Patent ID: 7493180

Claim:
A method of RIAA correction of audio frequency signals, comprising using in a RIAA-correcting pre-amplifier a first transformer having a primary winding and two or more secondary windings, with two of the secondary windings playing an essential role in RIAA-correction, a first triode having an anode that is electrically connected to the primary winding of the first transformer, a second triode having a grid, a second transformer having a primary winding connected to an anode of the second triode and a secondary winding for providing an output, wherein frequency correction of a signal coming from a first secondary winding of the first transformer is carried out on a resistance and capacitance circuit (RC-type of correction) while frequency correction of a signal coming from a second secondary winding of the of the first transformer is carried out with the use of an inductance and resistance circuit (RL type of correction) wherein the resistance and capacitance circuit includes a resistor and capacitor, wherein the resistance and inductance circuit includes a resistor and inductance, wherein the resistance and capacitance circuit is coupled to the resistance and inductance circuit, and wherein the grid of the second triode is electrically connected either to the resistance and capacitance circuit or resistance and inductance circuit, wherein a leakage inductance of the first secondary winding is sufficiently small that a correction time constant z1 for the first secondary winding is approximately equal to a product of a resistance of the resistor and a capacitance of the capacitor.