Specification:
Nominal Basket Diameter 18", 457mm
Nominal Impedance* 4 ohms
Power Rating**
Watts 500W
Music Program 1000W
Resonance 27Hz
Usable Frequency Range 35Hz - 0.2kHz
Sensitivity*** 94.4dB
Magnet Weight 67 oz.
Gap Height 0.38", 9.53mm
Voice Coil Diameter 2.5", 63.5mm

Thiele & Small Parameters
Resonant Frequency (fs) 27Hz
DC Resistance (Re) 3.8
Coil Inductance (Le) 2.65mH
Mechanical Q (Qms) 13.24
Electromagnetic Q (Qes) 0.32
Total Q (Qts) 0.32
Compliance Equivalent Volume (Vas) 488.8 liters / 17.26 cu.ft.
Peak Diaphragm Displacement Volume (Vd) 796cc
Mechanical Compliance of Suspension (Cms) 0.25mm/N
BL Product (BL) 16.5 T-M
Diaphragm Mass Inc. Airload (MMs) 137 grams
Efficiency Bandwidth Product (EBP) 84
Maximum Linear Excursion (Xmax) 6.7mm
Surface Area of Cone (Sd) 1188 cm2
Maximum Mechanical Limit (Xlim) 15mm
Mounting Information
Recommended Enclosure Volume
Sealed N/a
Vented 85-283 liters / 3-10 cu.ft.
Driver Volume Displaced 367 cu.in. / 6.01 liters
Overall Diameter 18", 457.2mm
Baffle Hole Diameter 16.57", 420.9mm
Front Sealing Gasket Fitted as standard
Rear Sealing Gasket Fitted as standard
Mounting Holes Diameter 0.28", 7.1mm
Mounting Holes B.C.D. 17.25", 438.2mm
Depth 8.13", 207mm
Net Weight 17 lbs, 7.7 kg
Shipping Weight 20.5 lbs, 9.3 kgs
Materials of Construction
Coil Construction Copper voice coil
Coil Former Polyimide former
Magnet Composition Ferrite magnet
Core Details Vented and extended core

Basket Materials Die-cast aluminum basket
Cone Composition Paper cone
Cone Edge Composition Cloth cone edge
Dust Cap Composition Solid composition paper dust cap