posted
These were posted to a friend on a pro audio forum.
Please discuss.
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The decibel is a relative measurement that must be referenced to some
measure, and may be qualified by a weighting in order for it to mean
anything. It doesn't matter what the internal rules and regs are if
they don't provide that information, which they don't as far as I can
tell. They can tweak the rules all they want, but if they don't tell
us how they calibrate, there is no way for anyone (except the keepers
of the magic sensor and measurement tool) to know if one is louder
than another. They are comparing apples to hamsters
If they take it seriously, they may want to revisit their measurement
criterion and put it in terms that make the use of the decibel
meaningful. It doesn't have the be the same criterion as the rest of
the sound world, but it needs to have some reference point and
standard calibration method to be taken seriously at all. And if
they want any credibility with the rest of the professional audio
community, they can adopt standards and methods that are in fact
comparable to other applications. The numbers will likely be lower,
but then you can then compare apples to apples.
The biggest problem is that many will unknowingly accept the 170 dB+
claim, and move on to other audio endeavors armed with a completely
inaccurate view of what specifications mean. This is the mythology
being challenged in this thread, I believe.
I'm sure these dB Drag folks are having fun. I'm sure the numbers mean something and as long as everyone uses the same measurement method, a comparison is valid. So please don't take the following to mean I'm disparaging what these folks do. A hobby is a hobby, even if _I_ think that dB Drag, or fishing, or ham radio is a waste of time. *smile*
So, because I'm bored, I ran some numbers.
112 dB SPL 1 W, 1 m is a speaker with 100% efficiency. Impossible, I know.
To achieve 174 dB at 1 meter with that perfect speaker would require 2,691,534 watts. Yes, 2.69 million watts.
A 100% efficient amplifier, running rail-to-rail at 13.8 V would require 1.95 million amperes.
At 8 ohms, the signal would be 4600 volts and draw 580 ampers
Watt is a measurement of power and so is horsepower.
So, 2.69 MW = 3608 hp
"I checked the "certified definitions" and by laws you posted, and their definition of "dB" loudness is simply dB-SPL, with no reference (for example pascals, micronewtons or SOMETHING!) and no mention of peak, hold, RMS etc etc."
I checked the "certified definitions" and by laws you posted, and their definition of "dB" loudness is simply dB-SPL, with no reference (for example pascals, micronewtons or SOMETHING!) and no mention of peak, hold, RMS etc etc. Just because they are advertising some sort of high number in their test and "certifications" doesnt mean you should be a believer. It shouldn't be considered as accurate on a list serve that is trying to educate in my opinion. You can get to "176" (dB-SPL) physically but not with a car stereo organization that doesnt care about litigation and medical costs and doesnt require a hint of any calibration in their bylaws.
I spent three years doing calibration for a certifed ANSI test lab doing threshold and maximum SPL tests each day for E-A-R Corp. The steel room was rigidly and daily calbrated to $50,000 Bruel and Kjaer instruments (top of the line) with temp and humidity measured daily as well. We only used 1 inch B-K mic capsule daily and ANSI S1.21 semi reverberant standards for 113 m3 room. The most we could produce from a Crown amplifier (similar in size to the certs you posted), bridged/strapped into a 15 woofer with pure tones continuously was 134 dB-SPL, and that was not even free field but with the room factor added in too. We wore muffs AND earplugs and could still hear loud noise with both on. Legends and myths abound in sound, and especially the car stereo disaster world. So, just because one believes something never makes it true.
Actually Jonathon, you would not have survived with your life intact, - if you heard "170 dB+", (I assume you mean 170 dB-SPL). The loudest sound survival I have seen recorded was a poor soul in a test lab exposed inadvertently to a short burst into the mid 160's dB-SPL range. That man lost his eardrums instantly and was found unconscious. I believe one of the loudest sounds that can be produced is the Saturn rocket blast around 184 dB-SPL (a close range measurement)- so obviously a car subwoofer is not even remotely close tor "170+" by any stretch or metric. > > Most gun blasts measure around 120-140 ish, and the loudest concert with a line a rray of subs I have ever recorded was in the 120's on the floor- and I left within 5 minutes asking for a refund. I have never heard a car very close to that. Of course it all depends on distance, measurement duration etc. and how you measure pressures. But no one can hear 170 dBA-SPL and get away with it -
irst dB in the 12volt world is measured in milli-seconds and is really disingenuous and uses less than accepted scientific methods. Power and dB ratings should be "continuous at some specified standard" otherwise they have little to no relevance except to them.
posted
ol boy got his math messed up, typical case of being too smart for his own good.
