Alpine R2-W8D4 8" R-Series "R2" Subwoofer, Dual 4-Ohm, 350 Watt RMS PRODUCT OVERVIEW The next generation of sound performance is here with the new R-Series subwoofers featuring a larger motor structure for more accurate and authoritative bass. New Motor Structure – The new R-Series subwoofers now feature larger, double-stacked magnets that contribute more motor force for deeper bass and tighter bass control compared to the previous generation. Oversized Dust Cap – The new hybrid poly ceramic composite dust cap ensures rigidity while also providing incredible internal damping (vibration absorption) to smooth out the bass response and reproduce tight bass. Increased Accuracy – Alpine's High Amplitude Multi-Roll (HAMR) Surround Technology allows the cone to efficiently move air while staying cool resulting in incredible accuracy from the subwoofer. General Specs: Size: 8” Dimensions: 7.64” x 7.64” x 4.56” Frequency Response: 30Hz - 200Hz Power Range: 150W - 350W RMS Power Handling: 350W RMS / 1000W Peak Magnet Weight: 56 oz Voice Coil Diameter: 40 mm (2.6”) T/S Parameters: Sensitivity (1W/1m): 83.7 dB DC Resistance (Re): 3.6Δ + 3.6Δ Free Air Resonance (Fs): 43 Hz Equivalent Stiffness: 10.5 L Mechanical Q (Qms): 7.08 Electrical Q (Qes): 0.58 Total Q (Qts): 0.53 Cone Area (Sd): 201 cm2 Linear Excursion (Xmax): 12 mm Mechanical Travel (Xmech): 52 mm BOX SPECS - SEALED BOX RANGE: Net Internal Volume: 0.15 - 0.45 ft3 RECOMMENDED SEALED BOX: External Dimensions: 13” x 13” x 5.5” Gross Internal Volume: 0.30 ft3 Net Internal Volume: 0.25 ft3 VENTED BOX RANGE: Net Internal Volume: 0.25 - 0.7 ft3 Fb, Tuning: 36-40Hz RECOMMENDED VENTED BOX: External Dimensions: 11” x 9.5” x 21” Gross Internal Volume: 0.86 ft3 Vent Area (W x H): 8 in2 (8” x 1”) Vent Length: 17.5” Vent Displacement: 0.13 ft3 Net Internal Volume (Vb): 0.68 ft3