Build This! Dual Subwoofer

Here's Marc O's recent prize winning hybrid horn/reflex subwoofer design using the CF1840JD. Original notes included.

July 1, 2014

For this competition, I've choose to design a sub with high level capability, something that can compete with an F218 Funktion One in terms of SPL and low response. Yes, it is a great challenge with a speaker which has a Qes of 0.496, but I like challenges.


I've designed an hybrid horn/reflex. I've already built this type of cabinet: They sound right with very high level sound pressure, great dynamic. A lot of people in France love them and they are easy to build.

I use software like Akabak, Hornresp to make simulations. I well know them, they are quite accurate if properly set.

The sensitivity is 104.5dB 1w (2 volts 4 ohms) @ 1m

Theorical maximum continuous SPL: 137.5dB and 143.5dB peak

Low response:
One cabinet :
43Hz -3dB
39Hz -6dB
35Hz -10dB
Four cabinets :
38Hz -3dB
34Hz -6dB
29Hz -10dB

Recommended high pass filter : 34Hz 24dB/oct Butterworth
Ports are properly sized to not hear air noise at high pressure level.


Back to PA Tech