Measuring AC Power Line Noise

[Jim Smith]

Have been tempted to try Shunyata Denali, but my power line has its' own dedicated feed directly from the transformer 20' outside the listening room. Sound, by all accounts - not just mine - is outstanding - very dynamic & pure.

But most of us have a case of the "What ifs" - including me.

Since Shunyata shows AC power line noise as an issue, I wonder if anyone has - or has used - an affordable device to measure "before and after (installing the Denali)" power line noise?

[Mike]

Have been tempted to try Shunyata Denali, but my power line has its' own dedicated feed directly from the transformer 20' outside the listening room. Sound, by all accounts - not just mine - is outstanding - very dynamic & pure.

But most of us have a case of the "What ifs" - including me.

Since Shunyata shows AC power line noise as an issue, I wonder if anyone has - or has used - an affordable device to measure "before and after (installing the Denali)" power line noise?

Entech Line Noise Analyzer. That's what I use. I've heard the same from clients. I take the Entech to their house (and a Denali or AQ 1000/5000/7000) and the before and after is not subtle.

https://youtu.be/LxyxkCOlZsU


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[Jim Smith]

Thanks! Already ordered Trifield PLM (Power Line Meter). For whatever reason, was thinking the Entech was no longer available.

[CGabriel]

Entech Line Noise Analyzer. That's what I use. I've heard the same from clients. I take the Entech to their house (and a Denali or AQ 1000/5000/7000) and the before and after is not subtle.

https://youtu.be/LxyxkCOlZsU


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The Enteq is no longer being made. However, you can find some used ones on the eBay. The Enteq is useful for rudimentary demonstrations. However, it is not a good device for a comprehensive study of power line noise. First, it is has no standard references settings. You plug it in - you adjust the gain with the knob until you get a approximate 100 reading on the meter. This is arbitrary - not a measurement where you could compare two different power lines and certainly not compare readings between locations. It is however useful for a quick before and after of the same power line. You must be careful NOT to touch the gain control between readings and the readings should be taken very close together since power line noise is dependent upon the radiated RFI/EMI noise in the environment.

A Fluke Model 43 power line analyzer is relatively inexpensive but it doesn't measure noise.

For actual scientifically accurate readings you need a spectrum analyzer that is specifically setup to do power line readings. We several including the Audio Precision Analyzer with power module installed. If you have a PC based spectrum analyzer DO NOT plug it into your power line! If you don't know what you are doing - don't do it. You must take very specific precautions when connecting measurement devices to a live power line.

The Enteq only detects and rectifies frequencies to around 700KHz which means is it completely insensitive to some of the most harmful noise frequencies - those in the 1MHz to 10MHz ranges. But hey it is inexpensive, easy to use and it is nice to be able to "hear" some of the stuff that is on your power line. Your dedicated power lines, rhodium plated outlets and large gauge wires in the wall in no way immunize you to power line noise. Power line noise is picked up from radiated electromagnetic waves all around you. This includes AM and FM radio, wifi, cell frequencies and the list goes on. Furthermore noise reduction is always "localized". That means that just because you have a power conditioner that reduces conducted noise does not mean that the noise doesn't re-introduce itself farther down the line. So if you have some form of power conditioning at the electrical panel, the radiated noise will be picked-up by the in-wall wiring that acts like an antennae. This means you WILL have noise on the power line at the wall outlet. This is why we talk about the "distributed power conditioning" approach to noise reduction.

We are actually working on consumer level device that is more a modern and elaborate version of the Enteq. It will detect a broader range of frequencies and they will be calibrated so that absolute readings can be taken. This will allow you to see if you have a low, medium or high level noise on your line. And it will allow people to compare noise levels at different times of the day and at different locations.

[CGabriel]

Thanks! Already ordered Trifield PLM (Power Line Meter). For whatever reason, was thinking the Entech was no longer available.

Jim, I just looked up the Trifleld. It looks like a good device and it measures out to the important frequencies. I am ordering several for our demonstrations also. Let's see how well it works.

[Mike]

The Entec for ~$50 used is certainly not the end all and be all, but what it does is vocalize the noise and when consumers HEAR the noise on their line, it's much more impactful than if they see something on a gauge. With a gauge they say "yeah, but do I really hear that?" With the Entech's speaker vocalizing the noise, they hear it!


