High fidelity low frequency amplifier

The invention refers to a high fidelity low frequency amplifier, which includes a modulator containing a phase lock loop, achieved using a specialised integrated CMOS circuit (PLL); at the reference input of the loop (PLL) a signal yielded by a reference oscillator (OSC) being applied; at the output of the loop (PLL) resulting in a signal whose frequency is double the size of the one of the signal of the reference oscillator (OSC) and a filling factor modulated in accordance with the input signal (ln) which has to be amplified, the resulting impulse signal being amplified in a class D amplifier (AD) and then applied, through filter (LC) to a speaker (D) connected to the null device by a capacitor (C 6).