Posts: 1718 | From: Dickson,TN,USA | Registered: Apr 2000
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posted
Apparently this guy is not accounting for gains from enclosure design, and vehicle design, or the ability to "concentrate" the sound to one location in the vehicle.
Someone needs to invite this guy to world finals, and have him bring along his test equipment.
He may have some valid points, but I don't think he understands this sport, and how serious it is.
-------------------- Alejandro "Alex" Avila Sound Decision SPL Team - team captain http://www.sounddecisioninc.com Posts: 1464 | From: Montgomery, IL U.S.A | Registered: Jul 2000
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posted
If the measurment system we use was not calibrated in some fashion, then we would not see very consistent scores from a competitor that travels across the country and puts up the same number (or very close) at two different locations on two different Termlabs.
The Termlab is designed to track the B&K.
Basically this fool is saying the numbers we put up are way lower than we think... Mabye he should sit in Scott Owens truck for a test.
[ 07-26-2007, 07:39 AM: Message edited by: David McLean ]
-------------------- David "Quadzilla" McLean Posts: 3367 | From: Jacksonville, FL USA | Registered: Sep 1999
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posted
we need a link to this forum to talk to this person
-------------------- Do you know why no woman will ever be truly satisfied? Because no man will ever have a chocolate penis that ejaculates money..... Posts: 792 | From: Green Bay WI | Registered: Sep 2006
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posted
i bet it was IBANENDER he thinks he knows it all he was banned on a few forum because of misbeleving people on differnt ideas he had that where made up in his own head
-------------------- TEAM420 TEAM KINETIK TEAM MAXXSONICS T3AUDIO TEAM DCAUDIO SS 1-2 3rd PLACE 2007 INDY "REGIONALS" SS 1-2 1ST PLACE INDY AND 2008 NATIONAL CHAMPION.
posted
Once again, the engineers and such think they are SO much smarter than us! Just like if asked one of them to build something that they think would be loud, they would try to concentrate as much of the waves to the mic location as possible, which means they would seal off the subs in a gigantic wall, with cones forward! I think that is a good idea, invite this dude to finals, let him see what is really going on!!
-------------------- Only the most hated name on TPOT! Come get ya some!
AIM: KyleI13 Posts: 327 | From: Oklahoma City, Oklahoma | Registered: Aug 2006
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quote:Originally posted by Alemuthafukinjandro: Apparently this guy is not accounting for gains from enclosure design, and vehicle design, or the ability to "concentrate" the sound to one location in the vehicle.
Someone needs to invite this guy to world finals, and have him bring along his test equipment.
He may have some valid points, but I don't think he understands this sport, and how serious it is.
Bingo! x 2
-------------------- In Loving Memory, David Alfaro
2009 US.Top Cert.St C 158.7 2008 US.Top Cert.St C 158.4 2008 25-48NW NSPL World Champion 2007 U.S.Top Cert. Street A,B,C 2005 Db Drag St A World Champion 2004 Db Drag US.record 642 points 2003 Db Drag Points World Champion http://www.maxxsonics.com/
Back in 02 my girlfriend said I had to make a choice between her and DB Drag....I told that b-tch I've made harder decisions at the Coke machine. Posts: 4978 | From: Suitland,MD USA | Registered: Sep 2001
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posted
lol the loudest concert ever was 120 dbs huh? Little story. before lil john became big, like right when bia bia came out. I went to a club in athens GA where he had a show going on. I had no clue who he was at the time but he had the place rocking. Music was so loud it hurt my ears and had drinks vibrating off tables all over the place. His setup pulled so much juice that it actually tripped the breakers in the club. Im going to guess that he was well over 120 dbs in there.
-------------------- BEWARE OF SHADY SELLERS!!!!! Tom Orozco KB Audio Your name can be here too! Posts: 5560 | From: Newburgh, NY | Registered: Oct 2001
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posted
Sounds like this guy has his face buried in a book rather than actually experiencing a dB drag racing event.
These people tend to piss me off because they think they know better than the rest of us becaue they have some engineering degree and know a bunch of physics theories.
