King's Audio Prince II Electrostatic Speakers (TAS 210)

Equipment report
King's Audio Prince II Electrostatic Speakers
King's Audio Prince II Electrostatic Speakers (TAS 210)

Time was that a pair of electrostatics speakers was almost the shibboleth of the high end. When TAS began, of course, there were fine box speakers, the Spendors, the IMFs, and the Harbeths (rare in the USA), the large Advents, and those classics of American audio, the AR3as from Acoustic Research. But the electrostatics of the time, relatively old (the original Quads, the KLH Nines) and new (the Dayton Wrights, the Klosses, the Beveridges, and the Acoustats), combined extraordinary sonic qualities, especially of imaging, with the appeal of the exotic. No one except serious people owned them! Electrostatics seemed to symbolize high end in the late 1970s and early 1980s.

Times change. Today the market is dominated by box speakers, not just at the mass-market level but also at the highest levels of the high end. And yet, in the dark night of the audio soul, a still small voice is likely to whisper that what the electrostatics did that made them unique decades ago, they still do. And when day dawns, it behooves one to recall exactly what those things are. To listen to a convincing new electrostatic design is to remember all over again why they have always fascinated a certain segment of the audio world and still do.

King’s Audio is a relative newcomer. But to judge form the finely finished and carefully designed Prince IIs, King’s Audio has already reached a very high level both of professionalism and sonic performance in making electrostatic speakers. The Prince IIs are anything but a design feeling its way. This thoroughly thought-out speaker offers some most attractive sonic virtues. It is in effect a two-way speaker, with most of its width taken up by a bass/mid panel, and a smaller strip from top to bottom at one side acting as a tweeter. Both function in effect as line-source dipoles. The speakers are quite tall, a little short of six feet, and really do operate as line sources for all practical purposes. (The habit of audio people of calling any vertical row of speakers, however short, a line source needs to go. A true line source is necessarily floor to ceiling or close to it).

Dipole speakers, with their zero radiation to the sides, get the sidewall reflections largely out of the picture. But dipole line sources also take the floor and the ceiling out of the picture as well and float images in the vertical direction in a sense. The Prince IIs do this to a fare-thee-well. This matters enough that it is worth going into in some detail.

Point sources tend to compress height to zero, to make the music seems to come through a horizontal slit. Large multi-driver speakers diminish this, which is why large three-ways always sound better than little two-ways, other things being equal. It is precisely because the big three or four-way speakers are NOT functioning exactly as point sources that they sound good! Think about it: If sound comes out of a single point in effect, it is bound to be heard like that—spread horizontally but compressed into a single horizontal plane with no vertical extension. Of course, you get some spread from bounce off the floor but that bounce is always deleterious in other ways. For one thing, it gives the ear/brain a strong indication of where the speaker is, relative to the rear wall. People talk about speakers vanishing side to side but the real trick is vanishing front to back.

The secret here is a speaker with vertical extension and minimized floor bounce that, even so, sounds coherent. The latter is do-able albeit with difficulty with big multi-driver speakers, but just the automatic nature of the beast in a line-source electrostatic.

The line source really frees the music vertically. I was struck by this emphatically a few years ago, comparing the Soundlines of late lamented memory to a British small-box monitor. The box monitor was equally accurate tonally, but music coming out of it sounded small and squashed, once one had listened to the same music on the Soundlines. And here with the Prince IIs, which are line source from top to bottom (the Soundlines had a box woofer), the impression is even stronger. The big three-ways at close range spread the drivers enough to give some of this freedom, but line sources do the job completely.

Back in the horizontal image world, the dipole Prince IIs, which have a null directly to the sides, get the first sidewall reflections way down in level, too. The effect can be startling. On test CDs of in and out of phase (polarity, really) the difference is total, the out of phase being truly nowhere and the in phase being totally focused. Stereo imaging works as it should when this happens. Total success on this with the Prince IIs.

Put this vertical freedom and horizontal focus together and on something like the remarkably recorded Ceremony of Nine Lessons and Carols [EMI], and the sense of being in another venue, of actually being there hearing the speaking voices and the music in their real venue, rather than in your listening room, is about as good as one is likely to find from any speaker and far better than most. As I said, I have encountered the vertical freedom before, as many have, notably in the DALI Megalines a few years back. But every time it is startling how much it means in musical terms.

And combined with the dipole suppression of sidewall early reflections, it can be overwhelming. I sat down to listen to “Once in Royal David’s City” on the recording just mentioned as a test item and ended up listening to the whole (first) CD—hypnotic, indeed. And it was not even Christmas time. Not only was the radiation pattern of the Prince IIs, with their minimized sidewall and floor reflections, taking me somewhere else, the ultra-low distortion and purity were also making the music exceptionally beautiful.

Somewhat to my surprise—I cannot hazard a technical reason for this—the sound seemed even more beautiful with the improved power supply from VAC (thanks to Kevin Hayes for the loan) replacing the stock power supply. I did not run blind tests on this, but I did get that impression of smoother sound with quieter background.

