The Midnight Effect - Who-How?

You have high end equipment designed in a way to make it seemingly impervious to power line fluctuations. You add expensive conditioners and/or power line regenerators just to be safe.

You sit and listen to your system for a few hours and everything sounds great. Then, from nowhere, like someone flicked a switch…. the sound opens up… becomes more natural, more focused… the soundstage suddenly blooms and becomes more dimensional, more depth and more space around instruments. WTF just happened? The only clue is the clock on the wall and the empty wine flagon next to your chair.

I’m long past questioning whether the phenomenon is real. To what extent it exists depends on certain variables, but it exists. But how? I live in the boondocks, there’s no industry or commerce that suddenly shuts down at 23:00 every night. 
Do others experience this? Do you have an explanation? Perhaps even some empirical data?

Is it just the booze?




Booze for sure. And the fact you’re not as distracted at that time of the day/night. 

For a few years if I was back in my listening room and listening, I was drinking.  I have  cut way back since then  (I am on Miller 64 these days, and it doesn't taste good enough to make me want more than a couple of bottles) and listening isn't nearly as much fun.  I feel better, however.

More electrical grid calm can be noticeable for some cities in particular..

Or the influence of darkness on hearing...😊

We hear the best when we were in our mother womb in complete darkness...

The same is true in a dark room at night...

Or blind...


Whisky has nothing to do with that as in love making you may feel it is better with no more self restrainsts with alcool but it is not at all really better and may impede erection at last ...😁

Drunkness impair hearing as seeing but you felt it is better for sure ...😊



I can hear when each of the two systems I have "open up" and it has nothing to do with substance intake. The vintage system warms up faster- the Quad Loudspeakers are plugged in constantly so under full charge. The Quad II amps with real GEC KT66s open up after about 25 minutes. It is noticeable to the average listener.

The main system takes a minimum of 45 minutes to warm up the tube components and at least 3 sides until the cartridge sings. So, if I have someone visiting, I warm up accordingly, so we don't waste time. 

Drinking heavily and messing with a turntable is a recipe for disaster, but I am not condemning the liquor. 

caps and cables form… especially the exotics… warm is good.. and measure your ambient noise floor…you might be surprised….

my system takes a few LP sides….

Radio stations have to reduce transmitting power at the evening per FCC regulation.  It is Section 73.187 of the Federal Communications Commission's rules to reduce power from 2 hours before local sunset to 2 hours after local sunrise.

Whether you reside in an industrial zone or not, power load exhibits a similar time-of-day pattern universally. Particularly, the peaking is most pronounced during the summer months, as we all comprehend.  However, I find myself questioning: Is this truly what happens?


Just a couple things based on some comments above… equipment warm up is not what I’m referring to when I talk about the midnight effect. That’s real, but it’s a different thing altogether. I might start a listening session in the early afternoon, I’ll hear an improvement in sound for the first hour or so but it isn’t like I hear late at night or early in the morning.

The power charts and the whole concept of power line loading is the most obvious explanation, but it falls down when you consider that everything is running from regeneration and power line loading and variances shouldn’t be getting through to the system. 

 The FM radio comment is interesting. I wasn’t aware of that.

 I can also take alcohol out of the equation. While it was a small factor on Friday just gone, I’ve had plenty of long stretches where I’ve been alcohol free, including for two years around a decade ago.

So I’m still unsure. I heard it on Friday/Saturday morning and it was almost like someone had flicked a switch. Or more like someone had suddenly placed extensive acoustic treatments in the room.. the soundstage just opened up in all directions and the sense of presence and of natural tone…. I would pay a lot of money to have whatever it was become a permanent fixture, way more than I paid for the two PS Audio units, whose contribution to the sound is barely noticeable in comparison.

Any more ideas?

My dealer told me that a certain preamp he sells, which I do not own, takes about 5 hours to reach its peak. While my equipment sounds good after an hour, I do find it sounds better after a few hours, regardless of the time of day. I cannot say whether it’s psychological or not, but that is my experience.  So you are not alone. 

