Answer 7—Usually, the primary concern is high-frequency oscillation in amplifiers, because it’s generally easier to inadvertently create the necessary feedback phase shift at higher frequencies. However, in band-pass amplifiers that have a deliberately implemented lower cutoff frequency (especially if the slope exceeds 12 dB/octave), it’s also possible to create the conditions for oscillation at an extremely low frequency. This is known as motorboating. If you ever heard an audio amplifier doing this, you’ll instantly know why.

Contributor: David Tweed