Circuit for Neutralizing Low-Frequency Regeneration and Power-Supply Hum

In high-gain multistage amplifiers, low-frequency regeneration frequently exists which affects the amplification characteristics of the amplifier and commonly causes oscillations and "motor-boating." A simple bridge-balancing circuit has been devised to neutralize this effect. Besides reducing regeneration, it also reduces the effects due to hum present across the plate-supply filter. Reductions in the order of 40 decibels are attainable.