Vertical stacking is there a limit?

[beans-on-toast]

Line arrays are not the best solution (or the only solution) where the venue is wide and not deep, or where the seating arrangement does not fit with the primary characteristics of a line array format. For example, in a 3/4-arena configuration, it's more common to use an exploded center cluster or a cluster distributed in a concentric arc around the thrust. ESPECIALLY where the house is wide and not deep. We see this a lot in churches and music venues/theatres seating between 250 and 750 seats. Another example is an in the round venue where there may only be 30' of depth to any seating area, another example of the use of a distributed array simply for the coverage.

Other examples that I have worked on include large stadiums with open roofs, basket ball arenas that do not want the impact of long arrays embedded in a center score/display board. These types of venues, especially if they are acoustically very live, often benefit from distributed arrays configured in concentric rings with appropriate zone delay/processing. The benefits of this approach include bringing more seats into the near-field range, as well as being able to shut off zones that are not in use (especially the high perimeter ring of nosebleed seats) which reduce reverberant energy elsewhere in the venue.

Line arrays are good for a lot of things, and benefit from easier rigging, BUT they are absolutely not the best solution for every situation. Anybody who thinks so has not done the math and has not spent any time out in the real world listening to and working on these kinds of systems.

I see a line array as one end of the spectrum, but as you say there are always other options. I don't know if there is a best solution for touring shows. Everything is a compromise and the solutions are sometimes not ideal. Halls with permanent installations have it much better. They have the advantage of costly architectural acoustics designed for the room. Although even that is changing, designs can be done on the fly.

I attended an outdoor classical concert this summer. Not anything like I've seen for any bands. To support the classical instruments, they had an impressive array of acoustic treatments and mics. They had above, the back, the sides, all around the stage completely covered with treatments. Basically they constructed a studio with one wall removed. They used a little bit of everything, line arrays, speakers in front, remote towers. Being outdoors in an urban area, they also have to tune the system so there is no booming in the neighborhood. Something that they've been forced to pay close attention to in the last few years. The sound was excellent everywhere as I toured the grounds, from up front to way in the back and the sides. It truly was an example of current state of the art and a pleasure to take in all the technical aspects.

 

[Downunderwonder]

It's still tha same area under the curve.

I will post more later, because there are 2 principles depending on what you are looking at

I am aware that power of a sine voltage into a uniform load is independent of frequency.
Please continue.

 

[agedhorse]

So, for equal power, a woofer tends to reproduce 100Hz-1000Hz at the same SPL. How does your theory explain this?

To expand on this concept @downunder, where I think you are confusing things is because you are comparing (or trying to compare) the energy contained in a fixed number of cycles with the energy per fixed percentage of an octave.

So, the energy of 5 cycles of a slice from 20Hz-25Hz is the same at the energy from 2000Hz-2005Hz.

What changes is when you compare the energy of 1 octave from 20Hz-40Hz to the energy of 1 octave from 2000Hz-4000Hz. The second example will contain more energy because there are more cycles (1980-1960 more cycles).

This is the fundamental reason for using pink noise in broad band analysis. Pink noise rolls off at a rate of 3dB/octave as frequency rises to compensate for this effect which causes a rise at the same 3dB/octave.