The low frequencies filter is performed in a specialized PT2351 microschem that is used in high-level industrial saboveers. The signal through the inlet chains goes to the internal microschem cascades, where it turns into a mono signal and goes to the Sallen Ki third order filter. The filter cut frequency is determined by C3 and C7. There are two sets of capacitors in the kit to select the frequency of the cut - 60 or 80Hz. After filter processing, the signal shall be transmitted to the sabvuffeur through the C9 separator. The final sabfuver force may be connected to the FNL directly, without the use of a pre-energy. The microschem is about 10, so the maximum undetected amplitude signal of about 2 volts can be obtained at the outlet. This is more than enough for the majority of final power escalators.
The PM feeds from its own stabilizer R3, VD1, C6, so it can be connected to the power supply with a voltage of 12-15 volts. And when the R3 regenerator is used, the power supply can be increased further.