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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