The principle of the rotary kettledrum for orchestral use, known since 1821, has been combined in the SONOR rotary timpani with a tried-and tested system of central tuning. The technical advantage of the SONOR timpani lies in the unimpeded transfer of vibration from the head to the shell. It is important that there should be no contact between the rods holding the tension screw and the shell itself. In SONOR timpani the upper part of the drum - which transmits the vibration from the head to the shell - is free of any screw mechanism. The construction of the SONOR rotary timpani is based on over 125 years´ experience.