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MartinLogan Expression ESL 13A hybrid electrostatic speaker Review

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Changes made

MartinLogan completely redesigned the Expression, such that it should be thought of as a speaker. Significant changes include:
• More robust power supply.
• All electronics are mounted on a metal plate located on the bottom of the woofer enclosure. The plate can be removed by unscrewing six bolts. For the prior models you had to be a contortionist to get the boards out.
• The panel frame and woofer frame are significantly stiffer to prevent microscopic vibrations which can degrade the sound.
• The woofers have been redesigned “and optimized specifically for the needs of this speaker.” “The design matches the Electrostatic panel and the power amplifier to achieve optimum performance.”
• The woofer enclosure has forward and back facing woofers. The Summit X had one forward and one down firing woofer. The Expression enclosure is larger and more rectangular than the old enclosure. Both woofers are in sealed chambers and are phase timed (Powered Force Forward Bass) to reduce reflected energy from the font wall. MartinLogan states that this uniform frequency response results in “realistic bass effects you can feel.”
• The two class D amplifiers for the two enclosed woofers have been upgraded to 300 watts each.
• Binding posts have been improved to prevent eddy currents and vibration.
• Electronic crossover point is now 300Hz instead of 270Hz. The improved electronics and components are said to enhance mid-range clarity. The Expression operates as a true dipole speaker down to 300Hz.
• The Anthem Room Correction uses downloaded software to drive a built in digital processor that corrects lower frequency room anomalies. In many listening rooms there are significant room interactions, resulting in peaks and nulls. ARC measures the low-frequency sound output in a listening room with a calibrated microphone and compares it to optimal response curves. Correction are made so that the speaker output is essentially flat from 24Hz to 300Hz. To prevent overdriving the built in woofer amps, the total amount of correction available is about 6 dB. The microphone kit and cables to run ARC are sold by MartinLogan for $100.
• The bass control has been altered. Bass control is now ±10 dB under 75 Hz. Previously, the control had been from 25Hz to 50Hz. A new mid bass control was added. Mid-Bass: (150Hz to 250Hz) with 3 options –2 dB, 0 dB, +2 dB.

Compared to the Expressions’ “Mylar like” panel, its woofers have significant inertia and cannot react to changes in the signal as quickly. In addition, the radiation patterns of the woofer and panel are very different. MartinLogan claims to have solved this problem by using an electronic/passive hybrid crossover at 300 Hertz’s with 24 bit DSP processing to mate the woofer and panel and thus eliminate discontinuities. With the Expression, you get an electrostatic speaker that supposedly delivers pure clean, natural sound above 300 cycles with very low distortion and bass down to 24 cycles with the woofers. The company claims that most speakers, especially cone speakers, in the Expression’s price range produce significantly more harmonic distortion.

The MartinLogan Expression is able to generate high sound levels compared to other electrostatic speakers as the stators are closer to the charged Mylar like material than other brands of electrostatic speakers. The panels were also designed to have twice the radiating area of a traditional electrostatic panel of the same size. From my experience, very loud sound levels were obtained with 6 to 60 watts as measured by my amps wattmeter. The Expression is rated at 91 dB sensitivity and a nominal impedance of 4 ohms. However at 20,000 Hz the impedance drops to .5 ohms. Thus, the speakers may not sound crisp with some tube amplifiers in the higher frequencies.

My Equipment

McIntosh 601 Monobloc’s 600 Watts per channel
Krell Phantom III preamp
Esoteric K01X SACD player
PS Audio P5 Power Conditioner
MartinLogan Expression (13a) Hybrid Speakers
All cabling and power cords are OCC 99.99999% pure silver made by Wireworld.
Power Cords (Platinum and Gold Electra 5 squared)
Speaker Cables– Gold Eclipse 6
Interconnects—Gold Eclipse 6

Listening room
14’x23’ with 11’ ceiling. The 23’ back wall has a 13.5’ opening


Setting up

If you plan on keeping the box the Expression comes in, you will need a second person to hold the box when trying to pull the speaker out. That person is also required to lift the speaker when trying to remove it from the Styrofoam that protects the speaker’s base.

While every room is different, I would recommend MartinLogan’s suggestion that the back of the Expression woofer enclosure be at least 2 feet from the front wall and if possible the speaker be 3 feet from the side wall. I have not experimented but MartinLogan claims that the speakers can be placed as close as one foot from the front and side walls.


Changing the angle of the panels

One area I disagree with MartinLogan is the angle of the panels the Expression comes with. The speakers seem to be set up to be optimal when a person is listening standing up, but I think that most people are concerned about optimizing the sweet spot when sitting in a chair.

