How can I measure the noise on my AC mains with a 2ch oscilloscope?

I’m not an EE so although I have some nice test equipment I need help. Here is the problem, the AC Mains are 120 vac but I’m trying to measure the noise on the AC signal , millivolts. I’d like to answer two questions how bad is my power and second  does my isolation transformer make a difference.


thanks for the help 


Carlsbad2 - thanks for the graph. I’ve looked at my waveform and it’s clipped at the peaks and some junk on the wave too .  I’m really looking to see how well my power conditioner works. If we can agree that street power and house loads make it worse, but well designed gear will handle it, what was the reason you’re regenerating your power? Your PSA was an expensive investment?




OP stands for "Original Poster" or the person who started this thread.

It's a good idea to tag those you reply to so they are aware. 

Shame on everyone discouraging you from experimenting.  Shame!  We need more hobbyist and tinkerers, not fewer, and we need more of them to have first hand knowledge of home power noise.  It also doesn't matter WHY the OP wants to tinker.  I remember many years ago I was thinking about making my own power regenerator.  It was a fun project and I would have learned a lot.  I went into an EE forum asking for help and one member immediately pulled out some thread I had typed in an audio forum to basically say no one should help me. 

Here we are now in an audiphile forum and I can't believe the number of opinions discouraging the OP.  I'm really disappointed in those of you doing so. Maybe this is just a learning experiment for the OP, and that's all it has to be.

Here is an article on doing so with a scope and an interesting thread from Stack Exchange and another from DIYaudio.

Like Jason said.  Power doesn't matter.  Hook it up to a honda generator.  It'll be fine.  🤣

It’s surprising that Honda didn’t have a booth at Axpona.

Eric… I learned what OP means and that’s relevant! Perfect.

It’s amazing how much can be learned by reaching out to folks, and with a little bit of logic and some engineering, and like my Dad thought me … he would say well it’s already broke so we might as well try to fix it.

ok so I now have a fully active 3-way and subs open baffle system that I have turned . Convolution filters running in Roon with 132k taps to exploit digital processing!! Measurements with Earthworks Mic.

the amps I designed from Class D Pascal Audio modules … it’s amazing how critical it is the have amps that deliver Slew rates to follow the instruments!

Eric I try not to let “knuckleheads” get in the way of a hobbie !! Thank you for these links 


I just installed a PS Audio Power Plant 15 yesterday and has made a HUGE improvement in my listening enjoyment. I was using a APC H15 power conditioner previously with good results but as soon as I lit up the PP15...bruh. Clarity, detail and dimensionality were significantly improved. Slam dunk purchase for me. PS Audio is selling them a 20% discount r/n on their website.