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

Maybe, but maybe not. What I have noticed about electricians and electrical engineers is that they approach it from the perspective of meeting code and not starting fires. That’s not a bad thing in general, but if you’re chasing high fidelity sound you’re going to have a bad time with that approach (minus the not starting fires goal, haha!)

If code allows for a 5% voltage drop in a 120V line, then you’ll see fluctuations between 114 volts and 120 volts depending on the load. That’s completely unacceptable for hi-fidelity sound. You want that voltage sitting at 120 constant and not budging an inch. Sure, a good power supply will minimize the effects of voltage fluctuations but why would you want to deal with that hurdle if you don’t have to? Make it as easy as possible for your equipment to perform, which means going well beyond what a code book would tell you. 

Your advice with a dedicated line is spot on, however, it won’t fix problems upstream of your panel such as a loose lug on the meter socket. There are other things going on outside of my audio system that strongly indicates a poor ground or bad neutral connection.

I could pull a dedicated line, I could buy a filter, I could buy a regenerator, and I probably will some day, but there has to be a better method than “just try whatever and see what helps.” If you can diagnose the problem properly, then you can apply focused solutions which saves time, money and headaches.

Early in 2020, on the recommendation of my electrician and @jea48, I contacted our Power Company and requested a power quality analysis. They installed a special meter and downloaded weekly readings for a month. It resulted in some repairs to our service, and to neighbors’ service. One repair improved voltage consistency. 

It was free. Well worth investigating.

That’s exactly the type of thing I wanted to hear about, tvad. Thank you!

Besides poor audio quality, two examples of what I’m experiencing are:

1) Playing music with bass at low to moderate levels causes dimming lights.
2) Slowly walking on a treadmill causes the lights in the room to substantially dim with each foot step.

I’ve had electricians tell me that the best way to wire things is to have the lights and outlets on separate circuits so that things like treadmills don’t dim the lights, but there’s just no way a slow paced walk on the treadmill is pulling down the voltage that much on a normally functioning electric service. The problem seems to affect the whole house which makes me think it’s upstream of my panel. I’ve had all the lugs in my panel tightened and I even dug up the top of the ground rod to verify it’s connected and it is.