what causes the TV monitor at a drive through window to jiggle and bounce around when you look at it when playing heavy bass?
i know it is not really moving... is the bass causing the wavelength of light to be diffused via the jiggling eyeballs?
why dont other types of light behave this way? for example a stoplight...
someone else please tell me youve seen this too...so i wont think im crazy after all these years...
i know it is not really moving... is the bass causing the wavelength of light to be diffused via the jiggling eyeballs?
why dont other types of light behave this way? for example a stoplight...
someone else please tell me youve seen this too...so i wont think im crazy after all these years...
Clipped said:what causes the TV monitor at a drive through window to jiggle and bounce around when you look at it when playing heavy bass?
i know it is not really moving... is the bass causing the wavelength of light to be diffused via the jiggling eyeballs?
why dont other types of light behave this way? for example a stoplight...
someone else please tell me youve seen this too...so i wont think im crazy after all these years...
It's the wires you are using. There is an issue with the temperature of the wire.
The solution is simple...replace the heavy guage wires you are currently using, with a twisted pair of #32 Magnet wire..
The time it takes for the system to stop this effect will depend on how loud you play it.
When the wire reaches 1062 degrees C, you will no longer notice the effect.
Cheers, John
ps..either the monitor is vibrating, or your speakers are broadcasting enough magnetic field to affect a CRT. (not a field issue if the display is plasma or LCD.
no no, when you go through a mcdonalds and you look inside the window and they have that monitor that shows the cars drivng up...not the plastic sign.
maybe i am crazy...c'mon you guys have had to have noticed this before...any crt actually...
the monitor isnt vibrating, because i actually asked a drive through employee one time if the picture on the monitor was shaking... maybe it has something to do with the refresh rate.
but this also happens at intersections with countdown timers, i can see the numbers jiggling around...
maybe this: the light from the crt hits the windshield and gets diffused by the vibrations of the bass? cant remember if this happens without going past the windshield first...
maybe i am crazy...c'mon you guys have had to have noticed this before...any crt actually...
the monitor isnt vibrating, because i actually asked a drive through employee one time if the picture on the monitor was shaking... maybe it has something to do with the refresh rate.
but this also happens at intersections with countdown timers, i can see the numbers jiggling around...
maybe this: the light from the crt hits the windshield and gets diffused by the vibrations of the bass? cant remember if this happens without going past the windshield first...
Maybe your eyeballs are being pressurized from the bass notes and its affecting the lenses haha! Just kidding. Yeah mine does it too, not sure if its emf or vibration but I would sway towards vibration since you really don't know how well the monitor is mounted inside the sign. Also, the body of the vehicle is metal and is going to shield a lot of the emf from the speaker wires and woofer coils. Anyone else know for sure???
ppia600 said:
As I said, the magfield of the woofers can modulate CRT's.
The autobody panels that are NOT plastic or glass, are certainly not designed to confine solenoidal time varying magnetic fields.
Given a 1 to 1.5 tesla flux in the magnetic circuit of most high power speakers, the saturation of the iron causes a lot of the audio-signal-produced magnetic field to leak out of the structure into the surrounding air.
This is a common problem for particle accelerator magnets. Iron is only effective at confining the flux below 2 tesla, afterwards too much energy slips into the surrounding space. MRI's are also bad in that respect, that's why you are not allowed to bring iron into the room, and why girls aren't allowed to wear mascara or eyeliner (eddy current heating).
Cheers, John
ps..perhaps I should have stated that I do indeed know this magnetic goop. Also, I've watched my own speakers modulate CRT's. The old ones weren't as bad, as they were higher voltage due to the old phosphers, so were not as susceptible to external fields...the newest ones have lower voltage, so require less field strength to scan..
richie00boy said:
Interesting thought. I discount it because he stated stoplights were not affected. Perhaps you are onto something..
Have you (the OP)noticed the effect when looking at newer taillight assemblies at night? The LED based ones are pulsed at a duty cycle when the parking lights are on, not when brakes are applied., and would also show the effect if it's strictly as you suggest. (alas, I do not know the pulse rep rate nor duty cycle for the taillights, but I'd think somewhere in the 20 to 60 hz regime.)
If it's visible on LED parking lights, you are correct and I am incorrect. If it's not, it may be that I am correct. (hey, it sometimes happens..)
