Tubular TL Subwoofer

Designed & Built by
Nick Huntington

This design is an 8' tube transmission line using a 12" Radio Shack 4-1350 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 1 1998).

Subjectively this works well and the construction is dead easy.

*The old ones were designed by Albert Von Schweikert, evidently, and they came in a white box. The current 1350A's come in a blue box. The 40-1350A which is probably all you will find anymore, has about 2mm Xmax.

Radio Shack 4-1350 DVC   Line Configuration

  Sd 856 cm2 (~90 in2)     Physical length 8 ft
  Vas 547.7 liters     Physical fs at 1/4 wl 35 Hz
  Cms 00 e-4 N/m     Begining cross section 107 in^2
  Cas 00 e-6m5/N     Terminus section 107 in^2
  Mms 00 g     Taper 1.2 : 1.2 Sd
  Fs 21 Hz     Stuffing Miraflex
  Bl 00 N/A  
  Re 5.72 Ohms  
  Qms 7.14  
  Qes .575  
  Qts 0.42 (coils in parallel)  
  Pmax 60 Watts  
  Xmax 8.8 mm  
  SPL 92.3 db/2.83v/1m  


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