subwoofer 4"

this is a prototype for subwoofer with 3 helmholtz resonators for one loudspeaker cone.
parts used for this model:
Tang Band W4-992C 4" Subwoofer
RUBBER RING, 2 INCH, FOR A UNIT WITH A CONE SIZE OF 2,3 CM (R2Ct2)
3m vhb tape

here's some details about putting parts together
https://youtu.be/Ztz0TgGbcFI

resonant frequencies are around 25, 50 and 80 hz.

availability of the parts used for this model is poor, so there will be upgraded model for this subwoofer type, later.