Does anyone have the formula for determining the resonance of a tubular speaker enclosure? If I remember correctly, there are two scenarios. One has both ends of the tube open and one has the speaker end closed. I'm trying to build a "tunable" enclosure for cw work which will "peak" and "clean" signals between 6-700 hz on CW. I have long misplaced the formula. I think it was something like L=1100/f or something like that for both ends open. Anyway, thank you all in advance for helping this old guy to remember something... Bob.