The Sundown U Series is our premier “standard suspension” woofer series. It is the most direct replacement for the world famous Z v.3 woofer line which we produced from 2011 to 2016 before launching the “new platform” Z v.4 series. Due to numerous advancements in our design process the U Series is able to deliver performance on-par with the Z v.3 series but at a much lower cost.

We start with a double-stacked / 8.66” wide Y35 grade ferrite magnet system coupled to a one-piece, bumped T-Yoke and a 0.6” thick top-plate. Just as with the Z v.3 before it and 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 U 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 we use in our X v.2 series and, thus, the U series has the same 1500-watt RMS ratings. The coil temperature is kept in check by a heavily smoothed / high-velocity pole-vent and a series of ten direct air-gap vents in the back plate. The U series also features newly 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 series features an all-new cast aluminum frame series to the Sundown line which allows for taller cones than the older frames used on the Z v.3 series. The taller cones provide enhanced coil stability and increased mechanical excursion capability. We also tooled matching cast-aluminum surround clamps for the U series to ensure durability in the most demanding situations. The surrounds and cone bodies have been fully custom tooled especially for the U series and are stronger / support more excursion than the Z v.3 series cones and surrounds. The new cone bodies also feature an indentation for the same wide-flange, ultra-strong dust caps as our new platform subwoofers.

If you are looking for a woofer that sounds similar to the SA series but handles significantly more power… the U series is exactly what you need. It has been designed to live up to the reputation earned by our Z v.3 series both in terms of every-day music enjoyment and SPL competition.

• Features (U-10 / 12 / 15 / 18)

  • Black Aluminum 3” voice coil former for superior heat dissipation
  • High Temperature Round-Wire CCAW voice coil with high-temp black adhesive
  • Double stitched surround
  • Heavy duty cast basket
  • Spring loaded terminals accept up to 8 gauge
  • Stitched-on double-XL tinsel leads
  • Rear vented pole piece
  • 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

   
  

  Specifications

  • T/S SPECS	U 18" D2	U 18" D4
    RE (Ohms)	3.8	6.1
    FS (Hz)	31.3	31.4
    VAS (L)	135.4	135.4
    Qes	0.37	0.42
    Qms	3.41	3.55
    Qts	0.33	0.38
    Le (mH)	2.62	3.97
    BL (NA)	29.9	35.3
    Mms (Grams)	444.1	441.3
    Cms (uM/N)	0.06	0.06
    Sens (dB @ 1w/1m)	92.3db	91.8db

     
    

    Enclosure Specifications

    • 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	10.11″
      Outside Diameter	18.66″
      Cut-Out	16.69″