and even though the average AC voltage was "regulated", the peak current would be stiffled.
In any case, many folks have found out the hard way that ferroresonant transformers are not all that great for audio systems, at least, if you want them to sound good.
As a last comment, unless there are compelling reasons to use armored AC wiring, such as extreme rat infestation or a real chance of physical abrasion of the wiring, sonically, it is not a help, but a hinderance.
The AC wiring should be kept away from steel, iron, and metals of any sort, as much as this is possible, for maximum sonic performance in a home playback environment.
I use Sola transformers between the wall and my amps, and between the wall and my pre-amp. When I first placed a Sola transformer between my pre-amp and the wall, I noticed that the noise floor dropped significantly. I could not hear the high frequencies stifled any. But I put new capacitors in before I began to use them permanently. I put an industrial noise filter (Tokin) between the Sola transformer and the pre-amp which cleaned up the signal, put space between the instruments, improved the imaging.If these devices hadn't improved the music, I wouldn't have used them, but YMMV.
.
Hi JonI had a big Sola in my home system for a while but I can’t say it made a difference and it did make acoustic noise on its own. It was quickly located to another room.
Here, if a person were wiring a dedicated circuit and plumbing (code here requires steel conduit or BX if less than 3 feet) then the isolator can be located at the breaker box end.At Intersonics, we were in an industrial park and line voltage usually didn’t look pretty on a scope and varied all over the place during the day. They got a bunch of Sola’s which were used on the test benches and computers and such.
At least by measure, the voltage coming out looked nice on a scope and meter and it ended the issues that existed with the sensitive stuff although being all over the room, there was a steady audible buz if the stereo wasn’t on to mask it, the speaker division made sure it was always on.A more well thought out answer to the original post would have been to ask a few more questions like “what is the problem you have which makes you consider a dedicated line”. “Is everything on one circuit now?”
Most of the time, when people get desperate and look at the power end, they are chasing hum or noise that while driven by AC, is a result of ground loop currents in the signal cable.
It is unfortunate that hifi isn’t balanced as in Pro but good transformers or circuitry cost more than the unbalanced RCA cable.
In this case, a good AC or signal isolation transformer would provide the rubber glove for a leaky pen fix.
While having a given item may give conflicting result due to additional unaccounted effects (like for example not also having a parallel choke to block common mode noise), I am not clear how having clean quiet constant voltage AC alone, could cause a decrease in accuracy in the performance of the what is connected.
Best,Tom
My main problemt that I'm trying to solve is that my music has a certain harness or glassiness at the top end. I like adult contemp and rock, and I like it pretty loud. No buzz or hum.Other factors working against me (that, unlike my musical tastes, I could change) are that I listen to CD's exclusively, and my Thiel speakers can be very revealing. Also, use solid state amp (Ayre) to drive the Thiels.
I am RCA to the preamp, then balanced from the BAT tube preamp to the Ayre SS amp.
-Tim
Hi.First off, have you used any so called "isolation transformer" at all? Or just hearsay.
Years back, I did use one, 1KVA custom-built like a tank, with static shield, & housed in a large shielded metal housing, exclusvely for my audio gears, feeding the dedicated power lines direct from my house fuse panel powering my gears only some 20ft apart.
Frankly, I am NOT impressed at all by its sound. It slowed down the sound bigtime & put up a thick veil over the music. The music came back to its life & rhymthm instantly again after the isolation transformer removed out of the system.
Don't overlook the ever exisiting parasitic capacitances btween the primary winding of the so called "isolation" powerline transformer & its secondary winding. It is the series-coupling capacitances plus the shunt-wire resistance/inductances of the ground wires of the equipment effectively form a highpass filter for the EMI noises ride through.
You believe what those power hardware vendors told you? I did but today I don't after this costly experience.
Of course, one does not need to drop a huge bundle for exotic wires, but I would not use THHN, XHHW, RW90 cheapie types building wires to power my audio rig.
c-J
Hi.
