According to a diagram of a Leslie Organ Speaker, we're looking at the vacuum tube amplifier. I really enjoyed trying to get a clear shot of these beauties. Straight out of the camera, taken with the camera sitting on the floor and held up at a slight angle as I snapped several photos in sequence. I couldn't tell what I had until I uploaded them to iPhoto. I like this one the best and have left it crooked to give you an idea of how I must have looked, leaning over from our booth, setting my camera on the stage floor and clicking away. No one on the stage could see me, and no one in the audience gave a hoot about what I was up to--it was not a brightly lit corner there beside the stage--because the music had grabbed hold of them and wouldn't let go, period. I know 'cause that's what it did to me.