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Thoughts on power conditioners?

Speedskater

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Remember that 'power conditioner' is an undefined term. It could mean almost any combination of the following.

a] Noise filter - a low-pass EMI/RFI filter.
b] Surge protector - although it's better to have surge protection at the home's service entrance.
c] UPS - note that many UPS's are not really UPS's!
d] Line voltage adjuster.
e] Balanced power transformer.
f] Isolated power transformer.
g] DC blockers.
h] Regenerators (PSAudio)
i] Power Factor Correction
j] I forget? But I think that there are more.

****************************

AFAIK a power conditioner does the following things:
- Gets rid of as much of the EMI/RFI noise (LC filters). This can also be done with inexpensive conditioners with EMI/RFI filters built-in.
Seldom are these filters very effective at the problem noise frequencies.
Much of the noise is generated by the other hi-fi components.
Well designed hi-fi components should be able to deal with this noise on their own.

- Surge and over-voltage protection, usually done with varistors (MOV), gas dischargers and fuses.
A whole home surge surge suppression system is a much better solution.

- AC regeneration from expensive conditioners will restore your AC mains perfect sinewave
an AC regeneration system can create it's own problems.
a power supply does not need perfect sinewave power, as the current waveform of the power supply is mostly harmonics.
 
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SIY

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Kevin, to reiterate your earlier point, any measurement of efficacy should be at the audio output, NOT the output of the conditioner. This bears repeating because the power conditioner peddlers will almost never show that, they use power line waveforms (real or otherwise) for higher FUD factors.

An interesting argument could be made that a perfect sine might not be the optimum waveform for powering....
 

Speedskater

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Kevin, to reiterate your earlier point, any measurement of efficacy should be at the audio output, NOT the output of the conditioner. This bears repeating because the power conditioner peddlers will almost never show that, they use power line waveforms (real or otherwise) for higher FUD factors...................................................
It's hard to deal with all the audiophile misunderstandings & myths and marketing department propaganda in just one post.
 

SIY

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Or ten posts. Of course, if you get the Curl-Bybee conditioner, your system will run at 200% efficiency with an infinite S/N.

But my last pondering wasn't entirely rhetorical- is there a technical reason that a pure sine wave is the optimal waveform? I would think that having a lot of low order odd harmonics could possibly be beneficial.
 

DonH56

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The power company would like a power factor near 1. Adding harmonics means the transformer must deal with higher-frequency energy and it will probably run hotter as a result. That also leads to more harmonic spray in the ground lines and potentially more harmonics at the output unless you add additional caps to handle the higher frequencies.

Of course, the current waveform is usually nothing like a sine wave anyway...

Switching power supplies are not only more efficient but their fundamental and harmonic mess can be designed to be well above the audio band. Have to watch the RF filtering, but power supply caps can be much smaller and still achieve lower ripple than conventional supplies. They have their own issues, of course...
 

SIY

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Adding harmonics means the transformer must deal with higher-frequency energy and it will probably run hotter as a result.
I would think that 180, 300, and 420 would couple more efficiently from primary to secondary than 60?

Power factor is a separate issue, and yes, 1 is the power company's fondest wish. I was looking at the PFC used by a Class D commercial amp company (Powersoft) and their PFC gave impressive results. I don't think it would be possible to do that well with conventional amps.
 

DonH56

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I would think that 180, 300, and 420 would couple more efficiently from primary to secondary than 60?

Power factor is a separate issue, and yes, 1 is the power company's fondest wish. I was looking at the PFC used by a Class D commercial amp company (Powersoft) and their PFC gave impressive results. I don't think it would be possible to do that well with conventional amps.
I do not know what you mean by "couple". Transformers are designed to work at a target frequency and generally are "less happy" at other frequencies. They have hysteresis that limits their bandwidth and conversion efficiency so higher frequencies typically just mean more heat in the core rather than more output unless the transformer is designed for higher frequencies. A transformer is a big coupled inductor and the bigger the inductor the more it will reject (resist) higher frequencies. Parasitic capacitance will couple more energy at higher frequencies but that is generally undesirable noise and contributes insignificantly to the useful power output.

Going to higher frequencies allows smaller transformers. Years ago fluorescent lights switched from using 60 Hz ballast transformers to little switching units to bump the frequency to ~60 kHz so they could use much smaller transformers. Virtually all fluorescent lights now use some variation on that theme. But getting the power grid to change frequencies is likely to be challenging... Higher frequencies will lead to more loss in long lines. If you were to bring in 60 Hz and use a circuit to generate higher frequencies locally, that would work, though kick back HF pulses into the power lines... That essentially leads to switch-mode power supplies with PFC.
 

