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

I think some mistake noise in the system to a ground loop.

Let me preface with "not trying to be argumentative" - you both seem to know what you're doing and have things under control. But let's nto tell others that up is down or up isn't really high enough to matter.

I’ll answer to both of you guys (immediately above) that a star ground is the gold standard. And while you may claim things are "good enough" or "not a big deal" any divergence is in fact wrong -- less than ideal. period.

Any resistance between reference points can result in noise of various kinds - in AC power typically 60Hz or 50 Hz (outside ’murica). Why bait fate? You are simply arguing that you can sometimes get away with it. we can get away with many things, until we’re caught.


Now, when you move all the plugs/grounds to one circuit,and the hum decreases, you know its source. Its a reference differential. So there ought to be no mistake if you follow the golden rule: don’t change anything else, one variable per equation please.

I'm simply saying that i have used this in many systems to remove a ground loop hum.  Sometimes you have the same reference on two outlets, sometimes you don't.  But the simple fact that they are not the same places violates the principle of star grounding out of the gate.

I've never encountered a ground loop from running more than one dedicated outlet, it would be rare. I think some mistake noise in the system to a ground loop.

The reason that many (including me) say that equipment ought to be on one leg, is that in fact I say it must be plugged into the exact same outlet (with outlet strips as needed. This is the only way to minimize ground loops.

I am also a believer in feeding audio equipment, (that is connected together by wire interconnects), from the same Line, leg. I do not subscribe to the theory the equipment must be plugged into the same outlet to prevent the chance of ground loops though.

I have two 20 amp dedicated branch circuits that are 75ft each. Wiring is 10/2 NM cable, (Romex Trade Name). Both circuits are fed from 20 amp breakers that are directly across from one another... My system is dead quiet.
(Tube power amp and tube preamp).

Dedicated circuits get a bad rap and are wrongly blamed for ground loop hum, imo...
Things to blame:
1) Poorly designed audio equipment that uses an EGC where the circuit designer directly connected the power supply B- / signal ground to the chassis/EGC.
2) The wrong type of branch circuit wiring was used.
3) The wrong wiring method, installation, was used.


See page16 and read pages 31 thru 36.
An Overview of Audio System Grounding and Interfacing

.

@jea48 :
Careful. You're talking mostly about things that impact the power company and/or maximum utilization of your step down trans.  Nice, but not huge sonic issues.  The reason that many (including me) say that equipment ought to be on one leg, is that in fact I say it must be plugged into the exact same outlet (with outlet strips as needed. This is the only way to minimize ground loops.

Since  your equipment in aggregate is probably drawing 100-400 watts maximum, its really no big deal.

I could never figure out why the load on the two legs has to be balanced, do your electric devices all turn on and off at the same time? There is always going to be an imbalance.

Yes, 120V loads may be turning on and off at various intervals but there are times the various loads are on at the same time. That is why the known 120V loads should be balanced somewhat within reason on both Lines, legs.
Known 120V loads? Refrigerator, dishwasher, microwave, kitchen two small appliance circuits above the counter tops, chest freezer, central vac, furnace (blower motor. Also used for central air conditioning), cloths washing machine, multiple lighting circuits, sump pump, Bathroom(s) above the counter outlet(s) for hair dryer(s), ect.


Here’s a big problem I see... Occasionally I will read a post on an audio forum where the home owner, audiophile, on his own moved all the 120V motor loads, plus micro wave, and other such loads to one Line, leg, and have his audio equipment on the other Line, leg. This is not good for the home owner’s electrical service or the utility power company’s transformer. Especially the utility power transformer. The power company does not size the transformer by adding up the size, amperage rating, of all the electrical services that are fed from the transformer. The Power Company roughly calculates the average demand load that might be placed on the transformer. A power transformer is most efficient when it is loaded near its rated KVA rating. A Utility Company never adds in a fudge factor when sizing the transformer. Fudge costs money...

