Update: Chris Lewis... And His Decibel Chart Article Inside

[Big P]

That whole article just smacked of failure to me. The sheer difference you can get in dB by changing pathetic little things means any mathematic modelling of a system is fairly meaningless.

For SPL it is only real world testing that matters.

His statement that concrete and lexan are pointless seems woefully ignorant. Go tell Alan Dante that.

Also tell me how Dante does 180.1 with 'only' 28000w to a single 18" woofer

28000w = 10x2800 = 10x10x280 = 10x10x10x28 = 10x10x10x2x14 = 10x10x10x2x2x7

So chart numbers:

Chris: 10 + 10 + 10 + 3 + 3 + 8.5 = 44.5

44.5 + 116.6 = 161.1 = Failure

Your numbers:

11.25 + 11.25 + 11.25 + 2.25 + 2.25 + 7.875 = 46.125

46.126 + 116.6 = 162.725 = Failure

Have you ever actually done an SPL build? You would probably know little things like 'maths never equals real world' and that totally seperating the rear wave (usually) does NOT make a car loud - as well as amazing facts like simple cars = loud cars, take one look at the Euro street scores and that would become very apparent.

I agree drag racing and car audio = mathematicians ulcer giving nightmare

[99vic]

I agree drag racing and car audio = mathematicians ulcer giving nightmare

i thought it was some kind of foreign language

[quakecitystudio]

But, you have to realize that the testing that he did his mathmatical speculations were not in a vehicle. It was based on how woofers are tested at 1w/m. Even if it was a theory, it was one man's attempt to help another from possibly making costly mistakes, as in constantly rebuilding setups.

The reason why Alan Dante and other competitors have hit higher than their calculated output is because:

1. the calculated output is a minimum of what the spl would be at 1 meter, based on how that particular woofer is tested

2. his system is efficient, meaning he is getting all the output that the amp is sending to the woofer, this is based on the spl based on the amp's wattage

3. like the other chart that Chris Lewis included that had competitor like Alma Gates that have managed to hit well over their calculated output, due to CABIN MODIFICATIONS, AS WELL AS A REDUCTION IN CABIN VOLUME, so that there's less air to compress yielding a higher spl. You would have caught this if you were reading the rest of the article.

Since Alan hit 180.1....

180.1-116.6= 63.5 dbw well over the 116.6 efficiency mark, just like the other competitors in the last chart. This states that you can achieve higher results by doing modifications to the vehicle when you've reached the limit of the amp as well as the subwoofer's output. Try the chart with a regular (non extreme) competitor and see what you get.

Oh, and for those of you that may not like it when I post a chart, or anything at all, and feel like that have to get on my case, do me as well as any other person that may take interest in my topics a favor, go elsewhere. There are plenty of topics for you to check out besides mine.

[mrrairai]

The numbers kinda threw me off at first but after your last post it does make sense. Makes a lot of sense to me although I'm not an SPL person.

[suburban ant]

those were my first subs

[meade916]

Im with Tommy. Charts are dumb. None of it is even close to close. It was interesting reading an oldschool article though. Kinda annoying with all that shit you underlined and your math at the bottom but i tried to ignore it as best as i could.

the calcs on chickens hoopty seem pretty close and thats cool but theres probably hundreds of people that if they were given the same subs, same car and same amp, if they didnt know what they were doing may not even break a 150. That throws everything out the window.

what about people that have multiple subs, thousands of watts and DEFINITLY POUNDS... but are barely in the 50 club? What about the CRX with 2 10's in a street A car doing a 155+? (or is it more now?)

again, nice article, i like reading old shit and see how we USED to think.....but in the end there is too many variables.

[quakecitystudio]

I agree, there are too many variables, and there probably will not be a way to get a straight answer as to what a system could do based on numbers at 1 meter. I still give him props for taking that challenge because the way I see it is that there isn't anyone else who's attempted it. We just need to understand that, his calculations are at 1 meter, not in vehicle, and that higher numbers can be achieved with modifications to the vehicle.

[meade916]

well if his calcs are at 1w 1m, then why is he posting up the SPL legends scores and pics of the rides/systems? show me a sub hanging from a chain with a mic exactly 1 meter away and then write an article about it. It will make sense then although very boring and no one would care

[quakecitystudio]

As I understood it, it was probably his mistake to include that, but by comparison he wanted to show that there are ways of hitting above the 116.6 efficiency mark, i.e. full blown competition vehicles, because if you just did the math on what spl the competitor would have scored based on just the wattage and the woofer's sensitivity being 116.6 then the competitor's score would be less than what they've actually hit.

Now you can do a measurement inside the car, by measuring from the dash to the subwoofer enclosure and taking that 1w/m and subtracting 3 db when the distance is twice the distance than the woofer was originally tested being 39.37 inches.

For example, say a woofer was tested and hit 91.3 db at 1w/m. Well at 78.74 inches it would be 88.3 db at 1w/m.

Edited June 17, 2008 by quakecitystudio

[tommyk90]

But, you have to realize that the testing that he did his mathmatical speculations were not in a vehicle. It was based on how woofers are tested at 1w/m. Even if it was a theory, it was one man's attempt to help another from possibly making costly mistakes, as in constantly rebuilding setups.

The reason why Alan Dante and other competitors have hit higher than their calculated output is because:

1. the calculated output is a minimum of what the spl would be at 1 meter, based on how that particular woofer is tested

2. his system is efficient, meaning he is getting all the output that the amp is sending to the woofer, this is based on the spl based on the amp's wattage

3. like the other chart that Chris Lewis included that had competitor like Alma Gates that have managed to hit well over their calculated output, due to CABIN MODIFICATIONS, AS WELL AS A REDUCTION IN CABIN VOLUME, so that there's less air to compress yielding a higher spl. You would have caught this if you were reading the rest of the article.

Since Alan hit 180.1....

180.1-116.6= 63.5 dbw well over the 116.6 efficiency mark, just like the other competitors in the last chart. This states that you can achieve higher results by doing modifications to the vehicle when you've reached the limit of the amp as well as the subwoofer's output. Try the chart with a regular (non extreme) competitor and see what you get.

Oh, and for those of you that may not like it when I post a chart, or anything at all, and feel like that have to get on my case, do me as well as any other person that may take interest in my topics a favor, go elsewhere. There are plenty of topics for you to check out besides mine.

Those competitors in the last chart are NOWHERE near the "efficiency mark" of today's competitors. Not only are the scores of today 10-15 dB higher than those of the chart, those scores are on the old decibel meters. Those cars today would probably be 5-10 dB quieter on the termlab.

Even stock cabin cars are way above that number.

Take the panda for instance. These guys are doing 156+ with ~7000 watts on TODAY'S meters. Their scores on the meters back then would likely come close to breaking a 160. But doing lewis' calculations would only put them at ~154 on the OLD mics (which are 5 dB louder than todays, sometimes more). Like I said before, it's just a big waste of time to be doing all the math.

And I'll be honest, the formula actually came very close to the score in my truck, but the same equipment in a trunk car would likely be at least 5 dB quieter than I was simply because of the car itself.

Theorys are all fine and dandy on paper, but 9 times out of 10 serve no purpose in the real world. That's why they are theories and not fact. Constantly rebuilding setups is part of SPL competition. The loudest people in the world are the ones that build and test the most, not the ones who try to apply mathematical theories.

Edited June 17, 2008 by tommyk90