Sound Lab Ultimate U-4iA electrostatic speaker Review

A romp with the Exogal Comet and Ion

I have saved the best for last in terms of systems and the performance of the Sound Lab U-4iA. Far and away the most remarkable experience with the U-4iA happened with the Exogal Comet and its new partner, the Ion PowerDAC. You will want to take the time to read my extensive review of these products, as they are a marvelous example of a new breed of components with the ability to vastly improve your enjoyment of the hobby. In the review of the Ion I go so far as to say that the digital amplification it represents will upend the domestic amplifier sector of the audiophile HiFi market.

The Comet and Ion are two of the most wondrous pieces of electronic kit I have laid hands on in 12 years of reviewing. They whisper to me that we live in a magical age of audio, a time when the convergence of convenience and sound quality is reaching a high state of synergy, and this is happening below the cost level expected of extreme audio components.

The Ion contains a true digital amp (as opposed to Class D, or “switching” amplification), is rated at 100Wpc, and was not designed with an eye toward driving less efficient panel speakers such as those from Magnepan or Sound Lab. However, used within slight limitations it is extraordinarily good sounding with them. The Comet and Ion were most praiseworthy with all five speakers of various technologies I used in the Ion review to the point that it set new performance standards for all five! In my reviewing, I have never witnessed any system, much less one brand of gear do such a thing. Usually I have to reconfigure the system, that is exchange components, to address each speaker’s strengths and weaknesses, but the Comet and Ion optimized every transducer’s characteristics. Consider that an invitation to try them.

The chief attribute for which electrostatic speakers are treasured is a sense of speed, or quickness in transients, and perhaps only certain horn speakers are on a par with electrostatics in that regard. There is a vibrancy and invigorating feel to hearing a fast panel speaker in full flight. Imagine how much more the magic of a panel speaker is enhanced when the electronics can operate commensurately quickly. As I discuss in detail in the Ion review, the Exogal combination of DAC and PowerDAC are blisteringly fast, and they snap even electrostatic speakers to attention as though they had been previously sloughing.

Treble and midrange

One might wonder how this superfast combination affected the treble, as it is not uncommon for speakers perceived to be “fast” to also be considered harsh. Poor treble reproduction doesn’t float, either it spits at the listener with staccato bursts, or seems melded into metallic smears with points of emphasis. The treble from the U-4iA hangs in the air and wends its way through the music, as opposed to spattering over the music. A fundamental reason for this is the width of the driver section dedicated to producing it. Treble as heard from the U-4iA is fundamentally different from a point source tweeter. In a wondrous fashion the treble is teased apart just a bit and opened up, making it perceptually more 3-D than point source treble. I realize we are speaking of very small waveform, but every instrument produces notes with their own acoustic envelopes, and treble notes are no different. When they expand ever so slightly from a wide-bodied driver such as the U-4iA they seem more natural and shimmering, less piercing.

The midrange also benefits from the curved, larger driver membrane. Like the classic Quad design where the midrange was centered, so also the midrange is centered in the U-4iA. Yet it avoids the “eight foot head” effect from stretching the image too tall. Those who love coherence and enjoy full range, high efficiency speakers will want to hear the new driver configuration of the U-4iA because the primary conditions that entice full range speaker lovers will be heard in the U-4iA. A spookily solid and warm character is fairly easy for the U-4iA to produce with a variety of gear, so vocals fans take note.

I do not spend much of my time listening to Classical music, but I do enjoy the sound of a symphony. I play soundtracks employing orchestras such as The Perfect Storm, Out of Africa, Transformers, etc. If I play masterpieces it will be from a “Best of Mozart” or “Symphonic Favorites” collection. Yes, I confess I lean toward schlock symphony, and I do not care if you are displeased. It doesn’t take uppity music to determine the superiority of an audio system, nor to enjoy it. When a person knows how to tune and assess an audio system any genre of music can be used, preferably the one that is listened to most consistently. It is possible to improve the sound of a system using only electronic music.

My point in discussing this lies in the fantastic detail retrieval and succulent midrange of the U-4iA. This speaker gives some of the most convincing choral and symphonic playback I have heard. I do enjoy John Rutter’s work and his choral piece, The Prayer of Saint Francis, is centering both spiritually and acoustically. The U-4iA is expressive enough that many individual voices are evident in the choir and their individuality preserved, yet melded together, as when one steps back from an impressionist painting until it just resolves and forms something closer to a photograph than modern art. Or perhaps the analogy of a camera lens focused to allow examination of the particulars of the subject is more apt. I sang in choirs from grade school through college, so I like hearing massed voices, and with Rutter’s work I never felt more able to slip into the male chorus and make my attempt at a sonorous contribution than when the U-4iA was playing it.

