Difference between 2 12s and 1 15

[skateboardkid 10+ year member]

15=176.62 sq in vs 2 12s=226sq using the math already done we can infer that

2 15" = 352 sq in

3 12" = 339 sq in

so closer in cone area than before.

you should be able to do that math.

 

[ARSkemp 10+ year member]

The flaw in your logic is assuming that the 17" sub with at least twice the moving mass of one of the 12s will move as far with 750w as one of the 12s would. The fact is that it wouldn't assuming the same motor force (same motor). It would move half as far and thus have half the swept volume for a theoretical decrease of 3dB in output in a sealed enclosure. You'd have to through 1500w at the big sub to get it to move as far as one of the 12s with 750.

I see your point, but how come the larger subs are not given a higher rms rating then their smaller brothers when they share the same motor? I know their is the heat aspect of it but i'm assuming there are subs that reach their mechanical limits before their thermal limits so why no increase in rms?

 

[patrick1202 10+ year member]

9 inches:fyi:

 

[patrick1202 10+ year member]

I see your point, but how come the larger subs are not given a higher rms rating then their smaller brothers when they share the same motor? I know their is the heat aspect of it but i'm assuming there are subs that reach their mechanical limits before their thermal limits so why no increase in rms?

some companys do increase the rms in size

 

[ARSkemp 10+ year member]

The flaw in your logic is assuming that the 17" sub with at least twice the moving mass of one of the 12s will move as far with 750w as one of the 12s would. The fact is that it wouldn't assuming the same motor force (same motor). It would move half as far and thus have half the swept volume for a theoretical decrease of 3dB in output in a sealed enclosure. You'd have to through 1500w at the big sub to get it to move as far as one of the 12s with 750.

If a 17" only moves half as far for a theoretical decrease of 3db, why would a 17" sub on 750 watts be louder than a 12" on 750 watts?

 

[skinnymofo 10+ year member]

because its double the surface area than one 12

 

[ARSkemp 10+ year member]

but the cone only moves half as far according to the other post. (double cone area --- 3 db increase, twice moving mass --- 3db decrease, so their should be no gain?)

 

[helotaxi 5,000+ posts]

The difference between 2 12s on 1500 watts and the one 17" on 750 would be 3dB. If you were to compare the 17 on 750 to a single 12 on 750, the difference would be 3dB with the 17" being louder. With the pair of 12s you have twice the surface area (+3dB) with twice the power (+3dB) compared to the single 12. With the single 17 you only have twice the surface area. The bigger sub is actually going to move more than half as much as the single 12 on the same power because of the non-linear nature of the BL curve and suspension compliance (at higher excursion the motor weakens and drives the cone with less force and the suspension stiffens up as it approaches its limits). The pair of 12s on 750 total would be louder than the single 12 on 750 as well.

Remember that this is all theoretical. The pair of 12s would still have an advantage in output and SQ because of power compression. That might be slightly reduced by phase cancellation because of slight variances in the exact specs of the pair of drivers. Also the larger cone of the 17 with 2x the Sd will probably weight more than 2x that of one of the 12s making the difference in efficiency less than 3dB as well.

 

[Pl8er 5,000+ posts]

First of all to understand what happened to killer, you gotta understand who killer the dog was. Now killer was born to a three-legged ***** of a mother. He was always ashamed of this, man. And then right after that he's adopted by this man, Tito Liebowitz he's a small time gun runner and a rotweiler fight promoter. So he puts killer into training. They see killer's good. He is **** good. But then he had the fight of his life. They pit him against his brother nibbles. And killer said "no man that's my brother, I can't fight nibbles" but they made him fight anyway, and killer, he killed nibbles. Killer said "that's it!" he called off all his fights, and he started doing crack, and he freaked out. Then in a rage, he collapsed, and his heart no longer beat. wow.

 

[helotaxi 5,000+ posts]

WTF was that? And whay would you dump it into what was one of the few intelligent and mature threads (at least the last 10 posts or so) on this forum?

 

[ARSkemp 10+ year member]

Alright, i think i understand now.

Somewhat offtopic but not really: Is their a reason that you can fit so much more cone area in a box when using multiple small subs?

Example:

10" FI Q has a max recommended volume of .6ft^3 for a sealed box.

15" FI Q has a max recommended volume of 2.6ft^3 for a sealed box.

In the size of the 15" box (2.6ft^3) you could fit 4 10" subs.

15" ~ 176ft^2 cone area

4 10" subs ~ 314ft^2 cone area

How come you can fit such a large amount of cone area in such a small volume when using multiple small subs?

 

[newyork2050 10+ year member]

How about a ported 15 vs 2 sealed 12s

 

[helotaxi 5,000+ posts]

How about a ported 15 vs 2 sealed 12s

Impossible to compare without actually doing it. You'de also have to specify what frequecny range and a lot more to make a valid comparison.