Before revision: Occurrence Although low frequency parasitic oscillations in audio equipment may be due to a range of causes, there are two types of equipment in which it is frequently seen: Older audio amplifiers with capacitive (RC) or inductive (transformer) coupling between stages.The problem was common in the early days of radio: This design is mostly used in vacuum tube (valve) equipment.
After revision: Occurrence Although low frequency parasitic oscillations in audio equipment may be due to a range of causes, there are a few types of equipment in which it is frequently seen: Older audio amplifiers with capacitive (RC) or inductive (transformer) coupling between stages.The problem was common in the early days of radio: This design is mostly used in vacuum tube (valve) equipment.