18" - why no love?

[Passinwind]

A 410 would be more than TWO 18's. --in my "Simple" Math!

Your simple math is not all that swell, with all due respect. Here are a couple of factory spec sheet comparisons:

Faital 18FH500: Sd= 1134 cm^2

Faital 10PR410: Sd =317cm^2 (times 4=1268 cm^2)

Now for extra credit look up Xmax for both cases and multiply by surface area for displacement, which is what matters if max volume willy wangling is your goal. Please post your work. Link Removed

If you have a football field's worth of surface area not moving, how loud is it?

 

[SanDiegoHarry]

I dont get your point about the center. The dust cap moves, it contributes to the sound. In fact it can be the source of higher frequency production.

Lets say that each speaker has a 1" surround. A 410 then has 201 square inches of moving cone. A 118 has 201 square inches of moving cone. So they could be equal. Some drivers may have smaller or larger surrounds, so you would need to be specific to know.

....

Fine - but a 18" driver will not push as much air as a 4x10 - agreed?

 

[Dash Lashes]

 

[elkkid2]

How's that? An 18" disk has a surface area of Pi*(R^2) which more or less is 3.14*81 ~254 sq inches, while a single 10" driver is 3.14 * 25 = 78; Yes, these are approximations, but still - the numbers are vastly different.

Lol! a 410 has 4 Drivers and 40" of Cone area...while two 18's have two Drivers and 36" of cone area. --My simple Math....as wrong as it may be, has always worked sound-wise, for me!

 

[CL400Peavey]

Fine - but a 18" driver will not push as much air as a 4x10 - agreed?

Depends on the drivers.

Your simple match is not all that swell, with all due respect. Here are a couple of factory spec sheet comparisons:

Faital 18FH500: Sd= 1134 cm^2

Faital 10PR410: Sd =317cm^2 (times 4=1268 cm^2)

Now for extra credit look up Xmax for both cases and multiply by surface area for displacement, which is what matters. Please post your work. Link Removed

If you have a football field's worth of surface area not moving, how loud is it?

This is what really matters.

Faital 18FH500: Sd= 1134 cm^2 xMax= 9.25mm

Faital 10PR410: Sd =317cm^2 (times 4=1268 cm^2) xMax= 4.5mm

Time for some simple math.

 

[elkkid2]

Depends on the drivers.



This is what really matters.

Faital 18FH500: Sd= 1134 cm^2 xMax= 9.25mm

Faital 10PR410: Sd =317cm^2 (times 4=1268 cm^2) xMax= 4.5mm

Time for some simple math.

Yeah, I came up with my Simple Math back in 1972 when I was 11 or 12, growing up in a tiny Town full of Famous Musicians, and we were floored by Ampeg's 810. This is what made sense at the time. I'm a Musician, not a Math guy at all...sorry...but has always worked for me!

 

[groovaholic]

Math clarification:
PPMDAS
"powers" need to be figured first -- so the radius has to be squared BEFORE it's mutiplied by the number of drivers.

 

[CL400Peavey]

Math clarification:
PPMDAS
"powers" need to be figured first -- so the radius has to be squared BEFORE it's mutiplied by the number of drivers.

Depends on your notation.

9^2 x Pi = 9 x 9 x Pi = 9 x Pi x 9 = 9Pi x 9

 

[CL400Peavey]

Yeah, I came up with my Simple Math back in 1972 when I was 11 or 12, growing up in a tiny Town full of Famous Musicians, and we were floored by Ampeg's 810. This is what made sense at the time. I'm a Musician, not a Math guy at all...sorry...but has always worked for me!

Well if you took a minute to figure out the real math, you would see that your simple math doesnt match reality.

 

[groovaholic]

Order of operations - Wikipedia, the free encyclopedia

 

[SanDiegoHarry]

Lol! a 410 has 4 Drivers and 40" of Cone area...while two 18's have two Drivers and 36" of cone area. --My simple Math....as wrong as it may be, has always worked sound-wise, for me!

"Cone area" - you are confusing diameter with surface area. Easy mistake to make.
surface area of a circle is Pi x R^2, yes?
So the first thing to know is that the radius of a speaker is one half the diameter. 10" has a 5" radius; 18" driver has a 9" radius.
R^2 is, respectively, 25 and 81.
So...
a 4x10 has a surface area of ~4x(3.14 x 25) = 314 Square Inches
a 1x18 has a surface area of ~1x(3.14 x 81) = 254 Square inches

 

[groovaholic]

Faital 10PR410: Sd =317cm^2 (times 4=1268 cm^2) xMax= 4.5mm

That was the part I differed with.
317^2 = 100,489
4*(317^2) = 401,956

4*317 = 1268
1268^2 = 1,607,824

But -- the assertion that four 10-inch discs have more surface area than a single 18" disc is correct.

Or course, speakers generally aren't discs...

 

[elkkid2]

Yeah...and there you go , getting Complicated! LOL! Then you to go through Xmas, through the Deep, and then through the Portal! (II like the Deep...and small Ports!)

 

[CL400Peavey]

Order of operations - Wikipedia, the free encyclopedia

Yep. And once you understand that 9^2 = 9 x 9, it becomes just another multiplicative operator.

"a 4x10 has a surface area of ~4x(3.14 x 25) = 314 Square Inches
a 1x18 has a surface area of ~1x(3.14 x 81) = 254 Square inches

Which is still wrong, as you need to be specific about which drivers you are talking about.

Faital 18FH500: Sd= 1134 cm^2 xMax= 9.25mm

Faital 10PR410: Sd =317cm^2 (times 4=1268 cm^2) xMax= 4.5mm

This will show you that a 118 displaces twice the air as a 410.

That was the part I differed with.
317^2 = 100,489
4*(317^2) = 401,956

4*317 = 1268
1268^2 = 1,607,824

Those CM^2 are units of area. You dont actually multiply those through.

 

[DwaynieAD]

I want two of them Carvin 18s, run em at two ohms, sludge band. All about that look.

Not playing sludge anymore is the problem

 

[Arjank]

Well, in general, a 118 will shove more air then a 410, in general because the majority of 18"s has a larger xmax then most 10's.
When xmax is the same it's approx the same.
Remember that you need to shove 2 times as much air(volume) to increase the spl with 3dB.

 

[BurningSkies]

If you have a football field's worth of surface area not moving, how loud is it?

I tried that, but I could never get the rest of the band to help move it.

 

[Passinwind]

I tried that, but I could never get the rest of the band to help move it.

Football fields are pile-drivingly heavy.

 

[elkkid2]

Order of operations - Wikipedia, the free encyclopedia

Yeah...Math...I should go back and start with "Bonehead" Math, and see if THIS TIME I can pass Algebra...last time I did an 18 Unit OUTREACH class, and failed after a certain part...Thank GOD everyone likes my Bass tone/playing! (No one has ever beat me in Music Theory either! --That helps!

 

[Lindex]

I tried that, but I could never get the rest of the band to help move it.

Damnit...I even had issues with attaching the voice coil to the lawn...