Note: Speakers are non-returnable. The Eminence Sigma Pro 18A-2 is intended to be used as a woofer in vented enclosures for professional audio applications. Eminence Sigma Pro 18A-2 Features at a Glance: Nominal Basket Diameter: 18" Nominal Impedance: 8 ohms Power Rating: 650W (1300W, Music Program) Resonance: 28Hz Usable Frequency Range: 41Hz-2.
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