Ground Zero Iridium subwoofers are real multitalents in budget class.. Good overall soundquality and very versatile options for enclosures. You can play these with almost any kind of amplifier, since voice coil is single 4 ohm and sensitivity is very high. Or you can build up an army of subs without breaking the bank.
20 cm / 8″ Subwoofer, 150 WRMS
4 ohm, 38 mm / 1.5″ copper voice coil,
IMPP-cone, audiophile POLYCOT spider
Fs 38.4 Hz, Qts 0.48, SPL 87 dB