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What Is a Proper Sub Box?

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Copper - Posts: 81
Copper spacespace
Joined: January 13, 2010
Location: Florida, United States
Posted: January 13, 2010 at 5:49 AM / IP Logged  
forbidden wrote:

No it is not a form of isobarik loading. What it is is two drivers sharing the same airspace. It is commonly referred to as a common chamber. A common chamber can be used for a variety of sub boxes, most often though you see it in a sealed or ported enclosure. The purpose behind a center divider is two fold. One, it separates the two drivers so they do not interact with each other. If you have a failure of one driver, the other will still operate properly in it's given airspace while the other one is being warrantied or replaced. The second function of a center divider may be to isolate two different drivers and their required internal air volume requirement. The primary purpose for me when I build a box with a center divider, is to keep the box walls from flexing. Flexing walls is power being robbed from the output of your subs and causing the walls to move. Keep the walls as strong as possible to keep this from happening at all costs.

A coupled chamber box can also be made slightly smaller due to an effect known as Mutual Coupling. This allows the drivers to operate as one larger driver and has in my experience also gained that extra little bit of output. Note that in a common chamber box, the subs should be mounted as close together as possible to get this extra little gain without making the baffle board extremely weak between the area where the two subs are closest together. This is where that little center brace comes in that can be drilled out with large holes to allow the air from each side of the cabinet to interact with each other. Sometimes it is also beneficial to double up on the baffle board at the same time. In practice in a common chamber box, I have been able to shave off about .1 cubic foot of volume from each chamber when building a coupled chamber box.

With this Common Chambered box, I'd like to find out if when figuring out the cu.ft. of the box, do I figure it as 1 sub or do I have to multiply by 1.5 or 2?

Ex: 1-Kicker S10L7 needs between .66 cu.ft. and 1.0 cu.ft., to put 2 of the same subs into a common box. Would I need to have space for 1.32-2.0 cu.ft. or would I need to be somewhere inbetween?

Member - Posts: 1
Member spacespace
Joined: April 14, 2010
Location: Illinois, United States
Posted: April 14, 2010 at 9:30 PM / IP Logged  
Are angled boxes still known to be better that square, or rectangle boxes. Ive been building boxes all my life. Only in the last couple years did I switch to strictly angled, sealed boxes.
Ive put a lot of hours into this current sealed project, and started wondering if I was wasting my time with the angle stuff.
Thanks in advance, and I'm glad to be part of the crew. I
This site has already helped me immensely. Thanks 12volt
bump bump bump
Member - Posts: 9
Member spacespace
Joined: July 11, 2010
Location: Louisiana, United States
Posted: July 11, 2010 at 12:02 PM / IP Logged  
I build sealed boxes for my rides. I've quit using screws & nails. I use biscuits & carpenters glue with plenty of clamps. I seal the inside with 3M sound deadening spray. If I plan to paint the box I seal it with fiberglass first. I use bracing if needed. I never have a box to leak with my construction methods. I cut all my pieces the same length or width with the saw set once so they are equal sizes. It takes longer to use the biscuits ,clamps & glue but it makes a fine box. I have dn firing box in my truck. It hits hard & has good frequency range. I build SQ systems not SPL systems but I like to be able to shake the truck& get loud. Why have the power if you don't use it to be loud at times. You can't get too loud.
If the listening level is to high promptly tell the driver so he can put you out of the car
2003 Ranger Edge White
Boston Pro tweeter & Anarchy 6.5 mid bass
Elemental Design e5.10 sub
JL Audio 500/1 & Phoenix Gold ZX475 Ti amps. 0 g power cable
Big 3
lada niva 
Member - Posts: 1
Member spacespace
Joined: November 29, 2010
Location: South Africa
Posted: December 12, 2010 at 3:59 PM / IP Logged  

I fail to understand why particle wood can not be used for sealed boxes if the box is painted properly (or covered in fibreglass). The wood of the painted box is then sealed of from moisture and can therefore not absorb additonal moisture; so nothing can happen to the wood. All boxes must be constructed solidly and according to the material and jointing materials used. Particle wood inherently will resonate less than MDF or fibreglass because it is less dense.

I built a box from particle wood recently and started out with thicker wood than realy required (from the outset I wanted the box to be heavy to lower resonance and to experiment). Joining the sections together is very easy and no care have to be taken when using the correct lenght of dry wall screws, becuase the wood is strong. Always use a lot of carpenters glue and seal the seams of the box in the inside with a mix of glue and wood shavings (wood glue is much stronger than wood). I simply painted the box on the inside with Plascon trailer coating after assembly. 

The outside of the box was smoothed/finished with body filler ( (a winner on particle wood) for aesthetical purposes and to protect the wood from moisture. The box was also painted on the outside with spray paint (it will be covered with printed vynil next week for the looks).

Conclusion: Construct the box properly and seal it with paint and there is nothing wrong with particle wood. In fact, you will be very proud of your box. Tip: Build your box with thick particle wood and paint it inside and outside with at least two coats of Plascon trailer coating and you can use the box in the load area of your LDV. No worry about scratches and bumps (moisture - what moisture).

I will paste a picture later and report back after a year on the performance of my box made from material better left for kitchens. Only one guess who is going to laugh last!

I fly because I can. SQ because I love and respect quality and creativity of all involved.
Member - Posts: 2
Member spacespace
Joined: January 23, 2011
Location: Florida, United States
Posted: January 23, 2011 at 3:19 AM / IP Logged  

If you are not an expert the best box to build is a sealed box.  Reason why is if you are off on the box volume its not going to be a huge issue unless you are way off.

If you are an expert or have been doing boxes for a while, the best box to use is a ported box.  Some people will argue the fact because they do not have much experience with ported boxes or have built them and it came out wrong.  When building a ported box, NEVER EVER go with the smallest size they recommend.  Best rule of thumb is go half way between the max and the min. recommended, and adjust the port length and area accordingly.

If you are doing a SPL system, you can go for raw horse power and do a large number of subs, in boxes a little smaller than recommended (but only if you are doing 6 or more subs, if not it will sound horrible), and if you are doing Ported you are going to want to call the company that makes the subwoofer, and let them know what you are building and how much power you are using and they will give you very different specs than what they show in your owners manual. 

So all in all to answer the proper box question, it comes down to what you are doing, and what you are looking to get out of your system, and your experience level of building it.  Also I want to note, just because you go to a stereo shop doesn't mean they know how to properly build ported boxes.  Best bet is to talk to the company that you got your speakers from and ask them who the best local shop to go to for custom boxes if you are looking to have a shop build your box.  I live in Orlando FL and I would say maybe 30% of the shops/installers here have installers that can make a proper box.  The other 70% I am sure someone with little to no experiece can do just as good as a job by going to home depot and getting them to do your cuts and bring the wood home and put it together yourself.  But one warning, if you have no experience with ported boxes, I will warn you, that if you are off a little here and there you will blow up your speakers pretty fast, or in the best case, you will not blow them up but it will sound horrible.

Audio pump
Member - Posts: 18
Member spacespace
Joined: February 03, 2009
Location: Oklahoma, United States
Posted: September 06, 2011 at 7:48 PM / IP Logged  
can I stuff my bandpass box an it still sound good
Trent Schmidt
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