The secondary of a typical residential housing development power transformer have what is called a split phase winding. It will have a 240 volt winding that is tapped at its center point. From either outer lead, leg, of the 240 volt winding to the center tap (neutral) it will measure 120 volt, nominal. Basically two 120V windings that are in series are created. With this type of a winding only the unbalanced 120V loads return on the service neutral conductor to the transformer neutral. The balanced Line 1 (L1) to neutral and Line 2 (L2) to neutral 120V loads are in series with one another and are being fed by 240V.

Example, if there is a total combined load connected to L1 to neutral of 50 amps and a total combined load of 40 amps connected to L2 to neutral, only 10 amps will return on the service neutral conductor to the transformer neutral. The balanced 40 amps on each Line, leg, will be in series and will be fed by 240V. The transformer will see a total of 40 amps through the entire 240V winding and an additional 10 amps through L1 to neutral split winding.

Here is an example of a step down split phase secondary winding transformer. Such a transformer might be used to feed an audio system’s equipment. Primary wired 240V secondary 3 wire 120/240V. I will use a 10KVA power transformer with dual voltage 120V/240V secondary windings for the example. The secondary has two windings. Each winding is rated for half of the 10KVA, therein 5KVA each. Each winding has a voltage rating of 120V, nominal.

Some math:

5KVA / 120V = 41.67 amps maximum FLA.

So if the transformer’s secondary is configured, wired, as a 3 wire 120/240V power system from each Line, (L), leg, to the neutral leg the maximum 120V load(s) that could be connected is 41.67 amps.

L1 to neutral 120V load(s) 41.67 amps and L2 to neutral 120V load(s) 41.67 amps.

The two secondary windings are wired in series. The center point of the two windings is the neutral. (Per electrical code the neutral shall be grounded). From either outer lead, leg, to the neutral will measure 120V. From the outer leads, legs, of the entire series winding the voltage measures 240V. (5KVA + 5KVA = 10KVA / 240V = 41.67 amps maximum.)

For a full connected load example:

If L1 to neutral has a connected load of exactly 41.67 amps and L2 to neutral has a connected load of exactly 41.67 amps, zero amps will return on the neutral conductor to the center point (neutral) connection of the two series connected windings. The two 41.67A loads are in series with one another and fed from 240V. Current through the series 240V winding will be 41.67 amps. 240V X 41.67A = 10KVA... 10KVA / 240V = 41.67A

(Note: The neutral connection for each 120V load is still, must be, connected to the transformer neutral leg. The connection maintains a stable 120, nominal, voltage).

/ / / / / / / /

If the above secondary winding configuration is used to feed an electrical panel that will feed audio equipment the two 120V Lines, legs, 120V loads should be balanced somewhat within reason to draw power from both windings of the secondary. Say you have two mono amps that have an FLA of 8 amps each you would not want to put both amps on the same Line to neutral. That would load up one winding of the secondary. The correct way would be to connect one amp to L1 to neutral and the other amp to L2 to neutral. The balanced 120V loads of the two mono amps will be in series and fed by 240V.

How about those that say that all audio equipment that is connected together by wire interconnects should be fed from the same Line, leg, to neutral? Well as you can see from above if all the equipment was fed from just one Line, leg to neutral only one secondary winding of the 10KVA transformer would be used. 5KVA with a maximum FLA connected load rating of 41.67 amps.

If you want to have all your audio equipment fed from one Line, leg, and still have the full 10KVA rating power available wire both secondary windings in parallel, (OBSERVING POLARITY). In parallel the voltage out will be 120V only.

The full 10KVA power rating is available.(5KVA + 5KVA). Maximum amperage rating available for 120V is 83.33 amps.

10KVA / 120V = 83.33 amps.

Primary of transformer wired 240V, secondary wired for 120V.

(One leg of the 120V secondary shall be grounded)...

(An electrical panel is required).

/ / / / / / / /

How a 3 wire single phase split phase transformer winding works:

https://www.youtube.com/watch?v=eVamt9IdQd8

.

Let's disambiguate. (is that  word?)
Typically we worry about Noise. MC went on (correcly) on noise. The only solutions involve various type sof filtering, including normal filters and (better) isolation transformers. Bear in mind that YOU are likely the biggest polluter with your PC, TV, etc right there in your house.  Make sure you have filters between those noises and your sensitive analog components.

