USB-cpd powered turntable preamplifier

Abstract

The phono preamp, used to process the audio output signal from the turntable, is powered by a variable voltage adapter such as a USB-C PD power adapter.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 574063, filed January 12, 2022, entitled "USB-C PD Powered PHONO PREAMPLIFER", which is incorporated herein by reference. Background Technology

[0003] Consumers have limited access to high-resolution digital audio (audio files with a sampling rate greater than 48kHz or an audio bit depth greater than 16 bits). Lenbrook Industries Limited (owner of NADElectronics and Bluesound Music Systems and the applicant of this application) began developing a new high-resolution media audio playback system in 2004 and demonstrated such a system in 2009. By 2011, the NADMasters Digital Suite Home Sound System enabled consumers to experience music via one or more networked playback devices. With the launch of the Bluesound brand in 2012, the system's BluOS operating system was extended to more affordable devices. Through software control applications installed on controllers (e.g., IR remotes, wall-mounted controllers, smartphones, tablets, computers, voice input devices), consumers can play their desired content in any room with networked playback devices. They can use the playback devices to access high-resolution music files in each room and combine rooms to play the same music synchronously. BluOS's modular software design also allows for a unified audio / video receiver (AVR) device, reducing software development costs compared to the highly proprietary MCU / DSP software currently used throughout the AVR industry.

[0004] This application generally relates to phono preamplifiers, and more specifically to USB-CPD powered phono preamplifiers connected to a local area network (LAN).

[0005] The phonograph is one of the most important inventions of the 20th century. While most music is played on mobile devices and enjoyed in digital audio formats, the phono "turntable" remains incredibly popular among music collectors and other discerning consumers who appreciate the authentic listening experience it provides. Many of the world's most successful music recordings were originally recorded and mastered for playback on the turntable. While digital re-releases available on CDs and music streaming services allow users to conveniently enjoy these recordings, many believe the original vinyl copies sound better. This has led to a revival of classic album re-releases on high-quality vinyl, and the online sale of rare original vinyl copies considered to represent the best releases or "presses" from recording companies. Audiophiles and collectors also have a vast selection of vinyl playback hardware—including newly manufactured turntables and diamond styluses available from established and emerging equipment brands.

[0006] Before applying audio power amplification to drive large loudspeakers, high-quality turntables still require dedicated processing of their output signal. This processing step is performed by the phono preamplifier and includes high-gain amplification and normalized frequency equalization. The phono preamplifier effectively modulates the small electrical signal of the magnetically coupled diamond stylus of the turntable. The large signal gain and frequency equalization profile of the phono preamplifier present significant technical challenges.

[0007] Without careful attention to the power supply quality of the preamplifier, the small musical signals from the turntable can easily be masked by electrical noise. Furthermore, the high dynamic range of the turntable's musical signals and the frequency equalization of the circuitry require a relatively high voltage from the preamplifier circuitry. The voltage level provides sufficient "margin" to prevent saturation during loud musical passages. Saturation can potentially damage expensive audio power amplifiers and speakers. When the goal is a high-performance phono preamplifier, low noise and high-voltage power supplies represent the most expensive part of the phono preamplifier unit. The best phono preamplifiers currently on the market use traditional "linear" power supplies, which minimize electrical noise compared to modern switching-mode power supplies. High-end phono preamplifiers are equipped with expensive dedicated external linear power adapters, typically with a minimum voltage of 12VDC. This powers the operational amplifier ("op-amp") circuitry inside the phono preamplifier unit. This circuitry applies the gain and "RIAA" standard phono equalization curve originally specified by the recording industry.

