The tremolo mechanism includes a novel cam actuated lock having a plurality of parallel locking channels disposed on an engagement surface of a movable locking arm and further having a locking ridge disposed on an engagement surface of a locking block so as to be in aligned opposition with the locking channels. Each pairing of locking channels is separated by a chromatic spacing distance corresponding to a chromatic half step change in the pitch of the plurality of tensioned strings. The lock of the further including a cam actuated torsion bar to positioning the locking arm according to a cam follower's position on a cam profile. The torsion bar provides a flexible means of applying a motive force for moving the locking arm such that, with the locking ridge and a selected locking channel misaligned and the cam follower disposed upon the locked seat, the torsion bar elastically deforms as the locking ridge is received by a land disposed between the locking channels without damaging the lock. Further, any additional transverse movement of the locking arm relative to the locking block causes the locking ridge to slide across the land and seat into an adjacent locking channel.