Actually there is nothing going on at 16khz. Everything starts rolling off at 2k and by the time you hit 16khz there is nothing going on. In fact I just helped EQ the big houses at my theatre using a THX R2 unit which uses 4 mics and averages everything out to get a more even response around the auditorium. The equalization curve used in cinemas is called the X curve. All theatres are EQ'd to this curve. If not you would have a VERY harsh sound that is very bright due to the horns. The horns used in cinemas are aimed 2/3 the way back in the auditorium to cover the main seating areas. The closer you get to the more un even the sound gets.
As far as JBL being in 75% of all theatres is not very accurate today. It's more like 50 to 60 %. This comes a from a JBL rep I have dealt with on a few occasions. This figure was more accurate back in the late 80 early 90's. It's just a marketing ploy now. Before all the bankruptcy filings by the major circuits. EV is widely used in alot of theatres. Klipsch has also made big resurgance in the cinmea industry as well. The other thing to note is if the surrounds say JBL the stage system could be different. One of the theatres I help take care of is this way. JBL surrounds and EV stage systems.
The 4000 series is the most widely used JBL speaker that they make. 75 to 80% of their sales are these stage speakers.
http://www.jblpro.com/pages/cinema/4000.htm The 3 way systems are way to expensive for most theatre chains and are mainly used for special venues such as the Arclight cinemas in Hollywood. On oocasion a chain might throw one of the smaller 3 way systems in the big auditorium.
