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Experiencing the Sound Lab Ultimate 990PX electrostatic loudspeaker system

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Spotlight Framed

What kind of speaker will you choose if you could afford anything and you had a dedicated listening room with a twenty feet ceiling?

What kind of music would you play in the system you choose and in such vast venue?

Not many of us have the privilege of tackling such tacky issues, so imagine my reaction when Sound Lab of Salt Lake City came to my home to pick up the reviewed pair of Ultimate 545 and showed me a picture of a couple standing next to a pair of nine feet tall Sound Lab speakers that he just delivered sixty miles away prior to visiting me.

The speakers were the Sound Lab Ultimate 990PX, delivered to a Dr. Chen. I suggested an introduction, it was made, and Dr. Chen agreed to a visit.

Dimension of music room:

LxWxH = 22x18x20 ft
Front wall and 2 windows of music room:(WxH)=6/7/6 x20 ft
Distance of speaker to the front wall: 100 inches
Distance between midpoint of two speakers: 10ft


Speakers: Sound Lab U990PX
Source: EMM Lab TSD 1 CD transport and DAC2
Amplification: D’Agostino Momentum preamp, D’Agostino Progression monoblock amplifiers
Cables: Kimber Kable KCAG interconnect Or Kimber Kable Hero, AudioQuest Dragon or Kimber 8TC speaker cables


Dr. Roger West offers the following regarding Dr. Chen’s U-990PX:

“The first digit (9) of “990” represents a 9 feet tall speaker.  The last two digits (90) indicates that it has 90 degree dispersion.  The “PX” suffix represents our most recent panel design without the bass-focus technology.  If Dr. Chen’s panels had “bass-focus” they would be of our latest technology, which we now refer to as the Ultimate 990 minus the PX suffix.”

For the readers’ info, I took delivery of a pair of the company’s Majestic 645 in August this year. The Review of which is in progress.

The Sound Lab designs are akin to the Pass Laboratories design philosophy, in that all their products have the same level of resolution and tonal vividness, but the bigger ones are for bigger rooms and more demanding dynamic scaling requirements. Dr. Chen’s U-990PX is Sound Lab’s largest and most capable product supposedly in delivery of the most realistic dynamic scaling in a large space.

Then Chen mansion was in a secluded, gated valley community surrounded by rolling hills on all sides. A complete golf course adorned a central patch of land, surrounded by scenic drive routes.

The Ultimate 990PX were originally an earlier model, sent back to the Sound Lab factory in Salt Lake City for retrofitting, hence the PX limitation. A new pair of the Ultimate 990 costs $55,000 the pair. Still, Dr. Chen’s 990PX was positively huge. Each curved panel was 40 inches wide!

Dr. Chen enjoyed listening to chamber or solo music performances predominantly, for he felt the Sound Lab were among the very few designs in the world capable of producing the full body and spectrum of instruments, be it a piano or triangle. I presented my demo CD full of orchestral, synthesizer, heavy metal and what-have-you rambunctious music, including a sound field recording titled, “Night at the airport,” and was asked very cordially by a baffled Dr. Chen if I’d considered just enjoying the most natural and realistic presentation of the sound of solo instruments. Retrospectively, now that I have had months of experience with the Majestic 645 in my system, I think Dr. Chen was not amiss in the pursuit of music his way, via the Sound Lab. He is probably among the most hard cored of us all.


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6 Responses to Experiencing the Sound Lab Ultimate 990PX electrostatic loudspeaker system

  1. john vogt says:

    So I take it that you did not get to play the CD you brought along? That aside, how did the system sound with the material Dr. Chen chose to play?


    • John,

      Thank you for your readership and inquiry.

      On how the system sounded, as an invited guest, I was there to share with the readership what Dr. Chen put together, and perhaps sample the sound of his system. I wasn’t focusing on critiquing.

      That said, I did play my demo CD as described, and the experience led me to pursue a larger pair of Sound Lab panels for my own use, culminating in the Majestic 645.

  2. Marc Silver says:

    The Old Ultimate was my favourite loudspeaker ever.

  3. Evan says:

    I am considering SoundLabs for my modest listening room/office of 16’8” x 14’ 5” x 9’ H. I obviously can’t use the 990s. I’ve read your reviews of other sizes, but it’s not clear what the trade off is for say a 545 vs a 745 or 845? What impact does the 90 degree dispersion have vs. the 45 degree?

    • Evan,

      Thank you for your comment and readership.

      The dispersion range of the 990PX primarily addresses coverage of a 90-degree, larger listening venue for a more inclusive experience of optimal performance for a larger audience. Note that all current Sound Lab panels are manufactured to the 45-degree dispersion angle, and such controlled dispersion pattern on a large panel such as the 645 and up must be experienced for one to appreciate the way instruments big and small are carried into the listening space.

      I recommend a listening position within the equilateral triangle in relation to the left and right panels, preferably one nearer to the top of the triangle. This setup renders the most realistic soundstaging. Departure of this method deeper into the triangle diffuses the three-dimensionality while a listening spot outside of it defeats the stereophonic advantage. Experiment with toe-in to dial in the most discernible rendition of instruments’ three-dimensionality.

      On the models, I would begin with a 645, for it is already a 6-foot tall behemoth at $25,000 the pair. Few other speakers have comparable radiation area. The strength and precision of the bottom-end of the 645 panel already exceeds all speakers I’ve heard, including the $95k Vista Horn’s bass module, which has the most astounding scale of it. I suspect the 745 with its even larger radiating surface would surpass the Vista Horn colossally. But if you are prepared to spend the required $33,185 on the Majestic 745, I would not hesitate. For the incredibly even, directed dispersion in the 45-degree angle, complimented by flexibility accorded by the panel’s electronic crossover controls, means even the largest Sound Lab is highly flexible in allowing the owner to dial the pair in. Plus the panels, while heavy, are quite easy for minute nudging centimeters at a time to toe in and out.

      It also seems to me the size of your listening room calls for a moderately powerful amplifier for use with the Sound Lab. I rotate a pair of the Pass Labs XA200.8 pure class A monobocks with the $28,000 Bricasti Design M28 class AB monoblocks with the Sound Lab but you may not need that much output. The $13,500 Pass Labs XA60.8 pure class A high-current monoblocks should be ideal and sufficient, and its heat dissipation should not be overwhelmingly toasty, but I would be amiss without mentioning the class AB champions from Bricasti Design, such as the $12,000 M15 stereo. It should sound very close to the pure class A sound of the Pass Labs monoliths while replicating the M28 sound and surprise you with the purity of instruments along with world class jump factor. Get both and nothing else matters henceforth.

  4. Evan says:

    Thank you.

    I was able to listen to a pair of U745s driven by a Boulder 2160 and excellent upstream electronics yesterday and love them. I’m still struggling with the physical size, but am trying to figure out a way to make it happen. I’m leaning toward the AtmaSphere MA1 given how much I like the M60s, but also am considering the Pass 600.8 as it seems class A/B is a good fit. Roger West also recommended a Benchmark Class H/A/B but this is a new option and warrants more research on my part.

    The 645 seems like it could be an excellent compromise especially since I plan to keep my Swarm subs.


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