Radio stations have to reduce transmitting power at the evening per FCC regulation. 

That is completely false. In fact, broadcasters are required to maintain xmitter output to within 90 to 105 percent of authorized power output at all times.

There are some AM stations that are required to reduce power at night, and of course there are still some "daytimers" on the AM band.

I'm just trying to picture a flagon and a clock in the same setting.  The Middle Ages called...they want their wine vessel back.  he he  Just teasing...I couldn't let the opportunity go by as you maybe never see that term used.  But the imagery is cool!!  To eliminate flukes and misperceptions, repeat it.  So, is this a consistent phenomenon?  Does it happen every time the circumstances are the same?

@cleeds   This is from FCC website:

"Most AM radio stations are required by the FCC's rules to reduce their power or cease operating at night in order to avoid interference to other AM stations.  FCC rules governing the daytime and nighttime operation of AM radio stations are a consequence of the laws of physics."

@rooze - it was always an audiophile "truth" that systems sounded better at night when there was less demand on the grid. It does make some sense to me since you are essentially playing your power supplies with amplifiers and those in turn depend on what’s coming out of the wall receptacles.

I installed a very robust electrical "subsystem" for my main system (which ties back to the main household ground) and uses a large iso-transformer. I have fewer electrical anomalies here in Central Texas than I did in a small village along the Hudson in NY. I attributed a lot of that to newer infrastructure, despite the fact that I’m virtually "in town" rather than out in the country.

But, having said all that, when the temps here reach 110F in the summer (and we can have 60+ days of over 100 degree heat) I simply don’t use the main system much. We receive warnings about the grid being "iffy"- and it puts me off.

PS: As to the regenerators, I have no idea. I heard early iterations of those, but never lived with them.

PPS: I took a quick look at the PS Audio forum and there seems to be some suggestion that its regenerators are still susceptible to certain forms of noise. One user, John H, was a frequent contributor to those discussions.


You missed my comment about measuring you ambient noise floor at various times….. that’s ok….most audiophiles lack an SPL meter for level matching and other essential tasks…..


... Most AM radio stations are required by the FCC’s rules to reduce their power or cease operating at night ...

That’s true, although there aren’t many daytimers left anymore. What I was correcting was your previous claim that radio stations are required "to reduce power from 2 hours before local sunset to 2 hours after local sunrise."

As I noted, FM stations remain at full power. Any station - AM or FM - actually needs special authorization to operate below licensed power.



I heard it on Friday/Saturday morning and it was almost like someone had flicked a switch. Or more like someone had suddenly placed extensive acoustic treatments in the room.. the soundstage just opened up in all directions and the sense of presence and of natural tone….

It sounds as if the acid must have just kicked in.

I "warm up" my ears before seriously listening. I start at very low volume while "getting my head together". I allow my brain to "tune in" to whatever is on at that volume until I can hear details and depth. At some point the "switch gets flipped" and I turn up the volume. I'm sure there are various electrical and electronic variables changing, but my focus is already fixed on the sound of the music. 

Our electrical grid is an amazing thing where your power can be coming from a solar panel this morning, a wind farm this afternoon, a fossil fuel plant this evening, and a hydro station overnight - with none of them being anywhere near you. On its way from the source to your speakers, that power goes a long way, through all manner of equipment, and past all sorts of sources of interference.

Every time the utility changes the source of your power, there will be a corresponding change in the "hash" that is induced on the power lines and comes along with it to your doorstep. It might be radio frequency noise coupled from a nearby radio station (near to a power line 100 miles from you) or an ultra low frequency created by the fluctuations of a 345KV line losing a varying amount of energy as it slowly swings in the breeze on a foggy evening and some power bleeds off as static energy.  