This matter of recreating another acoustic venue is arguably the major distinctive goal of high-end audio. (Mass-market audio after all tries for truth to timbre though it seldom gets close.) And the Prince IIs vault into the “must audition” category with ease on this basis. But life being as it is, there are also certain restrictions and caveats that must be noted.

First of all, the Prince IIs are not really flat in the lower midrange on down. They lose energy in the region between 100 and 200Hz and tend consequently tend to sound thin and midrangey. This can be almost harmless or really annoying, depending on the material. I rather suspect that what is going on here is the dipole rolloff taking some toll before the tympanic resonance of the membrane pulls the deeper bass back up in level around 50-60Hz. In fact, the bass comes up to considerably above the nominal level around 60Hz. The dipole roll-off drops the bass off at the very bottom, but the bass extends quite surprisingly far down, though the bass is not what I would call tight. Its dipole character does ameliorate somewhat the effect that such a considerable rise would have in a box speaker, however. Above the warmth region, there is a return to level, and then some, in the 400-800Hz octave. About the treble, later.

This hole in the warmth region took some considerable toll on orchestral music. Things like the Telarc Rachmaninoff Second Symphony, by nature a warm piece and a warm recording, sounded very pure but somewhat thin and uptilted and midrangey. And Eargle’s amazing Wagner recordings from Seattle on Delos sounded, not bass-shy in the real bottom, but lacking in warmth and having un-natural midrange orientation. The deeper bass comes back in, as noted. The true bottom of the orchestra is definitely there. But in the warmth region between 100 and 200Hz, there is a definite hole. This happened wherever I put them in a room where other dipoles have not done this. So I am supposing that this is actually a property of the speaker, not of room/speaker interaction.

The Prince IIs sound elevated in the treble directly on axis, but there is an axis on which the speaker sounds quite smooth and flat, at least up to the very top, This is somewhat off the geometric “on axis” position. Experiment with angling the speakers to find the best balance! Having the flat-response axis, not the one with the most high-frequency response, would be a risky business, indeed, in a box speaker with wide dispersion—too much top in the room sound would result. But since there is rather less room sound with the more directional Prince IIs, the room sound balance is far less significant than it would be in the wide-dispersion case. Except for the thin lower mids, the speaker in a proper setup can sound quite nicely balanced though personally I preferred it, truth to tell, with the treble pulled down a bit even on the best axis. (This reduced the faint glare that seemed otherwise present). But this is a matter where standardization has not really happened, and you may appreciate the sense of treble detail, as is.

Independently of frequency response matters, the Prince IIs sound quite considerably the best if one positions oneself at their geometric center vertically. This somehow locks the image in more convincingly, and presents the alternative space of the original recording venue the best. For me, this involved sitting on a rather low seat (I am a tad under six feet but tall from the waist up). Do arrange this—sitting in the middle vertically. It matters!

The Prince IIs demand a lot from the amplifier. Sensitivity figures for dipole line sources are difficult to give in a way that compares them directly to box speakers because the sound is projected into the room in a quite different fashion. But to judge from the volume settings needed to match volumes in listening terms, the Prince IIs are considerably less sensitive than say my Harbeth M40s, themselves only in the mid-80dBs, one watt, one meter. The Prince IIs were not giving of their best with the 100Wpc amp I tried to begin with, which seemed to clip at the drop of a hat. They really cried out for—and got—the big power, the Bryston 14’s 500Wpc. The Bryston had the power, but this normally imperturbable amplifier seemed not to drive the top end of the speakers well—electrostatics can present a really low and capacitive impedance in the top end. The top sounded tilted up to a considerable extent and somewhat glarey.

Enter the Sanders Magtech stereo amplifier (circuit also available as monoblocks, even more power). Roger Sanders is himself a designer and maker of electrostatic speakers, and some years ago he designed an amplifier specifically designed to handle the unique load they can present. The Magtech amplifier also offers extraordinary performance for dynamic speakers [see sidebar]. The Sanders amplifier surely succeeds in its goal of being able to drive electrostatic loads. The Prince IIs sounded considerably better with the Sanders Magtech than otherwise. The amplifier had the power to drive them and it sounded unfazed by the load. Everything came together much better and the glare was much reduced. (No one will accuse me of over-rating the importance of amplifiers, but these speakers have special needs.)

Even with big amplifier power, the Prince IIs are not the speakers for rock concert levels. But once I got the Sanders amplifier, I did not feel dynamically constrained to any substantial extent with acoustic music, even acoustic music of large scale.

One can do a little judicious EQ to fill in the lower midrange hole and adjust the treble a bit. And the results can be very gratifying from that. To my ears, one really does need to do something for the thinness in the lower mids. Properly tweaked in this sense and tweaked with respect to placement, and one can hear something really special.

And special is the word. With everything just so, the results were remarkably convincing. This is logical enough: A speaker with such low distortion and with a radiation pattern that minimizes early reflections ought to sound really good if one fixes any little glitches in tonal balance. (Speakers like that are a natural for DSP correction.)