Now on to some things you said about lights dimming etc. under loads. This is a very different issue, that comes from a hgih impedance of the AC line - maybe from the utility, but also maybe your own wiring.  I have two "home run" outlets from my listening room to the 200A service in my garage that is on 12 AWG copper and bypasses all the other house wiring.  I also have several filters (all home made). But they do jack $H1T for hgih impedance (aka: low current capability - same deal).  An electrician ought to be able to find this - basically you load test it just like you load test your batter y and alternator in your car. Apply load; measure voltage drop.


BTW noise on the line changes every minute, second, hour, day and season. One measurement means little.

I could never figure out why the load on the two legs has to be balanced, do your electric devices all turn on and off at the same time? There is always going to be an imbalance.

The requirement to be balanced is not to within 0.0001 %, but to avoid severe imbalances, especially at 50% or higher load. Being within 20% is probably OK. This reduces the need for the neutral to be 2x as big, and I believe also has consequences on the transformer.

If you have a 200A service and are drawing 30A you care a lot less.

I use something very similar to this little gadget since it measures the main and neutral at the same time.

A good indicator of poor or loose wiring is either the main voltage dropping, or the neutral voltage rising.


https://amzn.to/3m0kEzW

Sadly the one I actually use is no longer carried, but you get the idea.

Power regenerators do absolutely nothing for sound quality unless your components are very poorly designed.

In my experience, everything is on a spectrum. It’s not binary. Clean power is very, very important. Every time I’ve cleaned up my power in any way, I’ve experienced positive results. The better designed equipment didn’t benefit quite as much as inferior designs. In the end, it’s up to the listener. Does a specific power upgrade provide enough benefit to justify the cost?

use a power plug extreme 
made in china for only 10$

 I wonder if my amplifier would sound better without those SMPS’s on the same circuit. I also wonder if they interfere with each other.

Not if your amplifier is competently designed.

Save your money. Power regenerators do absolutely nothing for sound quality unless your components are very poorly designed. You’ll be better off upgrading your system components. When you own good gear you’ll find that distortion on your grid has absolutely no bearing on sound quality. Companies like PS Audio thrive off hawking such garbage because they’ve realized most audiophiles don’t have any clue how their gear works. 

Interesting. I am in the same situation as you. I have a couple SMPS’s on the same circuit as my other gear. I could power them off a 12V battery using a 120V AC inverter or run a dedicated line for them. I wonder if my amplifier would sound better without those SMPS’s on the same circuit. I also wonder if they interfere with each other.

I had 3 dedicated lines installed a year ago and now wish I had 5.  Each line had a new breaker, I wish I had replaced all the breakers.

I have a PS Audio P10 Powerplant.  I never get 0 % distortion but the readout says it is better.  I have noticed the P10 adds its own distortion to the line depending on various settings.  It can be a very detrimental effect.  I only use the P10 for my digital gear and it is on its own dedicated line.

The P10 is very susceptible to line noise from the components on it.  I had to remove 2 SMPS's as they were injection an awful distortion.  

On the subject of SMPS's I found a great benefit taking them off all of my dedicated lines.

It’s fed underground. 
Another update:

The electrician came out and repaired the bad neutral lug and tightened everything up. The utility turned the power back on. The first thing I did was run some “tests.” Dimmable lights that used to buzz loud are quieter, the treadmill no longer dims the lights with each footfall (it does a little bit but it seems normal now whereas before it was like being at a rave), and best of all the sound quality of my audio system improved! No wonder - I’m sure the current flowing through the bad neutral lug wasn’t helping in any way with power delivery!

I’m really glad I put in the effort to follow through on this. I am very thankful for all the good advice from this community! I knew something was wrong with the power. I am happy that I didn’t go off on tangents with dedicated lines or power regenerators. I still plan on doing those things, but they would not have completely solved my problem in this case.

mkgus OP281 posts

08-31-2021
10:57am


Quick update: I called my utility company and they sent someone out immediately. They discovered that the neutral lug on the homeowner side of the meter was loose and the bolt is stripped. An electrician is on the way to replace the neutral lug.