As an electrical engineer who has done load flow analysis for utility companies, I have worked on power systems where they had thunderstorms in the power plant switchyard when the salt fog rolled in off the ocean, and the same system needed to put out 370KV at the plant to get 345KV out at the far end of the line. Most of the rest bled off into the air although some was lost to resistance heating and other equipment losses. What shows up at your door constantly goes through all kinds of waveform shaping, matching and combining of multiple power generation sources, weather conditions, temperatures, and equipment load variations - some planned, and some not. 

Where I live, there are two predictable utility changes that happen every day. One is when the water company switches from one pumping station to another about 1:30 in the morning.  For about 2 months some years back, there was enough difference in the water pressure to create a water hammer pulse in my area that was strong enough to trip the pressure alarm in my building's fire suppression system and we had 30+ families rousted out of bed until the fire department confirmed the true source of the call-in. There were a lot of really ticked-off people until the alarm company was able to tweak their settings to match the changes being made at the same time by the water plant.

On the electrical side, a similar thing occurs every evening as the power company changes the regional source of power to our community.  Massive load changes that are seldom considered can include when a hydro system switches from providing power with their turbines all day and evening when loads are high and then switches to using those same turbine-generator systems to pump millions of gallons of water back up hill to a pumped storage reservoir overnight. That big supply becomes a big load, and the whole system must adjust accordingly. Again, it may be in another state, but it is part of your power supply.  


Literally everyone's situation will be different, within your house, building, neighborhood, community, state and so on.  Some people will have "cleaner" power at night, and others may find it is worse.  With luck, each of us will find our "sweet spot" where and when what we hear is the best music to our ears. 

Electromagnetic radiation or ambient electrical noise may play some role, but we are also getting quiet at the evening.  Our internal noise is reduced and focus increased (and the booze of course).

@cleeds   They have to operate at reduced power,  but I misunderstood definition of critical hours.  Critical hours is 2  hours before sunset to sunset and sunrise to 2 hours after sunrise.  It has something to do with greatly increased propagation of the signals during critical hours ("skywave propagation").  I don't understand if critical hours are in addition to reduced power at night or power has to be reduced only during critical hours.  In previous quote from FCC they mentioned "reduced power at night" (inconsistent).   They mention daytime and nighttime power.  Do they require nighttime power in addition at "critical hours".   Few years ago I was listening to interesting AM program and always around 6-7PM signal was dropping rapidly resulting in a lot of noise.

"For AM broadcast stations, the term critical hours refers to the time periods of sunrise to two hours after sunrise, and two hours before sunset to sunset.  During these periods, the ionosphere has commenced its transition from daytime to nighttime conditions (or vice versa), resulting in greater coverage than would be expected from a daytime-only analysis.  But because the transmitting station operates with its daytime power between sunrise and sunset, the extended skywave signal can be strong enough to interfere with other stations.  This daytime skywave phenomenon was the focus of a protracted rulemaking proceeding that commenced in 1947 and terminated in 1959 (see Docket 8333 for a limited number of decisions in this docket) with the adoption of Section 73.187, Limitation on daytime radiation (also called the "critical hours" rule), and Figures 9, 10, and 11 in Section 73.190.  The rule provides for operation at a lower power during critical hours time periods to limit interference from new or changed Class B or D stations (where the changes were made after 1959) operating on frequencies specified in Section 73.25, to Class A AM stations on the same frequency."



They have to operate at reduced power ...

You are misreading the FCC. In the U.S., broadcast radio stations operate at authorized power output at all times although, as noted, some AM stations have lower authorized power at night and others ("daytimers") sign off at night. (There is such a thing as "pre-sunrise authorization" that some stations obtain.)

FCC regs call for the transmitter to be within 90 percent to 105 percent of authorized power output at all times. Special authorization is required otherwise and stations can be fined for failing to follow the reg.

@kijanki I believe the text you're referring to is used to calculate power (so as to avoid interference) during the licensing/permitting process. Once power (which is really ERP) is authorized, no further adjustments are allowed without application.