“First off, have you used any so called "isolation transformer" at all? Or just hearsay.”I have used them, mostly in lab work where they conditioned the AC for computers and test gear. I had one at home for a number of years, can’t day it made a difference though.
“Years back, I did use one, 1KVA custom-built like a tank, with static shield, & housed in a large shielded metal housing, exclusvely for my audio gears, feeding the dedicated power lines direct from my house fuse panel powering my gears only some 20ft apart.
Frankly, I am NOT impressed at all by its sound. It slowed down the sound bigtime & put up a thick veil over the music. The music came back to its life & rhymthm instantly again after the isolation transformer removed out of the system.”Well, normally one experience would be enough to convince someone of the futility of an accepted technical solution in other areas of electronics. Further, unless you refer to putting transformers in the signal path, I am not clear how having a smooth, constant voltage sine wave, isolated from mains would cause “problems” like you describe.
“Don't overlook the ever exisiting parasitic capacitances btween the primary winding of the so called "isolation" powerline transformer & its secondary winding. It is the series-coupling capacitances plus the shunt-wire resistance/inductances of the ground wires of the equipment effectively form a highpass filter for the EMI noises ride through.”
I’m not overlooking it and neither do the companies that make that stuff, that IS a world (outside of hifi) where people measure everything they can think of.. IF hf noise is a problem, a parallel choke is a simpler fix.
“You believe what those power hardware vendors told you? I did but today I don't after this costly experience.Of course, one does not need to drop a huge bundle for exotic wires, but I would not use THHN, XHHW, RW90 cheapie types building wires to power my audio rig.”
Hey, I don't blame you, I would be suspicious of anyone selling to the hifi market.
It may give comfort to know that out of the miles and miles of crappy aluminum and copper wire your power goes down, that the last few feet of "special wire" could have some significant effect over code.
TD
I found his post quite reasonable compared to most of what is posted in this forum. Many others have tried balanced power transformers without the drawbacks you claim. As you know I use one. A 1kva transformer is way too small however.If you feel THHN with virgin copper is terrible what code approved wire do you like? And please no silver in teflon sleeve stuff or audiophile only approved wire!
Hi.First off, do you know why dedicated powerlines with ISOLATED saftely ground are recommanded, which have decades long history of application in computer & digital electronic industries?
FYI, it provides a significant amount of wiring impedance btween the critical circuit (here our audio powerline) & other local powerlines to stop disturbances from other loads, digital or anologue, entering the critical circuit.
I verified this unnoticed EMI/RFI noises disturbances by measuring
them with a wideband powerline & EMI noise analyser on a powerline strip with a CD player hooked up to it. The noise level jumped up whenever the CD player was swithced ON !!!!!! How about those so many computers being used in the same location, residence or busiess alike?This hinted me to have get dedicated powerlines direct from my house fuse panel exclusively for my analogue audio equipment SEPARATED from digital equipment.
I need less than 300VA with one of my power amps playing. So how many KVA powerline transformer should I use, please tell me?
I never question ahout the theoretical function of a balanced powerline transformer, but I only concern if it does impair the sound or not. I had bad experience with mine.
Let's get back to the topic. How you can be so sure ALL building wires use "virgin" copper. I already asked one of the largest cable mills with in-plant copper smetlters in USA, I was told for building wires they build mostly used recyled copper (re-smelted in-plant). They supply tons & tons of building wires to the leading hardware stores all over USA & Canada.
Have you ever compared the sonics of powerline wires. I did. Being
installed OUTSIDE of the house wall structure, no building wires in metal conduits are needed. Now we can have choice to use the best sounding power cables, with oxygen free high conductivity copper with UL/CSA rating.FYI, I only use 4N silver & silver plated OFHC conductors in teflons for signal paths in my amps although my power cords are all 4N silvers.
c-J
PS: how are you so sure balanced transformer are really so practically balanced?
.
