Sundown U-6.5SW V1

The Sundown Audio U-6.5SW V1 impressively demonstrates that high bass levels do not necessarily require a large subwoofer. With a diameter of just 6.5 inches (16.5 cm), this compact woofer combines high mechanical strength with 400 watts RMS and an exceptionally large linear excursion.

Its design is particularly well-suited for installations where there is limited space for a subwoofer enclosure, but where powerful, deep bass is still a must. The sturdy cast aluminum basket provides a torsionally rigid base for the powerful driver and the diaphragm unit, which is designed for high excursion.

With an Xmax of 19 mm, the U-6.5SW V1 offers enormous excursion reserves for its compact size. The double-stitched surround and durable connection wires ensure mechanical stability even at high volume levels.

A sophisticated cooling system featuring rear-side gap ventilation and cooling channels in the upper pole plate improves heat dissipation from the driver. As a result, the U-6.5SW V1 is also suitable for performance-oriented car audio systems that require high power output over extended periods.

The subwoofer performs particularly well in small bass-reflex enclosures. Even with a relatively modest net volume, it’s possible to create a powerful bass system—ideal for compact single-enclosure setups or multi-woofer configurations with several 6.5"-woofers.

Technical Specifications

• Manufacturer: Sundown Audio
• Model: U-6.5SW V1
• Series: U-Series
• Subwoofer size: 6.5" / 16.5 cm
• Power handling: 400 watts RMS
• Voice Coil: Dual Voice Coil
• Impedance options: D2 (2 × 2 ohms) or D4 (2 × 4 ohms)
• Xmax: 19 mm
• High-Temperature Voice Coil
• Aluminum Voice Coil Carrier
• Sturdy cast aluminum basket
• Double-stitched piping
• Heavy-duty connection wires
• Spring-loaded speaker terminals
• Rear gap ventilation of the drive
• Cooling channels in the upper pole plate
• Short-circuit ring in the magnetic system
• Optimized for compact bass-reflex enclosures
  
  

Thiele-Small parameters – D2 (2 × 2 ohms)

• Re: 4.0586 ohms
• Fs: 41.9533 Hz
• Volume: 2.9053 liters
• Qes: 0.5238
• Qms: 8.5834
• Qts: 0.4937
• Le: 4.0112 mH
• BL: 16.7428 N/A
• Mms: 137.2546 g
• Cms: 104.8528 µm/N
• Sensitivity: 77.8706 dB @ 1 W / 1 m
• Xmax: 19 mm
  
  

Thiele-Small parameters – D4 (2 × 4 ohms)

• Re: 6.6274 ohms
• Fs: 38.6925 Hz
• Volume: 3.7701 liters
• Qes: 0.5005
• Qms: 7.2470
• Qts: 0.4681
• Le: 5.5892 mH
• BL: 20.0082 N/A
• Mms: 124.3518 g
• Cms: 136.0613 µm/N
• Sensitivity: 78.1460 dB @ 1 W / 1 m
• Xmax: 19 mm
  

Recommendation for bass-reflex enclosures:

• Net volume: approx. 0.25–0.35 ft³ / 7.1–9.9 liters
• Port area: approx. 4–5 in² / 25.8–32.3 cm²
• Tuning frequency: 35–40 Hz
  
  

Enclosed housing:

• Net volume: approx. 0.125–0.20 ft³ / 3.5–5.7 liters
• Subwoofer's internal volume: approx. 0.04 ft³ / 1.13 liters
  
  

Installation Dimensions

• Outer diameter: approx. 7.17" / 182.1 mm
• Installation diameter: approx. 5.94" / 150.9 mm
• Mounting depth: approx. 5.71" / 145.0 mm
  
  

The Sundown Audio U-6.5SW V1 is therefore an interesting solution for high-performance subwoofer installations in very small spaces. Its combination of 400 watts RMS, 19 mm Xmax, and very low required enclosure volume enables compact bass systems with astonishing volume potential
.