[0008] Reducing the cost of the aforementioned circuitry without compromising the final audio listening quality is simply impossible. Cost explains why most consumer device manufacturers began removing phono preamp features from their products in the late 1980s, as the widespread popularity of vinyl records was declining. Low-cost USB external power adapters emerged in the 2000s, but their low output voltage and digital switching noise prevented them from being used for high-quality phono preamps. It's conceivable that the voltage and noise issues of USB 2.0 power could be addressed with additional switching-mode voltage boost and linear regulation, although this would negate the desired cost reduction. Summary of the Invention

[0009] According to one or more embodiments, a phono preamplifier powered by a variable voltage adapter for processing audio output signals from a platter is disclosed. The phono preamplifier includes an audio input port cable-coupled to the platter to receive the audio output signal from the platter. A power input port in the phono preamplifier is cable-coupled to the variable voltage adapter to receive power from the variable voltage adapter. A power controller subsystem is coupled to the power input port to manage the power received at the power input port. A microprocessor subsystem is coupled to the power controller subsystem to control the operation of the power controller subsystem. An operational amplifier circuit is coupled to the audio input port and the power controller subsystem for amplifying and regulating the audio output signal from the platter. An analog-to-digital converter (ADC) is coupled to the operational amplifier circuit for converting the amplified and regulated audio output signal from the operational amplifier circuit into a digital bitstream output. The microprocessor subsystem is coupled to the ADC to receive and process the digital bitstream output for transmission over a wired or wireless network for presentation on one or more speaker devices.

[0010] In one or more embodiments, the variable voltage adapter includes a USB-C powered device power adapter.

[0011] In one or more embodiments, the operational amplifier power supply circuitry is coupled to the power controller subsystem and the operational amplifier circuitry. The operational amplifier power supply circuitry is configured to divide the output voltage of the power received from the power controller subsystem into two voltage-equivalent but opposite power rails to power the operational amplifier circuitry. In one or more embodiments, the output voltage is 12VDC, and the two equivalent power rails include a + / -6VDC rail.

[0012] In one or more embodiments, the operational amplifier circuitry performs high-gain amplification and normalized frequency equalization on the audio output signal from the turntable.

[0013] In one or more embodiments, the variable voltage adapter supplies a sufficiently high output voltage to the phono preamplifier to reduce the effects of electrical noise and prevent saturation during loud musical passages.

[0014] In one or more embodiments, the variable voltage adapter includes a switch-mode power supply circuit.

[0015] In one or more embodiments, the microprocessor subsystem configures the power controller subsystem to request 12VDC voltage from the variable voltage adapter.

[0016] In one or more further embodiments, a method is disclosed for powering a phono preamplifier for processing an audio output signal from a turntable using a variable voltage adapter. The method includes the steps of: receiving the audio output signal from the turntable; receiving power from the variable voltage adapter; managing the power from the variable voltage adapter; using the power from the variable voltage adapter to amplify and regulate the audio output signal from the turntable; converting the amplified and regulated audio output signal into a digital bitstream output; and processing the digital bitstream output for transmission over a wired or wireless network for presentation on one or more speaker devices. Attached Figure Description

[0017] Figure 1A and 1B An exemplary USB-C PD-powered phono preamplifier according to one or more embodiments is shown.

[0018] Figure 2 This is a block diagram illustrating the connection of a USB-C PD-powered phono preamplifier in a sound system according to one or more embodiments.

[0019] Figure 3 This is a block diagram illustrating an exemplary system architecture of a USB-C PD-powered phono preamplifier according to one or more embodiments.

[0020] Figure 4 This is a circuit diagram illustrating an exemplary operational amplifier power supply circuit for a USB-C PD-powered phono preamplifier according to one or more embodiments.

[0021] Similar or identical reference numerals are used to identify common or similar elements. Detailed Implementation

[0022] The various embodiments disclosed herein relate to a phono preamplifier for processing audio output signals from a turntable, the phono preamplifier being powered by a variable voltage adapter such as a USB-C PD (“Powered Device”) power adapter.

[0023] USB-C PD power adapters have recently been introduced. Because they adhere to industry standard specifications, many manufacturers can mass-produce USB-C PD adapters at a lower cost than traditional linear power adapters typically used in high-end phono preamp equipment. USB-C PD adapter devices can deliver significantly more power and higher voltage than their predecessors, USB 2.0 power adapters. USB-C PD supports variable output voltage. The voltage level can be set up to 12VDC via software negotiation with the device it powers. The USB-C PD standard power supply can be used to reduce costs without compromising audio performance. The new USB-C PD power supply employs a more modern switch-mode power circuitry than the previous generation USB 2.0, and devices, according to various embodiments, are designed to significantly reduce or eliminate any residual switch-mode power noise in USB-C PD devices.

