Abstract: The output signal converter for a tube amplifier includes semiconductor devices for amplifying or attenuating an output signal of the tube amplifier while maintaining the output properties of the tube amplifier. The output signal converter according to one embodiment has an output transformer (TR) having an input terminal (TRa); a first circuit branch (C1) connected between the input terminal (TRa) and an output terminal of the tube amplifier and a second circuit branch (C2) connected to the input terminal (TRa) of the output transformer (TR) and in parallel to the first circuit branch and including components that produce an electric current proportional to a current level in the first circuit branch. The first and second circuit branches are located between the tube amplifier and the output transformer (TR) and include semiconductor devices so that the output signal from the tube amplifier is amplified while maintaining the output properties of the tube amplifier.

Abstract: The output signal converter for a tube amplifier includes semiconductor devices for amplifying or attenuating an output signal of the tube amplifier while maintaining output properties of the tube amplifier. The output signal converter in preferred embodiments has an output transformer (1) connected to the tube amplifier, a current amplifier and a voltage amplifier serially connected with each other via a node, and a speaker (4). The current amplification factor (Ac) of the current amplifier (2) and the voltage amplification factor (Av) of the voltage amplifier (3) are related according to the following equation: Ac*Av=−k, wherein k is a constant.