Sound Lab Majestic 945PX electrostatic panel loudspeakers Review

A pair of the nine feet tall Sound Lab Majestic 945PX electrostatic panel speaker system costs $60,000, and it is the flagship model in the Majestic series. The ”945” nomenclature denotes the panel being nine feet high in a 45-degrees curving radiating surface. It is essentially a large canvas of mylar diaphragm stretched inside a strong, non-warping solid ABS frame that spans almost nine feet tall and over three feet across in a horizontal arc. A higher “Ultimate” series exchanges the beautiful outer wood frame for a metallic one for the final word in structural rigidity. (Update 3/7/25: Since 2006, the wood frame has been replaced by Acrylonitrile Butadiene Styrene or more commonly named ABS, which is a strong, durable, versatile thermoplastic polymer. Note that music instruments such as recorder and clarinet are made of ABS.)

For the first year or so back in 2020 when I had the Majestic 645PX, I never thought I would fancy the 945. The 645 at six feet tall was already one of the tallest speakers in the world and its performance peerless. But the memories of the PRO-STAT 990 at RMAF 2008 would resurface and I found myself becoming curiouser and curiouser about the possibilities that my listening room’s 9.5 feet to 15 feet high ceiling would hold. The thought became a question the answer to which I must obtain, and it’s not like I had to spend $100,000+.

Per Dr. West, Sound Lab owner and chief engineer, “The 945 has a width of seven cells while the panel is one single huge membrane in a structure that stretches it and bends the membrane 12 degrees every five inches. We use the term, ‘cell’, not to suggest there are independent radiators but to describe the flat vertical facets that the panel is comprised of, which provides a controlled horizontal dispersion. The geometry is set such that the sonic lobes of adjacent cells overlap, and they cross over above -6dB from the lowest bass frequencies to beyond 20kHz. This provides a perfectly smooth wave front and a full frequency response over the entire horizontal dispersion of the panel.

For example, a cell is about 5 inches wide, so an approximate width of the panel can be calculated simply by multiplying 5 inches by the number of cells. Thus, a 7-cell Sound Lab panel would have an approximate width of 7 x 5 inches = 35 inches.” Note that the membranes are encased inside a sweeping solid skeleton in all models.

Nothing on this planet weighing 225 pounds is easy to move, but each Sound Lab 945 stands on screwed-in pods that makes it easy to glide and wedge the panel into position. This flexibility in position experimenting makes for a rewarding ownership experience, and endless fun.

Because the Sound Labs are dipoles, they require ample back space for the backwaves to dissipate. In my 24 feet long, 17.5 feet wide and 9-15 feet high room, I first positioned the panels forty inches from the wall behind them, then I stacked two pairs of Acoustic Sciences Corporation tubetraps behind the panels for rear diffusion.

The M945PX are equipped with the LOW FREQUENCY LEVEL and BRILLIANCE knobs on the back plate, with the former a stepped knob in the -6 at 10 o’clock, -3 at 11 o’clock, 0 at 1 o’clock and +3 at 2 o’clock increments, the latter a continuous rotary knob from a 7 o’clock minimum to a 5 o’clock maximum. The M645 that I reviewed in 2020, on the other hand, were given the additional MIDRANGE knob. Sound Lab discontinued the MIDRANGE control so as to incorporate an air-core coil. Per Dr. West, “The previous core was tapped in order to permit switching to different levels of mid-frequencies. However, the coil used a metal core which begins to saturate at higher audio levels. The new air-core coil will not saturate, which reduces distortion at higher sound levels. However, air-core coils are much larger and the size of a direct replacement for the tapped metal-core unit was prohibitive. To adjust the mid-frequency level, if it is desired to increase the mid-frequencies relative to the low and higher frequencies, one simply turns the bass and brilliance controls down as desired.  Conversely, if it is desired to reduce the relative mid-frequency level, one simply increases the low frequency and brilliance controls.  In effect, nothing has been lost and a source of higher-level sound distortion is eliminated.”

