Box shape

[Diceman83]

Well, I got even more ambitious... I made a CAD model of it

[ Wire Frame ]

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[ Shaded with dimensions ]

[ponchonutty]

Originally Posted by Diceman83

Well, I got even more ambitious... I made a CAD model of it

[ Wire Frame ]

[ Shaded ]

[ Shaded with dimensions ]

Well, ok. What's those little boxes the tubes are connected to? Those little boxes open? If so, you are messing up the frequency and it probably won't sound good. Also, I usually keep the port inside the box because it just looks better. The only time I don't is if the box is too small or port is too large or if I'm building something strange like a 4th order box with the port going up through the rear deck of a car.

Personally, I'd just go with a sealed box but that's just me.

[Diceman83]

Originally Posted by ponchonutty

Well, ok. What's those little boxes the tubes are connected to? Those little boxes open? If so, you are messing up the frequency and it probably won't sound good. Also, I usually keep the port inside the box because it just looks better. The only time I don't is if the box is too small or port is too large or if I'm building something strange like a 4th order box with the port going up through the rear deck of a car.

Personally, I'd just go with a sealed box but that's just me.

It is sealed... I'm just trying to distribute the volume around the inside of the trunk to maximize the usable space in my trunk. I'm planning to make it out of 3/4 MDF with 3" diameter PVC pipes connecting the main chamber to the two smaller chambers. I'd use permanent glue on all but one of each side of the boxes with a silicone seal on the last side so I can open them up easier later. I'd probably use high strength epoxy with some screws embedded in the side of the main box to attach the tubes.

[CBFryman]

ummm im not seing why you need to do tis, why not make one larger box made to fir around the corners and all in your trunk? these 2 extra chambers conected via a smaller tube may cause some scary dampening factors.

[ponchonutty]

Well, I'd still just go with one big box instead of what you are trying to do. I know you are trying to save some space. You should of thought of that before buying a subwoofer requiring that kind of space.

[Diceman83]

Well, the bigger center chamber is technically big enough for the sub, I'm just trying to get closer the maximum rating. I can probably just get rid of the side boxes if it really sounds bad, but I'd like to do some tests anyway. If it's really bad, hey, I can just sell them as a premade sealed boxes that someone can put a hole into. Has anyone ever tried anything like this? We can put it down in the history as the first (and probably last) attempt at multiple sealed chamber subwoofer enclosure design. Wow, that was a mouthfull.

[bumpinstang77]

Originally Posted by ponchonutty

Well yes and no. Most other sub makers can have a sub tuned to the same frequency as these you talk about but in a box 1/2 the size. I know it doesn't really matter to you guys. It didn't back when I first started either. Today it does. I don't want a 10cu/ft box when I could have a 3cu/ft box sound as good or better. These subs you guys like requires large boxes because the motor structure is weaker and that is also how they are tuned. They are just a copy off of their home stereo line.

You don't know what your talkin about...... A weak or strong motor structure has nothing to do with box size. Take a look at ohh lets say an XXX it need a hell of a lot bigger box then a brahma, but has a significantly stronger motor. Take some of your beloved directeds (the sx model since its the only one on their site) Let's compare it to RE's SE (12's) since they should be pretty close to each other. The directed has a BL of 25 (bl is motor strength) the SE has a BL of 17.1. And holyshit your precious directed sub needs 3.762 cuft. for a .707 alignment. Yea and the EBP wants it sealed (not that it matters a whole lot) Ported...... well that sub is wierd b/c the graphs of its response are fine at 2.5 cubes ported..... yea I guess you can't seal it....... even though its phtsically better for a sealed box. What a shame.....ok on to the SE........ 1.6 sealed for a .707...... 2 cubes ported...........hmmmm I guess BL has NOTHING to do with box size. BTW about your "HT subs" comment. No RE sub is build for HT...... they're strictly for car use....... brahmas are made for in car use along with kodas (shiva's and tempests were made for HT but work well in home) And Ascendants subs were specifically designed to work in car or in a room.

[GSteg]

arguments and debates are getting out of control! lol

here are my pennies:



even though some subs are generally designed for car use, they are usually ok in a Home audio application also. the sub itself does not care what environment it is in. One of the bigger difference between car audio and home audio is the constructions within the woofers. Take say a mid 1990 subwoofer and throw it in the car. chances are, the surrounds are weak and it won't stand up to the car environment as well. You can use an Directed sub in homes just like you can use an RE xxx. i have witnessed the xxx in home when my friend was testing out his 3.5 cubic feet box for his 12" sub. yes it rocks. lol.


secondly, the strength of the motor does have something to do with the box size, but i generally don't really go around saying its very proportional to each other. generally the stronger the motor, the better it will allow you to play in a smaller box. Of course there are always other variables involved.

Last thing before i go off playing with my new toys, when we refer to motor strength that corresponds with box sizes, we are usually referring to the Qes, not the BL, even though the BL is a reference to motor strength. The Qes is a much better indication of motor strength than BL is when it comes to correlating motor strength with box sizes. The lower the Qes, the stronger the motor. Why BL is not the best way to indicate motor strength is because say you have a dual 4ohm in parallel (2ohm) with a peak BL value of 12 N/A. Wire the dual 4 in series and you get 8ohm and your BL also changes to 24 N/A. Despite the value being higher, the actual motor force does not double.


i'm done. sorry if i offended anyone by just coming out and spilling out my jibberish. I didn't read the whole thread though.

[Diceman83]

Well, as long as we're talking technical, here's a chart showing my sub's specs:



Mine's the one on the right (the dual 4 Ohm model).

What parts of this are important, and how do I translate it into optimum box size?