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[YuriKorzunov]

Have been tempted to try Shunyata Denali, but my power line has its' own dedicated feed directly from the transformer 20' outside the listening room. Sound, by all accounts - not just mine - is outstanding - very dynamic & pure.

But most of us have a case of the "What ifs" - including me.

Since Shunyata shows AC power line noise as an issue, I wonder if anyone has - or has used - an affordable device to measure "before and after (installing the Denali)" power line noise?

Jim,

I'd began from spectrum analysis of analog output of pream or power amp.

I seen video with demostration of power line noise meter. It's cool. But it is not matter for audio devices in the first approach.
Because audio device's power supply unit (PSU) should (if it work properly) suppress these interferences, that measured by powerline noise meter.
Of course, need check this for exactness.

But for end-user important noise at analog output of audio system. If connecting power conditioner or other filter decrease total noise level or remove noise fragments/harmonics at analog output of the system, this conditioner recommended for using.

If connection AC filters don't impact to output spectrum, have no sense connect input AC filter.

Also recommended check spectrum at internal DC powerlines of audio module for impact to external AC filter.

[Odyssey]

Thanks! Already ordered Trifield PLM (Power Line Meter). For whatever reason, was thinking the Entech was no longer available.

Jim, can you give us a link to where you acquired your Trifield? Any link on the background of the device would be great too. Thanks.

[Jim Smith]

http://www.trifield.com/content/power-line-meter/

[CGabriel]

Jim,

I'd began from spectrum analysis of analog output of pream or power amp.

I seen video with demostration of power line noise meter. It's cool. But it is not matter for audio devices in the first approach.
Because audio device's power supply unit (PSU) should (if it work properly) suppress these interferences, that measured by powerline noise meter.
Of course, need check this for exactness.

But for end-user important noise at analog output of audio system. If connecting power conditioner or other filter decrease total noise level or remove noise fragments/harmonics at analog output of the system, this conditioner recommended for using.

If connection AC filters don't impact to output spectrum, have no sense connect input AC filter.

Also recommended check spectrum at internal DC powerlines of audio module for impact to external AC filter.

Do you suppose that significantly reduced noise on the output of a million dollar medical imaging system might quality as evidence?
Do a little research - please.

[YuriKorzunov]

Hi Caelin,

Sorry, I don't understand, what kind of researh you suggest?

Does you mean what positive result at output one system obligatorily lead to positive result at other system?
I suppose, reducing of noise floor for one system, probably give reducing for other.

At my past work in radio communication branch, we are used AC filters.
But we checked it for each system for impact to noise floor at output spectrum, because there was used different power supply units, construction, schemes/devices, AC sources, etc.

P.S. As I understand, AC power conditioners is part of your business and you are expert in noise suppressing.
For me will interesting discuss with you the noise suppressing issue. It is way to get first-hand information.

[CGabriel]

Hi Caelin,

Sorry, I don't understand, what kind of researh you suggest?

Does you mean what positive result at output one system obligatorily lead to positive result at other system?
I suppose, reducing of noise floor for one system, probably give reducing for other.

At my past work in radio communication branch, we are used AC filters.
But we checked it for each system for impact to noise floor at output spectrum, because there was used different power supply units, construction, schemes/devices, AC sources, etc.

P.S. As I understand, AC power conditioners is part of your business and you are expert in noise suppressing.
For me will interesting discuss with you the noise suppressing issue. It is way to get first-hand information.

No arguments from me. Some power supplies are definitely better than others. Power supply design is often one of the most important in high-end component design.

[YuriKorzunov]

Yes. Important.

[AJ Soundfield]

I'd began from spectrum analysis of analog output of pream or power amp.

No, that would make too much sense. Please don't do that.

[YuriKorzunov]

No, that would make too much sense. Please don't do that.

What need do?

[hoosiertom]

Jim,

Thanks,for the heads up!!!!!

I ordered my Trifield PLM yesterday !!!

All the best,

Tom

[Jim Smith]

IF the Trifield works (mine is enroute but not here yet), seems as if it would be a good tool for dealers to have on hand, perhaps as a loaner or even a rental, (fee carried forward as credit if purchase of conditioner is made).

Since I am not a dealer, that's easy for me to say, it's just a thought...

