9th October 1997

Priceless gems do cost

ADELAIDE'S Duntech is a global name in loudspeakers. Many have ogled its majestic creations only to find the depth of our pockets restrictive. Duntech floor-standing speakers have been possessions of the dedicated enthusiast but, with the release of its new Opal, Duntech has sunk its teeth clean into the mid-market, lush with astute buyers of quality, not quantity.

The Opal is the first of a new range presented in a line-up called the Gemstone range. Measuring 975mm high by 180mm wide and a deceptive 200mm deep, each Opal uses three drivers vertically aligned in a two-way design. The handsome enclosures, finished in either rubbed Australian jarrah, Queensland walnut or black veneer, are fabricated using 18mm-thick MDF (medium density fibreboard).

Controlling internally generated vibrations needs three braces whose efforts are reinforced by the use of lead sheeting mounted at the base of the enclosure. This makes the enclosure far more rigid and stable and is neither affected by the movement of the internal drivers nor by external radiant vibrations. In this way, you are likely to hear the drivers not the box.

The top speaker is a 165mm bass/mid driver and, unusually for this style of configuration, it sits in its own infinite baffle (sealed) enclosure, cut off from the lower bass/mid driver by an internal partition. The lowest driver is of the same type but housed in a twin vent (ported) enclosure that consumes the remainder of the cabinet.

Sealed enclosures are praised for their control but condemned as they restrict the passage of lowest frequencies.

Conversely reflex or vented enclosures, like on the lower driver, provide bass assistance but add little control. This dual approach cuts both streams in an effort to deliver body and control. Both drivers use a vented double magnet system, and polymer composite cones are hand damped to ensure Duntech's tight specifications are met. The high-frequency driver sits between the other two, using a 25mm soft dome for excellent frequency range and dispersion.

The tweeters' performance is bettered by surrounding the face plate with star cut felt.

I believe Duntech was the first to use this simple and effective technology, designed to reduce audible reflections from the face of the tweeter itself. In the same way that bracing decreases the chance of hearing the enclosure, the star cut felt ensures you hear the tweeter, not the surplus sounds bounced off the cabinet.

The voice coils of all driver types use a special hexagon-shaped "Hexatech" aluminium wire, which exhibits excellent heat-conductive properties which, in turn, translates to greater linear power handling, stated as anything up to 250 watts RMS - but remember, keep it clean. If you hear distortion, back off. If you decide to rage on beyond your means, Duntech measures and stores performance data of every driver sold. During the speaker's build stage, the data are used to compile matched pairs left and right. Maintaining the data ensures you are served a matched driver by the simple quote of the serial number.

For total quality assurance, heavy-gauge, low-loss, silver-plated copper cabling is used throughout, terminated for the connection of your chosen speaker cable by gold-plated three-way bindings posts in two bridged pairs ready for bi-wiring. Floor spikes are included for extra stability on less-than-perfect floors. If you've an uneven tiled floor, try silicon stick-on-feet from your local hardware store or you can buy specialist stick-on cones from some hi-fi stores. These provide the same isolated grip as spikes but their protection cups protect the floor from damage.

Listening was done at home, with both valve and transistor amps of 40 and 30 watt rating respectively. When using all speakers, placement is an important consideration but I found the Opals were less placement-dependent. Perhaps as a result of their vented and sealed design, they never really offended, even when placed in corners.

The Opals provided an excitingly controlled performance across a broad range of music styles, from acoustic folk to rock, the latter needing a bit more whammy. Of note is the Opal's image projection and excellent portrayal of human voice.

Priced at AU$2,500, they are gems. For nearest dealer details, call Duntech direct on +61 8 8288-1822