[0024] Figure 1A An exemplary USB-C PD-powered phono preamplifier 100 according to one or more embodiments is shown. Figure 1B Some internal components of the preamplifier 100 are shown.

[0025] Figure 2 This is a block diagram illustrating the connections of a USB-C PD-powered phono preamplifier 100 in a sound system according to one or more embodiments. The phono preamplifier 100 is powered by a USB-C PD power adapter 102. It receives an audio output signal from a turntable 104 and amplifies and modulates the audio signal. The processed audio signal is transmitted by the phono preamplifier 100 via a wired or wireless network for presentation on one or more speaker devices 106.

[0026] Figure 3 This is a block diagram illustrating an exemplary system architecture of a USB-C PD-powered phono preamplifier 100 according to one or more embodiments. The phono preamplifier 100 includes a single board assembly 108 powered by a single USB-C PD power adapter 102. The board assembly 108 includes a dedicated USB-C power controller chip 110 and a microprocessor module 112 executing software. The microprocessor software communicates with the USB-C PD power controller chip 110. A USB-C socket 114 on the board allows connection of a standard USB-C PD external power adapter 102. When the external power adapter 102 is connected, the USB-C PD power controller chip 110 notifies the microprocessor software. The software then configures the power controller chip 110 to request 12VDC voltage from the external power adapter 102.

[0027] The power controller chip 110 informs the microcontroller software that 12VDC has been confirmed as available from an external USB-C power adapter 102. The 12VDC power supply is applied to a dedicated operational amplifier power circuit 116, where a single resistor splits the 12VDC into two equivalent power rails. This effectively provides the operational amplifier with a shunted + / - 6VDC rail, allowing it to operate with optimal signal performance. Other electronic component values ​​connected to the operational amplifier allow it to apply gain and frequency equalization to the incoming turntable signal received at port 120. The regulated audio output signal is applied to the input of a high-quality analog-to-digital converter (ADC) 118. The microprocessor 112 accepts the digital bitstream output from the ADC 118 for transmission via a wired or wireless LAN to which the phono preamplifier device 100 is already connected. The digital bitstream is transmitted via a network port (e.g., Ethernet port 122) in the phono preamplifier. Figure 1B The output can be sent to a wired network, or via a wireless network interface (e.g., WiFi module 124) in the phono preamplifier 100. Figure 3 The output is sent to a wireless network. In one or more embodiments, the phono preamplifier 100 does not include other audio outputs.

[0028] In the illustrated embodiment, the USB-C PD-powered phono preamplifier 100 includes a device separate from the turntable 104. In one or more alternative embodiments, the USB-C PD-powered phono preamplifier 100 is housed within the housing of the turntable 104.

[0029] Having described several illustrative embodiments, it should be understood that various changes, modifications, and improvements will readily occur to those skilled in the art. Such changes, modifications, and improvements are intended to form part of this disclosure and are intended to fall within the spirit and scope of this disclosure. While some examples given herein relate to specific combinations of functional or structural elements, it should be understood that these functions and elements can be combined in other ways according to this disclosure to achieve the same or different objectives. In particular, actions, elements, and features discussed in connection with one embodiment are not intended to be excluded from similar or other roles in other embodiments. Furthermore, the elements and components described herein may also be divided into additional components or combined to form fewer components to perform the same function.

[0030] Accordingly, the above descriptions and figures are for illustrative purposes only and are not intended to be limiting.

