Description: Hybrid electrostatic/moving-coil loudspeaker system. Drive-units: 48" curvilinear electrostatic midrange/HF transducer; long-excursion, sealed-box, 10", damped-paper-cone woofer. Crossover frequency: 250Hz. Crossover type: quasi-second-order, 12dB/octave. Frequency response: 30Hz-22kHz, ±3dB. Dispersion: horizontal, 30 degrees; vertical, 4' line source. Sensitivity: 89dB/2.83V/m. Nominal impedance: 8 ohms. Minimum impedance: 1.5 ohms at 20kHz. Recommended amplifier power: 80-200W. Finishes: light or black oak, standard; dark oak, walnut, custom…
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Sidebar 2: Associated Equipment
Digital Front-End: Krell KPS-20i/l, Naim CD3 CD players.
Analog Front-End: Linn Sondek LP12 turntable with Naim Armageddon power supply, Naim ARO tonearm, Transfiguration Temper cartridge; or VPI TNT Mk.III turntable with JMW Memorial tonearm, van den Hul Frog cartridge.
Phono Section: Naim Prefix/HiCap, Ayre phono module, or Krell KPE Reference.
Preamplifiers: Ayre K1, Conrad-Johnson Premier Fourteen, Krell KRC-HR.
Power Amplifiers: Conrad-Johnson Premiers Eleven and Twelve, Krell KAS and FPB-600, Plinius SA-100.
Interconnects: MIT balanced…
Sidebar 3: California Brisson and the Soundroom of Doom
MIT's Bruce Brisson and Joe Abrams flew to Santa Fe the day before Martin-Logan's Gayle Sanders, thinking that Gayle would prefer to hear the completely treated system upon arrival.
At 16' wide by 17' long by 14' high, my living/listening room is awfully close to a cube; still, the dining alcove behind my listening position gives me another space 8' wide by 12' deep by 8' tall, and this cuts down early rear-wall reflections. Exposed 2" by 14" beams support the ceiling, and the floors are large ceramic tiles set over a poured…
Sidebar 4: Trying to Control a Lightning Storm
Talking to Gayle Sanders is always a treat; he's enthusiastic and gestures effusively, staying in constant motion until something totally engages his attention. Then, it's as though you can see the intellect click on: His eyes narrow, and he seems to quiver as he brings his full attention to bear. This can cause conversations to move in an odd rhythm, but one adjusts. I recently realized that I had never heard the saga of Martin-Logan's early days. I asked Gayle to tell me how he'd gotten into hi-fi, and why he'd been driven to build…
Phillips: I suspect we're getting ahead of ourselves.
Sanders: True, our first transducer had none of those elements. I built that first speaker right out of a hardware shop: perforated aluminum for the stators, Plexiglas for the spacing elements, epoxy glue to hold everything together. I found some half-mil polyester film somewhere and sprayed insulation onto the stator. To get a conductive coating onto a diaphragm, I burnished graphite onto the film.
Phillips: You just rubbed it into the polyester?
Sanders: That's right. It gives a nice semiconductive surface—you don't…
Phillips: We were just talking about your prototype, which used flat panels. How did you determine that you needed curved panels?
Sanders: That's the classic drawing-on-a-napkin-in-a-Chinese-restaurant design story. Ron and I were eating dinner, chit-chatting about speaker design. As we talked, I sketched a waveform moving away from a point-source. It became clear to both of us that the information on-axis was farther away in time than the information coming from the sides—I drew these little points and we literally connected the dots. I looked at the napkin and said, "Ron, could it…
Sidebar 5: Measurements
I hate measuring panel speakers. Why? Because the usual assumptions you make when you measure a loudspeaker—that the microphone distance is large compared with the physical size of the speaker and that the mike is therefore in the speaker's farfield—are no longer true. As a result, the interaction between the microphone and the speaker is much more complex than is normally the case. In addition, the measured performance of panel speakers is enigmatic. Compared with a typical moving-coil speaker, the measurements can look worse—yet listeners like the sound more. So…
Moving on to the measured frequency response, this was taken on an axis level with the midpoint of the electrostatic panel, 42" from the floor. Visually smoothing out all the little ripples, the SL3's response appears to shelve down above 1kHz. Remember, however, that there will be an interaction between the speaker and the measured response due to the relatively close microphone distance. There will be a "proximity effect" that raises the speaker's apparent midrange output the closer the microphone is to the speaker.
This is graphically shown in fig.3, which shows the on-axis response…
In the time domain, the SL3's step response (fig.5) is beautifully coherent, the rise away from the time axis being almost vertical. Further analysis is difficult, so I have also shown the individual step responses of the panel and woofer (fig.6), plotted to a slightly different scale. The panel can be seen to overshoot the time axis on the return of its step to zero, with its second positive-going move overlaid with the slow rise of the woofer output. There will be some cancellation between the two drivers, meaning that the SL3 owner should experiment with the room placement to get the…
Sidebar 6: Manufacturer's Comment
Editor: I know when the team of Wes Phillips and John Atkinson get hold of a speaker the manufacturer is going to learn even more about his product than he knew before the process began. We are Martin-Logan feel that the SL3 represents new levels of audio performance and it feels good "back here in the Midwest, that your observations are close to ours."
A few issues regarding the testing procedures. Yes, our products are different from point source products in the way that they launch information and, as a result, our testing procedures differ…