Brahma Question

[mega1268 10+ year member]

If i have 2 brahma 12s it says it only moves 94 vas but the 15 moves 240 something..... so i get 2 12's a 15 will be louder then 24 inchs of cone........ how is that possible.

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[squeak9798 5,000+ posts]

Vas has nothing to do with how loud the sub can get, or how much air the sub moves. It is essentially a measure of how stiff the suspension of the subwoofer is.

2nd, two 12's don't have 24" of cone area. You need to compare the Sd values for the two subs. Though, two 12's should have more cone area than a single 15" (872cm^2 vs. 740cm^2). And since the 12's and 15 have the same excursion levels, we don't need compare the total displacement (Sd * Xmax) to know that the two 12's have the potential to be louder.

 

[T9X 10+ year member]

But the 12"s have to be louder, there are more of them! //content.invisioncic.com/y282845/emoticons/mad.gif.c18f003ab0ef8a0d9c27ca78d77a6392.gif

//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[mega1268 10+ year member]

I thought vas was the amount of Air that was being moved.... whats vas?

 

[squeak9798 5,000+ posts]

I thought vas was the amount of Air that was being moved.... whats vas?

No. As I said, Vas is essentially a measure of how stiff the speakers suspension is (laymen's terms). Vas technically is "the volume of air that when compressed to one cubic meter exerts the same force as the compliance (Cms) of the suspension in a particular speaker".

Again, nothing to do at all with how much air the subwoofer can move. Just a measure of suspension compliance.

 

[mega1268 10+ year member]

ok so Sd is effective cone area?

 

[squeak9798 5,000+ posts]

Yup.

 

[lostsoul 10+ year member]

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif just get two 15's

 

[mega1268 10+ year member]

So 2 brahma 12's wont be that much louder then a single 15?

 

[squeak9798 5,000+ posts]

Theoretically there would only be ~1.4db difference (using the formula 20*Log(Vd1/Vd2) )

 

[mega1268 10+ year member]

How much louder would it be if i put in 2 15's

 

[squeak9798 5,000+ posts]

How much louder would it be if i put in 2 15's

2 15's vs. 2 12's??

Theoretically ~4.6db if my math is accurate

 

[mega1268 10+ year member]

no im saying 2 15 vs my 1 single 15

 

[squeak9798 5,000+ posts]

Here you go:

20*Log(Vd1/Vd2)

Vd1= volume displacement of one speaker (Sd * Xmax)

Vd2 = volume displacement of the other speaker (Sd * Xmax)

Sd of the 15" Brahma is 740cm^2

Xmax is 2.9cm

Have fun //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[mega1268 10+ year member]

whats log lol....... im lost .... and last question........ is the xxx louder then the brahmas cause im looking at the SD the Xmax and it has significant more in both places.