Measuring AC Power Line Noise

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

Could Shunyata make a (superior to Entech & Trifield) version? :rolleyes:
 
Jim Smith said:
Haven't received mine yet - supposed to be Monday.

Could Shunyata make a (superior to Entech & Trifield) version? :rolleyes:
Click to expand...


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.
 
Do you guys see what I see on my meter ?

B5X8h3.jpg


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.
 
Elberoth said:
Do you guys see what I see on my meter ?

B5X8h3.jpg


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.
Click to expand...
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).

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


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

Elberoth said:
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.
Click to expand...

What is wave form at output of the PSU?
 
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...:huh:
 
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 :disbelief:
Incandescent light bulb: 22mV
 
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

 
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