What exactly are the Q's? I know they are related to how to build the perfect box for that specific driver, but I am not sure how to relate them to the dimesions of the box. I just bought 2 Alpine ZR 12's, and now I need to make the box for them. I know how to make a box, I am just not sure of the dimensions. Also, I want to make the front of the box out of Plexiglass, for show. Here are the Q's.

Sealed Box for Q=0.707......0.85ft.^3
Mechanical Q (Qms)..........6.64
Electrical Q (Qes)..........0.35
Total Q (Qts)...............0.33

Can somebody tell me how to relate this to building a box for them? Thanks.

 

to have a sealed box with 0.85 cubic feet, the Q's don't matter as much. You can use those #'s (as well as a few other would be needed) to run them in a program to get te correct size box needed. I'. asuming you'll be using at least 3\4" MDF, here are some rough sizes to play with. a Sealed box, with .85 cubic feet, (not including 10% for speaker magnet) is 14"wx14"hx11"d. Including the 10% it would be around 14"wX14"hX12"d. Remember that this is the size needed for each sub. To get the best sound they DO need to have their own chamber sealed off from the other.The total size for one box with 2 chambers including a divider should be roughly 28.5x14x12. Hope that helps.

 

Are those Exterior or Interior dimensions? BTW, I am going to be using 3/4" MDF. Thanks.

 

Those are extrnal. Sorry

 

how did you get those numbers? It's about time for me to build a box for myself too.
________
Brunette movie

 

They came with the Subs.

 

fs - speakers free air resonance
Qts - speakers total Q factor
Vas - speakers compliance stated as equivalent air volume
Qtc = 0.707 gives flat low frequency response
Qtc > 0.707 have a bump in response above the Fs and quickly drop in response below this point.
Qtc < 0.707 have greater low frequency extension at the expense of output and power handling.
a, alpha = (Qtc/Qts)squared - 1
Vb, sealed box volume = Vas/a

These formula's are for sealed boxes and not all drivers respond well to a sealed enclosure. Alpine has already done the work for you and calculated the sealed box volume. This is the internal volume not including any bracing, ie, just the volume of free air. Alpine may have(probably) given the volume of 0.85 ft3 with the volume the sub takes up already considered. If not then do as Whitemax suggested and add 10%(0.85+0.085=0.935)for the volume of basket, motor assembly, etc. I believe Alpine and most other speaker brands provide recommended encloure types and volumes. This is because no matter how much work goes into a formula they can not guarantee that the speaker will respond as indicated. So the manufactures - who have lots of drivers and box builders/programs, build test boxes to find what works the best.

 

http://www.kbapps.com/audiodesign/calculators/index.htm

has a nice calculator for em....

for sealed..

what type of speaker

also seach google for iasca faq ... there is an entire section devoted to speaker box building.. and carpeting..

enjoy