PERISCOPE Full-Range Transmission Line loudspeaker. by Giuseppe Pipitone Materials Used: Two Parts Express drivers (www.partsexpress.com part n. 269-469). Two thick water pipes (In Italy the brand name is Silere) of 105 mm of inner diameter and 8mm thick walls. Two 90 degrees junctions for the aforementioned pipes. Two small boards of MDF, 19 mm thick, to be used as (small) baffles for the drivers. They have to be glued to the pipes. Glue, lambswool. Drawings: feet like rocket stabilizers. The line is 95 cm long and, starting from the back of the driver, is stuffed with natural wool all but the last 20 cm. The loudspeaker must be kept above the floor. I employed three "fins", made by MDF, fixed by glue and a screw, going from the inners side of the pipe towards the outer side, you can see the drawing in the next picture. After this addition it looks like a hybrid between a rocket (bottom side) and a periscope (top side). Final Considerations If I think about the effort to build the things and I take into account the money I spent, I have to admit that, especially in rooms not too large, they sound astonishingly well. The subjective extension of the bass range, its intelligibility, the ability to build a realistic sound stage and the feeling of no veils between you and the Music are the most remarkable aspects of what you hear when you seat in front of this couple of singing pipes. But you must keep in your mind you will not get any kicking-in-your-stomach-bass. Before I conclude let me suggest that I suspect that some similar full-range driver with a lower Fs (Fostex Fe-103?) could possibly work even better. Top