I'd love to see them build an SPL vehicle then proceed to get their asses handed to them by "less intelligent" people.
-------------------- Competition setup: DD 9510F, kicker zx2500, ~ 2 cubes, 151.2 on the TL(outlaw, 43 hz), 145.0 legal.
"10 inches of terror"
Team Phat HertZ Team Kicker
2008 Bassrace 130-139.9 Regional and National Champion
Posts: 2213 | From: chicago heights, IL | Registered: Oct 2004
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posted
5001-up Scott Owens Phoenix, AZ 180.5 10/2005
That is Scott Owens retired USACi legal world record that was recorded with the B&K meter. Someone be sure to let him know.
-------------------- TEAM BUDWEISER 2005 MECA AS3 World Champion 2006 Street C World Finals 3rd Place Team Budweiser 2006 SS 1-2 World Champions 2006 USUCKi Street Beat 3 World Champion 157.1 Posts: 682 | From: Springfield, MO | Registered: Apr 2005
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posted
His calculation of 2.6 MW to reach 174 dB is completely invalid since, as someone mentioned, it does not take into consideration the transfer function of the box/vehicle which results in huge gains. Speaker efficiency is measured in an open test environment and I do believe that it would take that amount of power to reach 174 dB outside of a vehicle and a box. He is right that 112 dB is 100% efficient in a 1W/1m measurement, but his application of this number is just ignorant or everything we do in car audio.
Obviously the termlab is not calibrated exactly to DBA scales, but it certainly is not 30 dB out like this guy says. I wonder if he is a aware that the B&K has been used in the SPL world as well and has had similar results. By his calculations they would have needed over 200 kW to produce the 160+ dB level he mentioned.
If he has admitted that someone has produced 160+ dB levels in a test lab, why does he seem to believe that tuned and tested SPL vehicles cannot approach these values?
His statement that "dB in the 12volt world is measured in milli-seconds" doesn't even make any sense. Since SPL does not continue indefinately, it has to be a sample and the termlab takes 1-3 seconds to take its sample. You cannot sample a 50 hz tone in milliseconds since it is less than 1/10 of a cycle anyways. The non-logarthmic units of the dB scale are W/m^2, and the reference is that 10^-12 W/m^2 is 0 dB (so 120 dB is technically 1W/m^2 of sound energy at the mic position) and I believe that termlab is fairly close to this reference.
In short, this guy can crunch numbers and make assumptions, but in reality he has no clue what he is talking about.
Posts: 225 | From: Calgary, AB | Registered: Sep 2003
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posted
well, I agree with some of the things he had to say about vehicles really hitting 170. Db on the meter doesn't really equate well to real life Db. Like a gun firing. Or some engines are way louder than any system I've ever heard and there not doing 170Db are they?
Posts: 268 | From: Bristol, PA | Registered: Dec 2006
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posted
Frequency makes a huge difference when talking about acoustics, which is why 130 dB can be hurt and even damage hearing at 1 kHz, but doesn't hurt at all at 35 Hz. Both waves contain the same amount of energy though.
I have never heard at engine that even begins to approach sitting with my head at the dash inside a vehicle doing over 150 dB though, nevermind 170 dB.
Posts: 225 | From: Calgary, AB | Registered: Sep 2003
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posted
man, I tell you, sitting at GatorNationals, you feel the heat, you hear the BLAST of the engines. the rush of the turbulence...the sound in those tailpipes is probably hitting high numbers at lots of freq. the loudest soundwave possible in earth's atmosphere is reported to be between 195.9 and 196.7dB. after that it's a slower shockwave. and they estimate earthquakes to have created blasts of around 320dB...throwing 35+cubic miles of rock into the atmosphere. Outrageous. shock waves that last, circling the earth for months. and, yeah, doubling the power should mathematically yield a 3.01dB increase...but as we know, doubling your power usually won't give you more than 2.4dB.
Posts: 5899 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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posted
Hey now! Take it easy on the engineers! We dont all have our heads buried in a book 24/7. USACi uses the B&K meter which is certified as the standard in Scientific measurements as far as I know. I've personally recorded close to 158dB on it and I wasn't using a sealed enclosure either! We're not all nerdy guys walking around with pocket protectors and calculators
quote:Originally posted by seege: His calculation of 2.6 MW to reach 174 dB is completely invalid since, as someone mentioned, it does not take into consideration the transfer function of the box/vehicle which results in huge gains. Speaker efficiency is measured in an open test environment and I do believe that it would take that amount of power to reach 174 dB outside of a vehicle and a box. He is right that 112 dB is 100% efficient in a 1W/1m measurement, but his application of this number is just ignorant or everything we do in car audio.
