DIY a 40-20hz sub?

Helge A. Bentsen · Oct 15, 2023

I have two kind of subs. One that drops off around 37ish Hz, one that drops off at 28ish Hz. I played around using the 28hz subs as infra subs for the other subs, sounded quite nice with a lot of useable output. This got me thinking, have anybody ever DIY'ed a 40-20hz sub for live sound use?

Ran a few simulations in WinISD, looks like a b&c 21DS115 tuned to 20hz could get there in a 400L box. With a big port (airspeed roughly 19m/s) the total volume/size is comparable to one 2x18". There's a lot of DIY designs available online, but I haven't found one targeted specifically for going low except from the home theatre people.

Uwe Riemer · Oct 23, 2023

20-40Hz is M-force territory
the other question is integration into the system without creating tons of group delay

Helge A. Bentsen · Oct 30, 2023

Uwe Riemer said:
20-40Hz is M-force territory
the other question is integration into the system without creating tons of group delay

M-force is a cool technology, but pretty expensive.
I wonder what Meyer did with the 1100VLFC, it's rated for 16-32hz or something like that.

Art Welter · Oct 30, 2023

Josh Ricci's Gjallerhorn gets down to below 20Hz, big, complicated build:

Gjallerhorn

I have been working on a couple of tapped bass horn designs for many months now. This design is centered around a large 45x45x24" cabinet form and a single LMS Ultra 5400 driver. The weight with the 80lb driver loaded in is probably near 300lbs. The cabs are built from 18mm and 12mm BB and put...

www.diyaudio.com

His Skhorn is a 24x32x54" cab with dual opposed 18 or 21" pro drivers.
All vents open 30Hz tune, 2 vents open 25Hz tune, 1 vent open 17Hz Fb.
Huge thread, various measurements scattered throughout.