Capacitors in OCL amplifiers

Regarding the low-frequency characteristics of the OCL power amplifier, the feedback capacitor CF has the greatest impact. For the OCL power amplifier circuit, its
amplification factor has the formula Kv= (1+ Rf)/foot F. This is
correct under the condition that the capacitive reactance of the feedback capacitor is ignored . Since the capacitive reactance Xc of the capacitor is inversely proportional to the frequency, the capacitive reactance Xc cannot be ignored when the frequency is very low. Therefore,
the amplification factor of the amplifier should be Kv=(1+ Rt)/ RF + Xco.
    Example II: When CF is taken At 10lrF, for a frequency of 20kHz, Xc<1 n; for a frequency of 20Hz, Xc
can reach 0-79kfl. In general, RF in circuits is mostly between 0-5~2kCl. According to this calculation, the power amplifier's low-frequency amplification factor
and high-frequency amplification factor must be quite different. If you want to extend the low frequency to 10Hz or even 5Hz, the large impedance of CF
and its impact on the low-frequency amplification factor are obvious. More What's more, for a DC power amplifier , xc is infinite, the circuit
is regarded as an open circuit, and the amplification factor is O, that is, it has no amplification ability for DC.