[CGabriel]

IF the Trifield works (mine is enroute but not here yet), seems as if it would be a good tool for dealers to have on hand, perhaps as a loaner or even a rental, (fee carried forward as credit if purchase of conditioner is made).

Since I am not a dealer, that's easy for me to say, it's just a thought...

Jim, you are right. It is only $130 which any dealer should be willing to invest in.

We have received three of them and will be testing to see how useful they are. One caveat, as with all measurement tools especially simple ones there may be a tendency to rely on a single parameter to make decisions. All of these type of devices will only give a rough (averaged) reading of noise on the power line. There is no way with these to know "which" frequencies are actually on your specific line. And of course the noise components between locations and cities will be different. So as with the Enteq, this will be primarily useful to hear/see "relative" differences on a specific line at a specific time.

That said, it looks like a useful tool to have at your disposal. For example, using the Enteq at my house I found that I had a very strong radio station being picked-up by my upstairs power lines. I also could hear the very distinctive sound of LED lighting noise pollution. Quite insidious actually.

[a.wayne]

No arguments from me. Some power supplies are definitely better than others. Power supply design is often one of the most important in high-end component design.

The PSU is what you are mostly listening to , the amplifier is the oscillator ....

[AJ Soundfield]

What need do?

I was joking Yuri. сарказм

[Elberoth]

Bought one as well.

[La Dolce Vita]

Entech Line Noise Analyzer. That's what I use. I've heard the same from clients. I take the Entech to their house (and a Denali or AQ 1000/5000/7000) and the before and after is not subtle.

https://youtu.be/LxyxkCOlZsU


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+1 Jim, Mike is spot on. I completely agree. Same experience.


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[CGabriel]

While I had some high hopes, I must say I am a bit disappointed with the device. I found the Enteq to be superior at detecting things like dimmers and LED lighting being turned on. The Alpha barely moved when things like this were turned on. I will spend a little more time with it and see what exactly it is measuring and what weighting it is applying to different noise bands. But for now I am keeping my Enteq units. Simple devices - simple results I guess.

[Jim Smith]

Haven't received mine yet - supposed to be Monday.

Could Shunyata make a (superior to Entech & Trifield) version?

[CGabriel]

Haven't received mine yet - supposed to be Monday.

Could Shunyata make a (superior to Entech & Trifield) version?

You know there is the AudioPrism analyzer which looks to be similar to the Entech. I have never used one and don't see any specs on what frequency bands it detects. But that could be a good alternative.

I have looked far and wide for something that a consumer or dealer could use that is reasonably priced and fairly easy to use. So far, the only thing I have found is the Entech, this device that Jim discovered and the AudioPrism analyzer.

What is needed is something between a full blown spectrum analyzer (very expensive) and these simple gizmos. Yes, we have something designed that will give readouts in several different specific bands of noise. We are developing this in our medical division for use in hospitals. We will post something when the product is more fully developed.

[Elberoth]

Do you guys see what I see on my meter ?



According to the pic on their website (left), the meter should show a single EMI reading in mV and AC line voltage.

Instead, I get two different EMI readings (right pic), no AC line voltage reading and some '39% reduction' text on top. There are no buttons to toggle between different modes.

[YuriKorzunov]

Instead, I get two different EMI readings (right pic), no AC line voltage reading and some '39% reduction' text on top. There are no buttons to toggle between different modes.

The device controlled via computer?

[Elberoth]

No it only has a single AC input and no buttons.

[YuriKorzunov]

Looks like there 2 compared values. How you got 2 values? It is 2 last measurements?

[Elberoth]

I wish I know. The meter came without any manual.

[YuriKorzunov]

Adam, me seems, in your case need ask the tech support of the vendor.

[Melbguy1]

Do you guys see what I see on my meter ?



According to the pic on their website (left), the meter should show a single EMI reading in mV and AC line voltage.

Instead, I get two different EMI readings (right pic), no AC line voltage reading and some '39% reduction' text on top. There are no buttons to toggle between different modes.

My power conditioner comes with an accurate volt meter, but no EMI meter. I just assume the conditioner is working as designed. Though subjectively it audibly reduces line noise. I recall when my electrician installed my Furutech GTX-D(g) wpo he measured line noise on my old wpo which was in the normal range for an apartment (ie: not on the high side).

