Measuring Power Grid Interference in Practice

[DavidPiska]

We measured the high frequency noise in the power grid. The voltage going to the measuring kit is conducted by a common EURO cable and the RD Power Filter in order to compare their efficiency. I have made measurements on four different places for comparison.

Read more at: https://www.rdacoustic.cz/en/blog/2019/11/23/measuring-power-grid-interference-in-practice/

 

[Andik777]

Very good information. Thank you very much for sharing.

 

[Speedskater]

The only measurements that matter are at the audio outputs of your hi-fi components.
Part of a good hi-fi component design is dealing with power line noise. But power line noise is often caused by poor hi-fi component design.
So that's why measuring at the audio output is important.

 

[DavidPiska]

Of course, you can measure excellent output parameters with laboratory cleaned power in laboratory. But if you have big EMI noise at home, you will have the same noise in the output. This is about EMI filtration. Some audio components have good EMI filters, some not. All filters have some efficiency and if you place extra filter before your audio equipment, it is the step for better result.

 

[Speedskater]

Who would have a 'laboratory cleaned power in laboratory' ?

But if you have big EMI noise at home, you will have the same noise in the output.
Nonsense.Power line noise is a fact of life and your other hi-fi components are responsible for much of it. Good component designs deal with it.
Trying to measure the continually changing power line noise will confuse most audiophiles and is often nonproductive. Much easier to measure the signal-to-noise ratio at the audio outputs.

 

[Speedskater]

Thanks for sharing your interesting study David.
.....................................................
I was wondering whether you’d researched how much of the typically high frequency, high amplitude and transient noise actually bleeds through power supplies of various audio components to potentially effect audio signal paths?

Yes that's the question that really matters:
'how does it effect the audio signal path' ?

 

[NekoAudio]

That type of noise is why I included a 2-stage line filter in the Neko Audio DAC I designed. I kept around a fluorescent lamp with a noisy ballast specifically for testing purposes.

As for noise that exists on the grid, I do think it varies greatly by where you are located. My experience has been there is relatively clean power in the newer homes around where I live, and it can get pretty bad in parts of San Francisco.