Don't know where else to post this, so if it's in the wrong spot, sorry about that. http://www.fretlessguitar.com/guitarsite/school.html I found this site yesterday while surfing the net...The 'Tonal Center' creates a 'harmonically neutral' static key. I hear overtones, so I guess I don't understand fully what 'harmonically neutral' means, but anyway... I'm looking for something to practice my intonation with, so I figured I'd give it a shot. One question though, as far as drones are concerned, would this be better than a constant loop from something like a midi?