[Elberoth]

OK, I have figured it out myself. The upper row showes an avg of the first 5s of measurement (on hold); the lower row shows the real time measurement, which can go up or down, depending on AC line conditions.

I have played with it a bit and the results I got are quite amazing actually.

I got the highest reading in the kitchen (close to 2000mV), around 400mV on my general power lines (the reading is actually unstable, and goes from 200 to 500 all the time, with a brief peaks of 1400mV) and only 23mV past my power conditioner (which I use to sink all my computer related hardware - PC & all PC related PSUs, monitor).

I will do some measurements with pics and will post a separate post about this. It is a great fun !

[Elberoth]

One of the most interesting phenomenons I have observed so far, is that plugging to the common power strip an iFi Power switch mode PSU (with no load), actually reduces the noise on AC line.

One would think it should be the other way round - and it was certainly the case with three other SMPSs I have tried. The iFi Power SMPS is said to have an extra filter on the input, which prevents the noise from the SMPS to contaminate the AC line. It seems the filter not only works on the SMPS itself, but also provides filtering to the AC line. Interesting !

[tunes]

Interesting to hear about your findings Adam. Thanks for sharing.


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[Elberoth]

I have measured my dedicated AC line. The overall level of AC noise is quite low. However, it is ultimately compromised by high noise bursts:



Please note, that the measurement was taken at 2AM - during the day noise levels are much higher (which is probably why, our equipment sounds much better at night = less noise on AC line).

Same AC line, but this time meter attached to the power conditioner output:



The noise have almost vanished. The noise bursts are gone. The noise level seem to be constant irrespective of hours (same during the day and during the night).

Those noise bursts on my dedicated AC lines started me thinking. The noise on my general AC lines is ~3x as high, but I don't have those noise bursts. Is it possible, we have chosen the wrong (noisy) electrivcal phase ? I need to call an electrician to find out.

I need to investigate that further. Obviously, I would rather have my dedicated AC lines on the burst free electrical phase, and the general household AC line on the dirty one.

[YuriKorzunov]

It would be interested to know, how linked measured AC noise and noise at output PSU (on DC bus) of an audio device.

One of the most interesting phenomenons I have observed so far, is that plugging to the common power strip an iFi Power switch mode PSU (with no load), actually reduces the noise on AC line.

What is wave form at output of the PSU?

[Jim Smith]

My Sound room & office have their own transformer on a pole about 20' behind the building. Separately fed (and billed by the power company) from the house feed which comes in from a different pole & transformer.

Readings are generally 175-125 in my demo room, on dedicated circuits. House readings can be as high as 2000, depending on where I measure and what is running.

Wish I had a way to try a power conditioner & measure the results. Don't know if my readings are high or not. I thought of visiting my local dealer who is a friend and measure his readings with & without the P.C. in his store. But he has AQ, not Shunyata.

The sound here is very dynamic, yet very quiet & smooth, but I still have that perfectionist disease...

[Elberoth]

Jim,

If your readings have no spikes higher than those 125-175mV, than those must be considered excellent results.

I have learned A LOT about the quality of the AC in my house thanks to this little gizmo and I have to say - I'm not happy. My dedicated AC lines obviously have some noise issues - I need to investigate all 3 phases that go to the general house fusebox to find out which one is the cleanest. The 'dirty' line in my listening room, which also feeds kids room, has higher noise floor than my dedicated lines (300mV vs 100mV at night), but no noise spikes. I need to find out if changing phases will bring any improvement with regards to those spikes.

I will also start investigating various power conditiones.

BTW - I have measured today AC noise footprint of different PSU - various generic SMPS, Teddy Pardo PSU, iFi iPower, UpTone JS-2, all kind of Apple chargers and lamps. I will need to start a separate thread on this and post the results.

Here is just a snap shot:

Reference noise floor (via Power Conditioner): 22mV

Teddy Pardo Linear PSU under load: 34mV
UpTone JS-2 Linear PSU under load: 54mV

Generic SMPS under load: 300mV

Compact fluorescent light bulb: 1400mV
Incandescent light bulb: 22mV

[Elberoth]

I just made a short video from using the meter. I have compared two iPhone chargers: Apple original and a generic one from ebay. Holy crap ! The chinese one dumps 10x as much noise back to the AC line !

It is in Polish, but you will get an idea. Starts from 1:00s

https://youtu.be/oyFvGyVRhAg

[Champ]

Jim, you are right. It is only $130 which any dealer should be willing to invest in.

