Processing

Line arrays like this, a full range line array consisting of multiple drivers, all playing the same thing, don’t work without some sort of processing. The above graph was made with a piece of software called APL_TDA. Even though I’m not a user of this software myself, it is a great package to adjust audio at your listening spot. I only ran it in demo mode, just to see what the graph of my adjusted speakers would look like, you can find the history of that test here. Ran as a fun test to see what my processing had achieved.

I still love the way the data is presented in that graph, which is why I posted it. It shows frequency vs time in the exact sweet spot of both speakers. So included in the graph are room effects. It shows how fast every note reaches our ear across the entire audible spectrum. It also shows how the room reacts after that, those little bumps and ridges to the right of the peak value represent the reflective surfaces inside the room.

As said, I don’t use APL_TDA, I made use of many freely available packages plus a few paid solutions. I will list the packages on the right and try and explain what each does for me.

In order to be successful, it all starts with the room…

So let’s look at this room in a bit more detail. Looks like an ordinary living room, right? But it does have treatment! Behind both of those curtains are huge damping panels, absorbing the first or early reflections. On the wall opposite to the speakers we see a big Led Zeppelin poster (my all time favorite band). That too is a sound absorbing panel. Our couch is below the cushions you see beneath the poster. With these 3 simple means I was able to get the results presented on top of this page. 2 huge panels out of sight, one extra, disguised as a poster. That’s all I needed to get the bigger offensive reflections out of my measurements.

All other objects and equipment you see don’t have a large influence at all. This is because the line array consists of many small drivers, each having a unique position as seen from the listening spot. Each of them will have it’s own unique set of reflections that reaches the listening position. However the next one in the array is placed at a different height, so it does not have the reflections at the same position as the previous driver. This way all of the drivers combined average out all those reflections. Only the reflections they have in common are presented in our measurement. That’s the reason why the parallel planes to the arrays need some care.

With arrays the floors and ceiling act as acoustic mirrors, making the arrays seem taller than they are. A great thread about the theory of infinite line arrays can be found here. While it is describing a theoretical ideal, we can come pretty close to it by using this theory to our benefit.

What I write about here are things that can make arrays within a room have an advantage. No floor bounce, easy to treat early reflections… see how this choice for arrays is starting to make a little more sense? Once we start to see the room + speakers as one unit, meant to play together we can maximise its outcome inside our own environment. In my humble opinion this is where DIY has a huge advantage compared to commercial solutions. We can pick the speakers that can work within our room, make sure they can work well together. A commercial speaker builder has to make a good performing speaker but has no control over how it is going to be used.