Floorstanding loudspeakers — Martin Logan EFX

The EFX is a hybrid electrostatic speaker made by MartinLogan that pairs an XStat CLS panel with a cone woofer in a slim extruded aluminium AirFrame cabinet. MartinLogan designs it as an on-wall model, only 16.5 cm deep, intended to hang beside a flat-screen television, and it ships with pivoting wall brackets. The list price was USD 4,399.98 per pair.

Key specs that matter

The electrostatic transducer measures 71 x 22 cm for a radiating area of 1,562 cm2. Below it sits a 6.5 inch high-excursion fibre cone woofer on an extended-throw drive assembly, loaded by a bass-reflex design. MartinLogan rates the frequency response at 68 Hz to 22 kHz within 3 dB and the sensitivity at 90 dB at 2.83 V and 1 m. Nominal impedance is 6 ohm, and the speaker suits amplifiers rated for 4, 6 or 8 ohm. The cabinet stands 123.9 cm tall and 23.8 cm wide, and weighs 11.1 kg.

Engineering and use context

A crossover at 530 Hz hands the signal from the woofer to the panel, so the electrostatic element covers the midrange and treble in one piece. The network follows MartinLogan's Vojtko filtering approach, and technicians assemble it by hand using a custom E-I core transformer, air-core coils and metal film capacitors. Because an electrostatic panel needs a polarising voltage, each EFX takes a low-voltage DC power supply, drawing at most 2 W and less than 1 W in standby. The pivoting brackets let the owner rotate the speaker on the wall to aim it toward the seating area, which suits surround and front channel use in a home cinema. Satin Black is the standard finish for the aluminium frame and grille, and signal enters through custom 5-way binding posts.

Pairing

MartinLogan recommends amplification of 20 to 300 W per channel. As the woofer only reaches down to the high 60 Hz region, a system built around the EFX benefits from one or more subwoofers with a crossover set to cover the bass below it, and an AV receiver that can route low frequencies to a subwoofer makes a practical partner. The moderate load and good sensitivity mean that the power available from a mainstream receiver is usually adequate for home cinema levels, and because the panel has a low depth it can hang almost flush with the wall surface. A power outlet is needed near each mounting point for the DC supply.

Alternatives

The MartinLogan ElectroMotion ESL X is a floorstanding hybrid electrostatic model with a larger panel and twin woofers.