@cleeds  Thank you for the info.  Do I understand correctly, that some AM stations have to operate at lower power at night (and critical hours), while "some" means stations that operate at frequencies of other (older?) stations?


Do I understand correctly, that some AM stations have to operate at lower power at night ...

Yes, and it doesn’t stop there. Some AM stations may also be required to change the antenna "pattern" so as to prevent interference (it’s called "protection") with other stations. If it’s a particularly directional pattern, it’s possible that has a greater negative net result on the signal than the reduced power.

Echoing what others have said, power-line issues could explain what you’re hearing.

In my case, my house had been powered by a rooftop PV system (just panels, no batteries at the time). During the day, my stereo (kinda mid-audiophile, costing a total of maybe $25K at the time) sounded pretty good, albeit a little too bright & Class D-ish for my taste. But at night, it generally sounded better. A lot better, in terms of soundstage, imaging, and transparency. And recordings that I found hard to listen to during the day lost much of their D-type graininess and harshness after the sun went down. Huh?

It didn’t occur to me at the time that at night, the house switched from solar power to the grid. In case you’re not aware, the inverters integrated into most rooftop-PV systems produce far more noise than a typical electric utility.  Was that a contributing factor?

Then, a few years ago, I sunk 8 grand into an Audioquest Niagara power-conditioner + power cord upgrade. Using a consumer-grade line-noise meter I confirmed that the Niagara reduced my line noise by at least one order of magnitude. (Thanks, Garth Powell & Mikey Fremer!)

And you know what? Not only did the Niagara make a night-and-day improvement to my SQ overall, but now there was now no difference between "night and day" sonics (sorry!) I found that I could even shut off the entire PV system & run off the grid without a change in sonics.

Confirmation bias? Nah. I didn’t expect this to happen, so there was no belief to confirm. It was only afterwards, after consulting with some solar-power & line-conditioning engineers & contractors, did I finally figure out what was going on.

YMMV, but the differences I heard were dramatic, and were later corroborated by objective noise measurements. Nothing else changed in my system at the time, but it had never -- never -- before produced such a palpable, three-dimensional presentation or so convincintly reproduced the acoustic environment of a live performance. For a few weeks, I just couldn’t stop listening to my favorite, most familiar recordings.

So whenever someone asks about time-of-day variations in the sound quality of an audiophile-grade system, I always think first about time-dependent, cyclical factors that can affect AC line noise.

What I’ve learned: If I had the choice between spending $10K on either an amp upgrade or a mains upgrade, I might well choose the latter.


Oh, and to address the OP’s original question (yeah, it’s not all about me!), dramatic changes can occur in the quality of a utility’s delivered power as a function of time of day.

E.g., many utilities adhere to a daily network-switching schedule that accommodates the technical limitations of alternate power sources (such as solar plants v. coal-burning), or that routes power differently depending upon average time-of-day-related demands. If the OP thinks that the change in sound quality happens at about the same time every non-holiday weeknight, it might be worth a call to his or her utility to ask whether any change in topology or other delivery details occurs at a regularly scheduled time.

Empty flagon and the fact that you are relaxed play a big part of what you are experiencing. You've given your mind some time to de-stress and you are hearing the difference. Enjoy!

Pardon me but I'm going down to my dungeon open a flagon,  and spin some magic

@knittersspouse- I found your post informative. Can you focus on the OP's use of power regenerators? That is, devices like the PS Audio boxes that are akin to amplifiers and take power from the wall receptacle but then "regenerate" it? 

The impression is that these devices are immune to the changes that happen on the power line (or upstream on the grid) feeding into one's home. That's what the OP is puzzled by-- that despite his use of these regenerators, he hears different sound quality at different times. 

Warmth and darkness is where we came from.

Some fascinating explanations here of how procedures can alter the grid. Thank you all for that.


you asked: So, is this a consistent phenomenon?  Does it happen every time the circumstances are the same?

