heard by the performer using headphones and the like the various types of volume control knobs 3 adjust the volume of the audio signal and can set other parameters as desired it is possible to assign the midi messages to the volume control knobs 3 with which the parameters are set the display device 4 displays the midi channels that have been set and the values of the parameters and three digits of seven segments as well as dots that indicate various types of functions and the like are configured using an lcd the various types of switches 5 assign the midi channels to the operators of the keyboard and the like and set the functions and the like that assign the midi messages to the volume control knobs 3 that set the parameters discussed above the bender 6 is an operator with which a swinging operation is possible in the direction that the keys are lined up and at those times that no operation has been done by the operator the bender is maintained in the center when the bender is operated in the left direction or the right direction the bender information for the midi message that is the control signal with which the pitch of the musical tone is controlled down or up is output these various types of volume controls 3 the display device 4 the switches 5 and the bender 6 are soldered to a printed circuit board that is not shown in the drawing and the printed circuit board is screwed onto the.