We have received three of them and will be testing to see how useful they are. One caveat, as with all measurement tools especially simple ones there may be a tendency to rely on a single parameter to make decisions. All of these type of devices will only give a rough (averaged) reading of noise on the power line. There is no way with these to know "which" frequencies are actually on your specific line. And of course the noise components between locations and cities will be different. So as with the Enteq, this will be primarily useful to hear/see "relative" differences on a specific line at a specific time.

That said, it looks like a useful tool to have at your disposal. For example, using the Enteq at my house I found that I had a very strong radio station being picked-up by my upstairs power lines. I also could hear the very distinctive sound of LED lighting noise pollution. Quite insidious actually.

I came across another unit which seems to be very similar. It's called the "Stetzerizer Microsurge Meter"
No sound from it. But I've seen it pick up LED, Florescent, etc.
It's units are made up by it's designer. But they equate to 24volts/second.
With these units it's said to demonstrate both large spikes and high frequency.
No idea the efficacy of it. But Caelin could probably elaborate.
I'm too new here, so unable to post a direct link. But Google works well enough.

http://www.stetzerizer-us.com/Origin...lters_c_9.html

[joeinid]

welcome to the forum Champ, thank you for joining.

[CGabriel]

I came across another unit which seems to be very similar. It's called the "Stetzerizer Microsurge Meter"
No sound from it. But I've seen it pick up LED, Florescent, etc.
It's units are made up by it's designer. But they equate to 24volts/second.
With these units it's said to demonstrate both large spikes and high frequency.
No idea the efficacy of it. But Caelin could probably elaborate.
I'm too new here, so unable to post a direct link. But Google works well enough.

http://www.stetzerizer-us.com/Origin...lters_c_9.html

I have several of the Alpha and the Stetzerizer units. Personally, I prefer the old Entech unit. Entech was actually a very technically advanced group of engineers. Both the Alpha and Stetzerizer are similar in that they have a bandwidth that extends quite low for measuring RFI/EMI. They drop down to 15-30 kHz in there measurements. While this may seem to be an advantage it actually has a fatal flaw. Both aggregate noise from about 15 kHz to around 10 MHz and lump them all together in a single reading. Some frequency bands are more important to the performance of audio equipment specifically our research indicates the the most harmful frequencies are in the 100 kHz to around 1 MHz bands and then secondarily from 1 MHz to 10 MHz. Interestingly, I believe that the Entech engineers knew this and designed their device to be sensitive in the frequencies from 300 kHz to 700 kHz range. This makes the Entech particularly useful for finding noise sources in the specific ranges that are most noticeable in the context of music systems.

I have done direct side-by-side comparisons using all of the units listed. I would then plug a device into the power line that we 'know' produces particularly harmful noise effects as measured by our power and spectrum analyzers. In many cases, the Alpha and Stetzerizer would barely change their relative readings while the Entech would go off the charts. This is because the Entech is more narrowly focused and the other two are less so.

And then conversely I would connect filters that reduce power line noise in a known manner as verified by the power and spectrum analyzers and in many of these cases the Alpha and Stetzerizer would show only as small or marginal difference while the Entech would show a much larger and significant difference.

Look these are all very inexpensive devices and all of them can be useful. But they have severe limitations from a technical point of view. I found the most useful for the hobbyist to be the Entech. As I said earlier, we are developing a device that will be much more useful and will show noise in specific bands much like the old audio spectrum displays. This is being developed for our medical division where this device will be quite useful in identifying specific types of noise pollution in hospitals. I hope this is helpful.

BTW, I have three of the Alpha units and would be happy to sell two of them at less than what we paid for them. Just PM me.

[Elberoth]

BTW - I have spoken with the guys from Gigawatt on topic of the AC measurements, and inhouse they use this:


Keysight PA2201A IntegraVision Power Analyzer

http://www.triotest.com.au/store/sin...s-1-phase.html

I need to somehow negociate borrowing it for a day or two as Adam (the Gigawatt owner) is a good friend of mine.

[Melbguy1]

Adam, well Gigawatt as you know are very professional and are doing some amazing things. Having the best testing equipment helps.

[Elberoth]

I think I can see one of their units in my future

I have never considered one, as 'straight to the wall is best' - as we all know But after measuring the noise on my AC line, I'm not so sure anymore.

