Subscribe on iTunes, SoundCloud, Google Play or Stitcher.

Support Sound Design Live on Patreon.

In this episode of Sound Design Live, I talk with the head of engineering support at Nexo, François Deffarges. We discuss the troubling trend of uncoupled subwoofer arrays left and right of the stage and how to fix it, how to test subwoofer options for better LF results, why asymmetrical horns look upside down, and the time François was publicly shamed (mistakenly) in the French national press.

I ask:

• What are some of the biggest mistakes you see people making who are new to using Nexo speakers?
• I’ve always been confused by asymmetrical horns. Why do they look upside down? The bottom part is narrow, where you have wide coverage and the top part is wide where you have narrow coverage.
• Tell us about the biggest or maybe most painful mistake you’ve made on the job and how you recovered.
• FB
  • João Lopes Just tell him that N45 is one of the best wedges I had worked with 👍
  • Jason Raboin Why does Nexo opt for a single LF driver in their Geo M series while the rest of the major manufacturers opt for 2? What are the benefits and what are the trade-offs?
  • Devin Sheets I’d be interested in hearing him talk about the physics behind the latest port designs in the STM and Geo series. The design involves a slit in the port which seems to change the phase relationship of the harmonics so that there is linearity throughout the frequency ranges that are normally affected by port resonances.
    • How valuable does he think the cardioid low-mid functionality is in the market? They haven’t been pushing cardioid tops as much. Do they still offer cardioid modes for subs though?

My recommendation: keep 2-3 options open, test them, listen to them, and then make your decision.

François Deffarges

Notes

1. All music in this episode by “Kosu” – Shock of Daylight.
2. Tool Box: Trupulse 360r, Class 1 B&K Sound Level Meter, Smaart, SysTune, Lectrosonics wireless, NTI
3. Books: The Foundations of Acoustics by Eugen J. Skudrzyk, Wind, Sand and Stars: Terre des hommes “Land of men” – Antoine de Saint-Exupery
4. Quotes
   1. In life, you have external factors that influence your career.
   2. There are trends for mistakes, but they are mostly on the network side.
   3. One thing I don’t like when I see photos, is left and right stage subwoofers, because from the picture you know that this is not going to work.
   4. There are trends for mistakes, and the trends today are not the same as twenty years ago.
   5. The industry has really formalized/professionalized in the past twenty years from the manufacturer to the engineer. 
   6. When you do stereo design for subwoofers make sure the left goes to the left and the right goes to the right. 
   7. You cannot predict how the room will behave at 30-40Hz.
   8. My recommendation: keep 2-3 options open, test them, listen to them, and then make your decision.
   9. Music is transience and we want full respect of that transience.
   10. In an asymmetrical horn, a fast expansion you achieve a wider directivity. Where the throat is narrow you have a wider directivity because the expansion is faster.
   11. The smaller the source, the more omnidirectional it is.