Power Line EMI Meter - Alpha Labs (Demo Program)

Great Demo program. Thanks Dave.

I took measurements for a few days both during the night and day. Overall, the measurements for the same room at the same time of day were reasonably consistent. I’m pretty happy with most results being < 100 mV around the house except for the computer room. I can understand this with 2 computers, router, network switch, printer etc. It was only hovering around 300 mV. The Panamax downstairs significantly lowered the readings by approx. 30 units.

I definitely want to go to dedicated lines for the music system downstairs at some point. It’s just kind of a PITA with everything already finished. This should already be in dragon’s possession. Thanks again Dave.

Mike

dragon1952 wrote: »

To get a baseline I started with the desktop computer and the Furman both turned off and I was measuring under 50mV at the stereo outlet and all other outlets in the room. Low noise!

When I turned on the computer and the Furman still turned off the reading went up to 500mV at the stereo outlet and all other outlets. Wow...noisy desktop!
When I turned the Furman on, and with the desktop still on, the noise went back down to under 50mV, at the stereo outlet. But all the other outlets in the room were between high-300's to mid-500's.

What is the reading with the Furman turned on, and the computer turned off?

Interesting. It’s the same as the other outlets with the computer turned off. I would have thought the Furman outlets to be lower than the other outlets with the computer off.

Okay. Got it. Thanks.

motorstereo wrote: »

My Furman 20i does the same thing. It lowers the emi a lot on the dedicated circuit it's on and even more out of the back of the unit. To a lesser degree it also lowers the emi on my other dedicated circuits on the same 120 leg when it's turned on.
It also makes me wonder where is all this extra emi being disposed of? Does the furman send it away or does it gather it up and store it?

Anybody know?

All of the basic power filter circuits I know of sends the EMI interference to ground.

Well I didn't have to work this weekend so I'm home tinkering with the AlphaLab EMI meter (Thanks Dave!).

Initial tests showed some interesting things I was not expecting. With everything unplugged in the house, both the left and right bank outlets (separate phase circuits) showed low noise (50 to 52). The only things plugged in and running were the aquarium filter pump/heater/air pump and LED light about 15 ft away and my laptop which is plugged in via a power strip in a different outlet in the living room but on the same circuit as the right bank. Since I have my laptop on any time I'm listening to music I figured that's a constant that won't change. The aquarium stuff is run off a single power strip so I thought I'd see if it was adding noise. To my surprise when I shut it off the meter jumped up to almost double. Flipped it back down and the numbers dropped again. Somehow this setup was pulling unwanted noise out of the right bank circuit! Which is fine because when I'm listening to Steely Dan the fish prefer that their light is on for that mood effect... I then did the same test for my laptop power strip and it did the same thing only not as extreme but I was definitely getting less noise out of the right bank with the aquarium and laptop on. Hmmm.

Next I plugged in six way adapters to the right and left banks so I can test while plug in and out different devices. No change there. Plugging in my amps increased the noise from 50'ish to 70'ish on both banks (nothing I can do about that!). I had my CA 851N and Belles 21A pre plugged into a Data Shield surge protector in the left bank so I went ahead and plugged that in and the meter went nuts! Screaming at me. So I went ahead and removed that and plugged in the Belles 21A into the left band. This added maybe a few points but now the left bank was holding steady at 72-75.

On the right bank I plugged in the CA 851N (some increase) but the right bank was still holding at 95-105 which was higher than the left bank. I had a single PS Audio noise harvester that I'd picked up a while back and when I plugged it into the right bank it dropped down to 72-82 Now at least both banks are quite similar.

Conclusion to this is with both banks fairly matched I've noticed a slight improvement in the evenness of left and right channel clarity and imaging. Could also be my imagination. I don't run power conditioners here because we almost never have lightning and being only 20 miles from two hydroelectric dams our power here is quite consistent. I think I'm going to invest in a couple more of the PSA NH's and some better power cords (these are almost too short).