If so I think that is uncalled for an undeserved. I have always done my best to give you carefully thought out and well worded responses even when you were way out in left field on a subject. Of course I also acknowledge that you typically don't think you are "out in left field".You can spec virgin copper. Many places do. Last time I knew government did in some areas...and also required a certain % of recycled in other areas. But wire is your profession, not mine so you should know better. Now on to the questions at hand.
You ask about isolated grounds and act as if I know nothing about them yet you know I am a building engineer at a hospital so you "know" I know about them. Fact is, the original post was not about isolated grounds but about separately derived grounds, ones not referenced to the power panel. That, my friend, is highly illegal in the states so I simply can't support it in an open forum. With regards to digital and all that, if you saw my response in another forum (as well as in other posts) you know I advocate the use of individual isolation transformers for each and every digital gear or item that has a switching power supply. Only analog and linear power supplies go on the main balanced power transformer. I run 240VAC on the primary too. And I put an EMI/RF filter in front of it and then measure to insure the transformer windings are balanced.
When you wire a transformer for balanced power it is de-rated by 50%. I advise at least twice the VA of the peak load. So find the actual peak load of your 300VA load and multiply by four (if class AB, 300VA is an average and not a peak). I use a 3kVA myself for a 3 watt tube amp, preamp, and turntable.
Again you are being stubborn Jack. I don't dispute your findings with transformers and agree with you that 240VAC from the wall is best and lowest impedance. But not everyone has that option or is comfortable with it (for reasons beyond my understanding). But when so many report favorable results using a transformer for power conditioning I think a smart man would revisit the subject and try and discover why he had such dismal results. But instead you choose to condemn anyone who would advocate their use. Why is that sir?
Hi.I agree randomly planting grounding rods is a very dangerous game let lone being illegal. That's why I stay away from commenting until I get some more technical ground on it.
From us being consumers, no way we can "spec virgin copper" on purchasing small quantities from any hardware store. Take it (recyled
copper) or leave it. Hence my advice to stay away from building wires given other choices.I know too well where you come from. Professionally you use tons of isolation irons for your medical gears. But from a consumer's viewpoint, balance transformers is costly & not easy to make it right. Besides, it impaired sound as in my situation, which would happen to anybody else' home provided of course, your ears & gears can tell the difference. Unfortunately, I can detect the sonic differene.
Like it or not, I only use powerline transformers with no other options given their techically downsides. As I mentioned parasitic capacitances between the primary & secondary windings are already some huge headaches to resolve.
You may call me being "stubborn". My bottom line is, like those with keen ears, no brooks on sound quality despite whatever favourite techical reports published. We got to watch out the real thing or smoke mirrors with commercial interests behind them.
I am not sure why you suggusted 4 times the max load of my 300VA situation. I will dig more into your claim. You are lucky to have a overized 3KVA sucker to handle your 3W amp. Who else could have such previlege without wracking the wallet & the backbones (to carry it in).
c-J
Hi.He responded to it. It was simply a response to Cliff's post calling me "wiser ass".
Why should I call you bad name?? Have we known not long enough?
c-J
I too have used an isolation transformer to create a dedicated power line for my audio equipment only.I found it extremely effective and a 1KVA 230v:230V with interwinding screen powers the lot without fuss.
The only digital item I have is a CD player and that is connected via a fairly classic LCL power filter.
Hi.I am just speaking on my hands-on experience.
The isolation transformer I used was 1KVA 230V:230V, with I/P winding tapping with large ANALOLGUE meter monitering to maitain the O/P constant by manual adjusting. No fuse either. Only 120lb weight.
Anyway, maybe my ears are too rusted or my equipment too revealing, it just did not sound right until it was removed from the scene.
Why not try what I did? Try to bypass it completely to see if the music sound better or worse?
Listening is believing.
c-J
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The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
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The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
"Why not try what I did? Try to bypass it completely to see if the music sound better or worse?"I installed mine because I was having trouble with electrical noise! Why take it out again?
no!
... used in the sense of "Don't be a silly ..."If we want to get anatomical and ruder we stick an R in it ...
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