SIY

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I do not know what you mean by "couple".
Transform energy from primary to secondary (i.e., k in the mutual inductance equation). Generally, a 60Hz power transformer in a supply isn't a resonant system, and in fact some people have even adapted selected power transformers for signal coupling (e.g., output transformers or ESL stepups). That's a bit extreme, but if you think in the time domain about a waveform with the tops and bottoms compressed a bit, it could very well have lower charging currents and longer charging angle.
 

DonH56

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Transform energy from primary to secondary (i.e., k in the mutual inductance equation). Generally, a 60Hz power transformer in a supply isn't a resonant system, and in fact some people have even adapted selected power transformers for signal coupling (e.g., output transformers or ESL stepups). That's a bit extreme, but if you think in the time domain about a waveform with the tops and bottoms compressed a bit, it could very well have lower charging currents and longer charging angle.
Ok, mutual coupling I understand. No, it is not (SOLA-aside) a resonant system, but it is targeted to the expected line frequency and IME transformers can run hot and provide even more distorted output when presented with an input signal with significant harmonic content. Our experience probably just differs, and this is not an area I have looked at in years, so will leave it there.
 

amirm

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Well, it seems like I ought to do a few measurements because I truly don't know. :cool:
What I have read is what Don explained but you read my mind as far as trying to measure it. :)
 

trl

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I measured the noise with and without my "in-house" power conditioner (built from dedicated EMI/RFI filter + true sinewave UPS running on batteries + balanced output transformer) and found no improved in regard with output noise, output FFT graphs, RMAA and output jitter for my tested equipment (ASUS Essence One Muses MKii, Matrix HPA-3B, Mackie MR6mk3/MR10Smk3 studio monitors).

However, it was a slight hum on one of my Mackie studio monitor that could be heard from about 1-1.5m in a quiet environment (a combination of 50 Hz with 100 Hz) and I was able to get rid of it only after lifting the ground safely (with diodes and caps), after the balanced mains output.

So, in my case, given a pretty good input mains quality, a power conditioner is unlikely to be helpful. Will see how my mains will look like when the neighborhood will get full of new flats, in about 1-2 years from now. There are more than 500 apartments almost finished nearby (100 connected in the same transformer with my home, 400 in a different transformer) and next year will start getting "populated". Will do again some tests within 1-2 years from now.
 

RayDunzl

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Does a measurable 60Hz AC voltage between Neutral and Earth cause problems?
 

JJB70

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The power company would like a power factor near 1.
I worked at one plant where the main reason it was so profitable was because we exported MVARs to a large steel mill for their huge inductive blast furnaces. Happy days, the power factor on that part of the distribution network could be all over the place.
 

amirm

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I plan to do a bunch of power studies/measurements sometime in the future. Will probably have to wait until we are in dead of winter, and nothing to do otherwise than this. :)
 

trl

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Does a measurable 60Hz AC voltage between Neutral and Earth cause problems?
Measurable AC voltage could also mean noise, right? :)
I was able to measure >3V peak with vacuum cleaner ON here. If there's no hum noise or any other type of noise in the speakers/headphones, I see no reason for concern.
 

Speedskater

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Does a measurable 60Hz AC voltage between Neutral and Earth cause problems?
If current is flowing thru the Neutral, then there should be a voltage difference between the Neutral and the Safety Ground/Protective Earth. If they are both at the same potential, that would indicate a wiring error somewhere in the AC system.
 

Speedskater

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'trl' do you have a big amplifier with a traditional linear power supply?
If so you might make that same Neutral to Ground measurement while playing loud music. Notice that the current waveform is more like a squarewave than a sine wave.
 

trl

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I was measuring current between NULL and GND on my DAC & headamp, in my bedroom. Big amps are in my living room, I wasn't doing any measurements in there yet.

AFAIK, current between GND and NULL exists because it's returning from electrical appliances with metallic case, like: washing machines, microwaves a.s.o. I'm sure that while playing loud music with my big amplifier will not change the voltage & current between NULL and GND in that specific outlet, but I'll give it a try. Also, my amp is Class2, it only has 2-pole plug, no grounding. The only grounding is on the chassis and is to be connected to Audio_Ground and not to Earth.
 

amirm

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AFAIK, current between GND and NULL exists because it's returning from electrical appliances with metallic case, like: washing machines, microwaves a.s.o.
The only current that exists there is leakage to the chassis. That should be in order of milliamps per device or else, they would be violating safety standards.

There will be voltage drop between neutral and ground because the former carries the full load of the device using it whereas the latter is not supposed to. In US, UL allows a maximum voltage drop of 5% in branch circuit so for a 120 volt system like ours, this would be 6 volts. But since this is for both hot and neutral, then half as much would be for the latter or 3 volts.
 
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