I have no idea if this is the same as the one at the Montreal Symphony Orchestra but for anyone else who was curious about the specs on this beast:

• HEIGHT: 3.6 m (11.10 ft.)
• LENGTH OF THE SOUNDBOARD (uppermost board): 2.06 m (6.76 ft.)
• WIDTH OF THE SOUNDBOARD: 1.11 m (3.64 ft.)
• LENGTH OF STRINGS: 2.18 m (6.56 ft.)
• NUMBER OF STRINGS 3: (A-E-B)
• DIAMETER OF STRINGS: 5/16 in. (7.94 mm). 1/4 in. (6.35 mm) et 3/16 in. (4.76 mm)
• WEIGHT: 131,54 kg (290 lbs.)
• NUMBER OF PARTS: There are hundreds of parts, of which 237 make up the complex mechanism of this precision instrument.
• SPECIAL FEATURES: The octobass is the lowest-pitched and largest-sized instrument of the entire string family. The performer must climb up on a small stool in order to access the neck of the instrument, and it is only by means of levers and pedals - not with the hands that the strings can be reached and sounded. The octobass bow is longer and heavier than the bow of an ordinary string bass.

Apparently it can do as low as 25Hz. That would be badass to experience in person.