Hey, that sounds almost like what I'm going to do once I get a ride... I was thinking more along the lines of 4 tumults in about 6-8cubic feet apeice tuned to 10hz. Of course I'll put another port in the box tuned to 30hz or higher with a removable panel for when I really want to compete, but I'd really like a car where I can have someone sit in there and I can play that Brown note and make them **** themselves. Of course, once they say oh ****, they're getting kicked out of the car.
the astro wall was 9 adire bhrama extremes. He broke his door with those by the way, but a nice biiiigg crack in the door frame.
xstephanx said:
The Video on Adireaudio.com with the 9 brahmas is an SPL vehicle. Its Scottie Johnsons astro and he hits into the 170dB range around 42Hz i beleive. Since he is an SPL vehicle the ports are tuned near the resonant frequincy of the vehicle and there for the brahma's would not be able to extend down to 15Hz with out causing massive port noise and distortion. ill see if i can find the guy i am talking about on the net.
as for the idea of being able to hit 135dB@15Hz in your car that you drive.... prepare to spend a HECKaLOTTA money...
I've never seen one of these SPL compos. How do they set it up so that something like that doesn't deafen everyone in a 300 foot radius.
I just don't get the idea of having SPL competitions. That's like having a contest for who can look directly at the sun the longest except using your ears instead of eyes.
Oh wait...I get it now, you don't have to buy thousands of dollars worth of XYZ manufacturers equipment to look at the sun....
Oh wait...I get it now, you don't have to buy thousands of dollars worth of XYZ manufacturers equipment to look at the sun....
What do you consider a heck of alot of money cbfry? A single adire tumult can do ~112db @ 15hz in a 15hz tuned enclosure of 6cubic feet anechoically. Thats WinISD's simulation. It also says cone excursion will be around 11.5mm one way @ 15hz with 1600watts. So just assuming that 112db is near correct and an approximate cabin gain of 12db/octave below 80hz a single tumult would be over 24db of boost and an easy 136db. Not every car is the same, but I doubt that it would take much more than a tumult to hit 15hz at 136db in car. That adescent avalanche could most likely do it also at even smaller cost!
you're not supposed to be in your car without ear protection below 140db. Above 140db you're not supposed to be in there period. The idea isnt to deafen yourself, it's to have the most powerful system. Obviously you're not familiar with the American way. The most powerful is always the best, it doesnt matter if its cars, rockets, air planes, or even subwoofers.
I doubt that the better cars are actually even a deafening level outside the vehicle during a cometetion. The idea is to keep all the sound inside the car and any flexing the panels do is lost sound pressure.
I doubt that the better cars are actually even a deafening level outside the vehicle during a cometetion. The idea is to keep all the sound inside the car and any flexing the panels do is lost sound pressure.
I see now. I didn't get that SPL was measured inside the car. Does it have to be a production car, or can you enter a giant hamster ball with speakers inside in the competition?
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FYI in order to gain 3dB you must double displacement. soinorder to go from 115dB to 136dB you would need 14 times the excursion which means 14 times the power...can the coils/suspension handle it? Probably not.
CBFry,
I'm guessing you were saying that in response to my earlier comment about tumult being able to do 136db in car. I understand that in an anechoic chamber you need double the excursion for a 3db increase. From 115db to 136db there is a 21db difference which translates into over 100times the power, not a mere 14. Every 10dB represents a tenfold in power (although the percieved loudness only doubles) so 21db would be over 100x. Hitting 136db @ 15hz anechoic would be a real feat, but inside a car it just isnt quite as difficult due to the cabin gain.
I'm guessing you were saying that in response to my earlier comment about tumult being able to do 136db in car. I understand that in an anechoic chamber you need double the excursion for a 3db increase. From 115db to 136db there is a 21db difference which translates into over 100times the power, not a mere 14. Every 10dB represents a tenfold in power (although the percieved loudness only doubles) so 21db would be over 100x. Hitting 136db @ 15hz anechoic would be a real feat, but inside a car it just isnt quite as difficult due to the cabin gain.
I didnt know you needed 10 fold power to gain 10dB. but i do know 3dB=double power or surface area which inturn doubles displacement. Cabin gain drops off tramendously once you get around an octave below the resonant frequincy. say the air space left in the vehicles resonant frequincy was 46Hz. around 23Hz cabin gain is slim to none. This is because soundwaves are produced simply by pressure peaks and troughs, not because of a complete wafe form due to the lack of space to make a complete even a small partial wave form. I know sound waves are compression waves but a wave is loudest when it can complete is self one time just before it hits a barier and is reflected back. if the wave continues the waves traveling in opposite directions (if in phase with one another which they should be in this case) will cause positive interference (gaining amplitude and there for getting louder. when there is a lack of airspace sound is created simply from pressure changes by the moving cone.
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