In a discussion with a MartinLogan employee about my prior Montis, he suggested making the panels more perpendicular to the floor to increase the width of the sound stage. The Expression manual also mentions experimenting with the angle. For both the Montis and the Expression, adjusting the panels more perpendicular to the floor by a few degrees increased the clarity, detail and loudness at the listening position. The biggest difference from the Montis is that the Expression seemed less prone to be being boomy when the angle was decreased. It is worth experimenting with the angle of the panel.

18 Responses to MartinLogan Expression ESL 13A hybrid electrostatic speaker Review

  1. Gerry says:

    I’m surprised you are getting such good highs with a McIntosh amp. The problem with having a speaker that goes to 1 ohm at higher frequencies is that an amplifier with output transformers can’t impedance match at that frequency so power transfer is reduced. It was true that as each bigger amp was put in place the response improved but not enough. For me the sound never really opened up so I gave up on McIntosh at 300 watts per channel and moved on to a very good direct coupled amp. With my C2300 pre-amp there is excellent transparency and air yet it is never harsh. I will also say that if I was not retired I would buy these speakers for the room correction add-on.

    • Robert Schussel Ph.D. says:

      Like most men who are older/above 45 I have some roll off in the higher frequencies which may help explain why the Martin Logan Expression seems to have good highs for me.
      Also having all pure silver power cords, interconnects and speaker cables gives the system detailed and clean highs. I have used pure copper cables in the past but never enjoyed them as much as my WireWorld pure OCC silver cabling.
      Maybe getting older is the key to a better sounding system?

      • Gerry says:

        Although, at 66, (I have just had my hearing tested – excellent, particularly considering all the rock concerts attended) I do know that I can’t really hear much above 10KHz. That is based on my playing a disk that sweeps through the frequencies from 20 Hz through 20 KHz. Still the lack of air and high frequency detail that was missing with the McIntosh amps totally stopped me from enjoying my system. That said, the mid-range and bass were wonderful.

        • Robert Schussel Ph.D. says:

          What McIntosh amp did you own?
          I have been in contact with both McIntosh and Martin Logan. McIntosh’s technical person feels that when amps have a problem driving Electrostatics it is tube amps which tend to put out a higher voltage and lower current as opposed to solid state amps that put out higher current and lower voltage. The Martin Logan project manager told me that they have no evidence that McIntosh amps have problems driving their speakers. I would note that Martin Logan has used McIntosh amps to demonstrate their CLX electrostatic speaker.

          • Gerry Martan says:

            Wow, I just stumbled across this again after a long time. In answer to the question, the first amp was a 90 Watt per channel tube amp followed by the 402 and then a pair of 501s. With a transformer in play the output follows the impedance curve of the speaker so an 8 ohm tap driving a 0.5 ohm load would see reduced power transfer. A transistor amplifier with tremendous current reserves would overcome that obstacle to a degree and I will admit that with each increase of power the highs did improve somewhat but it would be stupid to spend the money for a 1 KW McIntosh when a high quality 200 watt per channel direct coupled amp worked so well. That said, I see that the newer amps do have 1 ohm taps which would obviously help but will have a minor detriment to the midrange. Now that I have a speaker with a benign load across the frequency range I am toying with the idea of getting one of the newer McIntosh power amps. I do miss my ML speakers but the wife is happier.

  2. Alan N says:

    I just recently upgraded from the legacy Summits to the Expression 13A’s, and your review is spot on! Adjusting “rake angle” really has significant effects. Of note, I previously purchased the Summit X leg assembly from ML ($500+), and they are fully compatible with the Masterpiece series. They allow adjustments from 11° backward to 1° forward tilt. I’m currently using a 3° rake angle with my Expressions (vs. the default 5°). I don’t know if ML still sells the Summit X leg assemblies separately, but definitely worth checking, if you want to experiment with a wider range of tilt than the default legs offer.

    • Robert Schussel Ph.D. says:

      I couldn’t agree more with your comments about the rake angle. Martin Logan understates the difference that can occur when the rake angle is changed.

      Most of my listening is in a chair in the sweet spot. Even a two degree change which sounds insignificant made a significant improvement in the way my Montis and now my Expression sounds. If someone owns a Martin Logan hybrid speaker I would encourage them to experiment with the rake angle.

      Thanks for the heads up about the leg assembly. I plan to contact ML after the holidays and see if they still offer them. I will let everyone know what I find out.

      • Robert Schussel Ph.D. says:

        Here is the reply I received from Martin Logan regarding the Summit X leg assembly.
        “The Summit X had special feet to adjust the rake. These will not fit the Expression. The feet included with the Expression offer significant rake adjustment”.

