Assassin Ported Box Complications

[Woodmister 10+ year member]

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

Subwoofertools.com http://www.subwoofertools.com/forum/ported-box.asp

REAudio http://reaudio.com/speaker_box/LPort_Box_Calc.html

Click to read more...

 

[mikey060 10+ year member]

pics no workie

and from what i have heard...the re calculator isnt very accurate

 

[Woodmister 10+ year member]

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

 

[kickerlivinloud 10+ year member]

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...

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 10+ year member]

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

Its kinda hard to mistrust WinISD right?

 

[Woodmister 10+ year member]

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 10+ year member]

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 10+ year member]

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

 

[mlstrass 5,000+ posts]

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

 

[mlstrass 5,000+ posts]

Why does it need to be 33" wide?

 

[Woodmister 10+ year member]

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

 

[mlstrass 5,000+ posts]

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

 

[Woodmister 10+ year member]

^ for your or mine?

 

[mlstrass 5,000+ posts]

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 10+ year member]

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"?