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How To Do You Measure the Quality of Your AC Power?

What is the best way to measure the quality of the AC power feeding your listening room? Is there a device you can plug into an outlet that will give you the voltage, frequency, the total amount of distortion relative to a perfect sine wave, etc.? Furthermore, how would you measure the ability of your AC main to deliver transient currents?
It seems like there may be a scenario where you could measure your power quality to be excellent but somewhere in the line you could have a loose or poorly made wiring connection which under heavy load (such as powerful bass notes) you could run into trouble with power delivery. In this scenario, an AC regenerator would not help you, or would help very little.

Just curious what methods people have come up with to systematically analyze their power and how they use those measurements to drive buying decisions or repair work, if needed.

Edit: My apologies for the title typo.
128x128mkgus
erik_squires
15,861 posts
 
Make sure your switches and outlets use real wire wrapped screw tightened connectors.

The little hole for the backstab connections are poor and I'm not even sure they are legal anymore. 


vk_onfilter
21 posts
 
EMI:  Time domain (i.e. oscilloscope) measurements are more relevant than frequency-domain ones (i.e. spectrum) simply because spectrum analyzers (with the exception of really expensive ones) would miss transients which dominate the type of electrical noise present on power lines and ground.   Measure both common mode (i.e. between Live/Neutral and ground) and differential (between Live and Neutral).  Here is an article I wrote on the subject for inCompliance Magazine that deals with these things: https://incompliancemag.com/article/measurements-of-conducted-emi-in-the-manufacturing-environment/   The tools to use: a portable digital scope (I use Hantek 1200 family, but others can be just as good - just make sure that the bandwidth is at least 100MHz), and power line EMI Adapter MSN17 (https://www.onfilter.com/emi-adapter-msn17) otherwise you won't be able to make any relevant measurements and can kill your oscilloscope.  Stay away from the tools that give you fuzzy relative data and no specification.
If you are interested in harmonics, you can use the same oscilloscope (make sure it has FFT - most do.   Read the user's guide!) and 100:1 probe.  Scope must be in battery-powered mode only!  Unless harmonics are quite severe (at the factories I have seen quite a bit, but not at homes), they are unlikely to affect anything of importance in this case.
speakermaster
738 posts
 
They make tools for evaluating and testing your power to your house but i would try to just run a dedicated line to your stereo and that should help significantly for you sound and be sure to connect all of your equipment to the dedicated line so it is all at the same ground potential.
millercarbon's avatar
millercarbon
12,531 posts
 
take the advice of MC. He is the only one here that has actually done it".....  

To wit:
What you do is what everyone does. Make all your connections from the panel to your room as clean and tight AND FEW as possible. This is where the "dedicated" (which really means direct) line comes in. Then from there you use as good quality outlet, power cords, and conditioner as you can.  
The better the quality, the better the results.
Strip away all the blather above and this is what you get. Every time.
drlisz
23 posts
 
@Mkgus  You could look at our purchasing a line conditioner.There is one made by Trip lite I think it's around 90 .00 it will not only protect against spikes but it regulate the voltage. If the voltage dropped to say 85 volts on your circuit feeding your audio system it we correct it to 120, also if it went to high say 130 it will also correct back to 120. Also a whole house surge suppression ( breaker) depending on the panels manufacturer would also help protect the circuits feeding your audio system as well as rest of the house. If you have power and all seems to work fluctuations are tough to troubleshoot and actually repair some people don't know there occuring. The conditioner will help with some piece of mind yes I have a clean 120v for the circuit.
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