2001: A SOUND ODYSSEY

above: The seven drivers of the Duntech Sovereign 2001 are symmetrically mounted, top to bottom, to maintain the symmetry of its radiation patterns at all frequencies.

I have been listening to loudspeakers and evaluating them, both personally and professionally, for more than 40 years. During that time, I have heard countless numbers of speakers of every size and shape, operating on every design principle devised by the mind of man. Thus, I am familiar with the infinite baffle, the closed box, and ducted, ported, and vented enclosures. I have auditioned a vast array of back-loaded horns, corner horns, and exponential horns. My ears have heard the blandishments of electrostatic, planar magnetic, ionic, and plasmatronic speakers. You name it, I've heard it! Over the years, I have encountered some really weird and bizarre loud speaker designs, many of which were obviously put together by inventors who blithely tried to circumvent the laws of physics. My experience, and just plain common sense, help to put some of the basic qualities and aspects of loudspeakers in their proper perspective. For example, no matter how cleverly a small loudspeaker is designed-even if it employs psycho acoustic trickery--you can't get a big sound out of a small box. In the words of my dear friend, the late Rudy Bozak, "There is no such thing as a miniature 30-Hz wavelength!" Years of listening make for a very discriminating ear, as well as a highly developed degree of cynicism. Perhaps I should not have made my reference the live musical experience. Be that as it may, I have diligently pursued that ever-elusive sonic dream-a loudspeaker accurate enough to present and sustain a true replication of the concert-hall listening experience. This will probably remain a fantasy, but a really close approach to the ideal would be rewarding.

For some months, I have been con ducting exhaustive listening tests and making a most comprehensive evaluation of a major new loudspeaker, the Duntech Sovereign 2001. Duntech International is an Australian company originally founded in the United States; their products are imported by W & W Audio ( 4821 McAlpine Farm Rd., Charlotte, N.C. 28226). John Dunlavy, who heads up Duntech, is a brilliant and innovative engineer and physicist whose speaker designs have always incorporated interesting new technology. This Sovereign loudspeaker is unquestionably his magnum opus, an engineering tour de force which far transcends the boundaries of current loud speaker technology.

John Dunlavy has wanted a flagship speaker for his company ever since I met him in 1976. Over the years, he has pursued this goal, and when he moved his operation to Australia, such a speaker was still a high-priority project. A few months ago, I got an excited call from John, telling me that he had discovered a new breakthrough in measurement technique that would en able him to develop the advanced technology that he had always wanted to incorporate into his "world class" loudspeaker.

Understandably, this new measurement technique is proprietary, but Dunlavy has indicated that it involves the use of Fast Fourier Transform analysis coupled with the Time Delay Spectrometry techniques developed by Audio Senior Editor Richard C. Heyser. Duntech's measurement technique provides a means of accurately characterizing both amplitude and phase response, along with the level of diffraction distortion, by examining the transfer characteristics implied by the shape of a step-function pulse reproduced by the loudspeaker. Dunlavy emphasizes that almost all of his speaker measurements are made at a distance of 3 1/2 to 4 meters, a more realistic listening position than the usual 1-meter measurement distances.

The great advantage of the new technique is that every parameter of speaker performance can be measured over the entire audio spectrum during the first few mS of the test. Dunlavy says that, even though this time period is very brief, the test is entirely free of any room reflections or boundary effects and is, in fact, analogous to an anechoic condition.

The Sovereign is a monolith of imposing and heroic proportions: It is 74 inches high, 14 inches wide, and 32 inches deep. The enclosure is fabricated from a special, high-density, laminated "custom wood" and ultra-high density particleboard more than 1 1/2 inches thick. With this massive, anti resonant construction, each Sovereign weighs a rather breathtaking 376 pounds! Seven high-power drivers are used for each Sovereign in an unusual con figuration. A dome tweeter, 20 mm in diameter, is mounted so that it is at ear level of a seated listener. Vertically arrayed above and below the tweeter are 75-mm midrange dome drivers. Above and below these are 177-mm mid-bass cone drivers, and 305-mm cone woofers are mounted above and below the mid-bass units to complete the driver complement. Duntech claims that this symmetrical arrangement of drivers creates point-source radiation at all frequencies, along with perfectly sym metrical radiation patterns. The mid-bass, midrange, and tweeter drivers are surrounded by special, highly absorbent, 1-inch-thick organic felt, a method of eliminating diffraction for which Duntech has a U.S. patent. All of the drivers are path-aligned (time-collimated) to obtain a propagation error of less than 20 mS at a distance of 4 meters along the geometric axis of the speaker.

