The design of the Tuning Bar "Onpen" loaded with additional masses is explained in this paper. The design charts for the lowering of resonant frequency and transferring of nodal points by addition of concentrated masses are also presented here. This tuning bar which vibrates transversally to its long axis, is used as a standard of low audio frequency and its stability is proved very good. Three types of the tuning bar are investigated and they are; (a) Center Additional Mass Type, (b) Both End Additional Mass Type and (c) Center-Both End Additional Mass Type. By adding concentrated mass in any point of the tuning bar, the nodal points at resonance are transfered to any position from the nodal points in the non-loaded case, but in the case (c) if Center Mass/End Mass=3. 29, the nodal points of the 1st mode are identical to those of the bar with no-load.
