Floorstanding loudspeakers — Martin Logan Impression ESL 11A

The Impression ESL 11A belongs to MartinLogan's Masterpiece Series of hybrid electrostatic floorstanding speakers. It joins an XStat CLS panel to a powered woofer section with two 8-inch drivers, their own amplification and a 24-bit Vojtko DSP engine. MartinLogan lists it at USD 11,999.98 per pair.

Key specs that matter

Specified bandwidth is 29 Hz to 23,000 Hz within 3 dB. Sensitivity is 91 dB at 2.83 V and 1 m, and nominal impedance is 4 ohms, reaching 0.6 ohm at 20 kHz. MartinLogan recommends 20 to 550 W per channel for the panel section. The crossover sits at 300 Hz. The woofer amplifier delivers 2 x 275 W into 4 ohms, with 2 x 550 W quoted as peak output. The panel measures 112 x 28 cm, acts as a 112 cm line source, has a radiating area of 3,136 cm2 and a horizontal dispersion of 30 degrees. Each speaker weighs 40.9 kg with dimensions of 154.3 x 30.2 x 69.6 cm.

Engineering and use context

Each 8-inch laser-engineered aluminium cone woofer has a cast basket, sits in a separate sealed enclosure and is driven by an extended throw motor, inside a non-resonance asymmetrical chamber layout. PoweredForce Forward alignment combines two ideas - PoweredForce, which lets compact enclosures produce high bass output, and ForceForward, which phase-times the rear-firing woofer against the front one to reduce bass energy reflected from the wall behind the speaker. The panel uses MicroPerf stators that expose almost twice the diaphragm area of a conventional panel of the same size, ClearSpar spacers that hold the vacuum-bonded diaphragm at exact tension, and an AirFrame Blade rail of extruded aerospace-grade aluminium. The panel is curved horizontally following MartinLogan's Curvilinear Line Source principle, and as a dipole it sends little output toward the side walls. The high-pass side uses a custom-wound audio transformer, air-core coils and polypropylene capacitors. On the rear panel, bass can be adjusted by 10 dB either way below 75 Hz, and a mid-bass switch offers minus 2, 0 or plus 2 dB.

Pairing

The amplifier feeding the panel connects through fully insulated WBT-0703Cu nextgen 5-way binding posts with gold-plated, nickel-free pure copper conductors. MartinLogan states compatibility with amplifiers rated for 4, 6 or 8 ohm loads. The posts and use a filigree conductor that MartinLogan describes as free from eddy current effects. The built-in woofer amplifier needs its own AC power connection.

Alternatives

A step further up the Masterpiece Series, MartinLogan builds the Expression ESL 13A with a 10-inch woofer size in place of the 8-inch drivers used here.