1st diggio article Optimizing

"Optimizing The Low End: Run & Gun Subwoofer Arraying Techniques" Analysis by Adam Gray


When using low to moderate quality omnidirectional subs it is no uncommon to use more than one to produce more sound. When the size of the array is increased however, pattern narrowing is created. The only way to really grasp this article we need to know and i mean know what phase is. Phase is the off set of two separate waves measured in degrees, therefor 0 degrees would be in phase and result in a dB boost and 180 would result in a 100% cancellation. The waves interact with each other depending on their degree of phase. An addition of 3 to 6 dB is expected between 0 and 90 degrees and 0dB at 120 and 180 degrees. This pretty much tells us that we need to concentrate more on the 120 to 180 degrees because of the loss in dB that occurs. Phase is hard to grasp because we don't think in cycles of waves we think in milliseconds. "A 60 Hz sine wave is about 19 feet long, and takes about 17 milliseconds (ms) to complete (1/60 of a second)." (Pg 2).  Since we do not live in a perfect world there is no way that we can make an array with perfect dB boost where the crown is and no spill where they are not but we do not so we have to live with spill and variances in frequency. Subs are usually arranged so that there is a power ally right down the center. This is where at 30hz 60hz and 120hz are in phase straight down the middle but if you walk around the area you can hear the phase differences at 90 and 120 degrees.....also at 180 degrees but no audience should be there. In this set up and depending on the frequency a good portion of the audience is not getting to hear the subs. To fix this we need to consider another sub setup. Instead of a left and right sub lets try 6 subs in a line across the stage 6 feet long. In this pattern the coverage is greater but the main speakers reach the back of the audience and the low frequency does not. To fix this you can use a digital delay or arrange the subs in an arching patten and have physical delay. The physical way is cheap and fun.