Does This Sound Right?

[E-Train]

Okay so I used the RE box calculator thing, and i'm gonna try and build my own box and I came up with this.

I'm going to be running 4 MTX Jackhammer 12's which require 2 ft of airspace a piece

This is what I got from the calc.

Box Width: 38.5in

Box Height: 17in

Box Top Depth: 28in

Box Bottom Depth: 28in

Wood Thickness: 0.75in

Square Port Height: 15.5in

Square Port Width: 8in

Square Port Length 1: 19.25in

Square Port Length 2: 10in

Total Port Length: 42in

Square Port Diameter: 12.5650986286284in

Square Port Area: 124

Square Port Volume Internal: 5208

Square Port Volume Displaced: 5229.375

Box Volume: 5.769ft^3

Box Volume: 9968.375in^3

Tuned Freqeuncy(Fb): 33.629

This is my first time ever using a box calc. so I dont think I got it quite right, but that size port was the only way I could get it tuned to 33Hz, any smaller port to increase box volume and the tuning went down to like 19Hz.

So any help would be appreciated, I really wanna do this right and not screw it up.

[Decaf]

its close but not right... whats the displacement of one sub

[E-Train]

How do I find the Displacement

[Decaf]

which series, jh45 or jh55

Edited August 17, 2008 by decafcappucino

[E-Train]

JH45

[Decaf]

ive got a better box for ya how about..

same outer dimensions

38.5*17*28

5.5" wide port with 1 port piece going in 20" for a tuning of 33.39hz

6.954cuft

85.25 sqin port (124 is way too much)

12.26sqin/cuft

ideally u need to make the box bigger by 1 cuft

*edited now that i know its jh45

Edited August 17, 2008 by decafcappucino

[E-Train]

I put those in the calc. and it still comes up with a tuning of 29Hz or should I even use the calc., and how would I make it bigger by 1cuft, i cant make the box any bigger than it is on the outside.

[roscoe1129]

I wouldnt use the RE calc personally.

[Decaf]

that calc doesnt account for sub displacement...

i use amatts spreadsheet calc which is spot on

if you cant increase the box size than the one i showed is pretty much perfect

1.75cuft per sub instead of 2 isnt bad

mtx reccommends 35hz tuning... but u want 33hz right?

[E-Train]

I was going for 35Hz but couldn't get it lol