Revision as of 17:00, 8 February 2008

Miata Trunk Sub

Preface: I've only done the math and selection for 10" woofers. I'm going to assume if you want something bigger and badder that you dont care about small trunk subs. I think 10 inches is about the sweet spot for size and output when given the constraints of the Miata's trunk.

Woofer Choices (to get you started)

Here are a few subs you can use in various price ranges.

• Tang Band WT-1427B 10" Neo Subwoofer ($59 on special at partsexpress, normally $87)
  You will get decent sound out of this for the money but it probably wont be eardrum crushing loud.
• Dayton RSS265HO-4 10" Reference HO Subwoofer 4 Ohm ($126)
  This will be pretty loud.
• Want it even louder? Build two of each!

Easy box size for the above woofers

Due to the flexibility of the design, all dimensions are +/- an inch or so but if you decrease some, increase others ok? OK. All use 3/4" MDF--the standard.

• Smallest Length and Width: 11" x 11" x 8-1/4" outside dimensions
• Thinnest for the Tang Band): 14" x 14" x 5-3/8" outside dimensions
• Thinnest for the Dayton HO): 12" x 12" x 7" outside dimensions
• Whatever you want: Just make sure the total volume is between 600-650 cubic inches. You can take the outside dimensions and subtract 1.5 from each (two .75" thick walls) and multiply them all together.

Example 11x11x8 box:

11 - 1.5 = 9.5
8.25 - 1.5 = 6.75
9.5 x 9.5 x 6.75 = 609.2in^3

Tuning your trunk sub box

• If it's rattly but doesn't have punch, remove the stuffing to decrease the apparent volume of the box.
• If it's too punchy/chesty and makes your hair twitch but doesn't have any deep sound, it's too small. Add a bit more stuffing to increase the apparent volume.

What else should I be aware of??

• It may be easier to find non-car subs with these numbers.
• As far as the CAR is concerned, I did nothing to the tunnels or parcel shelf. Just threw a box and big amp in the trunk. Works like a dream.

Warning about using other subs!

Not *every* sub will work for this. Some will be close and some will not. Some good starting points for Thiele-Small Parameters are: Fs: between 20-28 Hz Qts: between .25-.35 Xmax: bigger is better if you want it loud.