The squealing PSU fan issue was so bad, I didn't turn the KPA1500 on for many months. When I finally did, the squeal was gone. Since it did not turn up on burn-in, I can only guess that some jostling in shipping did something. After hours of running it has not come back. Better yet, with the piercing high-pitch scream gone, my Bose noise-cancelling phones again give me a quiet shack This is ironic. Amid many complaining about KPA1500 fan noise, my complaints of what turned out to be a defect condition got lost. The same thing happened to me with my KPA500, which made a house-filling buzzing sound. At that time many were complaining about the KPA500 buzz. I finally arranged a call with support, and was told as soon as I powered it up that that is not normal. In that case, support sent me a slightly different transformer bolt, and some different washers--problem solved. In the KPA1500 case, supoort sent me a new led board, and a 50v output resistor as well as new fans. Once I got the psu cover off, I saw that replacing the fans was beyond my current fine motor skills. The hive mind suggested taking sound readings with the Sound Meter app, so for those who care, here are the pre and post led board replacement numbers. I only wish I would have thought of this while that puppy was howling. Old board: quiet shack 3am 2.5 ft above fans 33db. KPA1500 in idle: 47db. Same cdx, new board quiet shack 33db, KPA1500 at idle: 42db. Noticeably quieter. Quieter than one of my AL800Hs. Quieter than Boudicca the cat purring. Now the sun is shining, my faith in Elecraft is restored, and I love the KPA1500 again. I should have known Elecraft would not release an amplifier that sounded like a 737 on throttle up. 73 Eric WD6DBM
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