Analyzing the power from the outlet


I've been reading threads on the various methods of power cleaning -- filters, regenerators, dedicated lines, etc. But I don't see a thread that explains a systematic way of evaluating the condition of the power at the outlet. Is there a thread or a link that instructs on how to analyze the power for noise, voltage consistency, etc from the point of view of an audiophile?
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It is entirely possible that you have exposed the pseudo science that many audiophiles thrive on. You are supposed to simply assume that your power needs improvement and then purchase a product to improve it.

A EE friend of mine just shakes his head at the majority of the audiophile power products, but does understand the use of a power regenerator in a county where the power grid is garbage.

My guessis that analysis before and after might yield a change, but it might be difficult to objectively prove an improvement.
Well, I've seen suggestions to validate the outlet voltage is consistently 120 V with a tolerance of +/- 3 V. Assuming the outlet meets that benchmark, that would, I think, obviate the need for a power regenerator. (At least I think that is the function of a regenerator.)

But, as far as the filtering of noise, etc. Does anyone know how to measure the amplitude and frequency of noise without electricuting yourself?

I'm not being facetious. I'm geninuely curious.

On a related note, it's my (limited) understanding that most audio components have a transformer as the first stage from the power input. Doesn't that automatically decouple most of the noise from the power?
There was a thread written here a month ago or so by individuals that are a lot more knowledgeable then myself. I thought they said that there was really no way of evaluating the condition of the power at the outlet or in the line.
Someone please correct me if I'm wrong.
you have my attention on to what a few very educated audiophiles I have spoken to here on audiogon will say in response to this thread, I want to know!
My PS Audio P-10, $3000 used approx. regenerator has a screen showing about 3% distortion and 118.5 volts which it reduces to .1% distortion @ 120.1 V. I can hear the difference and it's worth it to me (I have two.). Because this is a high price to find out, I suggest you borrow one from a friend as I did (they're heavy)-make an appeal here on audiogon- see if you can hear the difference and then ask yourself if it's worth it to you to buy one. Else, I think there is a trial period. While I realize this is a long winded way to say "try it before you buy it...YMMV" it's not at all intuitive otherwise: I live in the Atl. suburbs, a friend in the city has cleaner power! ; a friend in my same neighborhood even has cleaner power (closer to the transformer?). And so, even if you had a cheap, easy way to measure, what would the number mean? You still have to be able to hear a difference (there probably would be some, in any case) and decide if it's significant to you.
This is a device that can be plugged into a dual-trace O-scope, and will display the high freq noise, on your incoming AC(both line to neutral and neutral to ground): (http://pdf.textfiles.com/manuals/STARINMANUALS/ETA/Manuals/Power%20Probe.pdf) Here's a demo of it's display and the noise on an AC line: (http://www.youtube.com/watch?v=vOO89uHEprM) There are three parts to the demo on Youtube. Of course everyone's AC quality varies, depending on what's connected to the their local source(everything operating on your side of the neighborhood's single phase distribution transformer). ie: In your own home; anything digital that's operating is polluting your AC with very high freq noise.
The previous discussion to which Lak refers, of essentially the same question, was in this thread, beginning with the post the link opens at.

As you'll see, IMO measurements of AC noise, even with sophisticated instrumentation, are unlikely to be helpful.
I've seen suggestions to validate the outlet voltage is consistently 120 V with a tolerance of +/- 3 V. Assuming the outlet meets that benchmark, that would, I think, obviate the need for a power regenerator. (At least I think that is the function of a regenerator.)
Besides providing a stable voltage, a regenerator will also reduce or eliminate noise and distortion that is present on the incoming AC, since it is what generates the AC that is provided to the components it is powering. Essentially it consists of an oscillator generating a 60 Hz signal (or 50 Hz in some countries) driving a high powered amplifier which in turn supplies that amplified 60 or 50 Hz signal to the connected components, and a power supply which converts the AC from the wall outlet to the DC which powers its own oscillator and amplifier.

Although as you may have seen in past threads some people report that the regenerators they've tried seem to cause compromised dynamics or other issues.
It's my (limited) understanding that most audio components have a transformer as the first stage from the power input. Doesn't that automatically decouple most of the noise from the power?
The bandwidth limitations of the power transformer will significantly reduce the frequency components of the noise that are above a certain frequency. Noise on the incoming AC will also be reduced by filter capacitors and decoupling capacitors that will be present at various circuit locations in the design. It will also be reduced by voltage regulator circuits that are generally used in audio components, other than in the high power stages of most power amplifiers and integrated amplifiers. Finally, it will be reduced by what is known as the power supply rejection ratio of the amplification and other circuit stages which process the audio signal.

All of which is not to say, however, that cleaning up the AC power in some manner won't make a difference, to a greater or lesser degree depending on the specific components that are involved.

Regards,
-- Al
Proper voltage and current is easily measurable at an outlet as a start to make sure you are at least playing on a level field. What happens beyond that in regards to power and sound is not practically measurable it would seem. Trial and error is needed, but not blindly. Learn about solutions that solve particular problems, like reducing noise levels with line level gear and optimizing current delivery for power amps, and buy wisely. Lots of "noise" out there when it comes to high end power solutions that muddy the waters. Know the problem you are looking to solve and go from there to end up at a happy place soonest.

