The Callas is small-medium sized speaker. The internal volume is 14 liters dedicated to the woofer. The cabinet is made from MDF and veneered curved plywood . The thickness ranging from 25 mm (sides) to 50 mm of the front panel . The front panel on the inner side, in correspondence of the holes of the woofer, is milled so that turbulence does not arise in the vicinity of the speaker membranes.
Internal sides are non parallel. One of the problems of speakers are the resonances of the cabinet and the other is internal reflections Regarding the rigidity this is guaranteed by the thickness and the weight of the walls. In order to reduce internal reflections behind the woofers there are two layers of absorbent material with pyramidal profile for a total thickness of 20 centimeters.
The absorbing material is an open cell polyurethane foam with pyramidal profile ( with base 7 x 7 cm , 3 cm and 7 cm for the basic height of the pyramid ) . This porous material , with its particular profile , provides an absorbing coefficient of 60% at 250 Hz and reaches almost 100% at 500 Hz. Strategically placing the right amount of this absorbent material inside the cabinet befall both reflections ( which would produce masking ) and the normal modes of the cavity which would produce annoying noise .
Woofers are made by Seas on Opera specifications . It is an 7″ woofer with re-cooked polypropylene cone and rubber rim with copper ring above and bellow the T-shaped pole piece and 12 mm pk-pk displacement. (a Seas technology named Excel ). This component , although used with a cutoff at 2000 Hz is able to work perfectly up to 5000 Hz . This guarantees a perfect overlap between the woofer and tweeter two octaves
before and beyond the cutoff frequency . With musical program the Callas con easily produce more than 100 SPL in the listener position with very low distortion.
The diaphragm of the midrange is made with re-coked polypropylene (annealed) . The polypropylene has a good internal damping but a low stiffness. Subjecting it to an heat stress it acquires rigidity without losing too much internal damping . The annealing, however, is a delicate process . Scanspeak 9700 tweeter needs no introduction: it is one of the best tweeters ever made and , in some respects , is still unsurpassed . Currently, this tweeter is used on models Malibran , Caruso, Tebaldi , Callas Grand , 2014, Callas in 2014 and also on the new Opera Quinta 2014. Besides the quality of sound, this tweeter is also highly reliable.
System: two way, stand mounting, Reflex with rear duct, bi-wiring
Front Firing Drivers: 1 x 7 “long-throw woofer with polypropylene cone and re-cooked phase plug. 1 x 1 “Scanspeak 9700 tweeter without ferrofluid and double decompression chamber
Minimum Power 10 watts RMS
Maximum tolerated power (Long Term) 80 Watts RMS (no clipping) for 100 hours
Maximum Power (short term) 100 Watts RMS (no clipping) under music
Frequency Range: 40 – 25,000Hz
Impedance: 4 ohm (minimum > 3.2)
Sensitivity: 89 dB / 2.83 volts / 1 meter
Connection: Single Wiring
Dimensions: 102 x 24.5 x 43 cm 40 x 9.5 x 17 inches (HxWxD)
Tweeter: 1 1” Scanspeak Tweeter D26, Silk, decompressed, Magnetic fluid.
Woofers: (2) 6.5” woofer – Aluminium cone
Crossover PCB: 12 dB / oct. for the woofer
18 dB / oct for the tweeter
Crossover frequency: 2000 Hz approx
Dimensions: 42 x 24.5 x 42 cm (HxWxD)
Weight 15 Kg each