The soundtrack to Out of Africa would likely drive upper crust listeners bonkers with the metronome-like consistency through track after track. It’s not Vivaldi by any stretch of the imagination, but as I hear it from the U-4iA it captures theswaying grasses of the savanna and herds of animals roaming freely so well in my imagination that I can picture myself overlooking them from an escarpment. I hear the many individual strings  playing in concert to round the next note like fields rippling by individual stalk with nearly liquid fluidity, and I get lost in the moment. When a speaker can do that for a genre I don’t care all that much for, it’s a great speaker.

The one drawback of the Exogal and Sound Lab pairing

There are two aspects of the pairing of the U-4iA and Comet/Ion Power DAC components to be considered, the exquisite sound quality and the slight restriction on the listening level. Restriction on listening level is normally a deal breaker for those considering amplification. After all, if the amp can’t drive the speakers in an unlimited fashion, then what good is it? I ask you to hear me out on this issue, as the takeaway for those willing to accommodate a wee bit of governance in use of the Ion is more than worth the constraint. Again, for an extensive discussion of the operational interaction of the Comet and Ion with the U-4iA, or any panel speaker, see the Ion review. This will be a summary of that explanation.

The Ion is a complementary component containing additional DAC functionality for use exclusively with the Comet DAC (no exceptions for other brands and components, so don’t bother to ask Exogal). Think of them together as a two-chassis DAC. However, the Ion also has amplifier functionality, so the Comet is a DAC with preamp functionality, and the Ion presents an upgrade of the DAC with amplifier functionality. They combine to form a complete package of extreme performance DAC, preamp and amplifier. The Ion uses a unique digital amplification technology that is stable into electrostatic and magnetic planar speaker loads. However, when run at the limit, nearly at maximum output (about 97 or above on the Comet’s digital display) as the speaker’s demand for current exceeds that provided by the Ion, the protection circuitry triggers a shut down. No harm is caused to components or speakers. The Exogal components reset in a matter of about one minute from restarting. Exogal is working on a softer response to the excessive current demand in which the volume will be reduced incrementally rather than the components entering protection mode.

Note well, as with the First Watt J2 amplifier this is a discussion pertaining to compatibility of operations and not quality of the electronics. I have no doubt that if driven to absurd levels the Kingsound King III electrostatic speaker also would cause an over current demand and cause the Exogal Ion to shut down. However, I did not experience this, as I did not take the King III to as high listening levels as the U-4iA. The listening level at which the Ion shut down was 90dB, well above where I recommend audiophiles listen to music, save perhaps some symphonic music where the peaks might be briefer.

There are sizable differences in the recorded level of digital music tracks, and these come into play with low to moderately rated power amplifiers. Obviously, a piece of music engineered at lower volume must be played back at a much higher amplifier output to achieve a higher listening level. This is typically an issue with amplifiers having lower power ratings paired with less efficient speakers as it calls for the amp to operate near its maximum and, in the case of many amplifiers, the sound quality degrades at that point. My first point in defense of the Ion as an “amplifier” for a panel speaker is that the sound quality never degrades at any point in the operational range of the unit. It matters not whether the Ion is run at 50 or 98 on the Comet’s digital readout, the sound quality will be preserved. The Ion seems impervious to sonic degradation due to elevated output. There is no fading, falling away of dynamics or harshness introduced prior to the protection circuit being engaged.

The protective circuit, indicated by the letters “IONOVT,” was only triggered twice during the review period, though I had used the Comet and Ion with the U-4iA extensively for weeks and with a global sampling of musical genres and recordings. The instances when the protection circuit was tripped were when I inadvertently maxed the output, literally pegging it at 100, in an attempt to play a softer piece of music louder, and when Iplayed a track with extremely aggressive LF at a similarly high level. In other words, there are very defined instances where it is possible that the playback level of the music will be absolutely limited by the matching of the Comet and Ion with the U-4iA or another less efficient speaker.