Dunlavy is an acknowledged expert in the field of wave-guide and antenna theory, and holds more than 34 patents on antenna design. He told me that the Sovereign basically operates as an acoustical analog of wave-guide and antenna theory; its mid-bass and woofer drivers are mounted in special sealed enclosures whose design is de rived from these electromagnetic theories. The enclosures use special damping materials of variable density to achieve an optimum Q of 0.7, thus assuring accurate pulse response down to the lowest frequencies.

The Sovereign's crossover network is a computer-derived minimum-phase type of great complexity, configured to provide the optimum crossover frequencies and proper roll-off slopes without the necessity of bi- or tri-amplification. Crossover frequencies are 300 Hz, 2 kHz, and 6 kHz. This crossover uses massive air-core inductors, constructed of oxygen-free copper wire of very large cross-section. Input to the crossover is through large-diameter, gold-plated, five-way Tiffany binding posts. The imposing size of this loud speaker is matched by its ability to handle a full kilowatt of power for 10 mS over the entire audio spectrum! From the foregoing, it is obvious that the Sovereign 2001 is a most extraordinary loudspeaker, and probably de serves recognition as a landmark de sign. There are, of course, many factors that affect the performance of a loudspeaker. It also must be noted that some people argue that good objective measurements are not always equated with satisfactory subjective listening experiences. On the other hand, certain speaker parameters are generally accepted as indicative of high quality, and correlate well with subjective impressions. Dunlavy has documented his tests with an extraordinary series of oscilloscope photos.

His Sovereign loudspeaker does, in deed, reproduce a square wave, one with a very good shape, with barely 1 dB of overshoot and no ringing on the top. Furthermore, he shows square waves of 200-, 400-, and 800-RS width.

His tone bursts are very symmetrical, with virtually no ringing at the end of the burst. His 'scope photos of THD indicate less than 0.3% for second and third harmonics, at 90 dB SPL, at all frequencies from 50 Hz to 10 kHz. THD at 30 Hz at 90 dB SPL is a quite impressive 1.5%.

While we are talking numbers, I'll list some other pertinent specifications.

Frequency response, measured on-axis at 3 1/2 meters, is ±2 dB from 27 Hz to 20 kHz. Now, this is under the anechoic conditions of the new Duntech measurement technique. In a typical listening room, the response is nearly flat to 20 Hz, and is down only 9 dB at 16 Hz. The Sovereign loudspeaker that was sent to me is a production prototype; between 400 Hz and 7 kHz, its response was an incredible ±0.5 dB! Measured on-axis at 3 1/2 meters, phase response is less than ± 30° from 50 Hz to 20 kHz. The Sovereign has a nominal impedance of 4 ohms. The impedance curve is very flat, varying from 3 to 4.5 ohms. The Sovereign is a fairly efficient speaker, rated at 90 dB SPL for 1 watt at 1 meter.

Now that I've covered the anatomy of the Sovereign and revealed its vital statistics, it is time for general impressions, assorted ruminations, and, of course, an assessment of its sonic performance.

First off, as I've said, this speaker is big! However, its bulk is trimmed by its clean, simple lines, and it is so beautifully finished it is really quite elegant.

The pair of Sovereigns I have are veneered with a richly grained, light-toned American walnut. The grille is a welded aluminum frame that rigidly pressure-fits with the enclosure. Ever aware of diffraction distortion, Duntech has lined the inner reflecting surfaces of the frame with acoustic foam. The frame is covered with a black, acoustically transparent cloth.

In case you've been wondering what all this massive magnificence and super-sonics costs, the Sovereigns in standard American walnut or African rosewood sell for a rather lofty $12,999 per pair. The speakers are also avail able in a wide variety of exotic woods, like Brazilian rosewood and palisander, for $15,000 per pair. The price induces direct air shipment to the consumer; a special arrangement with the air freight company provides for unpacking the crates, moving these 376-pound beasts into your listening room, and even removing the crates! Needless to say, it is nice to have a muscular pal around when you start to position 376-pound speakers. The Sovereigns should be kept within 16 to 19 inches from the wall behind them: otherwise, you will attenuate the magnificent bass response. I had the Sovereigns angled so that the axis of the tweeters crossed in the middle of my head when I was seated in my listening position.