First thanks to Verb for setting this up and his generosity! Great stuff man!
The meter went out to Jumpingdick last Tuesday. I have passed him the tracking details.

My house is relatively new built in the late 80s. I'm fortunate to have a dedicated listening room with limited power needs. That was until It also became my home office with laptop and monitor.

Good news for me was regardless of what I plugged in to the outlets in this room the voltage barely changed on the outlet with the APC line conditioner and the rest of the equipment. Even better was this outlet was the one that already had the lowest readings in the house!

Below are average readings checking multiple times on multiple days

Outlet1: 19-24mV
Plugged in here is APC H15 conditioner with Rogue Amp and Pre as well as the Lumin T2 and the TT.

Outlet2: 22-26mV
Same wall 6' away nothing plugged in here - sometimes noise harvester which didn't appear to make a difference either way.

Outlet3: 31-35mV
one of those Halogen lights - increased by 4-5mV when turned on

Outlet4: 28-34mV
powerstrip with pc and monitor

Kitchen outlets ran 40-50mV
Basement outlets 20-30mV

Overhead adjustable lights in the basement had a very small impact on mV in the listening room. Dehumidifier, washer/dryer, dishwasher or AC units also made no noticeable difference. Overall the readings were quite low and I was quite happy.

That said there were consistent small spikes. Somewhere between 15 seconds and a minute apart and sometimes longer I would see tiny spikes to somewhere between 80mV and 150mV. I don't know if that is normal or if I can attribute that to anything in the house. For example...the fridge stayed plugged in ; ) I'd like to think its normal or beyond my control.

If anyone has any thoughts on these little spikes would be interested to hear your thoughts.

Thanks again for the opportunity Verb!
Rich

Unit arrived safe and sound. I will go through the measurements and will post the findings.

@ansleycor In my den I do have one of the MIT line filters. called a predator 3 You just plug it onto any outlet on the power strip and it takes the noise out. PS audio also makes one called a Noise harvester.

@verb -- thanks a lot Dave for letting me use the EMI meter to check the quality of the incoming current, especially in the media room where I have got the stereo system and HT system. The unit is now on its way to Jeff. Here is what I found:

Media room: I have my dedicated stereo system and HT system in the same room. Unfortunately, i do not have luxury of having a separate dedicated room for two channel, yet...The room shares a 20 amp circuit with one of the bedrooms. The breaker is a GFCI breaker.





When I first plugged the EMI meter into the outlets on PS Audio P10, the reading was around 55. This was higher than what I saw when the meter was plugged directly to the wall outlet (P10 gets connected to this same wall outlet). That was a bit disappointing as I thought P10 was suppose to "clean" the power via regeneration. One of the items attached to P10 was Lumin L1 (NAS with SS hard drive). When I disconnected L1, the reading from P10 went down to around 35. Still, this value of 35 out of P10 was very similar to that of the wall socket/outlet to which P10 is connected to. So, did P10 make any difference?

What I also noticed is that when the ceiling lights in the media room were on, the reading on the EMI meter was ~25-30. This was measured by plugging the EMI meter directly into the wall outlets. When the ceiling lights were off, the reading went up a bit to ~35-38 (same outlets). It did not make sense to me on this observation. The light bulbs were all LED. I was under impression that if the ceiling lights were to be on, it would spike the reading on the EMI meter.

The other observation is that my desktop computer is also on the same circuit as this media room. During testing with EMI meter in the media room, the computer was always on. Having it on or off did not change the reading. One thing to note is that I have connected the computer to CyberPower UPS. Could that be the reason why having computer on or off had no impact on the quality of the power?? There is no other variable...

Out of this exercise, it became clear to me that the use of GFCI breaker and plugs showed improvement in the quality of the power, as the measurements out of regular (non-GFCI) outlets/breakers were significantly high. The media room has pretty good quality power coming in. I am going live with what I saw. I am going to read up more on GFCI outlets/breakers and their impact on the quality of the power. But overall, happy with what I saw.