Moving the driver down will help null a ripple at some point in the FR curve, but the pipe still acts like a pipe.If you study Martin Kings page and Bobs page you can see that the upper closed area acts like a throat.The smaller the throat the longer the pipe. I had many misconceptions about TLs and horns and such when i first started building single driver TLs , TQWTs and horns.But after building about 10 of varing designs and actually measuring the results i came to the realization that you cant beat the physics of quarter wave designs.I was designing (using a very advanced waveform/pressure program) a 300 hz front horn for my currentFL/BL horn design. Well the results were that it was a great deal shorter than i had believed it would be. Its then when i realized (with some study suggested by GM)that i wasent violating the quarter wave principal due to the increased throat which makes a shorter horn. ron