Acoustic differences between configurations w/ same total surface area?

[creyc 10+ year member]

Lets assume total moving surface area is the same for this post.

So I have always tried to figure out wether or not to use many small drivers or few (or single) larger ones. I have heard much about faster transients and greater "punch" with smaller drivers, but also that a single larger driver can go much lower.

If I have a single 15" driver, with about 176 sq in. surface area of the moving cone and two 10.5"ish drivers with the same total 176 sq in. area, fed the same power, have the same excursion properties and in their appropriate boxes, what are the differences?

I modeled it up in Bass Box but the results were inconclusive, noting no major differences in response curves. Power handling seemed to favor the 15", the 2 10" drivers were really showing a lot of excursion.

Does anyone have any sound, scientific explanation of this? What am i missing here...

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[bballer123 10+ year member]

If im not mistaken, the larger the sub, the louder it will play at a low freq. compared to say a 10"

 

[creyc 10+ year member]

If im not mistaken, the larger the sub, the louder it will play at a low freq. compared to say a 10"

Yea I've heard that a lot.

Why?

 

[Fast1one 10+ year member]

The more drivers you have, the more of a chance you have them being out of phase. Every driver is different, and they will NOT pay in perfect harmony. The difference is very little, but it is there.

They will most likely play very similar. Depending on which drivers you choose, the 15 may or may not play slightly lower, and the 10s may or may not be punchier. There is just too many variables...

With that being said, I would go with the tens (assuming they are the same speaker) just because they take up less room. Average of 2 cubes ported for the pair v. 3-5 cubes for one 15...

To answer your question about the lows, its all physics. The 15 moves a lot more air with one stroke then a ten. For low frequencies, you need to have a good amount of excursion, or otherwise move a lot of air, to produce the sub frequencies efficiently...That is why the 15 plays lower (usually). With all that added mass (usually, not always) comes a price. A little less punchy or not as accurate as a smaller driver..

 

[mannyb18b]

dont forget cancellation issues

 

[creyc 10+ year member]

To answer your question about the lows, its all physics. The 15 moves a lot more air with one stroke then a ten. For low frequencies, you need to have a good amount of excursion, or otherwise move a lot of air, to produce the sub frequencies efficiently...That is why the 15 plays lower (usually). With all that added mass (usually, not always) comes a price. A little less punchy or not as accurate as a smaller driver..

I understand what you're saying, but does a 15" move more air than TWO 10s? Surface area says no....and for this examination I'm assuming excursion is the same, too. So they BOTH have the capability to move the SAME amount of air. And I think the variable of more mass goes to the two 10's. as you have twice the surround, twice the dustcap, twice the voice coil.

For the sake of making this as simple as possible and eliminating all the variables, just a 176 sq in cone moving air or two 88 sq in cones moving air. Any difference in sound?

 

[newusername 10+ year member]

With all that added mass (usually, not always) comes a price. A little less punchy or not as accurate as a smaller driver..

This is simply untrue. Transient response/decay/whateveryouwanttocallit is determined by the inductance of the driver. In fact, a frequency response curve is simply a fast fourier transform of a frequency inductance curve. Mms has very little bearing on response or accuracy, although one could argue that a high Mms driver usually has a larger voice coil which will also have higher inductance, but again, that is not a function of the size of the driver or the mass of the driver.

Neil

 

[Fast1one 10+ year member]

This is simply untrue. Transient response/decay/whateveryouwanttocallit is determined by the inductance of the driver. In fact, a frequency response curve is simply a fast fourier transform of a frequency inductance curve. Mms has very little bearing on response or accuracy, although one could argue that a high Mms driver usually has a larger voice coil which will also have higher inductance, but again, that is not a function of the size of the driver or the mass of the driver.
Neil

I stand corrected, thank you sir //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[newusername 10+ year member]

I stand corrected, thank you sir //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Not a problem.

Neil

 

[Thnking 10+ year member]

I understand what you're saying, but does a 15" move more air than TWO 10s? Surface area says no....and for this examination I'm assuming excursion is the same, too. So they BOTH have the capability to move the SAME amount of air. And I think the variable of more mass goes to the two 10's. as you have twice the surround, twice the dustcap, twice the voice coil.
For the sake of making this as simple as possible and eliminating all the variables, just a 176 sq in cone moving air or two 88 sq in cones moving air. Any difference in sound?

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

But inherently larger subs (more diaphragm area vs wave size) have less acoustic resistance and subs which have less excursion have less acoustic resistance, so given all things are equal and the 10's and 15 both excite the same quantity of air, the 15 will be louder with a different output.