What percentage of recordings in the universe of material available might fall into that category? It may depend somewhat on one’s preferences. For instance, a few older mono recordings or quiet chamber music requiring the Ion to be operated at maximum power may present challenges to playback at higher levels. However, the vast majority of music engineered is well above the plane where one would have to jack up the output to an appreciable listening level. I suspect that when listening to a wide variety of musical genres and artists one might encounter a level limitation once in every 500 pieces of music. Alternatively, certain genres of music have a ridiculous amount of LF, and if the listener wishes to hear them at close to live listening levels, then they would be bumping into the limits of the Ion’s output regularly. While this is an important point, it likely will not affect a large majority of hobbyists. That is why I am bullish on the combination; if it were a pesky issue I would discuss the combination of gear as severely limited rather than very slightly limited and recommendable.

When I encounter a potential drawback, as in the case of the high SPL limitations of the Ion with panel speakers, I consider whether the benefits more than offset the drawback. If the performance were not utterly glorious I would move on to another system configuration, but the outcome of pairing the Comet and Ion with the U-4iA is so special that it cannot be overlooked. It quite simply has yielded top-level sound, and not just for an electrostatic speaker, but for any speaker technology.

Thus we segue to the second aspect of the Ion and U-4iA match; I have been deeply impressed by the transients experienced with this system. The sharpness of images, the ability to stop and start superfast, to explode with instantaneous power and do so nearly without limitation to the listening level is akin to riding on a high performance motorcycle – you will not forget the ride! Playing contemporary music like Lorde’s “Royals” or London Grammar’s “Strong” surprises because the energy output of the U-4iA is monumental, while at the same time the finesse is exquisite.

Sound Lab has placed the U-4iA in the Ultimate line and promotes it as performing at nearly the same level as its flagship speaker, the U1-PX. The performance specifications are even closely the same. Having heard several representatives of the Sound Lab family, and the U1-PX, I concur with that designation. In fact, I consider the sound of the Comet and Ion together with the U-4iA when judged by strict audiophile criteria to be superior to what I have heard of the U1-PX with Atma-Sphere amplification at shows. That comment is not to be interpreted as the U-4iA being a better speaker than the U-1PX, not by any means. It is a statement that the U-4iA is capable of being every bit as superb, and that the Exogal Comet and Ion make it so. I do not think I am going too far out on a limb to state that the technology employed in the Comet and Ion will challenge nearly any system regardless of cost paired with the U-4iA. Bluntly stated, the odds are heavily against your DAC and amp being better than the Comet and Ion. Whether you wish to believe me that a PowerDAC might holistically beat the pants off your big gun amplifier or mono amps costing multiples more is your decision.

I adore the richness of the Exogal componentry with the U-4iA, the filigreed lines of acoustic contour achievable only with artistic precision and the utmost authenticity tonally, which lets the ears settle on nuances. There is no distraction, no “tut-tut” mentally arising from telltale softness in percussion, occlusion of a cymbal’s or chime’s full reverberation, or sibilance in vocals. The system producing this result was set up as follows:

• HD-Plex Linear Power Supply with Clarity Cable Vortex Power Cord feeding the Salk Audio StreamPlayer Generation III server/streamer
• Silnote Audio Eprius USB Cable
• Exogal Comet and upgrade PLUS Power Supply with Verastarr Grand Illusion MkII Power Cord
• Exogal Ion Power DAC with Clarity Cable Vortex Power Cord (Note: The Comet and Ion are linked via proprietary EXONET cable. Though it appears as an HDMI cable it is not, and HDMI cables will not work with the Ion.)
• Hybrid speaker cabling consisting of a parallel (not bi-wire) run of TEO Audio Standard Liquid Speaker Cables and Clarity Cable Organic Speaker Cables (Note: The placement of leads must be perfectly parallel, precisely matching connections. You do such speaker wiring configurations entirely at your own risk. I am not responsible for any possible improper wiring or incompatibilities resulting in potential damage to equipment!)
• Sound Lab U-4iA speakers with Clarity Vortex Power Cords.

The outcome with this system is such that it would take a monolithic dynamic or hybrid dynamic speaker system, fully 2 meters tall, to generate as generous a soundstage. The wide dispersion of the U-4iA’s midrange and treble are maximized by the Ion. However if the speakers are placed more narrowly relative to the primary listening position one should not expect perfect stereo imaging when sitting off axis. There is no “head in the vice” tightness, but the speakers, though curved, are still directional. Elevating them with the supplied spacers to tilt back the front baffle is recommended to raise the action happening center stage from about 3.5’ off the floor to about 5-6’ off the floor, an acceptable height for a realistic sensation of a live performance.

