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Rat Sound Message Board
Posted by Dave Rat on February 14, 2004 at 10:48:18:
In Reply to: Flown subd with Linearrays in big stadium posted by Rick Walker on February 13, 2004 at 11:24:23:
: Respect to all the people hanging out here, Checking on prosoundweb Mr. Rat knows a vdosc system. Just your thoughs on flying a array of subs on the outside of the left and right arrays.
OK, how about some quasi technical mumbo jumbo for a response? Here goes:
I must admit that my perception of the theoretical negative results of flying subs has limited my desire to thoroughly experiment with them.
I have used them though and my experiences have reinforced those theories. Here is a list of what I consider the issues with flown subs:
#1) If you fly some subs and ground stack other subs you create a scenario where the vertical dispersion of the combined 'flown/stacked' subs is reduced. What happens is; the people that are 1/2 way between the flown and stacked subs, altitude wise, are the only ones receiving the combined signals without time delay issues. A familiar example is the 'power alley' we create when the subs are stage left and stage right. Flying subs while still having stacked subs, in effect, creates 2 more vertical 'power alley' situations.
#2 If you fly all the subs, you are not taking advantage of the 3db 'half space' efficiency gain that subs so effortlessly achieve by being ground stacked. The result is needing to carry more subs and motors, points and rigging to fly this larger and less efficient sub system.
#3 Loss of efficiency is not the only down side to flown subs. The 'Half Space' 3db gain not only helps stacked subs but hurts flown subs. To LF, the ground with or without humans on it, is a really good acoustic mirror. That means that wherever a listener is in the venue, they will hear 2 sub signals from each sub array. One from the subs themselves and a second from the near perfect reflection from the floor. When the subs are stacked, the subs and the reflection combine and act like double the subs. When flown, the subs and their reflection act as two separate and interfering sources causing a complex set of summations and cancellations throughout the room.
In my experience the net effect of flown subs manifests itself as the subs seeming to lack power and impact. Keep in mind that I wrote this from a "rock" perspective. For lighter music and other types of events flying subs can have huge advantages. Saving floor space combined with "not blasting directly in front of the subs with lows" often will make flown subs a clearly superior choice.
DR