You're right the firing area was behind the stage, around 20 meters away and extends up to only 40 meters in length. It was a tricky firing area to shoot in because there were 3 positions, usually i put shells in the middle position but for this show they were all in pos 1 since the width of the space for pos 2 and 3 was just around 2-3 meters but the length was around 20 meters. Pos 1 was a parking area so it had a much bigger space for shells.
The announcers were on stage during the show but they were just there making a few comments while the fireworks were on going. All the products were made by our factory (all of the effects were custom made for the show) and the maximum caliber was 6"/150mm
Vander