Can Tom (or anyone else) explain this? <br>Even at nearly 60 I still have hearing that is sensitive in the higher frequencies (my nightmare is those ultrasonic devices to keep cats out of gardens - they keep me out too).<br><br>When I was a young'un, back in CRT days, I could always hear the 17KHz hum, which I found tiring but just about acceptable. The exception was the Sony Trinotron range, which was so loud it made me feel physically ill. Recently I walked into someone's house and knew immediately they had an old Trinotron still in use. <br><br>Why should that particular model have been so loud? Owners, back in the day, were very proud of them - apparently they had the sharpest video (or best something or other!). Maybe whatever was so great about them was also what caused the problem.