        • Alan N says:

          Hah! I just stumbled upon this review again, and noted ML’s erroneous information. Not sure who you spoke to at ML, but the Summit X leg assembly is most definitely compatible with the Expressions (and presumably the Impression, and Renaissance models as well). I’m still using them, but recently switched back to a 5° backward rake angle, as we replaced a heavy wool rug in our family/listening room with a very thin one, and the upper mids and highs became a bit “screechy.” The additional 2° backward tilt eliminated that issue. Amazing how that slight adjustment makes so much difference!

  3. kc says:

    Enjoyed the review. Long time stat fan (acoustat 2+2’s and Beveridge 2sw being notable speakers I longed for but could not afford). Purchased ML reQuests in 2001 and upgraded to my current Summits in 2008. Love the summits and like the other poster if not retired I would seriously consider this model based on your and Stereophile’s Mr. Iverson’s & Atkinson’s experience with the room correction on the bass response. Love Esoteric spinners and having a KO1X on the front end must make for some fantastic listening. Happy Holidays!

  4. Dan says:

    Excellent review! I personally own a pair of Ethos. Did you by any chance listen to ESL11A or Ethos? I want to upgrade to ESL11A and I am curious what improvements I would hear. Based on your review I already have a pretty good idea from extrapolation but maybe you heard them in person.

    • Robert Schussel Ph.D. says:

      I have not heard the ESL11A but did speak to a dealer that I trust who felt the 11A is a significant improvement over the Montis it replaces.
      You will hear a better integrated bass,better imaging and highs. What is tricky to predict is how much difference the room equalization program (ARC) will make in your room. In my case the difference was huge. I would urge you to try to audition the 11a before spending $10K.Make sure its exactly what you are looking for.

  5. Ron Cornelius says:

    McIntosh amps with output autoformers will certainly follow the speakers impedance just like any direct coupled transistor amp. They are all rated to be down 3dB at 100KHz so you should be fine.

    • Robert Schussel Ph.D. says:

      Thank you for the information. what you said seems consistent to the information I provided to Alan. Neither MartinLogan or McIntosh officials felt the speakers lower impedance at 20KHz would be a problem/issue

  6. PJ Lett says:

    I own the 11-a which in their own right is a nice improvement Obove any past ML venture
    Top to bottom better integration and parts quality. That being said the 3 capacitors that go from the mid Bass above 300 hz and mid high frequency panel .i upgraded the 3 stock capacitors to the new Clarity CSA capacitors and a Mundorf supreme , then bypassed .33uf with the Excellent Fostex
    Capacitors. This Loudspeaker sings more coherent then even the 15A .these capacitors a a true step up
    A true world class speaker to complement the Seamless Bass.

  7. GJW says:

    Great review. Very thoughtful detail in comparisons to the previous generation. I’ve been a long time fan of Martin Logan having owned the CLS (hooked me into electrostats), Quest, and lastly the Summit X. Along the way I’ve owned a number of box speakers but always came back to Logans. Various amps have been in and out along the way including McIntosh. Amp choice has a profound effect on the sound. Logans quickly reveal the amp’s ability to handle dynamic load impedance to the extreme. Autoformer based McIntosh amps can sound wonderful if properly mated with the correct autoformer tap and speaker cable. This can mean using my ears not necessarily matching the published speaker impedance with the autoformer tap. Which autoformer tap did you use for your evaluation?

  8. Dennis M Brennan says:

    Perfect Review. I own the Montis, and tested a few amps with the Montis and other Martin Logans as well. I find the Vintage Krell amps with getting them re-capped is the best I’ve heard. I have 3 Krells and currently using a Krell KSA-200S. The authority of the Krells and the Class A presentation is something I just love. Also, me and many others like to have a Pair of REL subs sitting next to the Logans. The RELs add another dimension to the music and the REL S series hooked directly to each channel on the Krell speaker outputs for a true stereo sub experience is quite the finished product for me. My only next step a few years from now is to get the Expression 15A or 13A model used. Just thought I would mention the Krell amps and REL subs for the Martin Logan speakers. Even a Magico Q5 Demo used the RELs to lift up the whole body of the music. I’m so happy with my system now, that going any further at this point would be selfish on my part. But maybe one day….. some 15As would be nicc.

  9. Hank says:

    Thanks for a great and objective review of the 13As. I too am a classical music fan, and prefer solid state gear over tube. Using acoustic music (classical especially) is the only way to truly determine the accuracy of an audio system…so thanks for doing just that! I have many of the RCA Living Stereo SACDs that you referenced. The bass response graphs are a big help too.

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