Power VS Cone area

[Jeremym5621]

Wondering what is better, more power or more cone area? For example:

Say 2 18s that handle 7000w each 

or 4 15's that handle less/about half the power each.

Is it better to move more air or to have more wattage and power?

I need a design for my build and am asking myself this question to help me decide which is best.

 

[AaronT]

Well the different sized drivers have different cone area not equally direct. Like lemme explain.

 

2 12s on the surface it seems like we have "24 inches" of cone.

3 8s on the surface seems like we have "24 inches" of cone as well. 

But this is not the case. The 2 12s have much much more cone area than 3 8s.

 

3 8s has an effective cone area of 150.72 sq inches.

2 12s has an effective cone area of 226.08

 

2 18s have cone area of 508.68 sq inches

4 15s have cone area of 706.49 SQ inches.

So it's a hard comparison on paper as things aren't equal.

 

Let's take a easier to deal with example of your question. We will use  15s. 2 15s with double the power handling capability of 4 15s.

 

2 15s gives us 353.25 sq in of cone

4 15s  gives us Exactly double @ 706.49 sq in.

 

Now we gotta take into account actual Xmax, or one way linear excursion.

 

Let's say the 2 15s have an Xmax double that of the 4 15s (which would be pretty much the case if we have 2 15s with 3500 RMS each) so for comparison purposes let's say the 2 big 15s have 30mm Xmax each where the 4 15s have Xmax of 15mm each 

 

So we got equal Xmax between the 2 different setups as it would seem. Don't know if you could use that as a direct correlation, but I'm just trying to lay out the little variables in this question for YOU to make your best educated decision.

 

They say 'no replacement for displacement" meaning the more surface area of a diaphragms or "cone" always wins.

 

But displacement isn't just 2d. It's 3d.

 

So would 353 inches moving 30mm of air be louder than 706 inches moving 15mm of air?

 

Your guess is as good as mine.

 

But I will lay out this anecdotal observation.

 

I've always used 12s, always a dual 12 setup, 3 12s, 4 or 6 12s. All my life I used 12s. About 8 years ago I started playing with the Chinese big motored (250+ oz) 3" coil subs in single sub setups. They perform . To date I've had a 12 inch American bass HD, a Soundqubed 312, and audio legion 1000 RMS 12 (can't recall the model) all of them in single sub setups.

 

To my surprise they perform as well as some of the older 2 12 setups in my younger days (between 2012 and now I been back into car audio, but prior to 2012 I wasn't involved in this hobby much , stopping in 2002 for 10 years till 2012 when I got the bug)

 

Now in my one current build I'm using monster 8s, 160oz motors, 2.5" coil, 28lb 8" subs.

 

I had 2 of them on 1500 watts (same amp used in all the single 12 builds) and the 2 8s sound way deeper and capable than the single 12 setups. I'm talking leaps and bounds over the single 12s setup. And the single 12s were in speced boxes at 2.5 cubes at 36-42hz depending on what single 12 I was using calked for.

 

Now the 2 8s were in a skar prefab, but it was slightly larger than specs for the subs, it was 1 cubic foot before sub displacement (subs callled for .55-.75 cubes each) but anyway the 8s I'd take over the single 12 all damn day.

 

2 8s have a area of 100.48 sq in. And single 12 had 113.06 sq in of area. And the 8s have an Xmax of 15mm each versus the 12s i used having more (soundqubed hds312 had 18mm, American bass HD had 30mm and audio legion had similar around 19 iirc)

 

So he had a scenario where more cone area ( by 13sq in) and higher stroke or Xmax wasn't as "loud" as the smaller cone area drivers with less excursion.

 

So I'd say the 4 15s would be much deeper and capable than 2 18s, based off my experience alone.

 

Ymmv, but use this as good  food for thought