jimi
Club Retro Rides Member
Posts: 2,201 
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Last Edit: Nov 15, 2024 1:00:47 GMT by jimi
Black is not a colour ! .... Its the absence of colour
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jimi
Club Retro Rides Member
Posts: 2,201
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Nov 16, 2024 15:40:47 GMT
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The lowest frequency you can hear is about 20Hz. The highest is about 20,000Hz. For decent hifi we want the response to be flat between those end points. So for a particular power across the frequency range we want the same volume out of our speakers. There is a lot wrong with those statements. For a start, at the low end there comes a point where it’s too low to hear it but you can still be aware of it. You start to feel it. If you’ve never done it go to a cathedral and listen to somebody playing a big pipe organ. The sound is unbelievable. The biggest pipes can get down to a few Hz. If my assumptions of my audience demographic are correct, none of you can hear 20kHz. About the only people who can are youngsters and they probably aren’t reading this ‘cos they are mucking about on X or something. Your hearing’s high frequency sensitivity drops off as you get older. Even when you could hear to 20kHz most of you would have had a notch at 15625Hz. That was the line frequency of an old tube TV. I’m not sure if we actually went deaf at that frequency or if our brains just filtered it out. Young people that have only watched flat screen TV’s don’t have that 15625 notch and they go nuts if they walk into a room with a tube TV in it. They can hear a loud whistle but they can’t work out where its coming from. It’s really funny. (He says speaking as an old person.) James, this reminded me of an early experience with Colour TV's  When I was in my late teens, around 1969/70 when colour TV's were first introduced in the UK (or at least in Scotland) one of my friends parents got one, I'd never seen one (my parents were still on B&W) so I got invited in to watch TOTP  I only lasted a few minutes as the high pitched whine did my head in, seemingly I was the only one in the room to hear it. It wasn't just their TV, for quite a while I heard the same from various TV's all colour, never heard anything from B&W TV's. By the time my parents got colour I no longer heard it. I seem to remember being told it was related to the HV on older colour CRT's, but that may have been B.S. |
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Black is not a colour ! .... Its the absence of colour
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Nov 16, 2024 22:57:11 GMT
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I seem to remember being told it was related to the HV on older colour CRT's, but that may have been B.S. The whistle came from the scan coils on the back of the tube, these things...  Or the transformer that drove them. To be honest I avoided tube TV's like the plague because they could bite you badly. And they were hard to fix. From what I remember the EHT multiplier was driven off the scan transformer. Maybe??? Now I don't believe that the EHT or scan system would have had to change much between B&W and colour. But if they did increase the EHT then I could imagine it might have made them whistle more. What would have increased the load on the scan system is if the shiny new colour TVs had a bigger screen... Your B&W TV wasn't 405 line was it? And I'm not taking the pi$$. I remember them turning off the 405 line transmitters in the early 80s so those sets were kicking around for decades. Oh the other thing that could have changed is that the B&W TVs were likely to be valve sets and the colour ones likely to be transistor. Again I don't know why that would make a difference but it's not impossible. James |
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I only lasted a few minutes as the high pitched whine did my head in, seemingly I was the only one in the room to hear it.