There is a relatively loud, continuous, high pitch whine that is unacceptable

As many people have stated, there's a high-pitched whine from the unit

I received mine on 5/16/2018 with a quality assurance tag dated 10/2017 and it exhibits the high pitch whine with chirp

As for the high pitched whine that some reviewers complained about - I noticed it

As others have indicated, this unit has a rather atrocious constant high-pitched whine that periodically (once every few seconds or so) ramps up into a louder "chirp"

Despite what the seller says in the questions section the high-pitched whine is NOT fixed

Well built UPS with a nice display, but appears to be making the high-pitched whining noise that others have complained about

My issue is a constant high pitch whine sound

The noise it does make is not the obnoxious squeak many report but rather a barely audible mid pitched whine that is not audible to anyone in the house when more than four feet away

Other companies are certainly improving, but when it's critical I always go with APC.

Not as bad as I first thought

They don' t require much power, like the Bridgeport mill and Republic Turnmaster lathe they serve

These machines also have state of art computer controls that require clean a/c current

My inverter just doesn't have enough power by itself or clean a/c

Other companies are certainly improving, but when it's critical I always go with APC.

Not as bad as I first thought