efficiency bandwith product (amplifier) (EBP)

Efficiency Bandwidth Product (EBP) is a simple formula for determining a speaker enclosure for a woofer. The EBP formula dates back to the 1970s by Richard H. Small, and provides a rough classification for subwoofers.

The EBP value results from the quotient of the resonant frequency (fs) of the woofer and its electrical Q (Qes): EBP = fs/Qes. The resonance frequency is taken as the frequency at which the woofer has its first impedance maximum, and the electrical Q is the ratio of the impedance at the resonance frequency to the ohmic resistance of the voice coil.

The EBP value should be between 35 and 120, depending on the loudspeaker cabinet. If the EBP value is below 100, then the woofer is suitable for bass reflex cabinets, and for values around 50, closed speaker cabinets are recommended.