At Danley, our philosophy regarding sound system design is to use the fewest devices possible. There are a number of reasons for this position, but the simplest is that multiple devices always interact, and interaction is rarely a good thing.
Some use these interactions to create directivity, and see this as a justification for using multiple devices to cover an audience. Indeed, there are only two ways that we know of at the moment to control the directivity of a sound source. You can use interaction / interference to create lobes of sound, or you can use horns. At Danley we have chosen the horn as a means to control where the sound goes.
In our literature, we do indeed refer to the SH50, for example, as a box that can be “arrayed”. Our illustrations always show 2 or 3 (never more) in horizontal arrays, never vertical. In the horizontal plane, it is more likely that the audience will be arranged so that an arc is formed with the center point at the apex of the horns. This rarely, if ever, happens in the vertical plane. When we show our boxes “arrayed,” they are always tight packed, that is to say, the sides of the trapezoidal boxes are touching so the apexes of the horns are as close together as possible. One of the advantages to the synergy horn design is the apparent source for all the drivers (7 in the case of the SH50) is the apex of the horn. At high frequencies, where the horn is very effective, you can put 2 or three of them together in a tight pack and get minimal phasing as you move through the seams. Although they are not perfect, they will perform better than any other trap box I have seen. If, however, you don’t tight pack them, you lose all the advantages of the synergy horn design. Here are a number of images from our mapping program to illustrate. First, a pair of SH50s tight packed.
You can see that even tight packed, there are areas of interference. But if they are not tight packed here is the result.
This is obviously much worse. The same can be seen with three boxes.
This is 3 SH50s in a tight array showing a coverage of 150 degrees with some lobes visible. But here is what happens if they are not tight packed.
It can also be seen in the predicted frequency response.
Here is the response of a pair of SH50s tight packed.
Take the same speakers and aim them so they are not tightly packed,
We have chosen to use horns, and develop our own patented type of horn, because we feel that if we can avoid using multiple boxes to cover an area, the results will be demonstrably better. However, this leads us to a challenge. What happens when the audience is larger than one box can cover, or when the sound pressure requirements exceed the limits of one horn? In this case, the line array has some advantage in that it is scalable in the field, at least to some degree. But line array builders agree that you don’t get a 6 dB increase per doubling of boxes beyond the first few. So if you have 10 line array units and you are 6 dB down in level, 20 units won’t get you there!
OK, so why not build a line array out of synergy horns and get the best from both worlds? Well, because the synergy horn is not a good candidate for a line array element. For a line array to work, each of the elements must combine to perform as a line source. The woofers have to be very close to one another, as do the mid drivers and the high-frequency drivers as well.
With a synergy horn, the woofers might be close enough to couple but the mids and highs are way too far apart when stacked atop one another.
If I created a stack of these SH50s, no part of it, except maybe the woofers, would behave anything like a line source, so you would get none of the “benefits” of the line source behavior. All you would get is destructive interference.
Instead of trying to make a better line array, our response is to build bigger horns! Our Jericho line of horns provides a number of horn patterns to choose from. If larger audience planes require more vertical coverage for example, as is some times the case in larger sports facilities, 2 or 3 large horns can be stacked in a vertical array to cover the desired area. Each horn is pointed to cover a a specific area. When these horns overlap, there will be the same sort of interference that you see whenever there is more than one source. But, as these horns are very large, they will have extremely high pattern control, even below 300 Hz. The sound tends to go exactly where you point the horn with very little overlap. We often try to place the seams in the walk ways so that the impact of the interference on the audience is minimal.
Finally, we believe that if you use horns instead of interference to direct the sound, not only is the sound more pleasing, the system is far more efficient. In an interference-based system, much of the power is dissipated in creating the areas of cancellation. With horns, since we are not using interference, the power can go to the audience. This can be seen very dramatically with subwoofers. Typical front-loaded double 18-inch speakers have sensitivity ratings in the order of 92 to 94 dB 1 watt/ 1 meter. Our woofers have ratings on the order of 114 dB 1 watt /1 meter. If you do the math, you find that it would take 14 double 18 boxes at 92 dB sensitivity, at 2000 watts per box to equal the output of one of the Danley BC418 woofers, with 4 18” drivers with 6800 watts behind it. This is the “power” of the horn! Some of our larger horns provide around 30 dB of horn gain. That is essentially free power! When you count up all the cabling and amplifier channels required for arrayed systems, you can see how a horn solution makes sense.