Dave Smith restarted making Prophet 5 synthesizers a few ago, and the initial batch of users complained that the high frequencies weren’t like the original but

Dave Smith restarted making Prophet 5 synthesizers a few ago, and the initial batch of users complained that the high frequencies weren’t like the original but when he tested them he couldn’t see any issue… Turns out he was testing by ear, and he was a few decades older since stopping the last production run, and his hearing had rolled off on the high end! Remake users were instructed on how to fix it and newer batches had the fixes built in - maybe by using a younger ear :)