Martin Logan Impression ESL 11A

The Impression ESL 11A sits within MartinLogan's Masterpiece series, alongside the Expression ESL 13A, of which it forms the more compact variant. It is a hybrid floorstanding speaker: the midrange and treble are handled by an electrostatic panel, while the bass is taken care of by a woofer section fitted with its own built-in amplification stage. The speaker is therefore connected to the mains in addition to the signal cables, which reduces the load placed on the upstream amplifier.

At the heart of the model is a curvilinear CLS electrostatic panel 28 cm wide. This horizontal curvature shapes the dispersion: it widens the listening area compared with a flat panel, whose radiation would remain very directional. The width of the panel, meanwhile, has a direct bearing on the available emissive surface and therefore on the ability to reach lower frequencies before handing over to the woofers.

MartinLogan highlights two defining elements on this model. The MicroPerf stator revises the perforation of the grille surrounding the diaphragm, so as to free up more usable surface for a given panel diameter, resulting in a higher output level. The highly rigid AirFrame Blade chassis holds the panel and limits stray vibration in the frame, the kind that blurs the transparency inherent to the electrostatic principle; it also provides the visual link with the woofer enclosure.

This type of speaker suits a listener attached to clarity and finesse in the upper part of the spectrum, listening attentively facing the system. The electrostatic panel calls for careful placement: sufficient distance from the rear wall, orientation towards the listening position, and a room in which the bass section can breathe. An ARC acoustic correction kit is available as an option to tailor the amplified section to the conditions of the room.

When buying used, a few checks are specific to this design. The electrostatic panel should be inspected first: no ingrained dust or trace of moisture on the diaphragm, film properly tensioned and free of perforation, silence on power-up once the charge has built up, and above all no popping or crackling, which would indicate an arc between stator and diaphragm. Other points to examine:

• operation of the internal power supply and amplification for the bass, on both speakers, as well as the condition of the mains lead and fuse
• suspensions and travel of the woofers, with no rubbing or mechanical noise
• rigidity of the AirFrame Blade chassis and its connection to the enclosure, no play or vibration when tapped
• condition of the connection terminals and any adjustments to the bass section
• presence of the ARC correction kit and its microphone, if it accompanied the set

An electrostatic panel becomes dirty over time and ages according to use and environment: extended listening, at several volume levels and checking the balance between the two units, remains the best way to judge how well matched the pair is.