# US 10,122,330 B2 · Apparatus, method, system and computer program for amplifying an audio signal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,330 B2 - Document ID: US10122330B2 - Status: Granted - Kind: B2 - Application number: 15/306,739 - Filed: 2015-03-23 - Published: 2017-05-04 - Granted: 2018-11-06 - Earliest claimed: 2014-04-30 - Assignees: Hifi System Components Limited - Applicants: Graham Slee - Inventors: Graham Slee - Web page: https://patentgrep.com/patent/US10122330B2 ## CPC - H03F 3/183: with semiconductor devices only - G06F 9/452: {Remote windowing, e.g. X-Window System, desktop virtualisation (protocols for virtual reality H04L67/131)} - G06F 9/54: Interprogram communication - H03F 1/083: {in transistor amplifiers (H03F1/10 - H03F1/22 take precedence)} - H03F 3/185: with field-effect devices (H03F3/187 takes precedence) - H03F 3/45475: {using IC blocks as the active amplifying circuit} - H04L 65/611: for multicast or broadcast (systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06) - H04L 65/70: Media network packetisation - G06F 2209/549: Remote execution - H03F 2200/03: the amplifier being designed for audio applications - H03F 2200/153: Feedback used to stabilise the amplifier - H03F 2203/45138: Two or more differential amplifiers in IC-block form are combined, e.g. measuring amplifiers - H03F: AMPLIFIERS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present disclosure relates to an apparatus, method, system and computer program for amplifying an audio signal derived from an audio signal pickup device, the pickup device having a pickup frequency response profile. The apparatus includes: an amplifier having a maximum open loop frequency response profile in a first frequency range including at least mid-range audible frequencies, the amplifier being configured to apply, in at least the first frequency range, a frequency response profile to the audio signal; wherein the frequency response profile applied to the audio signal is configured such that: it equalises the pickup frequency response profile over the first frequency range, and a difference between a maximum amount of gain able to be applied by the amplifier and an amount of gain applied to the audio signal by the amplifier is substantially constant throughout the first frequency range. ## Claims ### Claim 1 An apparatus for amplifying an audio signal derived from a constant velocity audio signal pickup device, wherein the audio signal is representative of an audio recording mastered to a record frequency response profile, and wherein the pickup device has a pickup frequency response profile having a consistent rise in the pickup frequency response profile of 20 dB per decade of frequency, the apparatus comprising: a voltage amplifier having a maximum open loop frequency response profile in a first frequency range comprising at least the range 100 Hz-5,000 Hz, wherein the maximum open loop frequency response profile has a constant rate of fall off of 20 dB per decade of frequency over the first frequency range, the amplifier being configured to apply, in at least the first frequency range, a frequency response profile to the audio signal; wherein the frequency response profile applied to the audio signal is configured such that: it provides a constant fall off response with increasing frequency of 20 dB per decade of frequency over the first frequency range thereby equalising the pickup frequency response profile over the first frequency range, and a difference between a maximum amount of gain able to be applied by the amplifier and an amount of gain applied to the audio signal by the amplifier is constant throughout the first frequency range; and wherein the amplifier is configured to apply a frequency dependent gain to the audio signal in a second frequency range that is configured to equalise both the effect of the pickup frequency response profile and the record frequency response profile on the audio signal in the second frequency range, wherein the second frequency range comprises frequencies lower than those of the first frequency range. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the first frequency range further comprises at least one of: low bass frequencies, high bass frequencies, low treble frequencies, high treble frequencies, low audible frequencies, high audible frequencies, and an audible range. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the amplifier is configured such its maximum open loop frequency response profile comprises a flat response for the second frequency range up to a first frequency and, following the first frequency, the constant rate of fall off in the response for the first frequency range. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the first frequency is at least one of: based on a frequency of an inflection point between two frequency regions of a record frequency response profile having differing responses, wherein the audio signal is representative of an audio recording mastered to the record frequency response profile; and 50 Hz. ### Claim 5 (depends on 3) The apparatus of claim 3, wherein the constant rate of fall off in the response is at least one of: based on a rise in the frequency response of the pickup frequency response profile; and 20 dB per decade of frequency. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the apparatus further comprises at least one means configured to apply a frequency dependent amplitude equalisation to the audio signal in at least a third frequency range to equalise the effect of the record frequency response profile on the audio signal in the at least the third frequency range. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the amplifier is provided with a feedback loop, preferably wherein the feedback loop comprises at least one of: a negative feedback loop; and a low pass filter. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the apparatus further comprises at least one of: means configured to provide peaking and damping for the pickup device; means configured to prevent load capacitance affecting an output of the amplified audio signal; means configured to provide an output buffer; means configured to provide pre-amplification of the audio signal prior to the amplifier applying the frequency response profile. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the apparatus is configured so as to provide: pre-amplification of a phono signal; equalisation of a pickup frequency response profile; and equalisation of a record frequency response profile. ### Claim 10 A method for amplifying an audio signal derived from a constant velocity audio signal pickup device, wherein the audio signal is representative of an audio recording mastered to a record frequency response profile, and wherein the pickup device has a pickup frequency response profile having a consistent rise in the pickup frequency response profile of 20 dB per decade of frequency, the method comprising: applying via a voltage amplifier, in at least a first frequency range comprising at least the range 100 Hz -5,000Hz, a frequency response profile to the audio signal; wherein the voltage amplifier has a maximum open loop frequency response profile in the first frequency range, and wherein the maximum open loop frequency response profile has a constant rate of fall off of 20 dB per decade of frequency over the first frequency range; wherein the frequency response profile applied to the audio signal is configured such that: it provides a constant fall off response with increasing frequency of 20 dB per decade of frequency over the first frequency range thereby equalising the pickup frequency response profile over the first frequency range, and a difference between a maximum amount of gain able to be applied and an amount of gain applied to the audio signal is constant throughout the first frequency range; and applying a frequency dependent gain to the audio signal in a second frequency range that is configured to equalise both the effect of the pickup frequency response profile and the record frequency response profile on the audio signal in the second frequency range, wherein the second frequency range comprises frequencies lower than those of the first frequency range. ### Claim 11 (depends on 10) An apparatus comprising means configured to cause the apparatus at least to perform the method as claimed in claim 10. ### Claim 12 (depends on 1) A phono preamplifier comprising the apparatus of claim 1. ### Claim 13 (depends on 12) An amplifier comprising the preamplifier of claim 12. ### Claim 14 (depends on 1) A system comprising: the apparatus of claim 1 and at least one or more of: an audio signal pickup device, an amplifier, an output for electrically outputting the amplified audio output, and one or more audio output devices for audibly outputting the amplified audio output.