I like Pangea power cord products in this regard. They are not overly expensive and each product is clearly designed to solve specific problems as I related above. A very good place to start if one must. Noise levels are often significant with modern gear, especially computer/digital based gear and worth tackling at some point IMHO, but only after the main components in any system are working together well, as an improvement, not as a solution to change the sound in a major way.

I also recommend a decent power conditioner as a must for line level gear (not for current hungry power amps)in most any serious hifi system these days. Furman is a line I like, but even the common Monster strip/conditioner works well.
like Truman, I use a PS Audio regenerator (the P-3) and the results have been incredible. Getting clean, consistent power is now the basis from which I start any system I put together in the future. I want to add a dedicated line next with upgraded wiring, ground, etc.
You can do this rather easily using a modern Oscilloscope. You will need to play with the resolution, try several different Hz, from 100 Hz to several thousand per division. This is easy to see. I am an electrical engineer and this is a simple thing to do. Depending on your area, congestion and the type of loads, power can be very dirty. Your electric company generally is not too concerned about this. Simply Google "Measure noise on AC line."
Besides providing a stable voltage, a regenerator will also reduce or eliminate noise and distortion that is present on the incoming AC, since it is what generates the AC that is provided to the components it is powering. Essentially it consists of an oscillator generating a 60 Hz signal (or 50 Hz in some countries) driving a high powered amplifier which in turn supplies that amplified 60 or 50 Hz signal to the connected components, and a power supply which converts the AC from the wall outlet to the DC which powers its own oscillator and amplifier.

But I understood the amplifiers require internal oscillators to operate? Why do you need to add an external oscillator?

The bandwidth limitations of the power transformer will significantly reduce the frequency components of the noise that are above a certain frequency. Noise on the incoming AC will also be reduced by filter capacitors and decoupling capacitors that will be present at various circuit locations in the design. It will also be reduced by voltage regulator circuits that are generally used in audio components, other than in the high power stages of most power amplifiers and integrated amplifiers. Finally, it will be reduced by what is known as the power supply rejection ratio of the amplification and other circuit stages which process the audio signal.

If all this processing is in the amplifier, why would it matter what you do to the power before it arrives at the amplifier? Maybe I'm missing something. But it seems to me that this is the design challenge of building amps. In theory, amplifying a signal is straightforward -- you buy an opamp and insert it into the signal path. But, addressing the departure from theory is what adds the complexity and $1000s to the price an amplifier. The designer building circuits into the amp that mitigate the problems created by the power supply. How could you market an amp that only functioned with a pristine power supply?
But I understood the amplifiers require internal oscillators to operate? Why do you need to add an external oscillator?
An oscillator is something that generates a signal. An amplifier is something which boosts some combination of the voltage, current, and power of a signal. What I was describing was a power regenerator, which takes in AC power from the wall outlet, and sends out "regenerated" AC to the components that are plugged into it. Power is regenerated in the regenerator by amplifying a signal generated by a 60 Hz oscillator which it contains. As I indicated, the regenerator's amplifier and oscillator are powered by DC which its own power supply creates from the AC it receives from the wall outlet.
If all this processing is in the amplifier, why would it matter what you do to the power before it arrives at the amplifier?
No design can reject noise and distortion on the AC it receives to an infinite degree. A substantial body of empirical and anecdotal evidence exists suggesting that designs at pretty much all price points can benefit sonically if the AC they receive is relatively clean.

Regards,
-- Al
Hello Al
Thank you for the response. I know you are a highly accomplished designer so I appreciate your sharing your insights.

Ok. So that's a regenerator. If I understand it, you are recapitulating a perfect sin wave.
-- an amplitude of 120 RMS and a frequency of 60 hz.

But, when people here talk about power conditioners, they are not necessarily talking about regenerating the ac signal. They are talking about other things such as power filters (Shunyata). Is a power filter actually a regenerator? Do they filter the noise off the power by regenerating the wave form and the side effect of the regeneration is to remove the high frequency noise?

Or is a power filter a different device?

Finally, there is the business about the balanced power devices. As I understand this, it switches from 120-to-ground to 60-to-60 and then subtracts the common mode noise. But, again, isn't that the basis of the front end of an amplifier. Isn't the first component in the amp a transformer or differential amplifier subtracting common mode? And doesn't an amplifier transformer switch from 120-to-ground to 60-to-60?
CJK, a power filter/conditioner puts the incoming AC through a relatively simple circuit which provides some degree of noise reduction. It may also include a provision for surge protection. It does not “regenerate” power.

As can be surmised from the description I provided earlier, a power regenerator capable of supplying sufficient power for a typical audio system will cost a substantial amount of money. Many (although certainly not all) conditioners are available for much lower prices than most regenerators, or at least regenerators that are well designed and have substantial power capability.

