BTL vs. Type X

[pawn man 10+ year member]

alright it's not exactly pi R^2 for the cone of a subwoofer, because that's the formula for a circle. a cone is not a circle, by definition.
For all intents and purposes though, the effective piston area of an 18" woofer is substantially larger than two 12" woofers. The power handling of an 18" and a 12" subwoofer of the same make/model will be similar, but the 18" will theoretically have 3db or more greater output.

The reason two 12" subwoofers of the same make/model is usually louder is because people are running double the power on nearly the same cone size. Every time you double the power, you theoretically gain 3db.

If you run the two 12" subs with the same power as a single 18" sub, the 18" sub should be louder given optimal conditions for both.

yes i know. that is why i put app. the pi x radius squared is formula for circle and does not account for the tapered cone.

 

[WheresTheButta 10+ year member]

yes i know. that is why i put app. the pi x radius squared is formula for circle and does not account for the tapered cone.

I didn't see that, sorry for the double-up on that information then //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

Comparing a BTL to a type X is apples to oranges though, the BTL is a SPL woofer, the type X is SQ....

(at least that's what they were designed for)

 

[Brian Owens 10+ year member]

yes i know. that is why i put app. the pi x radius squared is formula for circle and does not account for the tapered cone.

I am pretty sure the effective cone area really is not the "cone" it is the circle. The entire cone moves in a linear motion pushing air.

Think about it for a few minutes. . .

Brian

 

[WheresTheButta 10+ year member]

I am pretty sure the effective cone area really is not the "cone" it is the circle. The entire cone moves in a linear motion pushing air.
Think about it for a few minutes. . .

Brian

you may be right, but it's counterintuitive.

If you take the cone and flatten it, you get more area than the simple circle that you would get from taking pi*r^2

That means it's moving a larger volume of air than the circle would.

 

[Brian Owens 10+ year member]

But the cone is not flattened and it is moving in a linear motion, not in a motion following the shape of the cone. Air is being pushed in an area the size of the circle, not the size of the cone.

 

[bass_lover1 10+ year member]

xmax is how far the cone travels. That's all it means.
It's relevant, because the cone traveling further in and out moves more air. Moving more air = more deebeez

Xmax is the LINEAR travel of the coil within the gap. They can be rated in two different ways however. One is the amount of coil overhang that is out of the gap at rest, or the other is the 71% BL point on a Klippel or Dumax graph. Xsus would be the physical travel limit if the suspension. Xmech would be the physical operating range with everything taken into consideration. Basically if Xmech is less than Xsus, the coil will bottom out or completely leave the magnetic gap long before the suspension runs out of steam. The opposite is true as well. If Xsus is less than Xmech, then the suspension will lock up before the coil bottoms or before the coil completely leaves the magnetic gap.

Low frequency output is directly related to displacement, IE cone area AND suspension travel. Excursion is just one half to that equation. Think of this as being similar to an engine's displacement. It is measured by calculating the bore (piston surface area) and the stroke (piston travel). You'll see that the same goal can be accomplished in two different fashions, but both will come with their ups and downs. In the speaker world, those trade offs are up to you to decide which is more important.

 

[WheresTheButta 10+ year member]

Xmax is the LINEAR travel of the coil within the gap. They can be rated in two different ways however. One is the amount of coil overhang that is out of the gap at rest, or the other is the 71% BL point on a Klippel or Dumax graph. Xsus would be the physical travel limit if the suspension. Xmech would be the physical operating range with everything taken into consideration. Basically if Xmech is less than Xsus, the coil will bottom out or completely leave the magnetic gap long before the suspension runs out of steam. The opposite is true as well. If Xsus is less than Xmech, then the suspension will lock up before the coil bottoms or before the coil completely leaves the magnetic gap.
Low frequency output is directly related to displacement, IE cone area AND suspension travel. Excursion is just one half to that equation. Think of this as being similar to an engine's displacement. It is measured by calculating the bore (piston surface area) and the stroke (piston travel). You'll see that the same goal can be accomplished in two different fashions, but both will come with their ups and downs. In the speaker world, those trade offs are up to you to decide which is more important.

That is a fanstastic analogy. Thanks.

edit: yeah I simplified my definition significantly haha //content.invisioncic.com/y282845/emoticons/silly.gif.3549b64aaa5b6729eb8e865319a3234f.gif

 

[spencer321 10+ year member]

there is a massive thread (where i make an *** of myself) disputing whether cone depth has ANYTHING to do with displacement and i assure you it does not, here is an illistration that helped me, hope you all get it

both pictures have the same cone diameter and same excursion, one is a cone and the other is a circle, the area is identical

 

[WheresTheButta 10+ year member]

there is a massive thread (where i make an *** of myself) disputing whether cone depth has ANYTHING to do with displacement and i assure you it does not, here is an illistration that helped me, hope you all get it
both pictures have the same cone diameter and same excursion, one is a cone and the other is a circle, the area is identical

I prefaced what I said before by saying I could be wrong for that exact reason - math doesn't always agree with common sense, but I guess ya can't really argue with math huh //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[spencer321 10+ year member]

I prefaced what I said before by saying I could be wrong for that exact reason - math doesn't always agree with common sense, but I guess ya can't really argue with math huh //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

oh you can, like i said, the only reason i know is because there is a 10 page thread with me arguing with everyone, actually posed a decent enough argument i convinced alot of people, untill someone posted a sketchup picture with area and dimensions and i went "oops"

 

[snb778 5,000+ posts]

i don't think you realize what it takes to flex a vehicle daily..... you're not even in the right ballpark to do that.

 

[BassFreq 10+ year member]

1 15" btl on 2000+ watts would be signifigantly louder than 2 1000w 12's. Cone area is not always a winner.