Ported Box (xmax) Question

[OC*SS 10+ year member]

I'm trying to come up with dimensions for a slot ported box for 2 15's, however when I enter the actual xmax of 29mm, it spits out these crazy dimensions and the port looks like a freakin maze, face of the box not wide enough for 2 15's, etc.

When I change the xmax to 15mm, it is perfectly simple and clear. Would this affect how the box plays, the tuning frequency, etc.? Here's the plans with 15 mm xmax:

http://www.subwoofertools.com/forum/ported-box.asp?Ew=40&Eh=18&Dia=9&Xmax=15&Vd=.48&NumW=2&Vb=4.5&Fb=32&Qts=&Vas=&Fs=&CE=0

Click to read more...

 

[OC*SS 10+ year member]

TTT would there be any difference in a ported box w/ 29mm xmax subs or 15mm xmax subs?

 

[Death By Bass 10+ year member]

when you increase the xmax, it increases the port area...

you may have port noise if you make the box with the "15mm x-max"

but, it should be alright...

 

[ultimate157 5,000+ posts]

The higher the Xmax, the more air your driver will likely displace while playing. You need more port area to displace that air. You may have port noise with the 15mm xmax enclsoure.

 

[OC*SS 10+ year member]

So should I extend the port, maybe one or two inches?

 

[Immacomputer 10+ year member]

So should I extend the port, maybe one or two inches?

Port area is the problem, not the length of the port.

 

[coolahan 10+ year member]

Port area is the problem, not the length of the port.

...

 

[OC*SS 10+ year member]

I guess my question is how can I compensate for the extra "14mm of xmax?" I only want to do this once.

 

[PowerNaudio 10+ year member]

you need to make the port opening " port area" bigger. to allow for the greater amount of air that the subs will be moving without restriction, and to keep the same tuning, youll need to make the port longer. now you can tune the enclosure higher wich will give you a shorter port. and you may be able to get away with a smaller port area. or you can change the enclosure volume it self. to a smaller one but then again youll need a longer port to keep a lower tuning.

so i would sugest first finding the max avalible space you have for the enclosure. then see how much volume the subs needs to play at the give frequency and see if you can then fit the port.

and keep going to you find a good point where both the port area, port length and the needed enclosure volume for what ever freq you chose, fits in the availble space you have in your vehicle.

or go sealed.

or as a last resort, instead of choking the hell out of the sub, and placing them in an enclosure that is all wrong because you lack the space for a big box.

go with a single sub. building the best posible enclosure for that one sub will give you way better sound then stuffing two of them in the wrong ported enclosure.

 

[OC*SS 10+ year member]

Space is not a problem. I could probably put 4 H2's in my trunk with sufficient space.

These are the dimensions I'm getting when I simply change the "xmax" from 15mm to 29mm. How can they be so different?

http://www.subwoofertools.com/forum/ported-box.asp?Ew=40&Eh=18&Dia=9&Xmax=29&Vd=.48&NumW=2&Vb=4.5&Fb=32&Qts=&Vas=&Fs=&CE=0

All I need are dimensions but this calculator is not working for me. This is getting frustrating for a newb such as myself //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif .

 

[j3bus2k3 5,000+ posts]

Your net volume is wayyy too small for 2 15"s ported. you need to look into the region of 8-10cu.ft.

 

[OC*SS 10+ year member]

Your net volume is wayyy too small for 2 15"s ported. you need to look into the region of 8-10cu.ft.

So Orion's specs are wrong //content.invisioncic.com/y282845/emoticons/blackeye.gif.66a1670f5aaf7f406e783a63e3387dc5.gif ?

 

[j3bus2k3 5,000+ posts]

They're going to give you specs to give you a response that is going to last a long *** time but not really going to open up the driver. Ask one of the many, capabale box designers (I actually see Dante, so He'll chime in) and they'll give you a nice number to aim for.

 

[OC*SS 10+ year member]

Not sure who Dante is but I would some more input. If someone could get the dimensions right built to Orion's specs I will toss them a few bucks, or if I could go bigger and get more out of the woofers (not trying to blow them again, they're being reconed as we speak) that would be cool too.

 

[phantom240 5,000+ posts]

Well for my 12" sx i built a 4.1 cube net box.. it has 22mm xmax if that puts it into perspective for ya. Some ppl tell me thats actually a bit small for an sx... crazy