2 Sundown Zv5 12

[Miles5252]

I’m trying to learn how to build sub boxes. Any advice/pointer will be greatly thankful. Any software recommend? How to do it pen and paper? I’m open to learn anyway. I’m trying to start with 2 Zv5 in my 2010 Challenger. 

[JohnP]

Hi Miles,

 

I'll share what I know, have lived, built, and continue to learn from even after forty plus years of fun and games in audio... 

 

 To paper and pencil engineer out the dimensions for a ported, n-th order bandpass, or even sealed enclosure is a topic far beyond one response in a thread.   It's a headache of math, physics, and rechecking your math over and over.   

 

The good news is there's a proliferation of box software out there and all one has to do is search online for it. Parts Express used to sell a variant on BoxCad for about one hundred dollars or so however I'm not sure if they still do.   I used to use free boxware called "Win ISD" however it was limited to simple ported and sealed enclosures and was available back in the days of Windows XP.   I have no complaints at all about it and it worked for me.  

 

What you want to look out for with Box Software:  Can you manually enter the T/S  (Thiele/Small ) parameters for a given speaker or are you constricted to only what comes with the software and is available through some kind of licensing agreement you may or may not be receptive to ?  Is it limited to only sealed, ported, and what kinds of enclosures are available ?      Is there a "freeware" version you can try before you buy ?  

 

Better news:  Most car audio speaker companies will have a recommended box design you can use directly or enter the dimensions into your boxware of choice to get an idea as to what kind of an enclosure you want to work around or to given the dimensions of your vehicle and expected frequency response curve.    It is all in the response curve (Also called a "bode plot") as to what you hear however pay attention to the cone resonance (Fs) of the speaker as putting a little woofer in a big box with a sewer pipe sized port long as your arm probably won't yield "gobs O bass" rather a blown speaker suffering an out of control cone. 

 

Must haves:   

 

Tools:  A table saw, plunge router, circle cutting guide for the router, shop vac and dust catcher, good solid drill/driver , builder's square, speed square,  vise clamps, screw clamps, bar clamps all go a long way.   Yes it represents a huge out of pocket investment however if you want in this hobby and intend on building boxes the investment is best made at the start.  Yes it's cheaper to order a generic ported or sealed box that may or may not work best with your speakers.  

 

What I've found is 3/4" MDF,   2 x 4"s ripped into 2" x 2" for internal  bracing at every seam, construction screws every six inches at every seam, and construction adhesive are by far the best.  Even a modest sized box can be a boat anchor using this stuff however one can't beg, borrow, buy, steal, swap or swindle a more airtight enclosure.    Pre drilling holes for the screws and countersinking them also prevents the internal braces from splitting.  

 

Practice, practice, practice.   Run some scrap lumber through your table saw and cut some circles to dimensions using your plunge router to get used to how they feel and what to expect.  Speaker building is by no means a spectator sport.     Learn how to use a "push stick" with a table saw as NO speaker box is worth lost fingers. 

 

It also does not hurt to be willing to screw things up, learn from your mistakes, and laugh at yourself.

 

Best,

 

JohnP