The reducer is connected between the amplifier (head) and the loudspeaker. Here it converts the electrical energy of the amplifier into heat and transmits a reduced power to the loudspeaker. The art here is that the power reduction does not affect the sound, so play quietly with the original sound.
The desired reduction is first switchable, in steps of 3 dB and then 5 dB.
In the last switch position “Variable”, a load potentiometer is used to continuously reduce the level reduction from -7 dB to almost complete fade-out.