# US 11,617,046 B2 · Audio signal reproduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,617,046 B2 - Document ID: US11617046B2 - Status: Granted - Kind: B2 - Application number: 17/386,738 - Filed: 2021-07-28 - Published: 2023-01-05 - Granted: 2023-03-28 - Earliest claimed: 2021-07-02 - Applicants: Tenor Inc. - Inventors: Michel Vanden Broeck - Web page: https://patentgrep.com/patent/US11617046B2 ## CPC - H03F 3/185: with field-effect devices (H03F3/187 takes precedence) - H04R 25/505: {using digital signal processing} - G10H 1/16: by non-linear elements (G10H1/14 takes precedence) - G11B 20/10527: {Audio or video recording; Data buffering arrangements (G11B20/12 - G11B20/18 take precedence)} - H03F 3/183: with semiconductor devices only - H03F 3/1855: {with junction-FET devices} - H03F 3/211: {using a combination of several amplifiers (H03F3/60 takes precedence)} - H03F 3/45071: {with semiconductor devices only} - H03G 5/00: Tone control or bandwidth control in amplifiers - H03G 5/005: {of digital signals} - H04R 3/04: for correcting frequency response - H04R 25/43: {Electronic input selection or mixing based on input signal analysis, e.g. mixing or selection between microphone and telecoil or between microphones with different directivity characteristics (H04R25/407 takes precedence)} - G10H 1/14: during execution {(voice controlled instruments G10H5/005)} - G10H 2210/311: Distortion, i.e. desired non-linear audio processing to change the tone colour, e.g. by adding harmonics or deliberately distorting the amplitude of an audio waveform - G11B 2020/10555: {wherein the frequency, the amplitude, or other characteristics of the audio signal is taken into account} - H03F 2200/03: the amplifier being designed for audio applications - H03F 2200/549: the amplifier comprising means to emulate the vacuum tube behaviour - H04R 2225/41: Detection or adaptation of hearing aid parameters or programs to listening situation, e.g. pub, forest - H03F: AMPLIFIERS - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) - G10H: ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - H03G: CONTROL OF AMPLIFICATION ## Abstract 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. ## Claims ### Claim 1 A method of audio signal reproduction comprising: providing a source audio signal from an audio signal source; providing at least one amplifier stage for amplifying said source audio signal to produce an audio output signal; and feeding said audio output signal to an audio transducer for listening purposes, wherein a composition of total harmonic distortion (THD) in said audio output signal is changed to improve a listening quality, wherein said providing at least one amplifier stage comprises providing a loaded transistor amplifier circuit including an output load that causes greater second order harmonic distortion energy than third order harmonic distortion energy to be produced in said loaded transistor amplifier circuit, wherein said amplifying further comprises power amplification using a solid-state amplifier circuit that produces lower even order harmonic distortion energy than odd order harmonic distortion energy, wherein said composition of total harmonic distortion (THD) in said audio output signal has a balance of odd and even order harmonic distortion energy that includes greater second order harmonic distortion energy than third order harmonic distortion energy, wherein said solid-state amplifier circuit provides power amplification, while said loaded transistor amplifier circuit provides pre-amplification, and said composition of total harmonic distortion (THD) in said audio output signal is less than 0.10874%. ### Claim 2 (depends on 1) The method as defined in claim 1, wherein said loaded transistor amplifier circuit produces said second order harmonic distortion energy more than 5 dB greater than third order harmonic distortion energy. ### Claim 3 (depends on 1) The method as defined in claim 1, wherein said load is adjusted until said second order harmonic distortion energy is greater than said third order harmonic distortion energy in said output audio signal. ### Claim 4 A method of audio signal reproduction comprising: providing a source audio signal from an audio signal source; providing at least one amplifier stage for amplifying said source audio signal to produce an audio output signal; and feeding said audio output signal to an audio transducer for listening purposes, wherein a composition of total harmonic distortion (THD) in said audio output signal is changed to improve a listening quality by said at least one amplifier stage using 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, said load being adjusted until said second order harmonic distortion energy is greater than said third order harmonic distortion energy in said output audio signal, wherein said load of said input stage comprises a transistor string to reduce an amount of harmonic distortion by bending of the transfer function of said transistor amplifier circuit, and said load is adjusted by selecting a number of transistors in said string.