A Way to put Subwoofer in Joist????

[gcmarshall]

see link below. polk makes an in-wall/in-ceiling subwoofer. maybe this will help with your application. you can also download the owners manual to read about installation tips, if any.

http://www.polkaudio.com/homeaudio/products/csw100/

 

[Davy9]

A little math lesson

I forgot about pi. Thanks

But, 4 x 8" drivers is 100.48 square inches, isn't it?

8 x 3.14, then x 4 = 100.48

32 x 3.14 = 100.48

That will still equal one 32" cone in area. I'm not an engineer, am I missing something?

Assuming that we are just talking about circles and not cones (What we should be talking about):

If you are talking area, then the area of a circle is pi*(radius)^2. That being said,

For four 8" drivers:
Area: 4*(4^2)*pi = 64*pi

This is the equivalent of:
(8^2)*pi

-8 being the radius of the equivalent driver

Therefore:

Four 8" drivers has the equivalent surface area of one 16" Driver.

 

[bigpapa]

Pi*diamter is the circumference of a circle, the distance around the outside.

I bet you can figure out what I was doing in high skool

 

[bigpapa]

Thanks davy9 and jaxvon

^ 2 means squared then. I checked, I think that's it.

So, in english, it's pi times radius squared equals area, for a flat space.

I understand that properly calculating cones is a quantum leap in complexity. I'm sure we all don't have time for that.

I suppose ^3 would be cubed then.

So, not much damage done, I usually used my (incorrect) calc to estimate intake ducting for cooling racks. In error, I was always larger, so no harm done.

Really, thanks for the lesson. One golden coconut for each of you

 

[jaxvon]

The area for a cone, neglecting the dust cap (which is more like part of a sphere and can be calculated separately), the surface area of a cone is:

pi*r*sqrt(r^2 + h^2) where h is the height of the cone, measured from bass to point and "sqrt" means "square root". The square root is an implementation of the Pythagorean Theorem, which states that when working with a right triangle with sides a, b, and c (the longest side, the hypotenuse is c), "a^2 + b^2 = c^2".

 

[bigpapa]

The area for a cone, neglecting the dust cap (which is more like part of a sphere and can be calculated separately), the surface area of a cone is:

pi*r*sqrt(r^2 + h^2) where h is the height of the cone, measured from bass to point and "sqrt" means "square root". The square root is an implementation of the Pythagorean Theorem, which states that when working with a right triangle with sides a, b, and c (the longest side, the hypotenuse is c), "a^2 + b^2 = c^2".

OK, I think I can handle this;

pi times radius times the sqrt OF (radius cubed plus height cubed)? Is that it?

I understand the Pythagorean theorum, use it for screen calcs.

I appreciate your time jaxvon.

 

[bigpapa]

Hey guys, a new math lesson for me

Is there a calc to use when designing an inwall back box for a speaker?

I build back boxes a lot, but I usually call the speaker manufacturer for volume reqs. I was wondering if I could do it myself.

I usually do .7 cubic feet for 5.25" driver coaxials, .8 cubic feet for 6.5" drivers, and 1.2 cubic feet for inwall subs (two 8" drivers) or dual driver mains (two 6.5" drivers).

 

[jaxvon]

OK, I think I can handle this;

pi times radius times the sqrt OF (radius cubed plus height cubed)? Is that it?

I understand the Pythagorean theorum, use it for screen calcs.

I appreciate your time jaxvon.

One correction, it's pi times radius times the square root of (radius SQUARED plus height SQUARED).