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SIGMA PRO 18A-2
SPECIFICATION
Nominal Basket Diameter 18", 457.2mm
Nominal Impedance* 8 ohms
Power Rating
Watts 650W
Music Program 1300W
Resonance 28Hz
Usable Frequency Range 41Hz-2.4kHz
Sensitivity*** 99
Magnet Weight 120 oz.
Gap Height 0.375", 9.53mm
Voice Coil Diameter 3", 76.2mm

THIELE & SMALL PARAMETERS
Resonant Frequency (fs) 28Hz
DC Resistance (Re) 6.29
Coil Inductance (Le) 1.90mH
Mechanical Q (Qms) 8.28
Electromagnetic Q (Qes) 0.30
Total Q (Qts) 0.29
Compliance Equivalent Volume (Vas) 441.2 liters / 15.6 cu.ft.
Peak Diaphragm Displacement Volume (Vd) 695cc
Mechanical Compliance of Suspension (Cms) 0.24mm/N
BL Product (BL) 22.1 T-M
Diaphram Mass inc. Airload (Mms) 130 grams
Efficiency Bandwidth Product (EBP) 93
Maximum Linear Excursion (Xmax) 6.1mm
Surface Area of Cone (Sd) 1140.0 cm2
Maximum Mechanical Limit (Xlim) 18.0mm

MOUNTING INFORMATION
Recommended Enclosure
Sealed N/A
Vented 93-212 liters/3.3-7.5 cu.ft.
Overall Diameter 18", 457.2mm
Baffle Hole Diameter 16.56", 420.5mm
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 8.15", 207mm
Net Weight 24.5 lbs., 11.1 kg
Shipping Weight 28.1 lbs., 12.8 kg

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
Dustcap Composition Solid composition paper dust cap