Напольная акустика — Opera Loudspeakers Callas Diva

The Callas Diva is the three-way floorstander in the Callas line of Opera Loudspeakers, the Italian brand that shares its premises near Treviso with the Unison Research electronics company. The Callas line, reworked in 2014, is Opera's top range and consists of the Callas stand-mount, the Callas Diva and the larger Grand Callas. The current Callas Diva was completely redesigned from its predecessor of the same name and brings much of the Grand Callas engineering into a smaller cabinet intended for smaller rooms.

Key specs that matter

The Callas Diva is a reflex-loaded three-way design with a rear radiation system. On the front are one 8-inch long-throw woofer, one 7-inch midrange with an annealed polypropylene cone and a phase plug, and a 1-inch Scan-Speak 9700 tweeter. On the rear, two tweeters form a natural dipole. All crossover sections use 12dB/octave slopes, with crossover points at about 200Hz and 2kHz. Frequency response is 30Hz to 25kHz, sensitivity is 90dB at 2.83V/1m and nominal impedance is 4 ohms with a minimum above 3.2 ohms. Power handling is 240W without clipping. Each speaker measures 116 x 37 x 53.5cm high, wide and deep, at 65kg including its metal base, in lacquered mahogany or walnut.

Engineering and use context

The distinguishing feature of the Callas line is its back radiation system. Two tweeters on the rear, arranged as a natural dipole, feed the reflected sound field of the room from behind the speaker, adding to the ambient energy that reaches the listener later than the direct sound from the front drivers. Opera designs the rear system so this reflected energy does not interfere with the direct sound or blur transient response, and it is almost identical to the one in the Grand Callas. The 7-inch midrange uses annealed polypropylene, a material heat-treated to improve its stiffness and damping, and a phase plug in place of a dust cap smooths its response at the top of its band. The 8-inch woofer is a long-throw design, reflex-loaded for deep bass extension. Using gentle second-order slopes throughout gives smoother phase transitions between drivers than steeper filters. Opera recommends placing the Callas Diva at least 10cm from the rear wall so the rear tweeters have a surface to reflect from.

Pairing

This speaker is a friendly load for most amplifiers thanks to its efficiency, and Opera pairs its speakers with Unison Research electronics, including tube amplifiers. Leaving a gap behind each cabinet lets the dipole tweeters do their job.

Alternatives

Opera Loudspeakers' own Grand Callas is the larger floorstander of the line, with two 8-inch woofers in a 130cm, 75kg cabinet.