Using battery power to go off the City's power grid

@carlsbad, no need to spend money on a PS unit to measure THD. There is lot of test equipment that can do this, probably with more accuracy. You need to test it with real load as well, such as an amp with a linear supply. Most other equipment barely requires any power except tube pre-amps and some processors.

@sbayne,

THD is not very revealing of what, if any impact an inverter will have on audio equipment. I am not enamored with pure sine waves because I know what a meaningless goal it is when one considers the equipment connected. I am more interested in high frequency harmonics, and high frequency noise which may cause issues in equipment, noise between line/neutral and ground (if any), etc.

It is not always possible to reduce a complex set of interactions down to a simple number or answer.

No inverter in PS audio units. It appears to generate a voltage just above the input AC that follows the AC then uses a linear amp to make the output.

NO ONE KNOWS ANYTHING. How many brands of power amp are there? They all sound different.....How many brands of inverters are there? They all sound different.

If "only" there was some way to "test" inverters in a consistent, repeatable manner and provide some sort of "scorecard" that indicated how well they performed their function 😎

Most electronic equipment is 100% happy from 108-132 because they are designed to. Mass consumer gear will not even blink.  Only poorly designed, poorly tested audiophile gear has issues. And no, there is no research here, just some listening tests that could have been more about the glass in hand than the sound. The rest was too hard to read.

120V is the standard voltage. 125 is not even really high. That would be pretty common if you are the near end of a line run. Transformer hum is not from high voltage, it is from DC offset and sometimes from wickedly bad THD on the line. Likely there was an issue with the mains transformer and/or balancing on your line between phases causing a DC offset. Consumer electronics company (and motor, etc.) will do extensive reliability testing with low voltage, high voltage, etc. as field failures are very costly and easily prevented. A large DC offset if a much different beast. With transformers and motors there is nothing you can really do.

@ricevs , while I agree with you about Viber, are you not doing exactly the same ?  You have not done this testing on your own but are just repeating what your friend has told you. I think you have tested Goal Zero but not evident you have tested anything else.

No one has A/Bed inverters that I know of except my friend who said the Ecoflow Pro beat the Goal Zero Yeti 3000 and both where trounced big time by the 5000 watt Giandel. That is all I know. We are in new territory here.....this is why I suggested you or someone buy both the large and small Giandel, the Bluetti and have a comparison party. You could A/B cheaper heavy AGM batteries with LifePo4 batteries, as well.

I personally would go for the Giandel because my friend (who has an $80K super revealing tweako system using super modified Apogee speakers) is the one that tested the inverters......he has great ears.....

Why don’t you become the Inverter tester for the world. .........

You can afford it. I bet you have that much on a credit card (maybe $4500 total?). Whatever you do not like, you return for a refund. I would do this.....but I have no credit/money......

@ricevs you seem to be attacking people, but from a position of weakness. Your contribution has been to report what other people hear. I reported what a Tesla Powerwall sounded like, it my house, with my system (seeing as I have one for backup and solar). I also try to help people understand how audio equipment works. In a "field" so laden with misinformation it is easy to get led astray by people who know only slightly more than the person asking or worse know less but think they know more.

And @ricevs , trying to bring some engineering knowledge, and expertise to a topic, as opposed to just guessing and often being wrong is not stirring the pot, unless some people do have an agenda or need for attention and that interferes with it.

I didn't state that all inverters sound the same. I said that the Powerwall with my system has no sound. If you read what I wrote, I have pointed out that inverters are effectively large switch mode power supplies and people are just blindly promoting them without any idea of the noise profile. You, based on your friend, have made a ton of conclusions and promoted the Giandel as "great" when you have no idea of the distortion spectrum, or the noise spectrum and how that will behave with the vast majority of audio electronics out there.  I have pointed out, quite correctly, that pure since wave has no technical advantage in terms of reducing the noise of audio power supplies or improving how they operate. Sine waves are simply what we must live with due to the nature of rotating machinery as our primary power generation methodology. 

You also assume that one must have user reports of a specific inverter to have any meaning. Fortunately, there are engineers that don't have to work under your limitations.

unless you have poor equipment

Your point of view does not help anyone get better sound, it just gets them to spend money, needlessly based on limited data points, limited knowledge of how audio equipment works, and beliefs about what impacts audio that are not supportable.

all inverters do not sound different

I will emphasize a word here to assist in reading comprehension. ALL. That implies that every single inverter will sound different from every other inverter and that is just not true. With most equipment and most inverters (sine wave of decent quality), they will sound the same because power supplies are designed to reject noise/harmonics on the AC line and if they are designed properly, they will.  Some equipment will have poor power supply rejection and will be more susceptible to power line harmonics. That is a poor design.

@ricevs I do not answer to you. I will never answer to you. Please attempt to show some maturity.

So much for expecting maturity.

If you have cancer go for the loving doctor .....

@ricevs , I will just have to accept that you pull this loving "crap" when you are losing an argument.

I am sorry that you cannot interpret measurements and determine how something is likely to sound @ricevs and/or if something will have no additional sound at all. Measurements can help you significantly with one, and completely with that other. That some audiophiles do not believe this does not make it true, it just makes those audiophiles wrong.

w.r.t. inverters, given every single piece of equipment will behave differently when exposed to a different harmonic / noise signature of an AC power source, the best that can be done is generalizations, and one of those is a well designed products will be immune to all but fairly bad AC power. Whether you accept that or not does not change that fact. Additional comments could be made, such as certain distortion characteristics could reduce AC hum on tube amps, or no/low global feedback amps may have issues with certain frequencies of distortion products.  Beyond that, any comments made in careful listening tests, i.e. switching between clean AC, wall, and "inverter" which would have to be made in such a way to reduce listener error, would be applicable only to the specific equipment connected and except in the most egregious cases, which would be readily evident in measurements, would not be at all transportable to other equipment and other connections of equipment.

