Loudspeaker Irrational Forms for More Spatial Sound

I had few cones left over and I wanted to create some loudspeakers which creates a more spatial sound for the rooftop where we play and listen to music.

The idea is to use uncommon forms to avoid resonances and give more spatial sound.

The system consists in 4 loudspeakers. One in the front, two at the side and a subwoofer far away.

Material list:

1. A subwoofer cone
2. 6 mid range cones
3. 2 tweeters
4. 4 cross overs
5. cables
6. mdf wooden panes
7. insulating material
8. glue, screws...

In my case most of the material was a left over so I just bought the wood. Mid range cones can cost 30-40 EUR the pair considering car audio. Cross overs and other cones can cost a variable amount.

The subwoofer cone can be pretty expensive and luckily I didn't have to buy it. The woofers had a broken membrane which I replaced.

The construction description is better documented in the video. There are few important point I want to stress here.

Form:

1. The form is made to avoid waves to resonate, I use irrational degrees so no single frequency makes big resonances in response
2. Cutting and gluing irrational angles is tricky and needs practice. I use screws which help to hold up the structure and a lot of plaster to fill in defects
3. The subwoofer middle pane which serve as resonator compared to usual loudspeakers has an additional ramp which is used to enhance further frequencies apart from resonant ones.

Realization:

1. Heavy loudspeakers have good sound, I additionally glue some isolating material to prevent the loudspeaker to move at high volume
2. I paint with a spray gun, the result is coarse but I kind of like it
3. Better results came with using 2 layers of primer. Then once black paint and the final green one which partially covers the former one
4. Sanding between layers is essential

Configuration:

1. The array loudspeaker can be used both in stereo and mono with a simple cable swap. The idea is to rather use it as mono in front of the audience
2. The subwoofer should be really far away and not oriented on the axis of the room. The sound is really spread then

Tuning:

1. Building own cross-over is a really costly exercise which takes a lot of time and requires components which are expensive and hard to find. Here I use standard ones and I don't feel I would need yet to explore more custom ones
2. The L/R loudspeakers have a resonance tube which can be tuned depending on the size of the room.

It is really tricky to express in a video how a loudspeaker sounds. The final effect depends a lot on the room and the position of the loudspeakers and the audience. I'm thinking on how to render this effect in a next video together with response frequencies on test audio.

At the end of the video I use a candle to visualize the air movement but and the effect of the resonator cave.

I started as well to create a 3d simulation of the room to understand the optimal position of the loudspeakers. Here I use blender to create the 3D models and simulate the waves propagation.

Modeling sound in blender is tricky since the software is not meant to be accurate or effective to use. Being able to variate positions to find minima is tricky as well and requires a good strategy to run those simulations in bulk.

I tried to add the blender file but is not supported and the stl is far too large.