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SUNDOWN AUDIO U Series 18" v.2 (1750 RMS) D2


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SUNDOWN AUDIO U Series 18" v.2 (1750 RMS) D2

The Sundown U Series is our premier “standard suspension” woofer series. The all-new U v.2 improves on the already incredible performance of its predecessor.

We start with a double-stacked / 9.44” wide Y35 grade ferrite magnet system (3/4” wider than the v.1) coupled to a one-piece, bumped T-Yoke and a 0.6” thick top-plate. Just as with our other high-end subwoofers we also add a very thick (5mm thickness) aluminum shorting ring inside the magnets to reduce static inductance and level out inductance over stroke. The v.2 adds a pole-cap aluminum shorting ring which doubles as a heat-sink and airflow guide. The U v.2 series motor also features a 0.6” long pole-extension to keep the coil under control at high levels of excursion.

The voice coil is a 2.36” long / 3” diameter 4-layer aluminum winding / aluminum former unit – which is the same coil design from the U v.1 – but the new version is built with a stronger aluminum former. The coil temperature is kept in check via a high-velocity solid pole / machined pole channels arrangement and a series of 16 direct air-gap vents in the back plate. The U v.2 series also features custom tooled cast aluminum vent rings in between the frame and top plate to effectively exchange air at a high velocity over the voice coil beneath the spider landing.

The U v.2 series features an all-new, custom tooled, cast aluminum frame designed specifically for this line. The cosmetics are very similar to the original v.1 frames but every size frame is substantially thicker and even features stiffening / heat dissipation ribs around the bottom part of the frame. The new frame design allows for significantly taller cones and wider spiders on the 10s and 12s compared to the v.1 which greatly enhance mechanical clearances. Moving on to the 15 the spider is also wider than the originals. The 18 uses the same spider and cone height as the originals but the frame is, of course, much stronger.

Given the stronger motor (15% more powerful), stronger coil construction, superior motor air-flow characteristics, and enhanced mechanical capacity we boosted the power rating to 1750-watts RMS from the 1500-watt rating of the previous version.

If you are looking for a woofer that sounds similar to the SA series but handles significantly more power… the U v.2 series is exactly what you need. It has been designed to live up to the reputation earned by our U v.1 series both in terms of every-day music enjoyment and SPL competition.


  • Black Aluminum 3” voice coil former for superior heat dissipation
  • High Temperature Round-Wire ALU voice coil with high-temp black adhesive
  • Double stitched surround
  • Heavy duty cast baskets – all new, custom-tooled
  • Spring loaded terminals accept up to 8 gauge
  • Stitched-on double-XL tinsel leads
  • Solid pole with vent channels and aluminum shorting ring cap
  • Rear drilled gap-venting
  • Innovative high-velocity cast aluminum vented frame spacer ring
  • Magnet ID shorting ring
  • Top-Plate Cooling Channels
  • Cast Aluminum surround bolt-on rings
  • Optimized for small ported or bandpass enclosures


T/S SPECS UV.2 18" D2 UV.2 18" D4
RE (Ohms) 3.8710 6.0767
FS (Hz) 30.9541 30.9212
VAS (L) 111.7625 114.6901
Qes 0.5669 0.6572
Qms 5.6396 5.5116
Qts 0.5151 0.5872
Le (mH) 3.3981 4.7475
BL (NA) 27.4023 31.4938
Mms (Grams) 565.4130 552.1551
Cms (uM/N) 46.7560 47.9807
Sens (dB @ 1w/1m) 89.4169 88.8733


Sealed Enclosure 3.0 cu ft
Ported Enclosure 4.0 cu ft
Recommended Tuning 35Hz
Recommended Port Area 64 sq in
Displacement 0.26 cu ft
Depth 10″
Outside Diameter 18.63″
Cut-Out 16.9″
Physical Dimensions Download

Extra Information