Posted by Bob Brines [ 148.63.220.187 ] on December 12, 2005 at 09:50:55:
In Reply to: folded voight pipes??? posted by Jim Denton on December 10, 2005 at 11:34:10:
The "Voigt Pipe" is a design attributed to Paul Voigt, incorrectly, I might add -- Voigt's patented tapered pipe is completely different. It is tapered front to back, coming to a point at the top and being rather deep at the bottom. The driver is roughly 1/2 way down the pipe and there is a port at the bottom front. The best known "Voigt Pipe" is the Lowther Club of Norway design. This design most likely used the PM6A or PM6C.
Any "Voigt Pipe" can be folded, that is bent back on itself 180 degrees. The front then is the original pipe from the port up to the driver, and the top part of the pipe folds back toward the floor. In the case of the LCN pipe, this will reduce the height from 72" to ~ 40" high. A variation of the folded "Voigt Pipe" is the "Weems' Pipe", named after David Weems.
Neither the LCN "Voigt Pipe" or the "Weems' Pipe" variation are very good designs. They were build empirically without any real science behind them. They suffer from significant and very audible roughness in the 100-500 Hz range, right where the music is. Now that we have Martin King's worksheets, we do much better. You might investigate the MLTL design.
BTW, although I may get flamed for saying so, the "Voigt Pipe" is really a type of back horn. All of the same physics apply.
Bob
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