Load box and sound quality improving method

A load box comprising:

• a reactive load that is connected to a vacuum tube amplifier;
• an operation element of the reactive load;
• and
• a correction unit that corrects an output signal of the reactive load in response to an operation of the operation element.

A sound quality improving method comprising:

• outputting a signal that responds to an audio signal by using a reactive load,
• wherein the audio signal is output from a vacuum tube amplifier in accordance with impedance characteristics in which the impedance characteristics simulated impedance characteristics of a speaker cabinet, the reactive load has the impedance characteristics in which impedance characteristics in a first frequency band include a first impedance characteristic pattern selected from a plurality of first impedance characteristic pattern candidates on the basis of a type of the vacuum tube amplifier, and impedance characteristics in a second frequency band that is higher than the first frequency band include a second impedance characteristic pattern selected from a plurality of second impedance characteristic patterns on the basis of the type of the vacuum tube amplifier;
• and
• performing a correction on an output signal of the reactive load.