The first time you listen to Sovereign loudspeakers can be a bit overwhelming because of the emotional impact of their sheer musicality. This is particularly true when listening to large-scale symphonic music. In a tumultuous, triple-fortissimo passage of a Mahler symphony, the Sovereign projects a huge presence: The sound stage extends laterally beyond the boundaries of the speakers, and the depth of the sonic image makes you sense the size and acoustic character of the hall. Instrumental localization is very well de fined, with the point-source radiation of the Sovereigns preserving the proper vertical and horizontal perspectives of the orchestra.

I listened to a great variety of music on the Sovereigns. In addition to the symphonic music, I played a lot of op era and oratorios, chamber music, solo vocal and instrumental recitals, organ music, jazz, and big-band music. The Sovereigns reproduced all of this with equal facility. Whether it was the delicate strains of a string quartet, the soaring sweetness of a great soprano voice, the floor-shaking thunder of organ pedals, the coruscating high frequencies of a ride cymbal, the brazen blare of French horns, the sharp explosive transients of tympani, the visceral impact of a concert bass drum, the searing trumpet of Wynton Marsalis, the piano filigrees of Horowitz, or even the raucous squawk of a fuzz box, the Sovereigns reproduced them all with breathtaking verisimilitude. Imagine a loudspeaker with the transparency and transient attack of the best membrane type speakers, a speaker that can plumb the most subterranean depths of low frequencies, a speaker that can reproduce the harmonics and over tones of high strings with silken sweetness, a speaker that remains utterly clean, even at 120 dB SPL! These are among the qualities which characterize the Sovereigns.

As you might expect, the Sovereigns are notable for cleanness and tremendous reserves of dynamic range. No matter how great the dynamic range of the music, it was always reproduced without the slightest sense of strain. On a London/Argo CD of Mendelssohn organ works (414420-2), there is a thunderous, 19-Hz pedal tone that the Sovereign reproduces with awesome power and authority. Similarly, on a Philips CD of the Saint-Saens Third Symphony (412619-2), the second movement has a 16-Hz pedal tone, and the Sovereign literally lets you feel its mighty pulsations. I played a piano tape Ray Dolby had sent me, recorded with his new Spectral Recording System. The SR system is capable of a dynamic range of over 100 dB. For the first time ever, I was able to play some triple-fortissimo piano chords at live listening levels without breakup. This was an amazing feat for the Sovereign, and the realism of the piano was staggering.

The smoothness, openness and transparency of the reproduced sound, as well as its warmth and musicality, were what I had anticipated, given the point-source radiation of the Sovereigns. String sound was extremely smooth and natural; the string quartets sounded as if they were seated in my listening room. The Sovereigns reproduced high strings with ravishing beauty and compelling naturalism. Equally good was the very ex tended, well-defined low-frequency response. An example of this could be heard on the London CD of Mahler's Third Symphony (414268-2). The opening fanfare for eight French horns was magnificently full-bodied and brazen. Shortly thereafter, there were some very low-frequency bass drum strokes, played at very low level. On the Sovereigns these were heard with much detail, with the skin tone and timbre perfectly preserved. Another striking example of the resolution capabilities of the Sovereigns is with a CD from Digital Music Products, New York Cats Direct (CD-453). The second track has some awesomely high-level, very low-frequency synthesizer tones which are reproduced cleanly down to their lowest fundamentals.

No, phonophiles, I haven't abandoned the venerable vinyl disc. Using the magnificent SME Series V arm on a VPI HW-19 MKII turntable, plus the Shure Ultra 500 cartridge, I have been getting the best record reproduction I've ever gotten, from some of the top DMM recordings. The Sovereigns are certainly compatible with vinyl! In summation, it must be said that the Sovereigns are very expensive loudspeakers, but if you can afford them, I believe you are incontestably getting the best. The speaker is mercilessly revealing and is not tolerant of inferior equipment. In the months I've used these speakers, I haven't been able to fault them in any respect.

Above all, they give you a feeling of freedom, and they engender tremendous confidence because you know they are capable of dealing with the most demanding, highly dynamic pro gram material. John Dunlavy claims that the Sovereigns are the most technically and musically accurate speakers in the world. After living with these magnificent speakers, I'd have to say that their performance makes a very strong case for his statement.

(adapted from Audio magazine, Nov. 1986; Bert Whyte)

= = = =