Obviously the termlab is not calibrated exactly to DBA scales, but it certainly is not 30 dB out like this guy says. I wonder if he is a aware that the B&K has been used in the SPL world as well and has had similar results. By his calculations they would have needed over 200 kW to produce the 160+ dB level he mentioned.
If he has admitted that someone has produced 160+ dB levels in a test lab, why does he seem to believe that tuned and tested SPL vehicles cannot approach these values?
His statement that "dB in the 12volt world is measured in milli-seconds" doesn't even make any sense. Since SPL does not continue indefinately, it has to be a sample and the termlab takes 1-3 seconds to take its sample. You cannot sample a 50 hz tone in milliseconds since it is less than 1/10 of a cycle anyways. The non-logarthmic units of the dB scale are W/m^2, and the reference is that 10^-12 W/m^2 is 0 dB (so 120 dB is technically 1W/m^2 of sound energy at the mic position) and I believe that termlab is fairly close to this reference.
In short, this guy can crunch numbers and make assumptions, but in reality he has no clue what he is talking about.
E=Mc squared x pie(sweet potato) divided by 16.69314 meganachos is the theory that i use to determine the parsects per million of reverberation passing through my flux capacitor by the time the termlab takes it's sample. almost forgot..... divided by 1 = purdy gotdam loud and stuff!!!! That is all......
-------------------- Tim Heath Audiosports NORRIS B!TCHSLAPPING EXTRAORDINAIRE 2000 DB DRAG World Record Holder (9+ 0-5K) 5-Time N.S.P.L. IRONMAN (Loudest At Finals) 2003 IDBL World Champion (ULT-3) 2003 IASCA FINALS (Loudest Vehicle) MEMPHIS FORCE--04,05,06,07 2005 EXTREME DEATHMATCH 2nd Place 2006 EXTREME 5+ 2ndPlace(175+db)
Posts: 334 | From: Deep Run, NC | Registered: May 2004
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quote:Originally posted by T3audios160s db JEEP: i bet it was IBANENDER he thinks he knows it all he was banned on a few forum because of misbeleving people on differnt ideas he had that where made up in his own head
Put your boner away and pay attention. I haven't been banned from anywhere for "misbeleving" anybody. Sometimes you have to set your boner to the side and look at the real facts.
The post in question was not based on a complete list of facts as was mentioned. He may be correct in an open air environment, which is not the case in car audio. What he said was based on information he had, he didnt ask for more variables nor were they given to him.
Posts: 226 | From: Spartanburg, SC | Registered: Mar 2001
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posted
well, I will say this this about the scores though. I do feel that they give a pretty accurate competitor vs. competitor difference. No matter what the number is on the screen, you will still know if your louder than the next guy at the same competition if you win. People remember winners, not numbers.
Posts: 268 | From: Bristol, PA | Registered: Dec 2006
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quote:Originally posted by Maddog: well, I will say this this about the scores though. I do feel that they give a pretty accurate competitor vs. competitor difference. No matter what the number is on the screen, you will still know if your louder than the next guy at the same competition if you win. People remember winners, not numbers.
People still talking about Scott owens 180+ and Craig Butler 179.8 and even Alan Dante's 179.7 with one sub! You are right most people remember names but when the numbers get that high most remember them!
Posts: 562 | From: South East, USA | Registered: Sep 2006
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if this is so ,then why the hell is Alan Dante still alive?
-------------------- In Loving Memory, David Alfaro
2009 US.Top Cert.St C 158.7 2008 US.Top Cert.St C 158.4 2008 25-48NW NSPL World Champion 2007 U.S.Top Cert. Street A,B,C 2005 Db Drag St A World Champion 2004 Db Drag US.record 642 points 2003 Db Drag Points World Champion http://www.maxxsonics.com/
Back in 02 my girlfriend said I had to make a choice between her and DB Drag....I told that b-tch I've made harder decisions at the Coke machine. Posts: 4978 | From: Suitland,MD USA | Registered: Sep 2001
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