signal is supplied to a sound system (not shown), and tones are produced from the audio signal through the sound system. The sound system includes a headphone, and the string player hears the tones through the headphone. Since the prior art electric double-bass does not have any resonator, the strings 3 merely generate faint tones, and the faint tones are not a nuisance to the neighborhood.
Although the prior art electric double-bass is narrower than the acoustic double-bass, the prior art electric double-bass is so large that the string player feels the prior art electric double-bass bulky. In other words, a problem is encountered in the prior art electric double-bass in the portability. The manufacturer makes an electric double-bass on an experimental basis. The manufacturer eliminates the shaping boardwith a motor and fan, in which a cartridge is interchangeably loaded. That contains a battery and a chemical retainer which holds a chemical therein. The fan is driven by the motor to produce an airflow with which the chemical in the cartridge is allowed to volatilize and diffuse into the atmosphere. At the end point of the chemical at which it has been fully consumed, the cartridge including the battery is disposed of and the apparatus is reused on loading with a new cartridge.
In the conventional apparatus mentioned above, however, in which a cartridge is designed to be accommodated in the cylindrical housing of a given and limited size, the cartridge must be limited in size by the size of the cylindrical housing, and so must naturally