<html> <blockquote type=cite class=cite cite>  What's the main culprit in causing the tuning to drift in a concert situation -- the humidity or the temperature?    --David Nereson, RPT </blockquote> David,    Temperature. The data I collected for a class in Nashville blew me away. I watched pitch go all over the place in minutes. It really only takes about ten minutes for the major changes to cycle through, depending on lights. It works out to about .8 cent per degree F in the midrange. Whew! Had a lot of fun cooking a D at NMSU with the help of the stage lighting fellow. Took tons of measurements over short time segments. Radio Shack has a really cool mini infrared thermometer for around fifty bucks. Amazing how well you can predict string temp changes after a couple of concerts. "Space blankets" is what quite a few wrote in their notes at that class. Y'know, the four buck camping type. Enjoy, Guy</html>