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Sound Lab Ultimate 545 electrostatic loudspeakers Review

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Dr. Roger West and Dr. Dale Ream founded sound Lab on July 1, 1978. Their founding belief was that electrostatic transduction is the optimum loudspeaker technology. Over the decades since, the company has continued to offer updates to older products. The Sound Lab Ultimate 545, the subject of this review, is the same speaker that Dagogo Senior Reviewer Doug Schroeder reviewed in January 2017, though at the time the product was called the U-4IA. Doug detailed the design and setup aspects of the speakers in his article, so I will focus on my take on the speaker’s performance in this article.

The torchbearers in today’s panel designs are Quad (UK), Magnepan, MartinLogan and Sound Lab. MartinLogan pursues the hybrid designs of coupling an active cone subwoofer system underneath an electrostatic panel on all but one of its products, namely the pure-panel CLX Art. Quad, Magnepan and Sound Lab offer full-range panels with no cone subwoofer integration. The Sound Lab Ultimate 545, the subject of this review, is one such speaker system.

Since Doug’s review, the U-4IA was renamed the U-545 wherein the 545 designation refers to a 5 foot t high panel with a 45-degree dispersion angle. For normal living rooms with 8 foot ceilings, the Ultimate series (U-545, U-645, U745 andU-845) is offered as the highest-performing product group in the Sound Lab lineup, featuring steel frames as opposed to the wooden frames in the rest of the company’s panels. The largest version of the Ultimate series is the U-945, which is offered for those who have a ceiling that can accommodate 9-foottall speakers. According to the company, the steel frames used on all models of the Ultimate lineup provide higher reactive mass and enhanced rigidity, thus supposedly allowing a more efficient conversion of electrical energy to acoustic energy of the panel.

But the U-745 and U-545 are not to be mistaken for the ultimate solution for all rooms, especially larger ones. For my approximately 3,700 cubic foot listening room that measures 14 feet wide and 30 feet long with a 9 foot ceiling, the U-545 was not what Roger had in mind originally. The entire propter quod for the Sound Lab method is the line source, which produces not just a primarily forward sonic wave front, as in a dynamic tweeter or midrange, but a 360-degree pattern from a floor-to-ceiling dipole line around which the sound pressure remains uniform, true to the radiating pattern of a live object. Because of this, Roger wanted to send me the Majestic 945 instead, which is 2 inches short of being 9 feet tall, but agreed to let me review the U-545 instead because of my unrelenting insistence. His remarks:

My calculations show that in order to achieve proper acoustic balance with the [Ultimate 545’s] the listening room should not have a volume greater than about 2400 cubic feet. In contrast, your room has a volume of nearly 3800 cu. ft. However, the speakers are mounted on the narrow aspect of the room and thus low-frequency energy travels on a “corridor” past the listening position, somewhat like a wave-guide, which could increase the energy density of bass energy and somewhat offset the maximum room volume requirement. This is new territory for me and I’ll be most interested in the results. 

“Normally, based on the volume and ceiling height calculations of your room, I would have recommended our Majestic 945’s. Just day before yesterday I received a note from our Japanese distributor that a customer of his who recently received a pair of the Maj-945’s, and whose listening room volume is similar to yours. Some of the customer’s remarks are attached as provided by my distributor. The Maj-545 and the Maj-945 are identical in every way with the exception of radiating area – the low-frequency energy density in a given room is a direct function of the radiating area. Normally, the smallest speaker that I would recommend for your room volume would be the Maj-745. The Maj-845 and the Maj-945 would do even better. I apologize for my “thinking out loud”, it’s just that I’m a bit concerned about your room having a much larger volume than I would normally recommend. However, let’s see if the shape of your room helps to compensate for this.

“The Maj-545’s can handle upwards of 600 linear watts in case you need to push them a bit to fill your space. It is my tendency to be overly conservative for which I apologize. Please keep me posted.

3 Responses to Sound Lab Ultimate 545 electrostatic loudspeakers Review

  1. Jay Chung says:

    Thank you for a very informative review of U545. I heard from someone that a cheaper but larger speaker like M645 may be better than U545. In other words, larger size may be more important than the steel frame for sound clarity. I have a very small room (880 cu ft). Would this principle apply? I would love to hear your thoughts.

  2. Jay,
    God’s Peace to you,

    I appreciate your enjoyment of the review! You ask an intelligent question in regards to size or construction of the speaker. My understanding is that the stiffer frame resulted in a tightening up of the sound, perhaps a tweaking towards cleaner sound. However, whether that would be considered so significant as to overshadow a much larger model’s sense of grandeur I doubt. I do not think the larger size would get you more “clarity” per se, but rather a bit more bass extension in frequency and larger scale. It would have a sense of a bit less strain or work in reproducing the music. It is very possible that well set up the U545 could be more precise, or have more clarity. So much depends on the actual system set up and cabling.

    If I understand the dimensions of your room correctly, it does not seem so small, as it would be at least 20’x40′! That’s a pretty good sized room. In a room such as that, with a ceiling that is high enough (Sound Lab suggests you can size the speaker to just under ceiling height) I would likely go for the larger speaker. You can always use other gear such as cables to tune/clean up the sound, but you cannot duplicate the scale of the speaker’s performance with a smaller model.

    Douglas Schroeder

  3. Roger West says:

    There is no room too small for even our largest speakers, as long as they will physically fit into your room. This may not be the case with point-source speakers, but with the line source speaker, such as ours, it is one of their advantages. Performance-wise, the massive steel framework of the Ultimate series protects and preserves the critical tolerances of the electrostatic panel, eliminates frame vibrations, thus eliminating frame resonance and insuring that all sonic energy is converted to music. Acoustically, however, the Ultimate, Majestic and the Audiophile series are equals. This is because the structural framework of the panel alone is sufficiently rigid and massive to provide full sound quality. Also, the electrostatic panel and the interface electronics of a given series size are identical. In fact, all panel sizes use the same internal construction and interface electronics, thus the only difference among all models is radiating area. Therefore, the 645 series would deliver improved dynamics compared to that of the 545 series, regardless of the styling.

    My regards,
    Roger West

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