MartinLogan Aerius loudspeaker Page 2
Power amplifiers were either a pair of Mark Levinson No.20.6 monoblocks or a YBA 2 HC, while the preamplifier was either the Melos SHA headphone amplifier used as a line-stage or the YBA 2. A Mod Squad Phono Drive EPS amplified LP signals from a Linn Sondek/Cirkus/Trampolin/Lingo/Ekos/Arkiv setup sitting on an ArchiDee table. Digital source was variously a Theta DS Pro Generation III, a Counterpoint DA-10 with UltraAnalog DAC module, or a Meridian 263 Delta-Sigma, driven by a Mark Levinson No.31 transport via AudioQuest Pro 2 ST-optical and Digital Pro coaxial links, respectively. Interconnects included 1m lengths of Siltech 4/80 between digital processor and preamps, and 15' lengths of AudioQuest Lapis between pre- and power amplifiers. The speaker cable was a 5' bi-wired set of AudioQuest Sterling (the Aerius review samples were supplied with the bi-wiring option). All source components and preamps were plugged into a Power Wedge 116, itself plugged into one of my listening room's two specially installed AC circuits. (The Aeriuses' electrostatic power supplies were plugged into separate circuits.)
My dedicated room measures approximately 19' by 16.5', with a 9' ceiling. The wall behind the speakers is faced with books and LPs, while further book- and CD shelves occupy the positions on the sidewalls where the first reflection from each speaker would occur. The room is carpeted, and there are patches of Sonex foam on the decking'n'viga ceiling to damp the first reflections of the sound. The other wall has RPG Abffusors and ASC Tube Traps behind the listening seat to absorb and diffuse what would otherwise be early rear-wall reflections of the sound that might blur the stereo imaging precision. More Tube Traps are used in the room corners to even out the room's bass resonances, the result being a relatively uniform reverberation time of around 200ms from the upper bass to the mid-treble, falling to 150ms above 10kHz.
In the excellent and comprehensive manual provided for the Aerius, (footnote 2) MartinLogan stresses the fact that the sound of the speakers will change for at least the first 30 hours, due to the need of the woofer's butyl surround to be broken-in. The Aeriuses were run in on high-level pink noise for approximately 72 hours before any serious listening was performed, therefore. Each Logan was used with its three carpet-piercing spikes—two at the front, one at the back—making contact with the tile-on-concrete floor beneath the carpet. MartinLogan stresses that the Aerius does need some boundary reinforcement to achieve its correct tonal balance. I ended up with the center of each cabinet's rear panel 2' from the front of the record cabinets behind it. Each speaker was almost, but not quite, toed-in to the listening seat.
"Seamless." That's the word. Right from the get-go, I was struck by the unity of the Aerius's sound, the integration between woofer and panel. Unlike its rather larger brother, the Sequel II, which I always had trouble with in the crossover region, the Aerius is excellent in this respect. In fact, the transition from moving-coil to electrostatic driver is so smooth that when my son, recently embarked upon his odyssey through the "terrible twos," pulled out the woofer connection to one of the speakers, it took me most of an evening to realize that the sound had lost 3dB of its bass oomph!
With my ears 36" from the ground, pink noise sounded very smooth (though there was a touch of boost in the presence region). Moving up a few inches in my chair added excessive treble "bite" to the sound, while standing drastically cut the highs. Interestingly, with dual-mono pink noise, while only minor vertical Venetian blinding was noticeable as I moved from side to side—the MartinLogan CLS was severely afflicted by this problem—moving even a few inches forward in my seat changed the midrange character significantly, the main effect being to change a trace of "eee" coloration. This could only be detected while I was moving, however, which suggests that it is due to position-dependent interference effects—minor comb-filtering and the like—which are trivial.
Given my enthusiasm for the seamless nature of the Aerius's sound, it would seem unfair to break its performance down into the traditional frequency regions. But hey—it's hard for a reviewer to break audiophile habits.
Starting at the very top, the highest treble octave seemed shelved-down, the sound lacking top-octave air. This bothered Sam Tellig more than it did me; I only really noticed it when I listened for it, and with recordings that themselves lacked energy in this region. I suspect that whether or not it becomes a significant factor in the Aerius's balance will depend on how large a room its owner has, and how well-damped the walls and furnishings are.
Footnote 2: It includes an article on the history of electrostatic speakers (with due mention made of the pioneering work of Quad's Peter Walker), excellent hints on setup and room acoustics, and a list of LPs and CDs MartinLogan has found to offer exceptional sound quality.—JA