MythBusters Episode 58: Shattering Subwoofer
Air Date: August 16, 2006
One can design an automobile sound system such that the bass can quickly shatter all the windows of the automobile.
busted
While the obnoxiously large, diesel engine-powered subwoofer that Jamie and Adam built pumped out a whopping 161 dBSPL at 16 Hz (a level comparable to those found in cars specially designed for loudness competitions), it caused the sunroof of the car to jar loose, allowing for the pressure of the sound waves to escape. Because of this leakage, not to mention the fact that the forces behind the oscillation caused the woofer to break apart, the speaker system could not possibly create the amount of intensity needed to cause all the windows to explode as the myth stated. A best-case scenario would involve only one window failing, thus creating a path for the pressure to escape.
You will get a smoother ride on a rough outback road by driving faster.
confirmed
As far as driving on non-"washboard" roads there was no solid conclusion due to a conflict of data. However, when they tested a "washboard" road, like one the myth originally states, the build team were able to confirm the theory that driving at a higher speed will indeed cause the wheels of a car to travel over just the ridges and not into the troughs, allowing for a relatively smoother ride.
“You will get a smoother ride on a rough outback road by driving faster.”
Same holds true when sailing over speedbumps. Ask any cab driver in Vegas that goes bombing through a valet/cab turnout at the casinos, and they’ll tell you the same thing.
June 23, 2007 at 4:31 PMHahaha, I remember my brother decided to ‘glide’ over a speed ramp, which is like an elongated speed hump. Very smooth at slow speeds, namely 25 kph. He hit it at 120kph, and lost the sump, and we nearly broke our necks on the ceiling. Yes, we had our belts on.
Still, on the dirt roads, I have also found this to be generally true, the faster I go, the smoother the ride, or so it seems.
June 26, 2007 at 10:43 AMI agree, here in Sri Lanka the roads are rough and at about 50km/h your ride gets better than at 25km/h
October 31, 2007 at 3:22 PMSpeakers, windows? I’m not exactly sure what was done wrong but with enough pressure, a window WILL break, shatter twice in my case. Perhaps because of the thinner window on the rear hatch versus the position of the quad 15″ DVC seperated box. Bass works by vibrations. So, though the air pressure wouldn’t change inside the car, the vibrations on the glass CAN cause it to shatter and make you shell out $130 for a new rear shield.
November 15, 2007 at 11:13 AMGeeeeze Come on Mythbuster Guys! Why Do you think That The Hardcore Winners of the SPL Competition have Re-inforce Body, Thicker Windows And Even With Cement Base (Yes, Its True), To get the most pressure? The idea of his speaker was a big joke. Take a Small Hatchback civic and a couple of square kicker and you’ll have yourself a good reciepe for destruction hahaha. I don’t understand why they made a bid deal out of this, because I’ve seen this happend so many time busted window, loose fender lol).
December 10, 2007 at 3:51 AMAfter seeing what joke you pulled with making your own sub i think you should really show the people what a powerful sound system can do. I mean it is kind of a dis respect to guys that have thousands of dollars in the stereo it would only serve it justice i mean i love the show but really get with someone who knows what they are doing and you will see destruction. PLEASE REVISIT THIS MYTH IT IS NOT BUSTED!!!!!
December 15, 2007 at 5:56 PMAlain and Robert,
Please read the myth before commenting. Apparently you have some desire to appear cool and defend the car audio guys of the world, but the myth states “One can design an automobile sound system such that the bass can QUICKLY SHATTER ALL THE WINDOWS OF THE AUTOMOBILE.”
You are citing instances of one window breaking, not all of them quickly shattering. That would take one bass note at an SPL that might not be attainable in a car audio system. I’ve seen many competition vehicles and have never seen one that could quickly shatter every window in the vehicle. Maybe there is one, but it is highly improbable.
December 20, 2007 at 4:14 AMI agree with Mike. While damage to your car is possible, a good friend of mine actually creased his trunk lid with his system, the scene in the movie that they were trying to replicate would not be possible with any sound system. The fact is that once any gap is created the car will lose pressure and no more damage will occur. The first thing to go will be a seal or maybe a weak window, but not all at once.
February 5, 2008 at 6:49 AMI think that the mythbusters were looking at the wrong aspect of the sound waves, I did only catch the last half of the episode but as far as i can tell they were only concidering the pressure. I think that it would have more to do with a med sound wave, not through the air but through the surfaces conecting the speaker to the glass. It would be something kind of like the experiment with the earthquake machine. A small to medium, constant, wave will eventually move the glass enough past its elastic potential for it to break. Maybe not all at once because it would depend on how far from the source the glass is.
February 10, 2008 at 12:15 AMAnyways thats my two cents.
Andrew
Please Redo the sub myth. my friend blew out the rear windo on his integra first day having it with 2 MTX 12″ subs and a Rockford amp….it can happen that speaker your built was crap. put 2 jackhammer in that car and it will blow out all the glass.
