Hi Steward, i choosed a tension that works well in 440 on the extension of my theorbo. Changing to 415 caused the 8th course to touch the fretboard when playing very loud, but putting something under the saddle on the extension (about 1mm) increased the forward pull on the extension so that this is not a problem anymore. I can now change from 440 to 415 without changing strings or doing any corrections on the saddle and do not notice any effect on the angle of the extension. I guess the key is that if the diapasons are parallel to the fingered strings (and extension) the effect on the neck with a different tension will be much less.
I change the tuning quite often between 415 and 440 - so far this was not a problem. Maybe you could get around the problem by doing adjustments on the upper saddle (like using different saddles for 415 or 440 to keep the angle of the neck)? Do the others on this list change the strings on their instruments between 415 and 440? Benjamin To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
