186db SPL world record

[140dbFox]

The world record for vehicle audio SPL is above 180db, how can this be??

My understanding of measuring the SPL of a loud speaker is supply it with an AC current of 1 watt (let's say 2 volts at half an ampere) at 1000Hz and from a distance of one metre, this is typically around the 90db mark and the speaker would be said to have a sensitivity of 90db. To make the speaker twice as loud, as persevered by our human earholes, the speaker must be fed with 10 times the power, therefore 10 watts will give us 100db or 10 bells, doubling the power will only give us 93db.

 

So, if I have an imaginary subwoofer of biblical proportions, let's say its 100 metres in diameter with a 20 meter 256 layer 1 ohm voice coil and has a 100 Tonne neodymium magnet (just like the one in my car!!) We'll have this in some kind of ported enclosure (don't ask!) Tuned to 30Hz and to make the mathematics (math for the Americans) easy, we'll say this behemoth beast is super efficient and produces 100db at 30Hz with 1 watt, (let’s make that 1000 volts at 0.001 amperes.) So far, so good...

 

Now, how do we get to 180db (18 bells.) In theory, 10 watts will give us 110db, 100 watts 120db, 1000 watts 130db and so on. Therefore, to get to 180db the power needs to be increased 10 fold, 8 times. My maths tells me this equates to 100'000'000 watts, or a mere 100 Megawatts. Mmm, let's say I have five thousand 20'000 watt amplifiers (which is possible), that'll do nicely, I'll need about 8 Million amperes at 14.4 volts to power them, that's the problem!!

 

I have gone seriously wrong somewhere, or, is this 180+db some what of a bull's doo doo's Or…. Am I just a complete imbecile, all I do know is my car was measured at 140.5db at the 1991 British car audio championships at Wembley, England. I had three 400w Sony amps and a couple of 300w Kenwood amps powered by two HGV batteries and a 60 Ampere alternator. This powered six 10inch Kenwood subwoofers in an unported enclosure which took up half of my car. This little setup was quite violent, at full thrust it was difficult to breathe and I felt my eyeballs being pulled about so badly as nothing was in focus, it also gave me a sickly feeling as my insides were badly shook up, I couldn’t take this for more than a few minutes. Oh and it also left my ears ringing

 

Modern videos show people sat in their vehicles listening to low bass tones (20 – 40)Hz at 150db, even 160+db, especially my favourite little bass head EXO, most of them show off their system’s raging at full pelt and they just sit there like they were listening to a wireless on a Sunday afternoon. At least EXO looks as if he is dying an agonising death whilst being tormented by car audio systems raging at 160db. That ‘160db’ is four times louder than the system I built in 1991, four times the sound pressure waves pounding the proverbial out of people crazy enough to want it, I can’t imagine just how loud 160db would be… Maybe it’s all about having the doors/windows wide open, I listened to my little setup with everything closed, but I didn’t have the dedicated bass “music” listened to by the American bass heads, I just had regular music with a decent bass line.

 

I’ve finished rambling on, all I wanted was an answer to the power to SPL ratio, 186db, yes, well!!

Ps. I only played around with big car audio systems for 2 or 3 years, 20 years later I developed Tinnitus, a 32Hz tone in one side of my nut would be great, but it’s a lot closer to 1KHz which is a B*

 

[Joe X]

Bear mind that you only need to be loudest at the microphone and not everywhere,  you can achieve sound pressure orders of magnitude above of what power can deliver just by promoting constructive interference avoiding destructive interference and by using resonance,  also by using extremely efficient custom drivers you can gain a lot, standard "Daily" subs are ridiculously inefficient, like 0.1 percent so that 99.9% of the energy (amp power) is lost to heat and only that 0.1 percent or so is converted to acoustic power.

 

Also when you see extraordinary achievements like 185 dB you know that likely physicists using advanced hardware and software tools are involved to optimize the system not some guys putting together stuff just to see what happens.

 

This is just to give you some idea, and not extend the post too much.

[Kyblack76]

And, some more salt in your wounds....  That mic you used in 1991, was most likely off by a db or 3.   Welcome to the new world.