As discussed earlier the Kingsound King III is another critter altogether with its line array type technology. Previously, I had not found another decent sized panel speaker – magnetic planar or electrostatic  that was in the realm of affordability to compete well with it. The U-4iA surpasses the King III in terms of overall coherence, the spatial relationships of performers on the stage, as well asgreater bass output and impact. To get the King III to perform on a par with the U-4iA I had to use the VAC Royal Power Supplies, two of the Legacy Audio XTREME XD Subwoofers, and aftermarket interconnects and power cables, pushing that speaker system’s cost to $27k.

Especially with the Exogal Comet and Ion, the U-4iA reminds me of very costly dynamic speakers (think high five figures). I anticipate the U-4iA will give some vaunted and perennially well-awarded dynamic speakers a tough run for the money. In the U-4iA I hear many of the admirable qualities of such speakers, but without their drawbacks. Neither are horn nor horn hybrid speakers safe from this comparison. The U-4iA’s full bodied, full figured midrange reminds me of the best SET amp and horn speaker systems. In a phrase or two, the Exogal and Sound Lab produce extreme audio and are a match made for discerning listeners. I do not often recommend specific electronics components with speakers in reviews, especially if there is a caveat, but in this instance I will.

A great, not-quite-as-big slice of Sound Lab magic

Sound Lab has succeeded in a towering accomplishment, making a more affordable, real world proportioned speaker that captures the essence of the enormous Sound Lab Ultimate experience. Let electrostatic fans around the world celebrate. Let fans of nostalgia Quad speakers graduate to a serious ESL. Now that the barriers to the Ultimate experience have been removed, let theEuphoria begin. For those who have coveted Sound Lab sound but have been unable to accommodate it, now is the time to pull the trigger. Fans who love electrostatic speaker sound and have found the reach to own a Sound Lab Ultimate series speaker too great, it is now within reach. If you have heard the U-1PX you have heard the soul of the U-4iA and you can confidently move ahead without fear of being shorted, pardon the pun, in the experience. If you want to skip intermediate steps and move to a showcase system, perhaps the best the U-4iA has to offer without spending another $25k minimum on components, match it with the Exogal Comet DAC and Ion PowerDAC system ($7,350). Euphoria awaits!

Associated Components:

Source: Salk Audio StreamPlayer Generation III with ROON interface
 Streaming Music Service: Tidal
 Playback Software: ROON
 DAC:  Eastern Electric Minimax DSD DAC Supreme with Burson, Dexa NewClassD and Sparkos Labs Discrete Opamp Upgrade; Exogal Comet DAC and upgrade power supply, LampizatOr Big 7
 Preamp: TEO Audio Liquid Preamplifier; VAC Renaissance Signature Preamplifier MkII;  Cambridge Audio 840E
 Amps: Red Dragon S500; VAC Phi 200; First Watt J2 (two)
 Speakers:  Kings Audio Kingsound King III; Legacy Audio DSW Clarity Edition; Kings Audio King Tower omnidirectional; Vapor Audio Joule White 3; PureAudioProject Trio15 TB (Tang Band) and Treo15 Voxativ
 Subwoofers: Legacy Audio XTREME HD (2)
 IC’s: TEO Liquid Splash-Rs and Splash-Rc; TEO Liquid Standard MkII; Clarity Cable Organic RCA/XLR; Snake River Audio Signature Series Interconnects; Silent Source “The Music Reference”
 Speaker Cables: TEO  Cable Standard Speaker; Clarity Cable Organic Speaker; Snake River Audio Signature Series Speaker Cables; Silent Source “The Music Reference”
 Digital Cables: Clarity Cable Organic Digital; Snake River Audio Boomslang; Silent Source “The Music Reference”
 USB: Verastarr Nemesis; Clarity Organic
 Power Cables: Verastarr Grand Illusion; Clarity Cable Vortex; MIT Oracle ZIII; Xindak PF-Gold; Snake River Audio Signature Series; Silent Source “The Music Reference”
 Power Conditioning: Wireworld Matrix Power Cord Extender; Tice Audio Solo

Copy editor: Dan Rubin