Ok,
When designing and building a box is the displacement of the speaker taken into account? For instance if a sub enclosure has 4.5 cubic foot of air space inside of it before the speaker is placed in the box does the actual speaker reduce the air space when placed in the box. So if the volume displacement of the sub was .5 cubic foot would the box now only have 4.0 cubic foot?
You follow what I am getting at?
Is this an issue or is it irrelevant?

Next,
From what I have read the actual frequency inside of the box can effect the subwoofers performance especially in a perfectly parellel box where the frequencies bounce off of the back of the box and come back directly at the sub. Would a couple of layers of dampening material or liquid solve this problem? Would loading the box with certian angles help this situation?

Finally,
There are neverending debates on the perfect enclosure. I accept that. But my goal here is to gain the knowledge to make whatever enclosure you are looking at getting/making perform at it's maximum potential.

Guidance from the knowledgeable is paramount!

 

You need to go through and delete one of these posts. No need having two. :D

 

you are correct if you have a 4.5 cuft box and you have a sub that diplaces .5cuft then the box has a air space of 4cuft

as for the box size...a sealed box the amount of airspace you have will dictate the boxes sweet spot most sealed boxes are arpound 40hz or so thats why lots of people stuff there boxes with polyfil or fiberglass insulation because it changes the properties of the box allowing for deeper bass notes....for a ported box i don't think the amount of airspace matters the only rule of thumb i know is if you build a bigger box (larger than specs call out) the port will be shorter...if its smaller box (smaller than specs call out) the port will be longer...but the bigger the box the deeper you can set your tuning freqency but there is other variables that will affect this as well like the speaker itself the port size and shape (round or slot) the amount of power the sub will recive...also you should keep in mind for a sq ported box you have to keeep in mind the port velocity so you don't get port whistle or port noise...i hope this helps and isn't to confusing

 

My subs came with a pamphlet that was very detailed. It had the optimum volume and specified that didn't include the .08 the sub took up (ie, I should add another .08 to the box). It also had another spot that told the total volume in case I could not add, I suppose. This would lead me to think that typically the specs do not account for the displacement of the subs. Also, the polyfill is a very good idea. I usually ripped apart an old pillow and fluffed up the fill and threw some in. It sounded MUCH better than the box I built w/o.

Also, the pamphlet was very specific about port size and length for the ported boxes and gave expected port noise long with the other measurements. I'm sticking to the one with the least port noise (not as deep bass and not the most SPL, but I prefer sealed anyway).

 

I have not noticed comments about passive radiators in any of the comments on enclosure construction in auto sound forums that I have read, admittedly few. Are passive radiators no longer in use? I would think that smaller enclosure size would be helpful and understand that smaller enclosure size is an advantage of the passive radiator enclosures.

http://basszone.stryke.com/thunder12.htm

http://www.diysubwoofers.org/prd/

 

from what i have been told a passive radiator box would have to be huge and the performance that you would get wouldn't be very good

unless your talking about a solobaric with a passive radiator then i could see the box being small

 

Angles and smoothed surfaces within an enclosure can make a big difference! Passive radiators are in use but not that frequently so I wouldn't put it into my calculations at all.

Volume, cuft of enclosure, port space, size, tuning frequency, resonant frequency of vehicle, amp power, sub motor strength, all of these and more will play a factor in your ultimate accomplishment.

Kind Regards,
Matt

 

Airspace, depending on the specs.. Crossfire manual will give you an displacement including sub but not including port.

You dont want a perfect sq. or rectangle.[/quote]

 

speaking of poly-fil . anyone know where to get some cheap? and how much would be needed for a 12" sealed hatch style box?

 

Try walmart or any of your local fabric stores for polyfil sometimes they have it on sale or if you want better find a place or a friend that has so R-19 insulation laying around use it...it has better acoustical properties

 

There is no exact amount of Polyfill to use. Just keep adding and/or subtracting until you get the exact sound that you are looking for.

Kind Regards,
Matt

 

Has anyone ever heard of professionals using concrete encloures?
That sounds insane.....

 

There is some infomation about enclosure desing here:
http://www.jlaudio.com/tutorials/boxdesign/index.html
There is information about enclosure types here:
http://www.jlaudio.com/tutorials/magic/index.html
There is information about porting here:
http://www.jlaudio.com/tutorials/ports/index.html

Happy learning! :D

 

Concrete is used in extreme competition vehicles for the floorboard, dash, etc. The vehicles become trailer queens in this case.

Matt

 

So I had a dream last night......
It was about a sub box....
I went to the car audio shop and I asked their opinion on the best materials for box building. Well the installer takes me to the side and he is like "check out this new technology". The box had two layers of wood and I noticed there was like a filling in between them. With that he commented "do you know what that is"? "No" I replied....
"That's play dough"......

Then I woke up.....but I've been thinking and I think I might have to patten that Idea before someone else does.....

I'm fu#^ing crazy man......

 

For polyfill, just go to the crafts section in walmart and it is called poly pillow stuffing or something like that. Dirt cheap

 

Years ago a company called Dynamat introduced "Dynaboard" which was sheets of double-thick wood with sound-deadening sandwiched in-between.

 

poly fill is in pillows, so you might could buy those cheaper or use old ones.

 

I guess the important thing is that the box is 100% sealed......
When I get my new box I'm going to check all of the seals and reinforce them if necessary.....

 

we sell polyfill at walmart, $2 for a big bag that could fill a good sized box for a single 15, maybe 2 12s, and deffinately 2 10s