5.4 Cap Selections

The capacitor selection in the analog amplifier is also important to the pop noise. Usually, the capacitors should have a tolerance of ±10% or better because the capacitor mismatch causes an impedance mismatch at the corner frequency and below if the corner frequency is within the audio band. For a flat low-frequency response, use large input coupling capacitors (1 µF).

Increasing the input capacitor may slightly improve pop performance as well. Increasing the input capacitor from 1 µF to 2.2 µF will slow the turn-on time of the amplifier, which may make any pop noise less noticeable.

Adding the capacitor before the input capacitor to ground, the short time voltage transient will go through the capacitor to the ground loop. However, the capacitor value is important for the high frequency performance. If the value is too larger, it will shrine the higher frequency response performance.

High-K capacitors, like Y5V and Z5U, that have large temperature coefficients typically also have wide tolerances, so the frequency response variability is large. These capacitors can cause large variations in audio performance. X5R/X7R material capacitor is more suitable for the input capacitor options.