​When designing a PA system for a large building, designer need to consider what the audio route should be. Here, we will classify the structures into five types and summarize the differences between each.

Multi route or Single route ?

The first thing a designer should consider is whether the audio route needs to be a single route or multiple routes. The figure on the left is a multi-route, and the figure on the right is a single route.

For example, airports have different broadcasts to different gates at the same time, so it must be multi-route. How many simultaneous independent broadcasts can be made at the same time for the broadcasting system. It is very important.

​Example

Some examples are shown in the figure below. System1-3 is single root, System4-5 is multi-root.

The "SS" in Sys3 and Sys4 is an abbreviation for speaker selector, which is a function that divides the signal amplified by AMP into several SP lines. It may be a product of its own, or it may be built into the AMP.
The "Matrix" in Sys5, please see here.

Notes on some systems. 

On drawings, it is often expressed as shown below. In the lower diagram, System2-5 in the upper diagram are drawn side by side. The upper figure shows the integration of these three systems.