Claims

1. A phono preamplifier powered by a variable voltage adapter for processing audio output signals from a turntable, characterized in that, include: An audio input port, configured to be cable-coupled to the turntable to receive the audio output signal from the turntable; A power input port, configured to be cable-coupled to the variable voltage adapter to receive power from the variable voltage adapter; A power controller subsystem, coupled to the power input port and configured to manage the power received at the power input port; A microprocessor subsystem coupled to the power controller subsystem to control the operation of the power controller subsystem; An operational amplifier circuit, coupled to the audio input port and the power controller subsystem, is used to amplify and regulate the audio output signal from the turntable; as well as An analog-to-digital converter (ADC), coupled to the operational amplifier circuit, is used to convert the amplified and regulated audio output signal from the operational amplifier circuit into a digital bitstream output. The microprocessor subsystem is coupled to the ADC to receive and process the digital bitstream output for transmission via a wired or wireless network for presentation on one or more speaker devices.

2. The phono preamplifier according to claim 1, characterized in that, The variable voltage adapter includes a USB-C powered device power adapter.

3. The phono preamplifier according to claim 1 or 2, characterized in that, It also includes an operational amplifier power supply circuit coupled to the power controller subsystem and the operational amplifier circuit, the operational amplifier power supply circuit being configured to divide the output voltage of the power received from the power controller subsystem into two power rails that are voltage equivalent but opposite in polarity to supply power to the operational amplifier circuit.

4. The phono preamplifier according to claim 3, characterized in that, The output voltage is 12VDC, and the two equivalent power rails include a + / -6VDC rail.

5. The phono preamplifier according to claim 1, characterized in that, The operational amplifier circuit amplifies the audio output signal from the turntable with high gain and performs normalized frequency equalization.

6. The phono preamplifier according to claim 1, characterized in that, The variable voltage adapter supplies power to the phono preamplifier with an output voltage that reduces the effects of electrical noise and prevents saturation during loud music passages.

7. The phono preamplifier according to claim 6, characterized in that, The variable voltage adapter supplies power to the phono preamplifier with a 12VDC output voltage.

8. The phono preamplifier according to claim 1, characterized in that, The variable voltage adapter includes a switch-mode power supply circuit.

9. The phono preamplifier according to claim 1, characterized in that, The microprocessor subsystem configures the power controller subsystem to request 12VDC voltage from the variable voltage adapter.

10. The phono preamplifier according to claim 1, characterized in that, The phono preamplifier is integrated into the housing of the turntable.

11. The phono preamplifier according to claim 1, characterized in that, The phono preamplifier outputs the digital bitstream to a wired network via a network port in the phono preamplifier, or outputs the digital bitstream to a wireless network via a wireless network interface in the phono preamplifier, wherein the phono preamplifier does not contain any other audio outputs.

12. A method for powering a phono preamplifier used to process audio output signals from a turntable using a variable voltage adapter, characterized in that, Includes the following steps: Receive the audio output signal from the turntable; Receive power from the variable voltage adapter; Manage the power from the variable voltage adapter; The audio output signal from the turntable is amplified and regulated using power from the variable voltage adapter via an operational amplifier circuit. The amplified and regulated audio output signal is converted into a digital bitstream output; as well as The digital bitstream output is processed for transmission via a wired or wireless network for presentation on one or more speaker devices.

13. The method according to claim 12, characterized in that, The variable voltage adapter includes a USB-C powered device power adapter.

14. The method according to claim 12, characterized in that, Also includes: The output voltage of the power received from the variable voltage adapter is divided into two power rails that are voltage equivalent but opposite in polarity, to power the operational amplifier circuit used to amplify and regulate the audio output signal.

15. The method according to claim 14, characterized in that, The output voltage is 12VDC, and the two equivalent power rails include a + / -6VDC rail.

16. The method according to claim 12, characterized in that, Amplifying and adjusting the audio output signal includes performing high-gain amplification and normalized frequency equalization on the audio output signal from the turntable.

17. The method according to claim 12, characterized in that, The variable voltage adapter is designed to reduce the effects of electrical noise and prevent saturation of the output voltage during loud music passages.

18. The method according to claim 17, characterized in that, The variable voltage adapter is powered by a 12VDC output voltage.

19. The method according to claim 12, characterized in that, The variable voltage adapter includes a switch-mode power supply circuit.

20. The method according to claim 12, characterized in that, Also includes: Negotiate the voltage level of the power received from the variable voltage adapter.

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