The X v.3 series is the entry into the Sundown Audio “ultra-high excursion” suspension and frame designs. They all feature our custom tooled and patented frames (US Patent Numbers D691596, D691597, D691598, and D741841).
We mate these new platforms to a triple stacked 225mm (8.86”) diameter motor structure featuring a hyper-extended pole and extreme clearances (allowing up to 4″ p-p travel before mechanical bottom). This motor drives a 3″ diameter 4-layer flat aluminum coil wound on a thick aluminum former to incredible levels of excursion. This is the same coil design utilized in the NS v.3 and Z v.5 series in the past. It is a proven coil with monstrous power handling potential. The combination of coil and updated motor for the X v.3 series brings its performance in terms of motor force to about 85% of the level of the previous generation Z v.5 series! So this makes the X v.3 an incredible value.
The X v.3 series was designed from the ground-up to become the new standard in the low-frequency / small ported box subwoofer category in this price range. They will work in the same small enclosures that you are used to using for Sundown Audio subwoofers, although, the will tolerate enclosures up to about 50% larger than those if you desire even more low-end extension.
The X v.3 series is really a different kind of woofer due to its incredibly linear suspension. They are designed for the LOWEST level of bass extension possible in a small enclosure while maintaining extremely low levels of distortion.

Specifications

• T/S SPECS	X V.3 18″ D1	X V.3 18″ D2
  RE (Ohms)	1.4	3.2
  FS (Hz)	26.650	28.207
  VAS (L)	130.302	109.935
  Qes	0.526	0.657
  Qms	2.793	3.091
  Qts	0.442	0.542
  Le (mH)
  BL (NA)	14.543	20.854
  Mms (Grams)	474.114	504.115
  Cms (uM/N)	75.224	63.154
  Sens (dB @ 1w/1m)	88.6dB	87.6dB

   
  

  Enclosure Specifications

  	X v.3 8	X v.3 10	X v.3 12	X v.3 15	X v.3 18
  Sealed Enclosure	0.3-.04cuft	N/A	N/A	N/A	N/A
  Ported Enclosure	0.75-1.0 cu ft	1.5 cu ft	2.5 cu ft	4.25 cu ft	7.00 cu ft
  Recommended Tuning	32hz	32hz	32hz	32hz	32hz
  Recommended Port Area	12-16 sq in	24 sq in	40 sq in	68 sq in	112 sq in
  Displacement	0.13 cu ft	0.21 cu ft	0.2 cu ft	0.22 cu ft	0.23 cu ft
  Depth	6.8"	9.4"	10.4"	11.6"	13.6"
  Outside Diam.	8.70"	11.65"	12.68"	15.51"	18.42"
  Cutout	7.36"	10.01"	11.09"	13.83"	16.69"