Mission 750

The Mission 750 is a two-way bookshelf speaker with bass reflex loading, designed to be installed on stands or placed on a shelf. Its most distinctive feature lies in the arrangement of its drivers: the tweeter dome is positioned beneath the woofer, an arrangement intended to equalise the acoustic path lengths reaching the ears of a seated listener, thereby making the arrival of both drivers coincide in time.

The woofer is a 5.25-inch, or 135 mm, cone made of mineral-filled polypropylene, paired with a 28 mm soft dome for high frequencies. The two drivers meet at 2.4 kHz, a crossover frequency that leaves most of the midrange to the cone before handing the top of the spectrum to the tweeter. The internal volume of 12.2 litres and the bass reflex port allow the speaker to reach 48 Hz at -3 dB, with extension down to 42 Hz at the -6 dB point: bass that remains within the reasonable limits of a compact format, without claiming to reach the very lowest register.

• Sensitivity of 86 dB (2.83 V at 1 m), nominal impedance of 6 Ω with a minimum of 4.5 Ω
• Recommended amplification power of 25 to 100 W, maximum sound pressure level of 103 dB
• Frequency response of 48 Hz to 20 kHz (-3 dB)
• 355 mm high on plinth, 216 mm wide, 270 mm deep plus 35 mm for the terminals, 9 kg per speaker

With a sensitivity of 86 dB and an impedance that drops to 4.5 Ω, this model requires an amplifier capable of delivering current: the stated minimum of 25 W is a floor, and the range up to 100 W leaves room for a well-specified integrated amplifier. The format is suited to near-field listening or a small to medium-sized room, in a stereo system. As magnetic shielding is not provided, it is best to avoid placing these speakers close to a cathode ray tube screen.

When buying second-hand, a few checks are worthwhile on this type of speaker. Run your hand over the surround of the 135 mm cone to detect any cracking or stiffness, and check that the 28 mm soft dome has not been pushed in by a curious finger, a common issue on a tweeter positioned low down, at child height. Listen out for any parasitic air noise from the bass reflex port, a sign of internal detachment, and operate the terminals to make sure they still grip properly. Finally, as these speakers are sold in pairs, check that the two units are properly matched and that their cabinet finishes have aged in the same way.