Media
Ambassador
 

Vol.7 No.1

Duntech Ambassador XL

AUSTRALIAN HIGH-END loudspeaker manufacturer Duntech has just released an XL variant to the Ambassador member of its "Classic Series" family of high performance loudspeakers.

A two-way design aimed at buyers in the upper range of the quality mini-monitor market segment, the Ambassador is an interesting floor-standing alternative with solid bass extension, neutral tonal balance and pin point sound stage. The XL (Extra Low) version builds upon the strengths of the established model and adds in-room low frequency bass extension to below 40Hz. The slender 1200 mm high, narrow profile column speaker has a foot print of only 230 mm x 355 mm (WxD) plus a modest 20 mm overhang for an integral plinth. A set of spikes are supplied as standard issue to ensure tight contact with the floor. The sealed enclosure is manufactured from massive 1 inch thick MDF and is internally braced with three full-width MDF shelve structures. All external surfaces are finished in exquisite timber veneers of either Mahogany, Walnut or Black 'Touchwood'. The concept of using the space below the actual drivers (that would otherwise be occupied by a set of stands, at extra expense) as part of the enclosure has considerable merit, and provides the larger box volume necessary to obtain decent bass extension and low frequency efficiency. The overall size still allows the Ambassador to be described as a "decor-friendly" loudspeaker.

Technical Matters

The Ambassador XL has four drive units, three of which are in a symmetrical array with two 6 inch bass/mids flanking a 1 inch dome tweeter. The fourth driver is a proprietary 8 inch bass unit mounted on the lower side of the enclosure, that is crossed over at 100 Hz to handle only the lower bass frequencies. The placement of this driver near the floor results in a natural reinforcement of low frequencies due to its proximity to the floor boundary, while a useful degree of bass tuning is obtained by placing the speakers with the bass drivers either outward or inward facing. One noteworthy technical performance attribute that simply has to be stated is the flatness of the "excess phase" curve. Between 800 Hz and 10 kHz, it barely deviates 1 degree ! The actual phase curve showed a peak deviation of only 15 degrees from 300 Hz to 13 kHz. These results are in fact quite outstanding, and seldom achieved in a production model loudspeaker. This unusually good "minimum phase" characteristic would certainly explain much of the Ambassador's excellent driver coherence, integration, speed and the stable images evident in the later described listing tests.

Common to all Duntech minimum phase designs, the time-aligned drivers are all located symmetrically in an array along a common vertical axis and positioned so that the full spectrum of sound frequencies simultaneously reach the listener's ear, with the correct relative phase to each other. This creates the illusion that the sound is being generated from a single point source even though the different frequencies are being reproduced through different drivers. Importantly, the point source character of the microphones used to record music agree recreated by this vertical layout of the drivers. In combination with first-order crossovers and properly designed drivers, another important result of this geometry is th speaker's accurate reproduction of complex musical waveforms with minimal distortion and alteration to the shape. Because all frequencies from all drivers arrive at the listener's ear (at a normal listening distance of 3 m) at the same time with he proper phase, "pulse coherence" is achieved. In simple terms, this means that the speaker can go very loud in an instant and can stop making sound and die away in an equally small instant of time, i.e. in line with true audiophile expectations, you are able to hear the music and not the speaker. Another results of this driver array geometry (known as a D' Appolito array) is the minimization of floor and ceiling reflections of the early arrival information which results in greater clarity, focus and improved vocal intelligibility. After years of research, Duntech engineers have long maintained that pulse coherent technology is the only way to achieve a truly accurate sounding loudspeaker exhibiting a perceived realism that correlates well with live music. When you think about it, it does make a lot of sense...this technology is in fact the only way to faithfully reproduce the square-wave, step and impulse time-domain waveforms (equatable with complex musical transients) that audiophiles demand from every other component in the audio reproduction chain, so why not carry it through to the final acoustic transducer?

Specially designed and shaped felt absorbing treatment is applied to the outside front surface of the loudspeaker baffle to minimise diffraction distortion (out of phase reflections from surfaces and cabinet edges near the drivers), as well as minimise driver interaction and reflections. This type of distortion manifests as a distinct blurring and loss in definition of sharp musical transients, as well as degrade the stability and focus of the stereo image. The absorber felt also contributes to the remarkably smooth ruler-flat frequency response that the speaker possesses. The first-order crossover network is based on minimalist engineering concepts and incorporates only the finest components in the signal path such as polypropylene capacitors and air-core inductors for the lowest possible distortion. It is noteworthy that Duntech have managed to cleverly avoid the need for any inductors in the critical bass/mid section, thus avoiding one of the potentially most non-linear elements of typical loudspeaker designs. It is also commendable that the bass/mid drives need no corrective manipulation and equalization to keep them properly controlled and suppress any low-level "honk" or "quack" colouration tendencies due to cone break up effects, etc. The absence of such additional crossover components brings the loudspeaker into desirably tighter contact with the amplifier to contribute toward greater sensitivity and sense of transparency and focus. Although rated at a nominal 4 ohms, the speakers' impedance curve rises to a maximum of 8 ohms in the midrange and dips to a minimum of 2.3 ohms in the upper bass region. The predominantly resistive load impedance is generally well-behaved, being free of excessive variations and non-linear reactive components that can cause amplifiers with puny current capabilities to sound edgy and aggressive. The sensitivity is an impressive 91 dB/W/m, but the impedance excursion down to 2.3 ohms means that only the more powerful and load-tolerant valve/tube amplifiers would be suitable. I would be sceptical as to whether many tube amplifiers could provide enough bass control and low-frequency extension. For a clean sound, and to derive maximum benefit from the speaker's dynamic range, the Ambassador definitely deserves to be teamed with any of the well known exotic high-power solid state amplifiers with lots of current reserves and excellent damping.

