Setting up the Theos was actually extremely easy. I followed the instructions in the manual to determine distance from rear and side walls. Proper toe-in is achieved by sitting at the listening location and pointing a flashlight at the panel. The light will reflect back at a certain point on the panel, adjust the toe-in of the speaker until the light reflects off of the inner 1/3^rd of the panel. Using the flashlight technique the speakers ended up pointing almost straight forward, with the light reflecting off of the inner 1/4^th to 1/3^rd of the panel. As seen in the measurements, the high frequency response smoothly rolls off as you move off axis. By pointing the Theos forward the soundstage opened up, the speakers disappeared, and treble was more subdued. 

The Theos are designed to be a little further into the room than other MartinLogan models. They ended up 46” from the back wall to the panel and 7’ apart. That put them a few inches closer to the side walls then the recommended minimum of 2’, but I was able to treat first reflections. The test equipment was an Oppo BDP-93, Denon AVR-3311, and a pair of Anthem M1 Monoblock amplifiers.

Listening Tests

CD: The XX - Coexist

If you enjoy alternative or ambient music, then you need to check out the XX. Their music is very bare, allowing one to really listen intently to one instrument or one voice. Many of the tracks also have deep, sustained bass. In the opening track, “Angels”, it sounded as if the solo female vocalist was right in front of me. The bass was clear and satisfyingly deep, but the Theos couldn’t quite reach as low as the song called for. As I cranked it louder the 2,000 watt M1 amps poured more power into the Theos but the 8” aluminum drivers never lost their composure. MartinLogan’s goal was obviously clean and articulate instead of subterranean bass.  In “Chained” there are two vocalists, one male and one female. I could easily distinguish their different places in the soundstage; the male on the left, female on the right, and a drum kit in between them. The entire CD felt sound natural and lifelike and at times the soundstage extended well beyond the confines of the speakers.

SACD: Alison Kraus + Union Station - Live

I recently picked up this SACD by accident. I thought I had bought a used CD from a local record shop but when I got it home I was delighted to discover it was actually an SACD. I was in for just as pleasant a surprise when put it in the Oppo and hit play. Have you ever sat down and listened to something and it sounded so good you couldn’t stop smiling? Well, that’s how much emotion the Theos were able to portray.

On Track 3 the female vocals were smooth, natural and laid back. Alison Kraus’ voice floated effortlessly and transparently in the middle of the soundstage with pin point accuracy. Every pluck and strum of a fiddle, guitar, banjo, and dobro from the Union Station Band was pristine. I could identify each instrument on the stage. On track 5 the standup bass emanated from the middle of the stage, set behind the other instruments. A quick glance at the album art verified that the standup bass player was right in the middle of the stage, behind the other musicians. On disc two there are a number of Dobro solos that the Theos played with incredible detail. The instruments didn’t sound like they were right in front my face, or set way back, they were the perfect size and distance. The only slight complaint was that sometimes the Dobro floated around between middle and left side of the soundstage, but it wasn’t bothersome. I may have been able to fix this by fiddling with the speaker placement a little more, but they sounded so good right where they were. What can I say, the Theos absolutely rocked every track on this two disc set. I could have sat listening for hours. (In fact, I actually did.)

Various

I threw a ton of music at these speakers and one thing became very clear, the Theos sound superb with quality recordings and revealed the flaws in bad recordings. Their ability to convey every bit of detail and lack of coloration means that if something was recorded poorly you will find out pretty quickly. With that said, I spent a number of hours listening to low bitrate music over Pandora and directly off my iPhone. For background music the Theos were great with compressed music, but for critical listening tests choosing high quality tracks is crucial.

The speakers also sounded good as I walked around my listening area. Stereo imaging did fall off quickly as you move from side to side, but the general sonic signature stays the same. For those hesitant about electrostatics because of a need to accommodate multiple listening positions, I would put that worry to rest. This doesn’t mean that all electrostats have wide enough dispersion for a multi-seat application; the unique height and curve of the Theos’ panel are what makes this possible. Electostats with short or flat panels will likely still exhibit a very small sweet spot.

Measurements

I used a Dayton Audio OmniMic test system with 1/12^th octave smoothing for frequency response measurements. I pulled the speaker into the middle of the room and took measurements at ear level (about 38”) and from distances of 1 and 2 meters away from the front of the panel.  Although the results were quite good, this is not how MartinLogan measures their speakers. Their concern is how a speaker sounds at the listening location, in accordance with their recommendations, I moved the speakers so they were between 2-5 feet (.7-1.5 meters) from the back and side walls, and took some measurements from an average listening distance of 2 meters. Not surprisingly, the measurements were slightly more linear.  

MartinLogan Theos In-room 2 meter Listening Window Response (1/12th octave smoothed)

I took a total of 7 measurements (on-axis +-15 deg & +-30 deg horizontal and +-15 deg vertical) and averaged the response for an overall impression of what listeners will hear. Other than the 4db boost at 3.5Khz, the response was very linear. The big bump below 300Hz was likely due to the room, so I cannot fault the Theos.                                                                      

MartinLogan Theos In-room 2 meter SPL vs Frequency Response (1/12th octave smoothed)
purple trace: on-axis; black trace: 15 deg off-axis; brown trace: 30 deg off-axis

The on and off axis comparison is a very enlightening graph considering the roll off of the ESL panel. The graph clearly shows the directionality of the ESL panel. During my listening tests the speakers were very laid back, this is largely due to the roll off of high frequencies when off axis. MartinLogan recommends that the inner third of the panel faces you, meaning that you are sitting about 10 degrees off axis. This position yields a smooth roll off the treble and gives the speaker a laid back presentation. As you can see, once you step outside of the 30 degree curve of the ESL panel the response drops off more quickly.

MartinLogan Theos 1/2 meter groundplane bass measurement (1/12th Octave Smoothed)

In order to accurately measure the bass response of the Theos I took a .1/2m groundplane measurement with the speaker standing upright (port facing the floor). The results were quite smooth, with a sharp roll off at above 300Hz. This was predictable because the Theos are crossed over at 425Hz and utilize a 2^nd order x-over. The Theos played strongly down to 40Hz, right in line with the official 43Hz -3dB point. It is nice to see a company report accurate measurements, far too many companies fudge their measurements for the sake of selling more speakers.

Conclusion

For $5,000/pr there are a lot of great speaker options on the market, but none quite like the Theos. The look of the speakers screams “high end” and they are sure to amaze anyone who has never seen an ESL speaker. They do need to be pulled out into the room a little farther for proper bass response than some other ESL’s from MartinLogan. For those of you that are concerned about this, the next step up in MartinLogan’s lineup, the Ethos, are a little more versatile with an on-board amp and level controls. As far as sound quality goes, you will be hard pressed to find better. The transparency and detail of these speakers is incredible. Whether watching movies or listening to music, the Theos are a treat to listen to. Highly recommended!