View Full Version : Check my calculations

Unfortunate

03-19-2009, 01:58 PM

Edit: all work done here just need an answer

(2) 4" aeros tuned to 38hz

I couldn't figure out what the calculator is asking for.

My box is:

3.13 cubes

.177 cubes sub displacement

.2 cubes port displacement

So what do i enter into the calculator for Volume of Box in Cubic Feet

http://www.psp-inc.com/

Either:

(1) sub displacement for... approx 3

*Flare Length Port required 13.71*

(2) sub & port displacement for... approx 2.8

*Flare Length Port required 14.83*

Cubes:

http://img.photobucket.com/albums/v297/DaRkMisT/RFwooferwizard.jpg

9BlackN*Black6

03-19-2009, 02:10 PM

Take your total box volume (3.13) and subtract total sub and port displacement. This give you your internal box volume.

Unfortunate

03-19-2009, 02:18 PM

Take your total box volume (3.13) and subtract total sub and port displacement. This give you your internal box volume.

Well, what number should i enter into the calculator because...

port displacement for:

3.13 - .117 (sub) to 38hz = length of 13.66 = displacement of .212

total internal 2.79

but if i enter this into the calculator is changed the length to 14.89 instead of 13.66 which gives me a whole different internal because the displacement is higher.

9BlackN*Black6

03-19-2009, 02:46 PM

3.14 x 4 x 13.66 = 171.56 x 2 = 343.12 / 1728 = .198cu ft <--port displacement(both)

.198 + .117 = .315 total displacement sub and ports

9BlackN*Black6

03-19-2009, 02:47 PM

How to Calculate Internal Box Volume

* Area (rectangle) = Length x Width

* Area (triangle) = 1/2 Length x Width

* Area (circle) = 3.14 x Radius x Radius

* Area (circle) = .785 x Diameter x Diameter

* Volume (rectangular box) = Area (of one side) x Depth

* Volume (triangular enclosure) = Area (triangle) x Depth

* Volume (cylinder) = Area (circle) x Length

* 1728 Cubic Inches = 1 Cubic Foot

* 28 Liters = 1 Cubic Foot

Unfortunate

03-19-2009, 02:54 PM

3.14 x 4 x 13.66 = 171.56 x 2 = 343.12 / 1728 = .198cu ft <--port displacement(both)

.198 + .117 = .315 total displacement sub and ports

Ok that makes sense. my only problem/confusion is even though the length of 13.66 was calculated for 3.01^cube box which now after all displacements is going to be 2.81 net internal volume this would make the tuning much higher around 40hz :crap: which is unwanted.

psp calculator is confusing because they don't clarify what they're asking for...

80INCHES

03-19-2009, 10:38 PM

make each port 13.5 long and u will be at 38hz

80

lowriderram_95

03-19-2009, 10:43 PM

what size sub is this for?

Unfortunate

03-20-2009, 12:01 PM

make each port 13.5 long and u will be at 38hz

80

thanks

what size sub is this for?

2 10's

Unfortunate

03-20-2009, 04:27 PM

anyone?