Features of W12K9D4:

• Rockville W12K9D4 K9 Series 12" Dual 4-Ohm Car Subwoofer
• Peak Power Handling: 4000 Watts
• Program Power Handling: 2000 Watts   
• CEA Rated RMS Power Handling: 1000 Watts 
• 3" 4-Layer Black Aluminum Voice Coils Wound with OFC Wire Made in USA
• This voice coil is stable up to 240 degrees celcius! The voice coil windings are made in the USA!
• Double Stacked 190 Oz High Quality Magnet
• Cast Aluminum Basket With Black Sanded Finish Makes This Sub Very Efficient And Lighter Weight
• Two Chrome-Plated Binding Post Terminals
• Black Non-Pressed Paper Cone With Beautiful Finish
• Our cones are ultra-stiff. They are thicker and stronger than other subs on the market making our subs able to handle more power.
• Thick Foam Surround Provides Incredible Sound Quality With Minimal Distortion
• Red Stitching Cone Reinforcement Ensures Long Life
• New Ultra-stiff  PolyPropylene (PP) Dustcap
• Impedance: Dual 4-Ohm Voice Coils
• Vented Hole on T-yoke Enhances Heat Dissipation
• Special Custom Rubber Boot Magnet Covers Make the Woofer Look Nice and Protects the Magnet
• Custom Rockville Mounting Gasket Looks Beautiful and Makes it Easy To Mount the Subwoofer Air-Tight
• High BL Magnetic Motor Gap
• We use the highest grade black glue that handles extremely high temperatures which allows our woofer to handle even more power than they are rated
• Nomex Spider provides tear resistance, strength and long-term reliability over regular cotton and poly cotton spiders
• Cutout Diameter: 11.13” inches
• Mounting Depth: 6.85” inches
• Frequency Response: 33 Hz - 1.5K kHz
• 10mm T-Yoke + 10mm Washer
• Sensitivity: 83dB
• Sealed Enclosure Volume: 0.9 – 1.47 Cubic Feet
• Vented/Ported Enclosure Volume: 1.8 – 2.75 Cubic Feet
• XMAX is 28MM
• Weight: 28.67 Lbs.
• Shipping Weight: 33 Lbs.
• Shipping Box Dimensions: 14.57" x 14.57" x 10.83" Inches

Detailed Info:

• Body: Non-Pressed Paper
• Gap Plate Inside Diameter: 95mm (3.74 inches)
• Gap Plate Outside Diameter: 190mm (7.5 inches)
• Gap Plate Thickness: 25mm (1 inch)
• Yoke Outside Diameter: 180mm (7.1 inches)
• Yoke Thickness: 10mm (0.4 inches)
• Yoke Pole Diameter: 75mm (3 inches)

TS Parameters:

TS Parameter	Wired in Series	Description of Measurement
Electrical Parameters
Re	8 Ohm	Electrical voice coil resistance at DC
Le	5.29 mH	Frequency independent part of voice coil inductance
Res	99.5 Ohm	Resistance due to mechanical losses
fs	31.7 Hz	Drive resonance frequency
Mechanical Parameters
Mms	271.8 g	Mechanical mass of drive diaphragm assembly including air load and voice coil
Rms	9.7 kg/s	Mechanical resistance of total-drive losses
Cms	0.09 mm/N	Mechanical compliance of drive suspension
Bl	28.2 N/A	Force factor (Bl product)
Loss Factors
Qms	5.59	Mechanical Q-factor of of drive in free air considering Rms only
Qes	0.54	Electrical Q-factor of drive in free air considering Re only
Qts	0.50	Total Q-factor considering Re and Rms only
Other Parameters
Vas	38.9 l	Equivalent air volume of suspension
SPL	85.4dB	Diaphragm area