@ mkgus

Well a loose service neutral in the meter socket could cause problems. Though there is an alternate current path connection from the Line side neutral conductor connection ’IF’ metallic conduit is used for the service wiring from the meter socket to the main disconnect service equipment panel. The neutral bus in the meter socket is bonded, bolted, directly to the back of the metal meter socket. And IF all the conduit fittings and locknuts are tight and solidly electrically connected together the conduit will carry the unbalanced load current from the neutral bar in the main electrical panel to the Line side of the meter socket service neutral conductor. (Neutral bar in the main disconnect electrical panel is bonded, connected, to the panel’s metal enclosure.)


Example of a 1 phase 120/240V 200 amp meter socket. The neutral bus and lugs is located in the center of the socket. Note the bus is bonded, bolted, directly to the back of the enclosure.
https://www.homedepot.com/p/Milbank-200-Amp-4-Terminal-Ringless-Overhead-Underground-Horn-Bypass-Met...

Now if you had said the top neutral lug was stripped causing the Line side service neutral to be loose that could/would cause big problems. You would have noticed while some incandescent lights would dim others would burn brighter. You would have also been replacing the brighter lit light bulbs more often. You also could/would have problems with 120V appliances with motors. Like the refrigerator, washing machine, and such. Even small electronic items failing due to being fed by a high overvoltage.

Here is a video that shows how the secondary of a split phase 240/120V power transformer works.
https://www.youtube.com/watch?v=eVamt9IdQd8

I don’t remember if you said the electrical service is fed overhead or underground.

They tested the line from the street to my meter. I don’t know what they tested exactly. Is that the same thing?

At our place, the power quality survey took four weeks. They installed a special meter at our service panel from which they downloaded data once a week for four weeks. The initial visit entailed checking the voltage on the lines, checking the connections at the service panel and power pole, and testing continuity of all the breakers.

So, not the same thing.

They tested the line from the street to my meter. I don’t know what they tested exactly. Is that the same thing?

Thank you for sharing your experience. Clean power is vital!

Quick update: I called my utility company and they sent someone out immediately. They discovered that the neutral lug on the homeowner side of the meter was loose and the bolt is stripped. An electrician is on the way to replace the neutral lug. 

Hi mkgus,

Twenty years ago, when we and the bank purchased our home, the lights dimmed when the fridge and furnace powered up.  A phone call to the Central Maine Power Company brought them out immediately to test.  The following Sunday at 10am, they installed a new pole, transformer and lovely ground outside of our house.  I later learned that on weekends, stand-by crews will often do the odd job, keeping them busy.

My supportive Master Electrician (who works Nuclear Submarine Panels, at nearby Bath Iron Works,) later isolated the two dedicated studio lines on our electric panel, away from the big power draws.  Over time, I've upgraded to a Furutech outlet w/cover plate, along with a replacement male Furutech plug for my hardwired Panamax M4300-PM line conditioner.  I suppose it's obvious by now that after 45 years of hi-fi, I consider isolated power and good wire no less essential to great sound than equipment choices.  For me, our hobby is a process, each improvement freshening our collections and triggering our passions. 

Now, let the eyerolls begin.  My most recent system addition is the Furutech NCF Clear Line AC power line optimizer.  In a small studio, I am always looking to add depth and MUSICAL micros to my soundstage.  It accomplishes that.  A caveat; I have no affiliation to Furutech and elect to  buy their products from The Cable Company, keeping away from black market concerns.  I'm always happy to pay full price in support of premium products.  

Thassaabboutit!  More Peace, Pin

Just wanted to say thank you to everyone that replied. There is a lot of good information here and I’ve got some good paths to go down. Will definitely call my utility and follow up on that.

If your power source is questionable you can install a line conditioner.  A good line conditioner will filter out noise in your power signal.  Often used in industrial control applications to feed clean power to the control system.  This power source should also be supplied from a panel dedicated to sensitive equipment.

If you really want the cleanest power you can get a dedicated panel installed for your AV equipment.  Professional recording studios do this.

