Line arrays like this, a full range line array consisting of multiple drivers, won’t work without some sort of processing. I made the above graph with a piece of software called APL_TDA. It’s a great package to view the timing of the audio at your listening spot. I only ran it in demo mode, just to see what the graph of my manually adjusted speakers would look like. You can find the history of that test here. Above all, I ran it as a fun test to see what my own type of processing had achieved.

The reason I posted the graph above is because I love the way the data is presented here. It shows frequency vs time in the exact sweet spot of both speakers. Also visible in this graph are the effects of the room itself, which shows up after that main pulse that hits our ears. This graph shows just how fast each note reaches our ear(s) across the entire audible spectrum. After that first wave-front, the room response will be seen. Those little bumps and ridges to the right of the peak ridge represent all of the in-room reflections and diffraction off of surfaces inside the room.

(The graph is from februari 2024, with the Scan Speak drivers and the frequency shading in place)

Bag of Tools

These days a license of APL_TDA is in my bag of tools. It’s just too convenient a tool to be missing. Even though I managed to do fine without it, it is a useful addition. For a visual confirmation of the timing that was accomplished using other means. See the page: Grabbing the bull by the horns for an example.

Other software in my bag of tools for processing includes:

  • JRiver Media Player
  • Room EQ Wizard
  • rePhase
  • DDMF Metaplugin
  • DMG Equilibrium
  • Voxengo MSED
  • Lexicon PCM Native Reverb plugin bundle
The Room

In order to be successful, it all starts with the room… or at least, how the speaker and room can work together.

Processing to optimize in-room results

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.

In fact, it only took 3 simple means to be able to get the results presented on top of this page. 2 huge panels out of sight, one extra panel, disguised as a poster. That’s all I needed to get the bigger offensive reflections out of my measurements.

Processing the arrays in the room

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. They all have their own unique set of reflections that reaches the listening position. Each driver in an 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 present in our measurement. That’s the reason why the parallel planes to the arrays need some care.

Infinite Arrays

With arrays the floors and ceiling act as acoustic mirrors, making the arrays seem taller than they are. Be sure to check out the following thread about the theory of infinite line arrays! Start reading it here. While it is describing a theoretical ideal, we can come pretty close to it by using this theory to our benefit. And by using processing to get us there.

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.

Commercial offerings

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. Commercial speaker builders need to make a good performing speaker, but have no control over how it is going to be used. Processing like it is used here in this project usually is outside of the scope of commercial offerings. Exemptions do exist.