[Elberoth]

Every PSU kicks some noise back into the AC line, which may have an influence on the rest of your gear connected to the same AC line.

I still remember a review written by Martin Colloms of some gear using onboard SMPS, where he claimed that simply connecting said component (otherwise not connected to the system) to AC line, made his system sound considerably worse.

So how bad is the problem ? Having bought a wideband AlphaLab EMI Power Line Noise Meter I decided check that out on various PSUs I had on hand.

The setup

To get a reference/base noise level I have used my old and trusty Audio Power Industries Power Wedge Ultra 215 power conditioner, which I normally use to 'sink' all of my computer related PSUs - main server PSU, SSD battery SMPS charger, UpTone Audio JS-2 powering two LPS-1 PSUs and a computer monitor.

The noise level measured at the output was just 23mV. I have used one of outputs to connect a simple power strip (with no filtering):




The PSU under test was connected to the same power strip, next to the EMI meter:





I had 8 different PSUs on hand: 3 linear ones and 5 SMPS (switch mode) types:





1. Teddy Pardo linear PSU
2. UpTone JS-2 linear PSU
3. SOtM supplied SMPS (PowerTek)
4. Meanwell SMPS (supplied by UpTone with Regen and LPS-1)
5. Some generic linear PSU I found lying around
6. Ktec SMPS that I got with an external HDD
7. iFi iPower SMPS
8 Co Ming Data SMPS

Since I have observed the level of noise beeing kicked back to the AC line varies with PSU load, I have measeured those PSUs in the following conditions:

1. Idle - PSU connected to the power strip, but nothing connected to the PSU (no load)
2. Noise under light load - PSU powering Regen, which in turn was powering AQ DragonFly DAC
3. Noise under moderate load - PSU powering SOtM sMS-200
4. Noise under heavy load - PSU powering the LPS-1 Ultracapacitor PSU, which in turn was powering the SOtM sMS-200.

The results I got are as follows (green = best case; red = worst case):


Please note that the smallest, generic linear PSU (last column) was not tested with LPS-1, since its power rating was too small.

Some things I have noticed:

The SMPSu in general injected much more noise than linear ones. Even the cheapest generic wall wart linear PSU was better than the best SMPS.

In many cases, the noise figures dropped at idle a few mV below the reference level. It is my understanding that this is due to filtering built at the input of those PSUs, which interacts / lowers the noise on the AC line.

The PSU noise readings were jumping up and down when the LPS-1 PSU was connected (chence the results are in ranges). You can see this on a short video I uploaded on youtube.



It is my understanding that noise spikes were caused by the LPS-1 bulit in (capacitor) charger - when the charger was running, the noise was higher; when the charger was idling, the noise was lower. I'm not sure if higher noise readings are caused by higher current draw or the noise is comes from the LPS-1 charger itself. Whatever the reason - some PSUs were much more sensitive to that than the other.

For kicks, I have also measured several other PSUs and even light bulbs:



- iPhone, iPad and MacBook chargers are pretty harmless when at idle. I wouldn't want to have one connected to my powerstrip when charging though (all of you using MacBooks and other laptops connected to your system take note).
- CFL light bulbs (and LEDs) are huge noise generators (unlike regular light bulbs, which generate close to zero noise).
- chineese iPhone charger knock off from ebay, creates some absurd amounts of noise - many times more than the original Apple accessory (one more reason not to buy knock offs).
- TeraDak linear ATX PSU that powers my CAPS v4 Pipeline server generate generates only 48mV of noise - suprisingly litte.

Final notes:

If you have lots of those generic SMPS around your audio system (powering DACs, HUBs, routers, external HDDs etc), it probably makes sense to replace them with something designed with the AC noise pollution in mind, like the $49 iFi iPower SMPS for example. Linear still seems to work best though.

Having said that, please remember, that the best PSU is not necessarily the one which kicks the least amount of noise back into the AC line. The best PSU is the one that has low AC noise footprint and offers stellar DC output performance.

[YuriKorzunov]

That's reason why ferrite ring on power cable is recommended.

[a.wayne]

That's reason why ferrite ring on power cable is recommended.

[Willco]

8 months later, wondering if Shunyata has made any progress toward developing a consumer grade noise analyser?