Still, any piece of electronics has a "sound."  Nobody understands what distortion measurements correlate with a particular sound.

No, any piece of equipment does not have a sound. This is Philelore and is not true.

Ricevs has a longstanding business as a modifier of electronics.  He has determined that different materials in wires have different sounds.  If you don't want to believe his claims, be aware that there are several of his customers I have known personally who vouch for his claims by being pleased with his mods.

And I personally know lots of people who believe stuff that is absolutely not true, but that does not make them or the large amount of people who believe the same thing correct.

Technicians are still in the dark ages of understanding the human hearing mechanism. 

Technicians perhaps,  lots of other people not so much.

Just because you may not find reliable measurements that explain sonic differences, understand that the educated ear is THE best measurement tool of all, in terms of sonic evaluation.

The ear is many things. A good measurement tool it is not. It is a poor measurement tool and a pretty good detection tool. However, it is easily fooled, and hence you must help it along so that it does not make mistakes.  Going to the last statement you make, it is very easy to simulate all sorts of distortion, highly accurately, controllably, repeatably, and then see how people respond to it. Anyone can do it with just a bit of Google research and not a lot of time. It is why I am suspect of so many claims of distortion audibility (as are many people) because it would be easy to demonstrate and validate.

A sincere doctor often can't get his article published because it conflicts with the agenda and business interests of the prestigious journal.

Oh come one. Put together the study, do quality research, repeatable study. You may not get into one of the more prestigious journals but there are so many that are desperate for content anyone can get almost anything published.  A good medical doctor will listen, but they will also try to understand enough about the drug to know whether the claimed side effect is remotely possible because not all side effects will be possible. If they believe blindly that the drug is causing the side effect the patient claims, they could very well miss the real underlying cause of what they are experiencing.

You start off with two false premises, and use that to arrive at a whole litany of false conclusions:

How do you determine the TRUTH of anything? We are talking about whether a piece of equipment, even a single wire has a sound signature. Inductive reasoning starts with observation, in this case listening under controlled conditions. Most audiophiles have repeatedly heard differences in their homes. They wouldn’t spend money and keep their components if they didn’t hear differences.

False assumptions:

- Ad hoc listening in the home is not remotely controlled

- Perceiving you hear a change is not remotely the same thing as there being a change. As a doctor, you should know this. How much you slept, how much caffeine you had, how comfortable you are in that chair, none of which changes the sound, will change your perception of the sound

- They wouldn’t spend money and keep their components if they didn’t hear differences. ---- There are a ton of things that people absolutely "swear by" that are absolutely not true. Heck, some of them violate fundamental laws of physics, not just common sense. Many of these things people continue to believe in and spent money on. As a doctor, you can certainly (I hope) recognize homepathic solutions as an example of this (something diluted to where the original molecule can no longer exist beyond a slight statistic probability).

Continued false assumptions:

- However, the measurement people start from a stubborn bias that measurement tells the story.

No, engineers and scientists start with the result of listening tests done in controlled circumstances using idealized stimulus that will maximize the ability of us humans to hear differences (or not). Out of an abundance of caution, they will normally use these results as a baseline of what is potentially audible, even though tests with real music show the limits of audibility of many of the things discussed as 20, 40, even 60db higher.

MORE

- "A good medical doctor will listen, but they will also try to understand enough about the drug to know whether the claimed side effect is remotely possible because not all side effects will be possible." This shows how little you know about clinical practice.

I specifically stated "a good doctor" and I am well aware of how and why the medical profession often fails at diagnosis. However, this was also a logic trap with two specific traps. You failed to acknowledge that some side effects are impossible, no matter what the patient claims, and by simply accepting them, you are just as bad as those other doctors you don’t like because you are ignoring their could be another as yet undiagnosed reason. That is what is called a bias trap. The other trap is your expectation that I, and we can assume others, accept your expertise with items of a medical nature as superior, while you try to tell me, who obviously has more experience in this area (including listening), that I am wrong based on ad-hoc reports and feelings.

And you finish with the Coup de grâce, this little diddy, far more indicative of your bias and mine. I could state the under pinnings of why you state something like this, but I see no point.

My conclusion is that either your listening skills are poor, OR more likely you have an agenda bias to interfere with your good hearing ability if it actually is intact.

@sns ,

No, not really. It is more an argument between made up and real.

For instance, one of the people arguing believes that they could tell the difference between $1/4 million of audio equipment either hooked up or not hooked up to a very high end inverters when listened to over Youtube at 192kbps AAC, when the issues between the two videos included auto levelling applied to both videos by Youtube, what appears to be an object blocking one speaker in one of the videos resulting in both a level shift and a significant frequency shift in one channel (I assume a person standing in the wrong spot), what appears to be AGC pumping (the noise floor was pumping +/-3 db which will bring low level signals along with it), and that was coupled with a high amount of reverb. 

It does not matter if you are purely subjective, purely objective, or somewhere in the middle. Any reasonable person will understand the ability to accurately pull a super subtle difference between two setups out of low resolution highly flawed videos such as those is not being honest with themselves.