Nathan Funk followed up with a blessing of the swarm concept:
“I was also thinking about the overall setup and with the controllers your looking at using with variable phase, while not as good as a time “delay” function to properly align all the subwoofers its possible you could get good results with 4 subwoofers placed around the room. It would for sure take a lot more time and effort to dial it all in to maximize the potential but the end results could be better, all comes down to overall room acoustics really. As I mentioned the only downside to each driver having its own cabinet x4, vs 2 drivers in each cabinet x2 is that the cost would be a bit higher. You could always stack them if two locations worked best, but it would give you more flexibility if 4 locations did turn out to work better.”
So the gap between Duke’s view and Nathan’s view has narrowed in this case.
I asked Nathan about the common view as to whether it might be better to use three 15” inch drivers rather than two 18” drivers since the 15” drivers should be “faster.”
Nathan replied:
“The best balance is to have as low of mass you can, while providing the perfect amount of motor “traction” to match the power available. With our ultra series motor the 21” is about the perfect match, the 18” does have a tiny bit lower distortion in the super low end but its starting to run out of “traction” already, the motor is really maxing out the cone area, so going to a smaller cone yet would not yield any benefits at all. For your specific needs, 10-30hz, the 18” is the perfect match and will yield the lowest distortion, the 15” would be only as good for distortion but would have lower output, and or require more of them driving the cost up to get that same output. If you were limited on cabinet footprint, a 3x15” would be a good choice but the 2x18” is the way to go otherwise.”
I still like the height of two 18” drivers in one box. Nathan has decided that he thinks the interior box should be made of aluminum panels, with Baltic Birch panels on the exterior of the aluminum box.
I give Folsom credit for promoting the custom idea for this project. It is nice that Nathan is designing a custom, low distortion, low impedance load solution focused on 10Hz to 30Hz from two 18” drivers using his strongest motor assembly. Throw in aluminum interior panels (thank you for this idea, Magico), and this 400 pound box should be a pretty serious, old-school passive subwoofer.
And all so Jack and Lloyd don’t ask: “Where’s the beef?”
Four 18” cones should make a lot of woofing! (Does Spotify list submarine movie soundtracks? Haha!)