Tubular TL Subwoofer Designed & Built by Nick Huntington
This design is an 8' tube transmission line using a 12" Adire Audio Shiva DVC driver. The driver is siliconed directly to the tube and sits on a milk crate to facilitate the terminus. Fortunately I have 9'8" ceilings! The line is stuffed with miraflex to a density calculated using the equation from John Cockroft's Speaker Builder Magazine article for a Hybrid TL (Speaker Builder One 1998). Stuffing density is 0.66 lb/ft3mSubjectively this works well and the construction is dead easy. For those where a 8' line is impractical, a version with a 6' tube and a stuffing density is 1.0 lb/ft3 would probably work out. There might be a slight loss of efficiency with the same diameter tube, but tube diameter could be increased to compensate (at the expense of more work -- you wouldn't be able to just attach the woofer to the tube). A Radio Shack 4-1301 DVC was used in an earlier verion, with good results Requires a driver that can be mounted facing up.You could though, lay the tube on its side, which would the mount the woofer in a conventinal orientation. Nick has also dissected the AQA Bass Box for us. Adire (aka Avatar) Shiva DVC Woofer   Line Configuration     Sd 481 cm2 (~75 in2)     Physical length 8 ft   Vas 144 liters     Physical fs at 1/4 wl 35 Hz   Cms 0.44 mm/N     Begining cross section 107 in2   Mms 118.3 g     Terminus section 107 in2   Fs 22 Hz     Taper 1.2 : 1.2 Sd   Bl 10.70     Stuffing Miraflex   Re 2.82 W per coil     Qms 10.72     Qes 0.40     Qts 0.38 (coils in parallel)     Pmax 350 watts per coil     Xmax 15.1 mm     SPL 87.7 db/1W/1m
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