Assassin Ported Box Complications

[Woodmister]

So I have a 10" AA Assassin.
AA says use 1.2cubes tuned to 32Hz
I have ran three 'calculators/programs' trying to figure out the correct size of the box/port/port area and the RE one seems to differer from the other two the most.
Help would be much appreciated

I need to keep the external hight (12") and external width (33") the same, with the depth being variable.

WIN ISD
http://www.caraudio.com/gallery/6/5/0/7/port1.JPG

Subwoofertools.com http://www.subwoofertools.com/forum/ported-box.asp
http://www.caraudio.com/gallery/6/5/0/7/port2.JPG

REAudio http://reaudio.com/speaker_box/LPort_Box_Calc.html
http://www.caraudio.com/gallery/6/5/0/7/port3.JPG

[mikey060]

pics no workie
and from what i have heard...the re calculator isnt very accurate

[Woodmister]

Lets try it now, i could see how the RE wouldnt be right since the other two agree with eachother...

[kickerlivinloud]

I wouldn't trust that calculator. I have found it to be way off from time to time. It also is spot on at times. Its just not constant. Here is an example...

http://forum.realmofexcursion.com/showthread.php?t=23030


In the thread a person used it to get a 2.2@32Hz

He had 42"^2 of port with a port length of 44.75"

I did a similar design a while back and it looked like this...
http://i162.photobucket.com/albums/t246/Kickerlivenloud/Black%20Mirror%20Designs/BMD1.jpg

As you can see the port area is the same and the volume is very close but, the port length isn't even close. Not by a long shot!


Also if you take the info giving my the online calculator and add it all up, its doesn't match. I explained everything the best I could in the thread.


I just don't trust online calculators. That my, I like to do it with pen, paper and a calculator. That why I know its right.



Jon

[Woodmister]

Well I only ask cause the WinISD calculation kinda matches the sites calculations/box plans.

Its kinda hard to mistrust WinISD right?

[Woodmister]

PS, just checked it with http://www.carstereo.com/help/Articles.cfm?id=31

For:
1.2 cubes 32hz
Port Height: 10.5"
Port width: 2"

It gives me a length of 41.27"

So now we have 3 sources that say ~40" of length for the same dimensions.

I checked the volume of the box, and its pretty darn close...

[kickerlivinloud]

PS, just checked it with http://www.carstereo.com/help/Articles.cfm?id=31

For:
1.2 cubes 32hz
Port Height: 10.5"
Port width: 2"

It gives me a length of 41.27"

So now we have 3 sources that say ~40" of length for the same dimensions.

I checked the volume of the box, and its pretty darn close...




One question, What is the gross volume of the enclosure??? I just did a design with 1.2 as gross (wasn't paying attention) and got a final port length of 41.2" for the same info given. This is not correct b/c I didn't have the right gross volume.

I didn't say its always wrong but it is inconsistent. For some enclosures its spot on but, others its not even close..



Jon

[Immacomputer]

I only trust winisd. Every enclosure I have built using it's port lengths have measured to be almost identical.

[mlstrass]

When using subwoofertools you need to change the xmax number around until you get the desired port ^2

[mlstrass]

Why does it need to be 33" wide?

[Woodmister]

To use in this cubby before it starts to decrease in hight. It goes from 12" in the center (under the material) to 11 at about 2" on each side

http://memimage.cardomain.net/member_images/8/web/836000-836999/836385_70_full.jpg

[mlstrass]

I used subwoofertools and got a decent box/port going narrower. Like 28" wide I think.

[Woodmister]

^ for your or mine?

[mlstrass]

For yours. Was going to send you the link, but GF got on the PC and closed the window out. Just trying doing a narrower box, changing xmax to get the right port size, and you should be able to get an "L" port.

[Woodmister]

Well I dropped the xmax to 15mm (instead of 15.5) and got an L port.
But it decreased the port area to ~18.75 sq in (1.75x10.5)
From 21sq in (2"x10.5")

WinISD didnt show a change in the vent mach (.04) from the two different port sizes, just saved me ~5" of port length with the smaller port...

What is an acceptable port area for a 10"?