But wouldn’t the elimination of the tone controls from the circuit present a purer sound? Dr. West: “Concerning your request to eliminate the tone controls, that’s no problem.  A fixed resistor would need to be determined to provide the high-frequency setting you prefer, and the low-frequency transformer would need to be hard-wired to provide the “0” dB switch position.  Not that I’m trying to talk you out of the changes, I am just concerned that eliminating the ability to make changes in the bass and brilliance levels might be frustrating when music sources or equipment needs compensation.  Let me just say this, the selector switch used in determining the bass level has been changed to a special unit that is manufactured in Europe.  I very seriously doubt if it would have any audible effect on the sound field.  This switch replaces the one in the plates that you have, and it can handle twice the rated power.  Concerning the brilliance control, it is wire-wound and thus has a very low noise characteristic.  The contact resistance of the rotor is extremely low and insignificant.  However, it might be wise to Include the controls in case they are desired in the future.”

And those are words of wisdom, for among the amplifiers I auditioned for driving the panels were one KT-120 based vacuum tube stereo amplifier and one solid-state stereo amplifier from the nineties, both possessing disproportionately prominent lower midrange that was their common sonic signature. Following Dr. West’s two-step process, I was able to flatten out the lower midrange prominence considerably first by the minimization of the LOW FREQUENCY LEVEL and maximization of the BRILLIANCE. The second step is a judicious increase of the preamplification volume so as to bring up the new sound curve. It is akin to the analog parametric equalization of old where the two knobs represent a sine wave spanning the entire frequency range the contours of which highly customizable by the user. The said solid-state amplifier fared not as impressively as its tube counterpart from this process, and the tube amplifier took on a new level of transparency with the newly unearthed lower to upper midrange.

Sound Lab’s implementation of this contouring is possibly the most elaborate, the quality of associated parts impressive, and least intrusive performance-wise. It is noteworthy that even at the minimal setting, the bottom-end of the panels remained definitive in articulation and transient. In addition, the controls are at neutral with the LOW FREQUENCY LEVEL at 0, and the BRILLIANCE at the 3 o’clock position.

Electronics utilized in this review includes the Audio Note UK IO Ltd cartridge system, the Technics SP-10 Mk2A turntable, the Pass Labs Xs Phono, the Stealth Helios phono cables, the $6,300 Aurender N200 network transport, the Bricasti Design M21 DSD DAC, the M20 preamp, the M28 monoblock amplifiers and the Pass Labs XA200.8 monoblocks. Also joining the audition was the $6,120 pair of Atma-Sphere Class D gallium nitride monoblocks, the $18,100 MP-1 3.3 preamplifier, the pair of $5,000 Orchard Audio Starkrimson Mono Ultra Premium GaNFET monoblocks, and the $22,000 Aurender AP20 DAC/integrated amplifier. The A.R.T. Sensor Haute Couture and Analyst EVO heavy-duty cable systems provided primary support in the majority of the auditioning sessions, except for the lightweight class D amplifiers from Atma-Sphere and Orchard Audio, for which the thin and nimble Audience AV frontRow cable system was selected. Two A.R.T. Distributor-X anchored system-wide power distribution.

Throughout the years I auditioned speakers of various drivers count and published my findings on a few flagship speaker systems of the larger physiques with the lowest drivers count, the most meritorious among them being the single-driver, dual-concentric Tannoy Churchill Wideband, the Tannoy Westminster Royal SE, the oversized horn of the Destination Audio Vista and the large electrostatic panels of the Sound Lab Majestic 645. Most noteworthy is the fact that Tannoy’s 15-inch dual-concentric driver was the only one with a solitary dual-concentric driver to exhibit nil excursion playing some of the most rambunctious passages I could muster from my music library. The importance of a woofer’s property of resistance to excursion cannot be overstated for a distortion-free sound, a problem resolved by the electrostatic membrane drive system summarily.