Hard to believe that after forty-something years of listening to hi-fi I finds myself back enjoying single driver twin cone full range speakers. Back then I bought a pair of 8" twin cone Kaltros to go with my very first Rotel based hi-fi system. Of course the 6" twin cone Fostex FE167E driver is far superior to the Kaltros but he Kaltros took an absolute pounding at the hands of Jimi Hendrix, Stones, Cream and a bunch of others. Not once did they whimper.
With the Fostex drivers comes two sets of box designs. A more complex one in which the top part of an integrated stand is part of the port loading and a simpler design 15L enclosure with a 50mm X 50mm reflex port. I built the simpler one. I really only built the speakers at alll because I needed an efficient speaker system to go with the two 6T9 valve amps I had just finished. At 94db efficient the 4.5W 6T9 amps drive these compact boxes with ease and at good volume levels.
The boxes were glued, nailed and clamped during drying. The internal back of the box is lined with dampening vinyl and all interior walls have a layer of Dacron. Grills were cut from the same thick 18mm particle board with black speaker cloth stretched over them. The grills are retained to the boxes with heavy duty Velcro. There is no Xover and OFC medium gauge speaker wire was used for hookup. For listening notes see article above.