Listening Session

For the record, all the ancillary electronics were from the McIntosh stable. The power amp was the MC300 driven by the C36 Control Centre and fed from a MCD7005 CD player. The speakers were single-wired with Wireworld "Atlantis" cables, although the Duntech's do have dual terminal posts for bi-wire capability. The Ambassadors simply did an exquisite job of reproducing my favourite CD recordings that I regularly use as audition reference material. Without exception, the wide ranging styles of music were rendered alive, involving and with a breathtaking clarity that opened up even the most complex musical passages. Hidden nuances (that only reveal themselves on the finest loudspeakers) were coming forth to inject stunning realism. First impressions established also related to the extraordinary smoothness and the overtly neutral sound. The openness, speed, transparency and clarity characteristic of the best electrostatic loudspeakers were plainly evident. Extended listening to the treble, midrange and midbass make it clear that this is a very flat design in terms of both frequency response and tonal balance. The soft fabric dome tweeter had a natural and silky sweetness whereby female voices were reproduced with a honeyed liquid and delicate character, while brass instruments had that distinctive brassiness about them without any tendency for offending harshness. The well-balanced treble was remarkably explicit and revealing with a transparency and detail resolution that is up with the very best. The Ambassador delivered a broad and deep "walk through" rock steady soundstage of tangible stereo imagery that readily immersed me in an intimate and emotionally satisfying musical presentation. On properly miked recordings, instrumental and vocal images were rich, multi-dimensional and utterly believable. The shear naturalness of chorales, and the ability to extract the fine detail in John Rutter's Requiem (Reference Recording RR-57CD) consolidated my impression that this speaker is really something special. Listening to Rob Wasserman's Duet (particularly the one with Lou Reed) showed a great ability in reproducing male voices. They appeared precise, without any nasal sounds or hardness. Double-basses and electric bass were notably accurate, with electric bass being particularly smooth, fast and effortless. The pistol shots in Explosions Polka from Johann Strauss's Ein Straussfest (Telarc CD-80098) were rendered with stunning accuracy and dynamics as the properly-times high frequency transient and low frequency sonic energy excited the listening room. Other recordings containing fast-transient drum percussion were equally impressive. These full-range speakers had almost boundless dynamic range and were able to play at enormous volume with no compression or strain at any frequency. At times the 300 watt Mac power amp was pushed into brief clipping, but the speakers showed not even a hint of stress. Percussion, kick drum, and electric bass had real power through these speakers, and pedal organ has to be heard to be believed. Low frequencies are delivered with authority, integrity, and tuneful finesse with no boom or one-note tendencies. Swapping the mirror matched pair of speakers over to place the side-mounted bass driver facing outward, produced an even more prodigious and fuller bodied bass output at the expense of some tightness and weight. This proved an effective and convenient bass tuning mechanism available to suit personal taste or room low-frequency characteristics. Are there any faults and criticisms ? Yes, only one! The terminal binding pots are too close together, and they are not rugged and robust enough to withstand the rigors of heavy speaker cables with heavyweight spade lugs terminations. One terminal post of the audition speakers had worked loose causing an intermittent internal connection. For a speaker of this quality, skimping on this important user interface detail is really out of character. Finally, it is worth noting that as well as being a superb transducer for fine music reproduction, they would be eminently suitable for the most demanding high level A-V and home theatre application. This is because the symmetrically concentric, virtual point source array configuration inherently provides a broad listening position that allows a number of persons to share and experience pin point imaging of the home theatre sound.

Conclusions

The Ambassador XL has once again embodied Duntech's uncanny ability to combine together technical excellence and state-of-the-art performance to create a high-end loudspeaker of exemplary quality at a reasonable price. There are now many loudspeakers available that do a credible job of reproducing "nice sounding" music. Very few, however, are capable of approaching the degree of accuracy implied to enable them to convincingly reconstruct the musical truth and realism of a live performance, i.e. induce that elusive, but magical state of transporting the listener to the recording venue for that rare "being there" feeling. The Ambassador is one of the privileged few members of an exceptional class of loudspeakers that honestly command this description and status. Sure, there are a few speakers around that outshine the Ambassador XL in one or two areas, but not significantly so, or at a comparable price. The loudspeaker will satiate the most critical and demanding listener by performing splendidly in all audiophile categories. Highly recommended for extensive comparison with other high-end speakers, regardless of their price.