Interesting..nice observation, though..
Cheers, John
no no no... its not the monitor vibrating or the emf coming from the magnets, its how our eyes receive the perception of that type of light when the bass is shaking us.
anyone who is not sitting in the car, will not perceive the jiggling monitor...because they are not directly coupled to the car, as we are, when we are sitting down.
i guess you would have to experience it to see (literally)what im talking about...
maybe with this type of light , it is extremely focused through a narrow stream (omnidirectional), unlike a lighbulb which is dispersed...
anyone who is not sitting in the car, will not perceive the jiggling monitor...because they are not directly coupled to the car, as we are, when we are sitting down.
i guess you would have to experience it to see (literally)what im talking about...
maybe with this type of light , it is extremely focused through a narrow stream (omnidirectional), unlike a lighbulb which is dispersed...
Clipped said:
Well, you have to say that...I can't guess that outside the car the effect is gone...sheesh...
You hafta give us all the info, dude..Richieboy, you are 100% correct....it's interaction between the vibe of the eyes and the refresh rate..
I stand corrected...(curses, foiled again..)
Happy holidays guys..
Umm, clipped? Turn the darn thing down...sheesh..
Cheers, John
Clipped said:
The coupling is more likely to be the sound coupling to the car occupants' heads and eyes, through the air, rather than through the seat. But try putting your head against the glass of a closed car window, while looking at the monitor. That might provide some significant extra coupling.
I think it is all refresh rates. What really gets me is the mpeg hd on these big flat screen tvs that cost thousands of dollars....when something moves fast across the screen and it flickers across. They call that quality? Kind of like going back to the old B&W films that flicker...or youtube. It can be so distracting to me I don't even want one. Maybe the screen has too fast of a reaction time for the mpeg.
Clipped said:... but the head and eyes are connected to the rest of the body
Well, yes. And the seat is connected to the car. But the important thing, here, is HOW they are connected. In this case, the seat is probably not rigid-enough to transmit vibration very well, to your body. And between the seat and your eyes, your body also has some padding and flexibility, etc, which would further-degrade the mechanical coupling. Bass is a low frequency, in audio terms, but is fairly high-frequency in terms of coupling through a relatively large mass sitting on a cushioned (damped), springy car seat.
I also wonder how much of the bass would actually be moving the seat. I can see that the lighter parts of the seat cushion assembly would be vibrated by the bass. But they seem too light to be able to transmit much into your relatively-heavier body.
And it might seem like the whole car is vibrating from the bass. But it seems likely that the seat mounts themselves are vibrating much less than the lighter parts of the car. And even if the mounts were being directly driven by something like a very large speaker driver or vibrator, the combination of the seat spring and cushioning, and your body's mass and cushioning, would probably severely attenuate almost everything except extremely low frequencies, before it reached your eyes.
I just remembered that back in the early 1980s, at work, I did a study (and a mathematical model) of the F/A-18 aircraft's airframe's structural vibrations' couplings through the pilot's body and into the control yoke. During the literature search, I came across a few papers that covered exactly what we're talking about, done in Great Britain, where they had strapped volunteers to a vibrating seat and measured the effects on their vision. Unfortunately, I don't remember any of the numbers they came up with. About all I remember is that they had to reject all volunteers who had ever had hemmorhoids (Or, "piles", as they called them, across the pond. I remember that part because I wasn't familiar with the term "piles", and had to ask someone, leading to me being somewhat embarrassed.)
So, the answers are out there, already.[Edit:] For comparison, maybe you could try getting out of the car but sticking your head in through the window, without touching the car, and looking at the monitor like that, with the bass cranked up.
[Edit #2:] Well, I forgot to think about including coupling effects from the BACK portion of the seat, when writing the stuff above. It seems more possible that there might be some contribution, from that, than from the lower part of the seat. It might be interesting to find out if you see much change in the effect when you lean forward, so you're not against the seat's back.
richie00boy said:
I agree on this 100%.
it also happens to me but only on the digital display for my parking sensor mounted on the rear view mirror. and that is around moderate volumes.
if that's happening to you when watching the countdown displays on stoplights (they are multiplexed LED's BTW) and monitors, then your listening at too high a volume. better turn it down before you lose your hearing.
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