An amplifier stage uses a loaded transistor amplifier circuit including a load that causes greater second order harmonic distortion energy than third order harmonic distortion energy to be produced in said loaded transistor amplifier circuit for amplifying a source audio signal to produce an audio output signal. The spectrum of the fundamental orders of harmonic distortion is adjusted to improve perceived sound quality or listening enjoyment.

An amplifier stage uses a loaded transistor amplifier circuit including a load that causes greater second order harmonic distortion energy than third order harmonic distortion energy to be produced in said loaded transistor amplifier circuit for amplifying a source audio signal to produce an audio output signal. The spectrum of the fundamental orders of harmonic distortion is adjusted to improve perceived sound quality or listening enjoyment.

An amplifier and a method of outputting a waveform of a music signal capable of outputting a waveform of a music signal exceeding a power supply voltage is provided. An amplifier includes a power supply, an input terminal for a music signal, an amplifying circuit which amplifies the music signal using the power supply, and a jumping-up circuit which is connected to an output end of the amplifying circuit and outputs a waveform exceeding a voltage value of the power supply.

In one example, a method to match a digital amplifier model to a real guitar amplifier comprises obtaining an amplifier output filter and an amplifier input filter for the real guitar amplifier, using the amplifier output filter and a model output filter to obtain a corrective output filter, using the amplifier input filter and a model input filter to obtain a corrective input filter, and applying the corrective input filter and the corrective output filter to the digital amplifier model. The amplifier output filter and the amplifier input filter can be obtained using exponential sine sweep (ESS) and a matched filter. Other examples and related methods and apparatuses are also disclosed herein.

An amplifier and a method of outputting a waveform of a music signal capable of outputting a waveform of a music signal exceeding a power supply voltage is provided. An amplifier includes a power supply, an input terminal for a music signal, an amplifying circuit which amplifies the music signal using the power supply, and a jumping-up circuit which is connected to an output end of the amplifying circuit and outputs a waveform exceeding a voltage value of the power supply.

A vacuum tube subwoofer extraction circuit system includes: a front-end circuit; and a vacuum tube subwoofer extraction circuit connected to the front-end circuit, the vacuum tube subwoofer extraction circuit including: a small signal amplification vacuum tube for receiving an input signal from the front-end circuit and outputting an audio signal; and a passive filtering circuit connected to the small signal amplification vacuum tube and adapted to perform a filtering process on the audio signal so as to output a filtered signal, wherein the front-end circuit includes a switch power circuit for providing low voltage to the vacuum tube subwoofer extraction circuit, wherein the small signal amplification vacuum tube does not have gain effect on the input signal.

A vacuum tube subwoofer extraction circuit system includes: a front-end circuit; and a vacuum tube subwoofer extraction circuit connected to the front-end circuit, the vacuum tube subwoofer extraction circuit including: a small signal amplification vacuum tube for receiving an input signal from the front-end circuit and outputting an audio signal; and a passive filtering circuit connected to the small signal amplification vacuum tube and adapted to perform a filtering process on the audio signal so as to output a filtered signal, wherein the front-end circuit includes a switch power circuit for providing low voltage to the vacuum tube subwoofer extraction circuit, wherein the small signal amplification vacuum tube does not have gain effect on the input signal.

Disclosed is a configurable dual vacuum tube triode amplifier. The amplifier comprises two vacuum tube triodes and a user configurable switching component. The user configurable switching component can be positioned into at least a first position and a second position to modify an arrangement of the two vacuum tube triodes to provide varying tonal characteristics of the amplifier. Positioning the user configurable switching component in the first position arranges the two vacuum tube triodes in a cascode configuration to achieve a tonal characteristic of a vacuum tube pentode. Positioning the multi-position user switch in the second position arranges the two vacuum tube triodes in either a single vacuum tube triode configuration to achieve a tonal characteristic of a single vacuum tube triode operating alone or two vacuum tube triodes operating in a parallel configuration to achieve the tonal characteristics of two vacuum tube triodes operating in parallel.

In one example, a method to match a digital amplifier model to a real guitar amplifier comprises obtaining an amplifier output filter and an amplifier input filter for the real guitar amplifier, using the amplifier output filter and a model output filter to obtain a corrective output filter, using the amplifier input filter and a model input filter to obtain a corrective input filter, and applying the corrective input filter and the corrective output filter to the digital amplifier model. The amplifier output filter and the amplifier input filter can be obtained using exponential sine sweep (ESS) and a matched filter. Other examples and related methods and apparatuses are also disclosed herein.

To improve voice sound quality using a vacuum tube amplifier. A reactive load that has impedance characteristics, in which impedance characteristics in a first frequency band includes a first impedance characteristic pattern selected from a plurality of first impedance characteristic pattern candidates on the basis of a type of a vacuum tube amplifier, and impedance characteristics in a second frequency band includes a second impedance characteristic pattern selected from a plurality of second impedance characteristic patterns on the basis of the type of the vacuum tube amplifier, outputs a signal that responds to a sound signal output from the vacuum tube amplifier in accordance with the impedance characteristics and performs correction on an output signal of the reactive load.