That’s a great question. Obviously it needs to be measurable and repeatable for it to be “real”. On the measurable side, it comes down to using and trusting one’s ability to discern differences in sound, much like reviewing a component or speaker positional change. I’ve no problem doing that, but I suspect that some other folks find it easier and some more difficult. So there’s no real standard for this type of measurement. As far as repeatability, yes it’s repeatable, but the degree of difference seems to be a variable and I haven’t been able to put my finger on why that is.

Verily, perchance an assay wherein copious amounts of potent spirits be administered at precise intervals might avail.


PPS: I took a quick look at the PS Audio forum and there seems to be some suggestion that its regenerators are still susceptible to certain forms of noise. One user, John H, was a frequent contributor to those discussions.

I wasn’t aware of that line of discussion. So it would be interesting to find out exactly what that “noise” is, as it could be something that’s assumed to be fairly benign, whereas in practice it could be responsible for a very large affect on the reproduction of sound. I will try to find that forum discussion… thanks.


You missed my comment about measuring you ambient noise floor at various times….. that’s ok….most audiophiles lack an SPL meter for level matching and other essential tasks…..

I caught your comment. It’s a valid enough point but I don’t think it’s responsible for the phenomenon that I’m talking about. I use REW for making room measurements and do notice changes in ambient noise levels at different times of day, but they’re very small changes. (Again, we’re in the boondocks and don’t have to deal with neighbors or road traffic noise). 
I can imagine some situations where it’s a significant factor in sound quality.


@knittersspouse okay that’s very interesting information. I hadn’t thought about electricity coming from different sources and each source carrying with it a certain type of “distortion”. That right there could be the answer I’m looking for. Skeptical me thinks that transformers and other components in the distribution network would remove these small line interferences but you seem to be saying not. Assuming you’re right, switches of this type should be noticeable and measurable using a ‘scope on the AC, right?

If you couple the psychological real effect in increasing sensitivity to sound at night with a more silent environment and generally no house heavy appliances working passed some late hours, less electrical disturbance in the neighborhood it does not need a Darpa research to feel a better acoustic experience in part resulting from decrease in the noise floor and more auditory sense relaxation ...😋


When i was doing my critical set of acoustics experiments for more than one year straight each day i waited in the evening late to verify the results and confirmed them or not,...Day listenings was not enough reliable...

By the way we do not remember sound details quality in a conscious way pass a very very short time. But my body remember it and remind it of some improvement or the opposite in the form of feelings when listenings...To experience this we must be totally relax with music we know completely well.. ..if it was not true i would have been unable to tune 100 resonators by ears mechanically . ( it was an acoustic puzzle because location matter)

By the way i never planned to do that, i make it one by one set of three without even knowing that it was a planned experiment at all i only go behind each small improvement and corrections ...More fun than buying  and we learn how to hear...

Then the improvement of acoustics parameters perception in the late evening is real ...



And kind sir, i missed your comment about the boondocks….. ;-) i’m a dual Condo dweller… i envy your solitude.

I probably missed it but is your system on a single 20 A dedicated circuit w a tightened main panel, verified excellent grounds and a new breaker ? fans and various motors on opposite leg of panel… and no inverters ?….after that…i’m out of bullets…. except for helping drain the flagon…

@tomic601 Honestly I'm embarrassed to say it but no, I don't have a dedicated line to the listening room. It's something I've thought about doing frequently but just haven't gotten around to it. Though....I'm skeptical about the potential benefits. I've done it one other time and heard no difference. But that's not to say it wouldn't improve my current situation. 

You never state your source.  If it is at all internet/cable provided, perhaps what is happening is on their end (e.g., a bunch of people log off around that time freeing up bandwidth).

@toddalin source primarily is files played back from a local hard drive which is plugged into a SGC i5 (like a NUC), wired into a switch then the switch wired (Ethernet) to a network player/DAC.
I don’t stream much from the internet, just for sampling new stuff.

Also some vinyl playback, but usually not late at night when I’m half in the bag.


