Callas Walnut

Callas is based on a pair of loudspeakers, selected with the same care that Opera takes with any of its products. The low and mid-range frequencies are reproduced by a 7-inch long-throw SEAS woofer, manufactured to Opera specifications within the Excel program. The annealed polypropylene cone is a material with a well-thought-out logic: the polymer is naturally well-damped, but not rigid enough. Heat treatment gives it the necessary elasticity, while maintaining internal damping. The result is a membrane that moves precisely and without its own coloration. 12 mm stroke, copper rings above and below the pole piece (SEAS Excel technology), a large magnet - all this gives a dynamic margin that is atypical for compact bookshelf speakers: more than 100 dB at the listening position with very low distortion.

The range above 2 kHz is handled by the Scanspeak 9700 tweeter - the same one used in Opera's flagship models: Tebaldi, Malibran, Caruso and Grand Callas. The symmetrical design of the magnetic system, a soft dome with a hand-sprayed diaphragm, and a wide linear travel are characteristics that have long made this driver a reference point in hi-fi. The crossover frequency is 2 kHz, and the woofer overlaps it by at least two octaves upwards, which ensures a smooth junction between the bands without artifacts.

The Callas second-order crossover - with completely separate sections for the woofer and tweeter, which allows for bi-amp connection. Component base: Mundorf capacitors, self-closing oxygen-free copper inductors, MOX resistors. Each component is selected with the expectation of minimal contribution of its own distortions to the signal. The crossover board is designed to avoid mutual induction between the windings.

A separate detail is the tone balance switch: the “+” mode raises the level in the range of 300–3000 Hz by 2 dB. This is the presence zone — vocals, the center plan, the breathing of live instruments. A small touch that allows you to adjust the sound to the acoustics of the room without changing the equipment.

The 14-liter non-parallel wall cabinet is made of MDF with a thickness of 25 mm on the side panels to 50 mm on the front — more massive than most competitors in the class. From the inside, opposite the woofer, there is a two-layer pyramidal absorption of open-pore polyurethane: the absorption coefficient is 60% already at 250 Hz and almost 100% at 500 Hz. This is not just a damping of resonances - it is an "acoustic trap" that eliminates internal reflections and modal noise, responsible for muddying the midrange and blurring the vocals. The front panel is milled on the inside along the contour of the woofer hole so that turbulence does not arise in the membrane area.

Outside - natural walnut or mahogany veneer in glossy varnish, the front panel is covered with soft leather (at the same time aesthetics and acoustic damping of diffraction from the edges of the cabinet), the top cover is made of acrylic glass with reverse spraying. Live wood, leather, acrylic - not decoration, but conscious design solutions.

The phase inverter is brought out to the rear panel - a distance of at least 30-40 cm from the wall is recommended. The acoustics are equally suitable for listening both from a distance of several meters and in nearfield mode - from a distance of one meter. Sensitivity of 89 dB and nominal impedance of 4 Ohms provide an amplifier with a confident current reserve of 30 W. Callas from Opera and Unison Research electronics form a natural tandem - aesthetically, constructively and sonically.