Audio analysers, such as the Audio Precision series have signal generators that for certain test purposes do not have a sufficiently high output voltage. That is why we have designed this ‘booster’ amplifier stage. It provides the same amount of voltage as a 300-W amplifier into 8 W. Applications for this amplifier include the testing of measuring filters or an automatic range-switching circuit.The amplifier can, with a ±75 V power supply, generate 50 VRMS, with an input signal of 5 VRMS from the signal generator. In other words, the voltage gain is set to 10 times. In many cases the full bandwidth of the generator is not available at maximum output voltage. For this reason the amplifier gain is a little more than what is actually required for this application.