Lots of good advice here save the link to the ASR clowns. Anyway, there are meters available (Entech, for example) which can measure a degree of noise in your home. My wife and I flip homes and do a majority of any electrical work in the renovations. Prior to buying, I measure the mains noise with an Entech meter and a Stetzerizer. Some readings come in low (<100) while other peg the meters out- these mostly in high rise condos- I avoid investing in these places. As JEA48 pointed out, often the problem can be from loose breaker terminals in the electric panel, especially in newer homes. FWIW, I am an electrical systems technician and can say that most service calls I go on have a common denominator- bad connections- by the prior service tech, of course!

I'll add in my $0.02 for what it's worth on the subject.  To answer the OPs question I don't concern myself with EPQ measurements of any significance.  For me, conditioning the incoming power is a very basic requirement to cleanup the harmonics and spikes you receive at the house.  I use legacy Monster brand conditioners on my primary and secondary audio systems.  These read a constant 120.1 vac all day long, and I'm good with that...condition it, fahgettaboutit! 

Is your incoming dirty?  Absolutely.  Is it a pure sine wave and distortion free?  Ha, no way!  Here's why. 

Power starts with a turbine/generator at your local station, leaves the building at 23 kv or so at a rock solid 60 Hertz.  From there it feeds numerous auxiliary/station service transformers (tx) and hundreds of motors back inside the plant.  When it leaves the building it hits generator step up tx units taking it typically to 230 kv, then 500 kv in the switch yard for transmission. 

Every tx adds in a bit of influence, and harmonic distortion especially in the 1st and 3rd orders up to the 21st order or so.  New tx included,  but even more so with aged units you also have internal partial discharge and external corona over a wide band of frequency ranges . IEEE/IEC standards dictate what level is acceptable for the particular vintage, class, kv and size of the tx .  Anything over 21 kv to ground will go into air corona unless shields are installed. Count in dozens of switchyard breakers, each with internal and external connections, as well as bushings, connectors, buss conductors, tap changers, wire, terminations, lightning arresters, insulators, switches, ground connections, cap and inductor banks, so forth and so on.

Leaving the switchyard down the transmission corridors the feed travels for miles; in my state there are over 30,000 miles of transmission and many hundreds of feeder substations to step down the power for distribution at low voltage, 25/14.4 kv and12/7.2 kv are common.  In these stations... more switches, breakers, tx, connections, etc. and miles of wire on the street.  I`m lucky, the closest generating station is < 20 miles from the house, and the closest substation is <6 miles away.

Regulators (regulating tx) constantly jog the distribution lines based on loading to keep voltages at your neighborhood, when stepped down by those little green boxes (or grey garbage cans on the pole) close to 240/120 volts.  These can be set to narrow or wide tolerances but keep the incoming between 115-125 vac at the kitchen outlet.  Is that dirty? Yes indeed.  Will you ever receive a pure sine wave off the street? Nah.

If you hang an Agilent or other such really high Q analyzer on your lines you would likely see flat tops and transient spikes in the voltage trace.  Harmonic distortion in the current trace will look more like a sawtooth than a sine wave.  Google spends millions on power conditioning at their data centers. As an audio aficionado I spend a little.

Every large utility will have an EPQ group, 8 or 10 guys and gals to investigate significant power quality issues.  Hospitals and industrials come first followed by commercial, the lonely chicken rancher who has
5 or 10 acres and 10,000 chickens that wont lay eggs, then Mr. & Mrs. Residential.  If you have a critical medical device in the home you just got upgraded.  Reach out, be cordial, ask for help.  It's what they do.

Most significant issues will likely be found in the ground connections. 

I hope I've added some value to the discussion.  Every time I flip a light switch, and the light comes on, I just smile a little bit.  Freaking miracle that is!

As mentioned many times above (very good advice) it seems like you have a voltage drop problem for whatever reason. Please pursue this with the appropriate pros as detailed above very well.  

If you are curious to "see" what's happening for yourself you can purchase this at Amazon for ~$28.  It will read out true RMS voltage continuously.
https://www.amazon.com/Poniie-PN2000-Electricity-Electrical-Consumption/dp/B0777H8MS8/ref=sr_1_3?cri...

