Noise figures of differential-pair input-stage equalizer preamplifiers

Noise characteristics of audio amplifiers with field-effect (FET) and bipolar-junction transistor (BJT) differential-pair (DP) input-stage and inductive source impedance are reviewed. The signal-to-noise ratio (SNR) for RIAA phono equalizers is evaluated, considering the influence of the source impedance and different ear-response weighting.