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Over the course of several years I have built seven subwoofers. These were all designed using WinISD, allowing different drivers and port arrangements to be explored. See the WinISD page for more information on obtaining and using WinISD.
Each project generally includes the following three WinISD graphs....
The WinISD values are for radiation into "Half space". In reality, most subs will be located near a wall (add 3dB) or in a corner (add 6dB). Room
gain can add around 6dB@10hz, 4dB@20hz and 2dB@40hz. Vent velocity Most
important because if the air is too fast, turbulence will be audible.
Using a larger diameter port will cut the speed, but the length increases
with the area of the port, thus my use of external ports in two of the
designs. Cone excursion With
a ported design, cone excursion below the working range of the port can
become a problem. This will be audible and ultimately destructive to the
speaker.
Flare-it screenshots The flare testing mentioned above, culminated in the writing of the Flare-it calculator. Each project has a screenshot showing how well the port flares perform. In most cases this analysis has been done after the sub has been built. Where "chuffing" is predicted, a second screenshot shows what sized flares would be required to fix the problem.
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About the same size and shape as a beer fridge, it worked well enough for a first effort at DIY. I was enthusiastic at the time, but looking back I see it was just a box with a hole and no soul, much better was to come!
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The
Sidewinder
With this one, I started to become a bit more adventurous with the presentation. I came to see that a ported sub needs to breathe. Of course large diameter ports mean really long ports which don't like to fit inside your box anymore. I think that DIY subs should be something to be admired - after all we spend a lot of hours building them. I made this one for looking at as well as listening to, with external ports wrapped around the side and veneered. Includes gallery of different views
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So called because the twin chamber, dual ports looked a bit like one. My third subwoofer gives plenty of grunt down to 25hz. With this one I decided to dispense with the veneering and make the most of the MDF. With three coats of polyurethane it acquires a honey colour which can be quite attractive. Includes construction gallery and graph of measured response along with a comparison with commercially available THX rated subs
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The name arises from the internal ports, which are folded into a snorkel shape. This is basically a "Beer Fridge" clone in terms of output, but smaller, with a better build and finish, and no port noise complaints
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Buddy
Subs
A pair of "Buddy" subs which run in parallel with the "Blast Furnace" This gives extension to 17hz without loss of Peak output
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Limited space dictated a slim design for this one. The internals of the original "Beer Fridge" were recycled to come up with "Slim Jim"
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A chance came to try an EBS design (Extended Bass Shelf). This sub uses the same amp and driver as the "Snorky" design, and has a pair of 20mm heat molded flares which are fitted with donut rings on the intakes
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The latest creation is an Infinite Baffle sub. It contains twelve 15inch drivers on two manifolds. The design is the IB12 investigated on the 15inch Venom driver page
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I hope you enjoy reading about my subwoofers as much as I have enjoyed building and listening to them
Last
update to this page 30th April 2008
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