March 15, 2008 at 5:03 PMok guys your subwoofer hit 161 decibel’s right? well digital designs makes a subwoofer that hit a record breaking 181.5 decibels from just one sub! that will shatter a window! it was constructed in a volvo station wagon, and the trunk was concrete filled! this is true! so take 2 of these subs and “burp” them at about 20,000 watts a piece and i garuntee you that something will break! please redo this myth!
April 17, 2008 at 10:01 AMIf there is in fact a myth that a stereo can destroy all the windows in a car at all. I think the Mythbusters are taking liberties with some myths lately. They seem to be fabricating some of these themselves. The stereo myth is bogus anyway, because its not air pressure that anyone is concerned with. Its sound waves that break a window in a car, not a diesel powered air baffle with a mixing bowl in the center. An actual car stereo producing enough vibration will easily break the windows in a car. Maybe not all at once, but who’s myth is that anyway?
May 8, 2008 at 1:04 PMthis is one i would also like 2 see redone.i think it would of done ALOT better if there was a cylinder wall like in an engine 4 surport.(to keep it moving strait up and down)i did like the diffrent aproch just wanna c what would happen going through the gears.theres always more to the storie.
August 20, 2008 at 2:18 PMThe conflict of data seen between the shocks and accelerometer on the rough-road myth surely just proves the shocks are doing their job. They are moving, yes – that’s a part of what gives you a smooth ride in the end. The glasses are the only real contradiction, but I guess at higher speeds the inertia is greater getting up to/down from speed.
March 22, 2009 at 5:55 AMyou guys chouls use a compathion styal suba and amps ans see what you get then you will have a diffrent resalt other that one you made your self
May 9, 2009 at 4:16 PMI think a redo on the “One can design an automobile sound system such that the bass can quickly shatter all the windows of the automobile.” should be done. Jamie and Adam should use multiple competition subs because I believe it can be done.
May 12, 2009 at 9:46 AMWhile a redo might yield different results, I doubt that it would “un-bust” the myth. Those claiming that the pressure level is not to blame and it’s the sound waves (ie: the frequency) should recheck their info. To shatter a glass object would require several seconds of high frequency sound perfectly matched to its natural resonant frequency. Couple the two facts that a cheap $6 glass cup has a resonant frequency of about 800hz (most subs don’t play above 200hz) and the fact that each window in the car would likely have different resonant frequencies do to being differing thicknesses and sizes, and you’d see that it’s not likely to work, even if it were the “sound waves” that were breaking the window.
May 26, 2009 at 8:53 PMI think the speaker myth should be revisited. They should go to a bass competition and get an expert to design an actual sound system. What was that thing they had in the middle of the car anyway? Who listens to one of those? How can you “bust” a myth that states, “One can design an automobile sound system such that the bass can quickly shatter all the windows of the automobile” when you don’t even try to use a sound system? They could possibly place at least one of the most powerful subs behind each window to vibrate the glass and see what happens.
July 8, 2009 at 5:40 PMCan you retry this myth with the MTX Jackhammer subwoofer…it is so powerfull that can will broke the windows of the car…
August 24, 2009 at 6:45 PMevery day I drive over a washboard road here in nebraska, I remember show about driving on all that angle iron, you couldn’t find a washboard road??? I’ve had a few scares of flipping over sideways, or loseing control in my pick-up, when I drove to fast. Granted faster maybe smoother, as long as your still upwright. Washboard roads are never even like your angle iron road.
September 6, 2009 at 11:42 AMI remember this episode 58 about bass shattering all the windows in a car. The Mythbusters are correct. Low frequency bass cannot shatter all of the windows in a car, not even Ultra Low can. Sure, you can pop a seal, loosen up a fender, shake down a poorly secured rear view mirror, cause a minor nose bleed in some people, pop open a sun roof, cause a girls hair to fly around, and cause hearing damage, but it can’t shatter all of the windows. Why? Wrong resonance. Doesn’t anybody remember the goblet shattering experiment in high school?… You need a much higher tone (~800Hz+) at around 140db with a constant sweeping pitch to shatter glass. And the best part is you only need a 150 watt system to do it with a commercial loudspeaker horn sitting close to the glass. The thicker the glass, the more power you need to do it.
Car glass is pretty thick and reinforced to take the vibrations. It’s usually the window seals that fail first in a car, not the glass itself. Bad seals + ultra low bass = broken glass, but Only tuned resonant upper freqs can shatter glass directly. Using a sine wave generator would be the best way to do it.
See, those bass stereo heads have been going about it all the wrong way. If they want to shatter neighborhood glass ALL the time, then they should be looking for a 2500 watt midrange horn… ha ha ha.
February 1, 2010 at 8:16 AMlavender was correct to point out that the suspension test results were misinterpreted. To demonstrate the suspension gauge, Tory pushed down on the car to show how the needle reflected the movement of the car in relation to the body. The suspension is designed to force the wheels down to meet the road when the body of the car is coasting on a level plain. Large variances in the needle only mean that the suspension is working, it doesn’t explain why it’s working. As for the water test, it was shown that Grant had lost control of the vehicle at the faster speed and had water all over his pants. That’d clear be from side-to-side motion, not the up-and-down bumpy motion described in the myth.
February 7, 2010 at 2:06 PM