I find mine very useful in the watt readout with individual pieces plugged into it.  Simply to see start start-up wattage versus idle wattage.

Plug this into the wall and plug the treadmill into it. 

This suggestion in no way negates your need to find a true cause.

Regards,
barts

Most audio components are completely immuned to dirty mains power. There are some exceptions (some Rogue Audio stuff for example), but otherwise, the most common problem is humming/buzzing toroidal transformers from DC offset. This is something your power provider can check for with a special meter. They should do that free of charge if you have a legitimate concern. 

https://youtu.be/OL23xkLfPTU

If dirty mains is an issue, it’s best to just stick with the bigger name brands that have competent engineering chops. 

I use PS Audio products which can measure the amount of incoming THD which is usually in the 3% plus range for me. After regeneration, the THD drops to the -0% range. I feel that that method of measurement and subsequent cleaning of power is beneficial to the overall sound quality. 
Additionally, I have installed Environmental Potentials EP-2050 power line industrial EMI/RFI/spike filter. These are used in massive server farms, IT systems, medical electrical systems, large corporations where critical systems rely on flatline clean power delivery. 

On cables, especially newer Shunyata with DCT to help with noise, hmmm, they are able to lower noise floors below the already impressive -0% noise floor. Can we even hear that? I mean really, can we hear that level of noise reduction or is it already below the perceptible hearing level that would make a difference. What  does a .0001 noise floor sound compared to a .001 noise floor? Can you hear it? Power cables are part of recipes…many in the community hear differences in what power cables do, myself included. Heck, my stock cables sound different, and better in some positions in my system than other power cables. Ahhh, different….what’s that? Noise floor, hmmm. Did that new cable lower the noise floor and I heard it, or, did it change the perceptible audio spectrum which alludes to more recessed mids, increased bass, and sizzling higher frequencies. Look, power cables are like ingredients in a recipe. They can alter the soundscape, but, be careful what you ask for. Power delivery by any cable to your system by default is going to be great. When changing out power cables, all you are doing is changing the ingredients in the power delivery chain which may or may not change the flavor of your sound. Trust me, I just splurged on a half dozen Shunyata Sigma NR 2s and experimented with different power configurations and each component reacts differently to power cables, sometimes to the detriment of sound quality. Get your ingredients right and in the right order. Another example of new Sigma NR2s in my system…my volume must be turned up at least 1/4” higher to get the same loudness level as before. So much for instantaneous power delivery of cables. My system already jumps out at you with instant speed and can play loud as heck…but, power cables alter something, maybe the background is quieter, but why? Ahhh, my highs are slightly veiled and lost some organic sound qualities. Switch the ingredients, maybe new cable break in. Another cable ingredient to consider. 
 I agree with other posters about your electronics and amps having the ability to cope with power anomalies to a certain degree which still results in awesome musical enjoyment. 
Methodically evaluate what you do and do it in small steps. Sometimes, the little things are the biggest payback in musical enjoyment. 

I do not think there is a "one size fits all" solution to troubleshooting electrical system problems. My power company came the same day I called to do some perfunctory testing of the service entrance and all was good. I had found a few spots in the system- funky xlr connector (which the manufacturer re-terminated at no cost) and a bad tube socket (which I had help replacing). Despite having gone to some lengths to set up a good electrical "subsystem" for my hi-fi shortly after I moved here 4 years ago, I still had an occasional intermittent burst of static, even after replacing every tube (I have tubes all the way through, from phono section and power supply to line stage to amps- a lot of tubes).
I think I was finally able to diagnose the problem with the help of the designer of my line stage. He suggested I pull the battery packs (it runs on lithium batteries when playing) and swap them. I noticed some dust between the battery packs and the plates where they make contact. So I dusted those while swapping them L-R and R-L.
System is now functioning as it should.
One thing I do recommend is a commercial electrician. I’ve done several rooms over the years and my experience with commercial electricians generally has been better than the garden variety residential person. Not to paint with a broad brush, but as @jea48 mentioned, there is a wide variety of experience and knowledge among those who do this stuff for a living. The guy who ran my project did not specialize in sound or studios, though they have done them-- they work on all kinds of big institutional stuff. Trick is finding a service company in your area that does both residential and commercial, since a lot of commercial electricians don’t want to bother with what they consider to be small residential household issues.
I’d also counsel patience- I know, you want it right and you don’t necessarily want to throw money at it in the hope of some band-aid. I’d start with the power company and find a good electrician who is savvy at troubleshooting. It could be something small.
For example, in a previous house, even with dedicated lines, there were certain appliances that could be heard through the system. Simple solution- avoid using those when listening.
I know people rely on power conditioning as an quick solution-- it may not solve the problem, but my bigger issue isn’t that- it is what the conditioner does to the sound. You may hear a difference with conditioning, but that doesn’t necessarily mean better. I’d try to solve the problem before I resorted to "conditioning" simply because filtering out noise is likely to filter out information you want to hear.
Good luck with this. You’ve gotten some good input here.

