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Cancelling out THAT high frequency from old TVs
Old 24th December 2018
Here for the gear
🎧 5 years
Cancelling out THAT high frequency from old TVs

Hi there,

This isn't specifically related to studio building as such but I thought, given your knowledge of sound-absorbing materials, that you might be able to help.

Basically, I have an old CRT-scan TV that I got out of the shed the other day. Turns out that if you plug an s-video cable, from an aux chord socket, into both the audio and video sockets, you can visualise music on the screen (different lines appear, which respond to the audio signal). In addition to this, I've found that I really like the sound quality that it brings to the music. It's much warmer and bassier than than the fairly low-end CD player I have in my room. I guess the appeal is similar to what people like about vinyl. I listened to the end of In Rainbows on there and it sounded great, especially combined with the weird, reactive visuals that it generates from the music. I think it could work really well as a monitor, to test out bass on my songs, and could be quite a cool source for music videos and live visuals.

The only problem is the really horrible high pitched sound the screen makes. I know all TVs did this back in the day but I would still quite like to try and get rid of it if possible as it increases my tinitus and is just generally annoying. I currently have the TV in a little chest of drawers by my bed and I was wondering if, by inserting foam or whatever around the edges, I could cancel out the screen noise while still maintaining the rest of what I like about the sound. The specific frequency I want to cancel out is 15625Hz (according to this video). Would this be possible and do you have any ideas about how I can do so?

Edit: Just realised I posted this in the wrong place.
Old 23rd January 2019
Lives for gear
pencilextremist's Avatar
9 Reviews written
🎧 5 years
it shouldn't be hard to make some kind of helmholtz resonator designed to absrorb at around 16kHz, it won't need to be deep because it's such a high frequency, once you've made it attach it to your head and ears?
Old 23rd January 2019
Gear Addict
I don't think there's too much that can be done about the acoustic noise from the HV oscillator, aside from trying several TVs and picking the quietest.
Old 22nd March 2019
Lives for gear
audiospecific's Avatar
The sound is acoustically getting reproduced by the high voltage flyback transformer. Sorry, even a good transformer can "sing". If you like that audio chip, you might find building it it on a project board be more portable than the whole tv. Just use the same parts and kind of parts. Alternatively, you could find what dc voltage you need, insert it after the audio's rectifier circuit, and lift the diode off the board that comes from its secondary winding of the flyback transformer.
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