Four hours with a pair of Martin Logan ESL 11A loudspeakers

Introduction

New year, new website, and a call asking if I’d like to listen to some fourteen thousand pounds electrostatic Martin Logan loudspeakers that can barely be moved, easily. Put it this way, when you’re taking your 30 kg Moor Amps Angel 6 power amplifier to a demo, things are serious. This is truly the mountain coming to Mohamed.

The idea here is something like having a planar magnetic loudspeaker that at least is attempting to remove the room from the speaker experience. The only issue with this is the electrostatic diaphragm can’t do bass very effectively, so a hybrid design is needed. This loudspeaker has a built-in active (powered) sub and mid-woofer. In the base of each loudspeaker are two 25.4cm (10 inch) powered aluminium cone woofers driven by dual 300-watt Class D amplifiers.

In fact, the electrostatic diaphragm (called a Curvilinear Line Source (CLS) Electrostatic Panel) is held in place by the rigid, characteristic aluminium blade, which is also powered. This makes these loudspeakers very easy to drive at around 4 ohms, with a Sensitivity quoted near 91dB 2.83 V/m. The blade provides the power for the magnets to excite the proprietary CLS panel.

Setup

Setting the Martin Logan Impression ESL 11As (their full name) seemed relatively simple once the Moor Amps Angel 6 was hooked up. The 11As had been well run in during the morning while I was driving down (and, in any case, had seen usage over the festive season).

Martin Logan suggests that units should be 10 inches away from the rear wall, being a 10” driver. This seemed reasonable and offered a solid platform from which to work.  A bass level adjustment at the rear of the base cabinet can adjust the bass response up or down ±10dB. In the slightly larger room I was in and with a stone-cold power amplifier, this was set relatively high to start with (8dB), but as the session progressed, I needed to turn this down to zero to reduce the immense bass response I was getting from both the Moor and the ESL11s subs.  Given the height of the blades, we also needed to adjust the feet to tip the blade forward a fraction to manage the soundstage.

The 11As were necessarily toed in a small amount, though I noted a 30-degree horizontal dispersion was quoted.  The 11As could be tuned to the room with Anthem Room Correction, though this was not done in this case for such a session.

Specification and Price

Four Hours

For this short session, I used an NAD M10v2 with BluOS, fixed output to the Moor Amps Angel-Pre, and a Moor Amps Angel 6 power amplifier with the refurbished Atlas Mavros interconnects and Atlas loudspeaker cable.

Here’s the Tidal playlist.

Performance

There are a couple of outstanding themes here in a listening session that I would obviously prefer to be both longer and in a more familiar space.  Nonetheless, during the brief time, I revealed two key learning points.  Firstly, the Electrostatic panel can deliver a huge scale underpinned with a dominant bass response.  Secondly, the resolution on offer is quite unprecedented.

Soundstage

Examining the first of these with the Billie Eilish/Rosalia track Lo Vas Olvidar, one can hear a dominant, deep bass response.  Towards the end of the track, you can hear the wind in the track very clearly, something I’ve only heard on headphones if I reflect on it.  Similarly, the bass response at the beginning of Radiohead’s House of Cards (Tidal FLAC 16-bit 44.1kHz) with that rasping ‘driver ripping’ introduction is tremendously exciting in these loudspeakers. If you like in-room bass, turn it up; this is impressive.  After a good hour of listening, I needed to turn the bass down from my high setting as the amplifier warmed to the task. Similarly, I also wanted to nudge the loudspeakers forward after a couple of hours. There was no loss of bass response with this adjustment, and if anything, the detail was enhanced.

Resolution

My key takeaway from these four hours with the ESL11s was the resolution being presented to me.  The ‘match strike’ and ticking clock at the beginning of The Chromatics’ Sound of Silence (Tidal FLAC 16-bit 44.1kHz) was remarkable.  The edge of the acoustic guitar in The Staves’ Jolene (TIDAL MQA 16-bit, 44.1kHz) was simply outstanding.  As I am coming off the back of the Kudos Audio Sigao Drive active loudspeaker project, I would liken these ESL11s to that active sensation, just live, visceral, remarkable and moreish.

Classical Music is similarly well presented; Lang Lang’s Liebestraum No. 3 (Tidal FLAC 16-bit 44.1kHz) is beautiful as you melt into the chair, feet up, reminding yourself how lucky you are on a random Tuesday in the new year’s grey and gloom. Current Lang Lang favourite, Schumann’s Arabesque in C Major, has a very dynamic piano performance and the same energy.

To finish off, for a bit of two-channel fun, it was time for some pumping electronica from the 80s with a complete 8-minute run-through of New Order’s The Perfect Kiss (Tidal FLAC 24-bit 96kHz) with the tremendous, noteworthy cymbal splash at 1’50”, which decays slowly and beautifully.  This was followed by some Kraftwerk (Tidal FLAC 16-bit 44.1kHz). These loudspeakers come over as tonally well-balanced. The crispy midrange is a feature with female vocals, and, at the end of this period, I have no fatigue, just energy and excitement after a remarkable listening session.

Overall

Having just liberated the Moor Amps Angel 6 from the Kudos Sigao Drive Crossover, this loudspeaker feels very active sounding to me, the highest compliment I can offer.  The scale, the detail, and the presence of the musicians in the room remind me of this.