Dirty electricity https://m.youtube.com/watch?v=18qneiDgR1E
It's more than just sound, it affects your health.
Stetzerizer filters and meterhttps://www.stetzerelectric.com/

I use to get hertz frequency readings around 600!! When every device needs 50/60.
Cleaned the sound immensely.

Peace and Freedom of choice.

Gian

I have a dedicated line into my system. 
Pretty quiet. I have had few problems.

Take a look in these videos from Shunyata Research. Power is their area of expertise. You may find some practical guidance on them. Good luck.
https://www.youtube.com/watch?v=4qCK--lRFd0
https://www.youtube.com/watch?v=LHXP19fXN60&t=39s
https://www.youtube.com/watch?v=Z6f1kwyZbM8&t=35s

The dimming lights synchronized with bass notes or walking on a tread mill is a dead giveaway that power is a problem. When contacting your power company make sure you tell them about this problem up front. They should take you very seriously just based on this one factor. Even a 15 amp standard circuit should not experience a significant voltage drop from a typical Class A/B amp running at normal volumes.

The dimming lights are a result of voltage drops when there is just a modest demand on the circuit. That means that no power conditioner will solve the problem. You are going to have to tackle the source of the issue which is your power (you knew that).

When approaching your power company I would suggest that you communicate that this is concerning you from a safety perspective. Don't just complain about your SQ - some people might just roll their eyes and blow you off. When you say the word "Safety" they are going to perk up and listen. Tell them that you have researched this symptom and found that it could be an indicator of a serious problem in your electrical service.

If you don't have a multi-meter you can pick one up for about 50 bucks. You can do a simple check of your AC voltage and you can get a sense of how much the voltage is dropping when you crank up your system. This will be good information to have if your power company responds poorly.

Thanks to jea48 and a few others for excellent detailed information. Except for the usual snarky drivel this has been a very informative thread.

The utility company in my area uses higher gauge wire than what is used for the service feeder. I guess they don't have to worry about the wire getting hot because it's in open air.

The responses above vary so much between “the power utility will do nothing so long as you have electric service” to “the power company will really help you with testing and equipment changes to arrive at a high quality of electric service.”   So, it really varies that much from one locale to another, and it is the luck of the draw what assistance you will get?

My experience (not particular to electric service or its affect on sound quality) is that the utility always wants me to have a professional check and repair problems within the home first before the utility will send anyone out.  The technician, having checked a few things, says “I checked the box and your outlets, so if you are still having problems you will need to call the utility . . . Just what are you trying to do? . . . Oh, I don’t know about that. I just verify that you have electric service and you do.”

The utility company works within a high range and low range of acceptable. As long as their test comes back within that range they will do nothing. You could be at the very bottom of said range but still considered acceptable. You need to do the rest on you own with a quality power conditioner and good cables. 

Hell,  20 years ago I found the best electrician I could find, he replaced my old service, weather head and tidied things up In the attic. 
He had the power company come out and they either on his advice or theirs,  put a pole in my yard with a transformer on it, it was at the street before. I'm in a rural area and the poles on the side of the property,  Ran new larger wiring from the street to my new service panel. I'm looking out at the now closer transformer and larger service than before. 
The power company will help you out. 