Your question about balanced power is a good one. Yes, the outputs of the power transformer in an audio component will often be balanced relative to ground. (Although keep in mind that the power transformer will often provide multiple outputs, at various voltages, some of which may be balanced and some not, for various reasons). However a main goal, and perhaps the main goal, of balanced power is to minimize noise on the AC safety ground. AC safety ground is connected to the chassis of the component, and much of the noise injected onto the chassis will inevitably find its way to the circuit ground/signal ground of the component. In some components circuit ground and chassis are even connected directly together, and in many others they are connected together through a low impedance.

The component’s power transformer cannot help with respect to noise coupling through that path, because it is not in that path. And in fact it can itself contribute to coupling of power line noise onto the component’s grounds, via stray capacitances that will inevitably exist within it.

Also, btw, a major source of the noise that balanced power can help reduce will be the components themselves. See this paper for a somewhat simplified overview, and this one for greater detail.

On another note, glad to see you’ve made some progress with the problem being discussed in your other thread.

Regards,
-- Al
There's a series of threads on Polk Forums, where one of the members, a college professor, ran a series of measurements on power line noise and line conditioner/tweaks. AFAIK, its the most extensive type of evaluation conducted by a product owner on any forum.

http://www.polkaudio.com/forums/showthread.php?71333-Studies-On-Residential-Power-Line-Noise-Part-1

http://www.polkaudio.com/forums/showthread.php?71382-Studies-On-Residential-Power-Line-Noise-Part-2

http://www.polkaudio.com/forums/showthread.php?71545-Studies-On-Residential-Power-Line-Noise-Part-3-PS-Audio-Power-Plant-Premier

http://www.polkaudio.com/forums/showthread.php?72539-Studies-On-Residential-Power-Line-Noise-Part-4-PS-Audio-Premier-SC-Power-Cord

http://www.polkaudio.com/forums/showthread.php?75093-Studies-On-Residential-Power-Line-Noise-Part-5-PS-Audio-Power-Port-Premier

http://www.polkaudio.com/forums/showthread.php?79010-Studies-On-Residential-Power-Line-Noise-Part-6-PS-Audio-Soloist-Special-Edition

http://www.polkaudio.com/forums/showthread.php?82496-Studies-On-Residential-Power-Line-Noise-Part-7-HiFi-Tuning-and-Isoclean-Fuses

http://www.polkaudio.com/forums/showthread.php?83644-Studies-On-Residential-Power-Line-Noise-Part-8-Audio-Grade-Fuses-For-Home-Theater
Here are a few things that proper power conditioning can correct:

The most important is the 5th harmonic. Fluke instruments printed a white paper on this subject some 20 years ago. The 5th harmonic (300Hz in the US) can cause power transformers to become noisy, power rectifiers to radiate noise, and certain types of AC motors to possibly spin backwards.

DC on the line can cause saturation of toroidal transformer cores and should be blocked else the transformer can become quite noisy. A second harmonic on the line can do the same thing.

High frequency noise can cause problems in digital gear but otherwise is not likely to do much to analog gear if the power supplies are properly designed.

Any skeptical engineers out there? If so, consider the fact that the best power conditioners were made by companies that directed their product at the commercial/industrial market. Elgar is one of those companies. If clean power did not help, companies like Elgar would not exist. If there is skepticism, it exists out of ignorance, which is easily curable.
Great inputs from Ralph (Atmasphere), as usual.

Gbart, thanks also for calling attention to the papers presenting the many measurements. I haven't taken the time to read most of them yet, but FWIW I would suggest to those who do read them that whatever conclusions are reached by the author be carefully scrutinized, and not just accepted at face value. I say that because not long ago, in connection with a thread here on fuse directionality, I did thoroughly review Part 7 of those papers, relating to fuses. My comments on it were presented here.

Regards,
-- Al
Tboooe - I am probably oversimplifying things, but if your regenerator is really generation new clean power, what would the purpose of a dedicated line be? Almost seems like it would be similar to pretreating dirty water going into water purification plant that produced perfectly clean H2O.
mceljo, I dont pretend to be an expert on electrical matters but your example makes sense to me. My only thought on why getting a dedicated line + an AC regenerator would offer benefits is that by supplying cleaner power and grounding, the regenerator does not have to work as hard? Perhaps there is noise that it cannot completely filter out?
You didn't pay for a "filter", that would be a power conditioner. You paid for a product advertised to regenerate the power. It seems that if you believe what they say then you should take them at their word.
Rodman99999, thanks for the links to PowerVar products. I enjoyed watching Part2 & Part3 & found the info useful.
Mr B- You're welcome. I was hoping someone would find it so. Happy listening!
As usual its always good to hear from Ralph regarding all things directed towards hearing and the love/wonder of music and how to expand our listening pleasures.Lots of good posts here.Speaking of PowerVar I had one of their conditioners about 10-12 years ago but cannot recommend it on any level.Thanks again to all the good info here,cheers,Bob
PowerVar products are not designed for audio applications. I wouldn't recommend them for that use, AT ALL. The probe that they sell could be useful, if someone wanted to actually view the noise on their incoming AC though.