Floorstanding loudspeakers — Martin Logan Motion 20i

The Motion 20i is a slim tower speaker from the Motion Series from MartinLogan, released in 2018. Instead of an electrostatic panel it uses a Folded Motion tweeter and two aluminium cone drivers in a bass-reflex MDF cabinet, and the list price was USD 2,000 per pair. The Motion range also includes the 15i, 30i, 35XTi, 40i, 50XTi and 60XTi.

Key specs that matter

Fitted drivers are a 1 x 1.4 inch Folded Motion tweeter with two 5.5 inch aluminium cone mid-bass drivers. MartinLogan quotes a frequency response of 45 Hz to 25 kHz within 3 dB, a sensitivity of 90 dB and a nominal impedance of 4 ohm. Recommended amplifier power runs from 20 to 200 W. Each speaker is 93 cm tall, 17.3 cm wide and 29.7 cm deep, and weighs 16.8 kg.

Engineering and use context

The crossover arrangement is of the 2.5-way type. The tweeter takes over above 2.6 kHz, while the lower of the two aluminium drivers rolls in below 500 Hz, so both cones share the bass and the midrange band is left to the top cone alone. MartinLogan builds this tweeter around a pleated membrane which presses air from between its folds instead of moving it as a dome would, which gives a larger effective radiating area within a small faceplate. The port fires from the rear of the cabinet, and the lacquered MDF enclosure is offered in gloss black, matte white or red walnut veneer. The narrow front keeps the speaker unobtrusive beside a television or in a small living room. Removable floor spikes are included, and MartinLogan warrants parts and labour for five years against faults in manufacture.

Pairing

Two pairs of 5-way terminals are provided on the back, so the tweeter and the lower drivers may be fed by individual cables or by two amplifier channels. Given the low nominal load, pick a stereo amp or home theatre receiver rated to handle it, and thanks to the high efficiency a moderate output is enough in a 20 m2 room. Since the port exits at the back, leave a gap between the enclosure and the wall behind it. The tall, narrow proportions put the tweeter close to the ear level of a seated listener without a stand. In a home cinema the model works with the matching Motion centre and surround speakers, and a subwoofer can handle the deepest notes below the reach of the twin aluminium cones.

Alternatives

The MartinLogan Motion 40i sits above the 20i as a bigger tower within the Motion Series.