Dimming lights? Treadmill affecting things? Let's start with something simple!
Most modern outlets use some sort of wire capturing spring. They're quick and easy to install. Strip and insert wire, done. While they may hold the wire fine, IMHO they're crap for a SOLID connection. If you're competent enough I'd suggest the following: Kill the power at your breaker box. Pull the outlets in your audio room and redo the connections using the *screws* on the sides of the outlets. (Or have an electrician do it, even better.) This will give you more conductive surface area and a more SOLID connection. I've done this in a couple homes I've owned and it made all the difference. No more dimming lights during loud, bass heavy music. Good luck!

Happy listening!

@hilde45:

@jea48 Thanks for the very practical answer and to @tvad for the tip on contacting the electrical company. We’ll see how they react, and if they can come out...

Tip: My electrician said to tell the Power Company that we had a problem with dimming lights, which would provide a reason for the Power Company to do a power quality check.

The Power Company found a neighborhood transformer that needed replacing, and they also found something on our power distribution pole that needed replacing (as well as a few neighbors, so they benefitted too).

They also tested every breaker in my panel for continuity (I think the term was continuity...it’s been a while), and said quite a few were out of specification and should be replaced, which I had my electrician do.

Thank you to @vk_onfilter for directly answering the OP’s question.

I could never figure out why the load on the two legs has to be balanced, do your electric devices all turn on and off at the same time? There is always going to be an imbalance.

@jea48 Thanks for the very practical answer and to @tvad for the tip on contacting the electrical company. We'll see how they react, and if they can come out, I now have a practical list of what to ask them to check.

I've asked this question before on threads and this is the best answer I've read to date. No condescension, just expertise. Appreciated, Jim.

Dimming lights from an exercise machine???????????

That's serious.  No-one else gets that, although I used to get it when I powered up my old Krell.
Sounds like you've just got bad or old or damaged house wiring.
Get a competent electrician to re-wire the house.  Put the hi-fi on a dedicated circuit back to the company fuse with 20 amp wire.
Then enjoy the music!

The quality of the mains sine wave does not matter too much as long as it is able to magnetically excite the transformers of your electronics.  Also noise, including RF noise is usually very well filtered out by good quality power supplies. What remains is the current delivery capability of your circuit when it matters. And that is usually dictated by the quality of the internal wiring of your house. İf you are noticing dimming, that is indicative of too much voltage drop in your wiring. İs your house wired with a lower gauge wiring ?  Or is it an older house with aluminum wires ?  Are there any loose, corroded or bad connections from your panel to the plug ?  İs there any 'coiling' of your wire anywhere, causing inductance which resists current delivery if it becomes significant enuf ?

I used a $20 meter and could tell that my voltage was fluctuating quite a bit during the day which was also moving the bias on my power tubes quite a bit.  I ended up trying a PS Audio regenerator and they gave me a 30-day return period if I didn't like it.  I discovered the THD on my line was at times over 4% and the unit brought it down to less than 0.1% while also blocking nearly all DC that might be on the line.  The regenerator substantially improved my sound quality and also massively reduced the noise floor on my SET amp while also providing electrical spike protection.

Here's a screen shot from a few moments ago of the display.  You can see it's taking the incoming 3.8% THD this evening and dropping it to 0.1% while also correcting the voltage to 120V and keeping it there.  My tube bias never wanders at all now and the system sounds fantastic.  I have no SQ fluctuations over a 24 hr period anymore and all my gear is plugged into it.  I'm not a huge fan of PS Audio gear other than their regenerators - this is what they really got right IMO.

https://i.postimg.cc/MKQR7Nqm/Screen1.jpg

Thank you  Jea. Nice display of patience.

Just one problem with an ungrounded isolation transformer: some manufacturers ground a metal case to the ground pin, and count on it to prevent electrocution in the event of malfunction.

Don’t get me wrong - I use isolation transformers for everything. But unless I built the electronics myself, I just grit my teeth and ground those transformers. To code.