👍 Two direct lines… one for amp and one for the remainder of your components. The failure rate of it not providing a significant improvement in sound quality is extremely small. If it happened to you once, then it is unlikely to happen again somewhere else.

Since you don’t have direct lines… that makes the likelihood of the change in sound quality likely to be in your house. Especially since you said something like the change is like a switch thrown. Some automatic function hidden in some large electronic device in your house?

My system sounds better on late Sunday night… has here near Portland Oregon and years ago in Tucson. But it was never an abrupt change.

"Shuts down at 23:00"

Do you have any automatic lights that turn off at this time? Our driveway lights are on a timer as were our front door lights and even a Grunfos high pressure recirculating pump that delivers instantaneous hot water and 11PM is when things shut off before I go to bed. Timers can be noisy as can the equipment connected to them.

I’m racking my brains but I can’t think of anything that happens automatically in the house at or around midnight. We’re pretty low tech. But this isn’t something I’m observing that’s peculiar to this location, I’ve heard it at other places I’ve lived in the past, and there have been a few. Though perhaps not to the same extent as I’ve heard here, particularly last Friday.

I should add that I’m an older specimen and my being up and around after midnight is pretty rare these days. 


Alcohol or late night delirium if no one else hears it, too.

One person on multiple nights is a repeated measure from a sample size of one. Not particularly conclusive.

OP, I’m not saying the phenomenon you describe isn’t possible; I’m saying it’s a sort of thing that’s extremely easy for people to assume whether real or not.

There is some evidence out there to suggest even very small (real) changes to the noise floor might be enough to trigger a “different/better/worse” perception from some folks. But add alcohol to that and I stay skeptical at most.

Stupid lucky, I'm going to assume....( ... yeah, I heard that....we all have our moments....)🤨

We've a 'live/work' situation in a small commercial ped traffic, just biz goings' on ....any 'day' music is just 'flow control' for mood....

At night, there's more of a reduction in 'exterior' noise, and any is what I make of it.

Outside, a small city asleep....Inside, as loud as I might....(spouse might sleep thru a nuke strike....lucky her...)

Plenty of available amps.....major hospital .5 mi. away, and reasonably 'quiet'....

HS closer, but effects the water more than power....

20ish dB nights......Space suks more, but a comm bldg. with high ceilings (14') has it's benefits....

I’m a bit surprised by the distribution of comments - there’s more pushback against the actual concept of the “midnight effect” than I expected. I thought it was a given that most, if not all people would have experienced this and I expected the conversation to be more about the cause, rather than whether or not it actually exists. That’s interesting. 
I think maybe you babies are mostly tucked up in your crib by 9:30 every night..


@rooze ....'Tis true, I haven't...nor wish to, lest the feds find it and you....

"Moonshine?!  Oh, 'ell no....high quality paint stripper....anyone drinking this would be crazy...." 😏🤞😎

9:30 AM on occasion, but throws me out of synch too much with the normal day2day.....besides, as a former SoCA sort, was much exposed to 'herbal remedies' in my disformative years....

I would not expect pushback either. It has been obvious to me for over thirty years. In addition to the power grid, there is a reduction of traffic. The vibration caused by truck and nearer cars are likely causes. I have a high quality seismometer on my wish list. I will probably not be getting it for 6 months.

Easier to understand:

-Fluctuations in power quality


More complicated/hard to understand:

- Shifting bio rythms of the human body

- Shifting etheric content, etc

When you lay off the booze and keep increasing the intensity of attention you pay towards yourself and things around you, the more complicated things in life can be perceived.


Get off the grid......Run your whole stereo off an inverter....many are doing it.  Check out my website....tweakaudio...for info.  You will have the same sound day and night.  Best to have another filter after the inverter as all inverters are not free from their own noise.......One of my friend loves his Puritan after his 5000 watt Giandel inverter and another friend loves the big PS audio after his inverter.....You want a separate ground rod and filter for your stereo too.   Noise lowering rocks.