And so they did! For example. Debussy’s “Reflets dans l’Eau” from James Boyk’s remarkable piano CD Tonalities of Emotion [Performance Recordings] sounded very lifelike, very much like being in the presence of an actual piano in a hall of moderate size, though the naturalness of piano tone as such was not quite so good as on my reference Harbeth M40s (original version). The Prince IIs version of violin sound on the Dorian recording of Violin and Piano Music of Dvorak was truly convincing, as was the string orchestra sound on the Dorian recording of Bach’s Art of the Fugue played by Les Violons du Roy/Labadie conductor and arranger (one of the best string orchestra recordings ever). And Eargle’s Delos Wagner recordings sounded as Wagner should, and very like an orchestra, as speakers go.

If one really wants to go to subterranean frequencies, one can always add a subwoofer, if one finds one that is precise enough to match well. I got especially good results with a pair of PSI subs (thanks to Simplifi Audio’s Tim Ryan for lending me these). This ran the total system price for speakers alone up to around $15,000. The subs did extend the very bottom and expanded the dynamic capability. And of course the subs have the advantage that one can DSP correct them with the DSPeaker Antimode 8033 without interfering with the main speakers.

So there you have it. Impressive dynamic capacity for a relative small electrostatic, though still a bit restrictive for extreme material; impressive if not subterranean bass extension as well; the ability to take your room out of the system to a surprising extent; ultra-pure low distortion and very detailed sound—all big pluses. In the minus column, restricted listening area for the best sound, though not as restrictive as some electrostatics; some irregularities of frequency response, especially some deficiency in the warmth region compared to the box speakers optimized for that; and an awkward amplifier load that requires special attention.

I found the Prince IIs fascinating, and on occasion exquisite, when either the tonal thinness was not exhibited strongly by the material or when the hole in the lower mids was corrected by EQ of either DSP or analog sort. The Prince IIs demand to be auditioned, and you may find completely addictive the sense of the listening room around you suppressed and the original venue. The Prince IIs can be almost irresistible. They have some remarkable sonic virtues, but they do require some special care.


Sidebar: Sanders Magtech Stereo Amplifier

This has to be short, so I’ll get right to the point: If you paid $5000 or more for a presently available amplifier and did not check this one out first, you should have. There are, in some important ways, very few competitors for this design. And some of these, like the Lightstar and its relatives, you cannot buy any more. This is not to take anything away from other power amplifiers, many of which work really well and sound all but perfect when they are not being stressed out too much. But when the going gets really tough, not just for loudness as such but for the complex and current- demanding loads that speakers present in the real world, what one needs is a regulated power supply. Hardly any contemporary amplifiers have this; this one does.

This idea is not news to long time TAS readers. Back in issue 25(!), Dave Wilson, then a TAS reviewer, wrote of some solid-state amplifier “The power supply is not regulated per se, but it is so stiff and so responsive that even on very deep, very loud material it is like unto a brick.” Implied was the idea that regulated would be even better!

In practice, regulated power supplies are a true rarity in the output stages of power amplifiers of any substantial power, though they are almost universal in amplification devices at lower signal levels like preamps. They are almost universal there because they work better. And it seems they work better for large-signal purposes, too. They are just hard to arrange.

I do not have room to explain what is going on here or even what a regulated power supply is. You can get the basics at Wikipedia and there is further information on this amplifier specifically on the Sanders site (

The Magtech does not have a switched-mode power supply, the usual way to get power supply regulation in a practical form for power amps. The Magtech has a patented linear regulation system, and that makes it unique.

Does that matter? I have not run double-blind tests and so on, and of course there would be other variables since there is no way to un-regulate the regulated power supply for comparison. But in informal albeit concentrated listening, the Magtech not only drove the tricky Prince II electrostatic load very well, indeed, it also delivered truly superlative performance into dynamic speakers. The sound from my Harbeth M40s (original version) sounded precise, controlled, defined, dynamic, perfectly balanced, and extremely clean with unusually silent background and extreme solidity even in demanding passages. Thundering piano music, for example, was as solid as a rock. The Sanders Magtech amp has power to spare, 500 watts per channel into 8 ohms, 900 into 4. But it sounds as if it had infinite power into anything with total stability.

The Sanders Magtech joins (really only, in my experience) the Lightstar family and the DALI Gravity in extreme ability to handle anything and sound perfect while doing it. An instant classic in my book. Try it before you decide I am exaggerating.


King’s Sound Prince II
Type: Dipole panel electrostatic speakers (powered power supply included, wall-plugged, conversion to DC)
Dimensions: 68” x 21” x 3”
Weight: 46 lbs.(each)
Price: $6500

25B Capital Trade Centre,
62 Tsun Yip Street,
Kwun Tong, Kowloon
Hong Kong
(+852) 2345 2323; (+852) 2345 2778

386 Beech Avenue,
Suite 5 Torrance CA 90501
(310) 212-5216

Saunders Magetch
Type: Stereo power amplifier with patented linear power supply regulation
Power: 500 watts RMS into 8 ohms, 900 watts RMS into 4 ohms
Slew rate: 500V/microsecond
Input required for full output: 2V
Dimensions: 17” x 5.5” x 16”
Weight: 55 lbs.
Price: $5000

12054 Deer Trail Road
Conifer, CO 80433
(303) 838-8130