[DIY design] Overboard subwoofer

DIY Overboard subwoofer!

Construction scheme

Product: DIY monster subwoofer
Company: not for sale, TNT-Audio free DIY design
Approx. cost: 160€ each woofer (x4), 120€ woodwork, 120€ crossover. Gross total: 880€
Author: Chris Templer - TNT SouthAfrica
Published: May, 2013

Construction of our extreme sub woofer tube is very simple. Screw and glue the tube sections together as per Fig. 1.
Note the staggered layout. This is so the tube will be square. If wanted brandering could be placed running down the corners but it is not necessary.

[Subwoofer scheme]

After doing this you have 2 X 2,800mm long tubes. Screws should be no further apart than 80mm. For the sake of simplicity and ease don’t join them yet. I only did the final join after the sub was almost in position.

Pick a tube and fit the 4 end bracing sections. These 4 sections should also be fitted as per Fig. 1 overlap scheme. Glue and screw but check there are no screws where you will mount the drivers.

Mark the position of the drivers and make the cut-out’s to suit. I positioned the drivers, 2 side by side, 1 set on the top and the other set on one side as the final resting place was hard into a corner and against a wall.

Before mounting the drivers join the 2 tubes together by means of the 4 Join Sections as per Fig. 2. These are only screwed together so that it can be disassembled. Now fit the drivers. I used cap screws and Nylock nuts. You need someone to go inside the tube to hold the nuts with a spanner unless you are a long armed octopus. Now fit the End Caps (2 layers). Screws only as you might blow a driver and need to get to the bolts without mining equipment.

Move the sub into position and add damping to suit. I used half a roll of Dacron but fiber glass wool or carpet underfelt is just as good. Damping in mine is in the open end for about 500mm only.

Wire the drivers. In mine 2 each in parallel and then those 2 pairs in series. With 8 Ohm drivers that will end up at 8 Ohms again. Keep the polarity correct in the harness and likewise in the system. With mine the point at which the sub comes in is 20Hz via a 18dB/octave filter but it works very well if a higher frequency is used. Sizes are not critical so if you need to scale things a bit feel free, my first version was 4,000mm long and 400mm square with 3 X 15" drivers. It just got better when I went bigger.

Refer to the pictures. The assembly of the sub took less time than drawing up this set of instructions :-)

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