Sundown Audio SD-4 8" D4 Neo Shallow Mount Subwoofer | 400W RMS

The Sundown Audio SD-4 8" D4 Neo Shallow Mount Subwoofer delivers high-performance bass in tight spaces, designed for today’s depth-restricted sealed box applications. As part of the SD v.4 Neo Series, this model is the direct successor to the popular SD-3, bringing advanced Neo motor technology, a redesigned “W” foam surround, and improved durability — all with a compact mounting profile.

With 400 watts RMS power handling and a Dual 4 Ohm (D4) voice coil configuration, the SD-4 8" is built for flexibility in wiring setups while maintaining Sundown’s signature blend of accuracy and impact.

Shallow Mount Engineering – Built for Tight Installs

The SD-4 series was designed with real-world vehicle limitations in mind. By removing the pole vent, the motor can be mounted flush to the back of the enclosure, while the new “W” foam surround reduces front clearance requirements to just about 1”. The result is an effective depth requirement nearly 2 inches less than most shallow subs — making the SD-4 perfect for trucks, sealed enclosures, and other space-limited installs.

Cooling & Motor Innovation

• Neo Motor Design – Lighter and more compact than ferrite, reducing angled depth needs.

• Side-Firing Gap Venting & OD Pole Channels – Provide efficient airflow and superior cooling.

• Shorting Ring & Aluminum Faraday Ring – Smooth frequency response, minimize inductance, and lower distortion.

Precision Sound Quality

The SD-4 features an under-hung motor topology, ensuring the coil always remains fully within the magnetic gap. This provides an extremely flat BL curve for accurate bass reproduction and low distortion. With 14.5mm of linear excursion one-way, the SD-4 8" delivers surprisingly deep output for its size, optimized for small sealed enclosures.

Built to Handle Power Daily

• RMS Power Handling: 400W RMS

• Voice Coil Configuration: Dual 4 Ohm (D4)

• Voice Coil: 2” 8-layer high-temp copper coil on black aluminum former

• Surround: Computer-optimized “W” foam surround for reduced clearance and enhanced durability

• Frame: Patented high-strength cast aluminum frame (US Patent D691595)

• Durability: Stitched-on tinsel leads, spring-loaded terminals, rugged spider design

Key Features at a Glance

• 400W RMS Power Handling

• Dual 4 Ohm Voice Coil (D4)

• 14.5mm Xmax one-way by 70% BL

• Lightweight Neodymium Motor

• Under-hung low distortion motor design

• Black aluminum voice coil former for superior heat dissipation

• Large aluminum Faraday ring for smooth response

• Optimized for small sealed enclosures

Why Choose the Sundown SD-4 8" D4?

For bass lovers who need tight, accurate, and powerful low-end in compact installs, the Sundown Audio SD-4 8" D4 Neo is the perfect choice. Its shallow design doesn’t compromise performance — instead, it delivers Sundown’s legendary bass quality in places most subs can’t fit.

With the D4 coil configuration, you also gain wiring flexibility for matching with a wider range of amplifiers, making it ideal for custom builds.