12s or 15s

No apology necessary, it's a perfectly understandable misconception. With any single given, SAME SIZE voice coil and motor structure, simply attached to a larger cone, your physics class would be correct. When manufacturers build their motors, they address the inductance, to improve the response of the cones.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

so my new question now is will a biger sub be louder?

blk1990gt wrote: so my new question now is will a biger sub be louder?

Assuming all else is the same other then the size of the subs, yes. Cone area is directly related to output so the more cone area you have the more output you have. That does not mean all 15s will be louder then all 12s or even 8s. There a lot of factors that determine overall loudness. But in general, yes, more cone area does mean more output.

blk1990gt wrote: so my new question now is will a biger sub be louder?

NO!!! Absolutely not. It is dependent COMPLETELY upon 1: the efficiency of the driver, and 2: the power handling of and power supplied to the driver. If you have an 8" woofer and a 15" woofer, both rated 85dB efficient, and the 8" woofer can handle 200 watts, but the 15 can only handle 100 watts, then the 8" driver CAN play twice as loud as the 15" driver.

whiterob wrote: Assuming all else is the same other then the size of the subs, yes. Cone area is directly related to output so the more cone area you have the more output you have.

That is simply wrong. Cone area has little to nothing to do with how loud a driver is or how loud it can play. It is motor structure that has FAR more to do with a given driver's output capability! By your logic, then there would never be ANY way that a 1" tweeter could EVER make as much noise as a 15" woofer. We all know this is not the case. The more air you can move, yes, but that IS NOT ANY INDICATION of how loud a driver will play, rather an indication of how DEEP that driver can play. Nearly ANY tweeter you can lay your hands on today will have every BIT of 8 to 12dB better efficiency than any current, decent, long-throw, high power handling woofer, thus, completely blowing your theory out of the water. :::::EDIT::::: I knew I'd find the thread I was looking for... SPL Formula thread.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

haemphyst wrote: blk1990gt wrote: so my new question now is will a biger sub be louder? NO!!! Absolutely not. It is dependent COMPLETELY upon 1: the efficiency of the driver, and 2: the power handling of and power supplied to the driver. If you have an 8" woofer and a 15" woofer, both rated 85dB efficient, and the 8" woofer can handle 200 watts, but the 15 can only handle 100 watts, then the 8" driver CAN play twice as loud as the 15" driver. whiterob wrote: Assuming all else is the same other then the size of the subs, yes. Cone area is directly related to output so the more cone area you have the more output you have. That is simply wrong. Cone area has little to nothing to do with how loud a driver is or how loud it can play. It is motor structure that has FAR more to do with a given driver's output capability! By your logic, then there would never be ANY way that a 1" tweeter could EVER make as much noise as a 15" woofer. We all know this is not the case. The more air you can move, yes, but that IS NOT ANY INDICATION of how loud a driver will play, rather an indication of how DEEP that driver can play. Nearly ANY tweeter you can lay your hands on today will have every BIT of 8 to 12dB better efficiency than any current, decent, long-throw, high power handling woofer, thus, completely blowing your theory out of the water. :::::EDIT::::: I knew I'd find the thread I was looking for... SPL Formula thread.

I've always heard that every time you double the cone area you will gain 3db. I know that is a theoretical value but doesn't cone area have an effect on output? Same as every time you double the power you gain 3db (again a theoretical value). I also may not have explained what I was meaning very well. When I said everything being the same I was implying that the subs had the same efficiency, same power handling, and all other specs being the same. I realize that this is not really a practical situation but assuming that this was true and only the cone area of the subs differed the larger sub would be slightly louder correct?

whiterob wrote: I've always heard that every time you double the cone area you will gain 3db. I know that is a theoretical value but doesn't cone area have an effect on output? Same as every time you double the power you gain 3db (again a theoretical value).

Yes, you are correct, that a doubling will add 3dB, but if you are starting with one woofer, 12 inches across, (hell... even 8" across...) with an Re of (for example) 87dB (typical today), and another woofer, 15" across, ALSO with an Re of 87dB, then if you double the cone area of either situation by adding a second identical driver, there will still be no difference. Just do the math... 87dB + 3dB = 90dB That will hold true no matter the driver diameter... Notice it doesn't say "an 8 inch 87dB, plus a second 8 inch 3dB, equals a single 15 inch 90dB". (I know that's ridiculous, but you get the idea, I think...)

whiterob wrote: I also may not have explained what I was meaning very well. When I said everything being the same I was implying that the subs had the same efficiency, same power handling, and all other specs being the same. I realize that this is not really a practical situation but assuming that this was true and only the cone area of the subs differed the larger sub would be slightly louder correct?

No. Whether it is practical or not, if they have the same efficiency (Re or "reference efficiency) and power handling, a VERY practical and possible situation, then there will be zero difference in output, no matter HOW many doublings of cone area, as long as you double the same number of times for either driver's situation.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

haemphyst wrote: whiterob wrote: I've always heard that every time you double the cone area you will gain 3db. I know that is a theoretical value but doesn't cone area have an effect on output? Same as every time you double the power you gain 3db (again a theoretical value). Yes, you are correct, that a doubling will add 3dB, but if you are starting with one woofer, 12 inches across, (hell... even 8" across...) with an Re of (for example) 87dB (typical today), and another woofer, 15" across, ALSO with an Re of 87dB, then if you double the cone area of either situation by adding a second identical driver, there will still be no difference. Just do the math... 87dB + 3dB = 90dB That will hold true no matter the driver diameter... Notice it doesn't say "an 8 inch 87dB, plus a second 8 inch 3dB, equals a single 15 inch 90dB". (I know that's ridiculous, but you get the idea, I think...) whiterob wrote: I also may not have explained what I was meaning very well. When I said everything being the same I was implying that the subs had the same efficiency, same power handling, and all other specs being the same. I realize that this is not really a practical situation but assuming that this was true and only the cone area of the subs differed the larger sub would be slightly louder correct? No. Whether it is practical or not, if they have the same efficiency (Re or "reference efficiency) and power handling, a VERY practical and possible situation, then there will be zero difference in output, no matter HOW many doublings of cone area, as long as you double the same number of times for either driver's situation.

Lol, I just realized the mistake in my logic.   I don't know what I was thinking but thanks for straightening that up for me.

got yet another question for u guys so lets say i were to buy 2 dual 2 oham subs that are 2000w each can i run 4 1000w 2 oham amps 1 to each voice coil?

Yes... (...and the word is Ohm... It's a man's name...) Are you seriously asking questions to learn, or are you just asking questions to get your post count up? We don't mind helping, really, but these questions are becoming a bit... ridiculous.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."