thxknight Posted February 9, 2001 Share Posted February 9, 2001 I've heard car stereo guys bragging about their systems, and seen advertisements on ebay and such that claim figures for their systems between 140-150dB of output. How in the world do they get these absurd numbers? With my understanding of SPL those numbers go way past the threshold of pain and are flirting with perforation of the ear drums. Any thoughts? Quote Link to comment Share on other sites More sharing options...
oosting Posted February 9, 2001 Share Posted February 9, 2001 Basically, dB is a given by the equation: dB = 10*log(power ratio) + base dB base dB is the speaker effeciency (104 dB at one watt at one meter for LaScalas). If we are generous and assume your friend's speaker effeciency is 100 dB, this would mean they would need a total power input of 100000 watts to get 150 dB output. Of course if you are inside a small car, you would need less power to attain 150 dB. Ed Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted February 9, 2001 Share Posted February 9, 2001 They're not kidding, exagurating or lying. Check out this link: http://www.iasca.com/ At these competitions, the participants stand OUTSIDE their cars (some distance away... ) and trigger the systems through remote controls. On the link I included, you'll see a dB rating of (**GASP**) 174.2dB. Only the fact that you're talking a small, fully enclosed volume inside the car allows attaining that kind of sound pressure level. Just to give you an idea, that's how loud a Klipschorn would at one meter if you put in 10,471,285 watts There've been a few reports from these shows in Stereophile, The Absolute Sound, Sound and Vision and other magazines. Check if out if you still don't believe it. Wonder what would happen if you had that guy's car, had the volume turned way up, and accidentally turned it on while driving down the road? Ray Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted February 9, 2001 Share Posted February 9, 2001 ...and if you're curious about what a car looks like that is capable of SPL in excess of "the threshold of pain", take a gander at this... Ray Quote Link to comment Share on other sites More sharing options...
thxknight Posted February 9, 2001 Author Share Posted February 9, 2001 thanks for the info guys, it still boggles my mind, but I guess I can buy it. The point of the whole thing kind of eludes me, my RB-5s soon to be mated to an M&K sub is plenty of volume for me. Quote Link to comment Share on other sites More sharing options...
BLOOMIS914 Posted February 9, 2001 Share Posted February 9, 2001 Believe it, next time your car audio shop is having a Db Drag race check it out, if for nothing else to see, hear and feel some serious bass and overall sonic bliss systems. Last time I was at one I watched a guy put about 10 quarters on the roof of his beater and then rolled up the windows and remote triggered his system with a bass demo disc......the quarters popped like popcorn at least an inch or two in the air and then he topped that when the back window spider webbed. Absurd, maybe.... entertaining, definitely. Quote Link to comment Share on other sites More sharing options...
Fat Bob Posted February 12, 2001 Share Posted February 12, 2001 quote: How in the world do they get these absurd numbers? Just up my alley. I used to be heavily involved in the Sound Quality (SQ) side of car stereo. I still have a lot of friends in the sport/hobby. There is a lot of work that goes into a DB Dragster. Think of them as the top fuel of car stereo. Have you ever actually needed to travel a quarter mile in under 4 seconds? The top DB Dragsters usually push in excess of 50,000 Watts. They use arrays of phase aligned 10" to 18" woofers. The vehicles are not very driveable, they go from the trailer to the "lane" to the trailer. Most of the vehicles have been seriously sound deadened, and any opening that is not necessary has been welded shut. The windows and windshileds replaced with thick plexiglas and reinforced with steel. The walls the the woofers are monted on are often made of metal. The power supplies are massive, dozens of batteries, capacitors, multiple alternators. These are speciality machiens. Check out: http://www.kicker.com/kcsc/mainx.show_page?p_filename=GatesdBDrag1.htm The real trick is that you can get a fairly exact volume measurement for the inside of the vehicle. You can easily calculate the resonant frequency for this volume. Then you can find a driver that resonantes near this point. Next, you find the point in the recording that you want to use that has the most energy at this frequency. Now you put that on an A/B auto repeat loop. Voila, a big burst of sound. Most of these vehicles play for two seconds or less in competition. So what't it all for? Reaserach and development. Just like real time drag racing provides information on auto parts in high stress conditions, DB Drag provides information back to the manufacturers about how their components work at the highest levels of stress. The guys at Kicker RMA can disect a woofer or Amplifer that is returned and tell you what caused it to blow up. Then work on improving constants in the next generation of the product. And it is a lot of fun to watch these cars go at each other, stuff is always smoking or melting or blowing up. Everybody has to have a hobby. And this one beats drugs. -Fat Bob Quote Link to comment Share on other sites More sharing options...
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