PURPOSE: To improve considerably a voltage distortion at speaker terminals, by constituting the circuit so as to cancel the resistive component of a connecting cord connecting the power amplification circuit and a speaker, for enabling the speaker to drive completely.
CONSTITUTION: The connecting cord 4 connecting a load such as speaker(not shown in figure) and the power amplification circuit 2 is inserted to one side of a bridge including operational amplifiers 8, 11, the resistive component is measured, a part of constants used for the measurement is taken in a current feedback network so as to constitute the circuit that the resistive component Rc of the connecting cord 4 is cancelled with output resistors R3, R4, Rf and Rb of the amplifiers 8, 11. Thus, the resistance value viewing the amplifiers 8, 11 from the speaker is almost zero, the speaker is driven with a full voltage and the voltage distortion at the speaker terminals is improved remarkably.
ITOU HIDEO
SHINODA RIYUUICHI
