In a TQWP the tapered pipe is folded in half, but the theory is the same, it just makes a more conventional looking cabinet than a 6 foot high tapered pipe. By tapering the pipe the re-enforcement is 'spread' over a wider range of frequencies and it also has some 'horn' characteristic. The 'quarter wave' refers to the length of the pipe, which is a quarter of the wavelength of the frequency you are trying to re-enforce - sort of like an organ pipe or blowing over the end of a bottle. The idea was that putting a drive unit half way down a pipe you'd get a bass resonance that would boost bass output. Back in the '30's that pioneer of hi-fi Mr P.Voigt designed the Voigt Pipe. They also allow access to unusual designs not usually seen in the commercial world, the IPL's transmission Lines, the PMT 'tubes' and now a TQWP from BD-designs.Ī Tapered Quarter Wave Pipe (or sometimes Tube - hence TQWT). The savings that can be made are considerable and rely on pretty minimal woodworking skills. In the past couple of years I've tried to have a look at some of the more unusual kit loudspeakers that are available to the home constructor.
