dynamic compression circuit

The simpler dynamic compression circuit is similar to the ALC (automatic level control ) circuit, but the requirements are slightly different, as
shown in Figure 1-117. In the figure, the control signal is taken from
the output end of the pre-stage , and the control output is connected to the input
end of the pre-stage. The control signal is converted into a DC control signal by voltage doubler rectification
. When the control level reaches the conduction value of the composite tube
, the composite tube is turned on, shunting the input signal, reducing
the intensity of the input signal, and achieving
the purpose of expanding the upper dynamics. o
    In the circuit, RPi is used to adjust the sensitivity of the start control. The RC charge and discharge circuit composed of cl.RPi and R:z determines
the front delay and back delay of the start control. The length of the front delay directly affects the circuit's response to strong The response speed when the signal is input. In order to
prevent instantaneous overload of the circuit , the pre-delay should not be too large and is generally controlled at around 0.1 Peng. The post-delay should be slightly
longer, which can not only reduce the gap noise of the signal, but also play a role in stabilizing the amplifier. However, it should not be too long,
otherwise it will cause greater attenuation of the following small signal, resulting in The signal-to-noise ratio deteriorates, generally taking about 10ms.