Sound Lab Majestic 645 electrostatic panel loudspeakers Review

Sound Lab Majestic 645 left panel, in my listening room and slightly toed-in.

A few months before the July 2019 California Audio Show, an attendee submitted a question in response to my rallying cry for questions to be directed to Dr. Roger West of Sound Lab at his anticipated seminar. The question was whether Sound Lab panels can be used in small rooms.

During the well-attended Sound Lab Seminar on Saturday at 10:30a.m., Dr. West preferred to stand in front of the audience versus sitting down. He needed to exert considerable arm movements to illustrate his points. It was the most dynamic and eloquent presentation I’ve seen, and it from a world-class manufacturer no less.

Thus inquired, Dr. West opined that any room ought to be outfitted with the biggest pair of Sound Lab speakers that will fit. This reminds me of the story of the fervent pianist who would have no fixtures in his apartment other than a Bösendorfer piano. Priorities in life and modern living. For myself, I’m preserving my hearing so that in my sunset years, when I am truly old and immobile, I may just sit in front of my final pair of speakers and be submerged in tunes of utmost sonority and serenity. That leads to my encounter with the Sound Lab Majestic 645, the subject of this review.

I reviewed a pair of the company’s smaller, $14,795 Ultimate 545 electrostatic panels in my 14’ x 27’ x 9’ secondary listening room. Although the U-545 was only five feet high, I experienced some of the most wholesome instrument tonal and textural reproduction ever in my experience. Then I visited the residence of Jam Somasundram while he was the Pass Laboratories headphone amplifier designer and heard his pair of early-generation Majestic 2. Standing six feet tall with a 40-inches wide curved surface and driven by a pair of the Pass Labs X600.8, the largest Class A/AB monoblock amplifiers from the marquee, it was another world altogether. And then I came across another pair of Sound Lab of monumental proportions in a large mansion, this time in the residence of a Dr. Chen in the San Francisco South Bay Area. It was a pair of the Ultimate-990PX, all nine feet tall with a 90-degree panel curvature dispersion, and arranged in a curiously and relatively nearfield listening arrangement no less.

Dr. Chen’s Sound Lab speakers had just received the latest update from the factory and were now carried the “PX” designation, which signifies a panel of the most recent design sans the bass-focus technology. Driven by a pair of D’Agostino Progression monoblock amplifiers, D’Agostino Momentum preamplifier, emmLab TSD 1 CD transport and DAC2, and wired with Kimber Kable KCAG/Hero interconnects and Kimber 8TC or AudioQuest Dragon speaker cables, the monumental panels were set to perform in a room 22 feet wide, 18 feet long with a 20-foot ceiling. Ten feet of space separated the speakers at the mid-body, and the panels were placed 100 inches away from the front wall. A vintage Tice Audio Power Block and Titan power conditioning system fed the electronics. Sound Lab customers are diehards for the see-through soundstaging and evocative tonal realism, which was what Dr. Chen’s U-990PX delivered that day. (Also read Experiencing the Sound Lab Ultimate 990PX electrostatic loudspeaker system.)

Dr. West wrote the following words for our readers on how the Sound Lab Single-Membrane Panel covers the full audio spectrum (also read Design Notes 3: Sound Lab “The Complete White Paper”)

“Our electrostatic speaker panels employ a single membrane. Therefore, the panel is in reality just one large electrostatic driver and every unit of area of the membrane carries the same spectral content. If a person were to use his ear as a detector, he could scan the entire area of the membrane from top to bottom and side to side, and the sound at each location would be identical. Further, we have chosen to permit both sides of the membrane to radiate freely into the room, making the speaker a dipole radiator. The reason for doing this is to eliminate sound colorations due to enclosure resonances. The next paragraph introduces innovations that we have developed in order to optimize bass response by eliminating two inherent problems of a vibrating dipole membrane: dipole cancellation and membrane resonance.

A stretched membrane will produce an acoustic resonance at a frequency that’s a function of the type of material used, the size and shape of the membrane and the tension it carries. With the electrostatic speaker this resonance occurs at a low bass frequency. In general, for a given input drive level the movement of a stretched membrane is the same at all frequencies except at resonance, whereat the membrane vibrates a much greater distance than at other frequencies for the same input drive voltage. Therefore, the membrane would strike the stators of the speaker (mechanical saturation) at a much lower drive level than would be required at other frequencies, therefore reducing the dynamic range of the speaker. To eliminate this limitation the single membrane is blocked into a series of smaller radiating areas, each having a different resonant frequency based on an equalization contour that offsets the effects of dipole cancellation. The highest resonating frequency employed in this process is on the order of 250Hz. Frequencies above 250 Hz are not affected. This technology provides a very flat bass response and preserves the dynamic potential of the speaker. We refer to this as “Distributed Resonance”.

Another innovation is used wherein the largest blocked-off sector of the membrane, representing the lowest frequency of interest, is placed at both the top and bottom of the speaker. Dr. Joseph d’Appolito introduced this approach using dynamic drivers. In effect, this makes the speaker appear to be a huge low-frequency driver, which increases low-frequency directionality and doubles the bass radiating area. Making bass energy more directional increases the bass energy density, which in turn provides greater bass dynamics. In our speakers we refer to this as “Bass-Focus”. Even though sound energy below 250Hz has been sectioned into a series of inter-related resonances, scanning the entire surface of the speaker with one’s ear will still appear to provide exactly the same sound at each point. The reason for this is that at lower frequencies the wavelengths of sound are large and thus bass energy is uniformly ubiquitous over the full surface of the membrane.

In summary, only one membrane is used on our speakers. Multiple drivers are not used to cover the full audio frequency spectrum. Two techniques have been employed, Distributed Resonance and Bass Focus, to eliminate membrane single-frequency resonance, to offset dipole cancellation and to optimize bass dynamics. Another important advantage of using a single membrane from which all frequencies are radiated is that the time alignment of all frequencies is perfect, which means that all frequencies that are related to a given sound reach the ear at precisely the same time. This is not the case when using a sluggish high-mass woofer that exhibits lower acceleration rate than a low-mass tweeter.”