It is three circuits of RIAA, amplification of low signals of heads [MM], following different solution, each one, as long as it concerns the eq. In the circuit of PHONO 1, we have deephasis with pathetic filter placed between the two departments of tube V1. In PHONO 2, is followed the classic solution of energy deephasis. In PHONO 3, finally exists also a combination of also two above solutions, pathetic for the high frequencies, energy in the low frequencies. The capacity of capacitor C1, can change so that it suits with the technical characteristics of each head, which the signal of will be called to amplification the each preamplifier.