USB-C PD Powered Phono Preamplifier

Abstract

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

Description

Background Art

[0001] This application claims priority to U.S. Patent Application No. 17 / 574,063, filed on January 12, 2022, with the title "USB-C PD POWERED PHONO PREAMPLIFER", which is incorporated herein by reference.

[0002] Consumers have limited availability of high-resolution digital audio (audio files having a sample rate exceeding 48 kHz or an audio bit depth exceeding 16 bits). Lenbrook Industries Limited (owner of NAD Electronics and Bluesound Music Systems and applicant of this application) began developing a new type of high-resolution media audio playback system in 2004 and demonstrated the system in 2009. By 2011, the NAD Masters Digital Suite Home Sound System enabled consumers to experience music using one or more network-connected playback devices. The BluOS operating system of this system introduced the Bluesound brand in 2012 and was extended to more affordable devices. Through software control applications installed on controllers (e.g., IR remote, wall-mounted controller, smartphone, tablet, computer, voice input device), consumers can play what they want in any room with a networked playback device. High-resolution music files can be accessed in each room with a playback device and in a group of rooms that synchronously play the same music together. The BluOS modular software design also enables the unification of audio-video receiver (AVR) devices and reduces the software development cost compared to the highly unique MCU / DSP software currently used throughout the AVR industry.

[0003] This application relates, more broadly, to a phonograph (phono) preamplifier, and more specifically, to a USB-C PD-powered phono preamplifier connected to a local area network (LAN).

[0004] The phonograph audio playback device was one of the most important inventions of the 20th century. While most music is enjoyed in digital audio formats via mobile devices, the phonograph "turntable" remains incredibly popular among music collectors and other discerning consumers who appreciate the authentic listening experience it offers. Many of the world's most successful music recordings were originally recorded and mastered for playback on vinyl turntables. While digital reissues available on CDs and music streaming services make these recordings easily accessible to users, many insist that original vinyl copies are superior. This has led to revivals of classic albums reissued on high-quality vinyl, and, occasionally, online sales of original vinyl copies deemed to represent the record company's best vinyl release or "stamping." Vinyl playback hardware is also a wide-ranging selection for audiophiles and collectors. This includes newly manufactured turntables and diamond styluses available from established and emerging equipment brands.

[0005] High-quality turntables still require specialized processing of their output signal before audio power amplification is applied to drive large loudspeakers. This processing step is performed by a phono preamplifier and includes high-gain amplification and standardized frequency equalization. The phono preamplifier effectively adjusts the small electrical signal from the turntable's magnetically coupled diamond stylus. The large signal gain and frequency equalization curves of the phono preamplifier present challenging technical issues.

[0006] If the power supply quality of the preamplifier is not carefully considered, the turntable's small musical signal is prone to overrunning due to electrical noise. Furthermore, the high dynamic range of the turntable's musical signal, along with the circuit's frequency equalization, requires a relatively high voltage supply to the preamplifier circuit. This voltage level provides sufficient "headroom" to prevent saturation at louder sections of music, which can damage expensive audio power amplifiers and speakers. When a high-performance phono preamplifier is the goal, a low-noise, high-voltage power supply represents the most expensive part of the phono preamplifier device. The best phono preamplifier devices currently on the market employ traditional "linear" power supplies to minimize electrical noise compared to modern switch-mode power supplies. High-end phono preamplifier devices come 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 device. This circuit applies the gain and "RIAA" standard phono equalization curves, which were first specified in the recording industry.

[0007] It was simply impossible to reduce costs on the above circuitry without compromising the final audio listening quality. The cost explains why most consumer electronics manufacturers began removing phono preamplifier functionality from their products in the late 1980s as vinyl's widespread popularity declined. In the 2000s, low-cost USB external power adapter devices became available, but these were unsuitable for high-quality phono preamplifiers due to their low output voltage and digital switching noise. While the voltage and noise issues of USB 2.0 power supplies can be addressed with additional switch-mode voltage boosting and linear regulation, this is considered to negate the desired cost savings. [Overview of the Initiative]

[0008] In one or more embodiments, a phono preamplifier powered by a variable voltage adapter is disclosed for processing an audio output signal from a turntable. The phono preamplifier includes an audio input port connected to the turntable by a cable to receive an audio output signal from the turntable. The power input port of the phono preamplifier is connected to the variable voltage adapter by a cable to receive power from the variable voltage adapter. A power controller subsystem is connected to the power input port to manage the power received at the power input port. A microprocessor subsystem is connected to the power controller subsystem to control the operation of the power controller subsystem. An operational amplifier circuit is connected to the audio input port and the power controller subsystem to amplify and adjust the audio output signal from the turntable. An analog-to-digital converter (ADC) is connected to the operational amplifier circuit to convert the amplified and adjusted audio output signal from the operational amplifier circuit into a digital bitstream output. A microprocessor subsystem is connected to the analog-to-digital converter to receive and process the digital bitstream output and transmit it over a wired or wireless network for playback on one or more speaker devices.

[0009] In one or more embodiments, the variable voltage adapter comprises a USB-C power supply device power adapter.

[0010] In one or more embodiments, an operational amplifier power circuit is connected to a power controller subsystem and an operational amplifier circuit. The operational amplifier power circuit is configured to divide the output voltage of the power received from the power controller subsystem into two power rails of equal voltage but opposite polarity, and to supply power to the operational amplifier circuit. In one or more embodiments, the output voltage is 12VDC, and the two equivalent power rails are ±6VDC rails.

[0011] In one or more embodiments, the operational amplifier circuit performs high-gain amplification and normalized frequency equalization on the audio output signal from the turntable.

[0012] In one or more embodiments, the variable voltage adapter supplies power to the phono preamplifier at an output voltage high enough to reduce the effects of electrical noise and prevent saturation in loud sections of music.

[0013] In one or more embodiments, the variable voltage adapter includes a switch-mode power supply circuit.

[0014] In one or more embodiments, the microprocessor subsystem is configured to request a 12VDC voltage from a variable voltage adapter.

[0015] In one or more other embodiments, a method is disclosed for powering a phono preamplifier that processes an audio output signal from a turntable using a variable voltage adapter. The method includes the steps of: receiving an audio output signal from a turntable; receiving power from a variable voltage adapter; managing the power from the variable voltage adapter; amplifying and adjusting the audio output signal from the turntable using the power from the variable voltage adapter; converting the amplified and adjusted audio output signal into a digital bitstream output; and processing the digital bitstream output for transmission over a wired or wireless network for playback by one or more speaker devices. [Brief explanation of the drawing]

[0016] [Figure 1A] One or more USB-C PD-powered phono preamplifiers according to one or more embodiments are illustrated below. [Figure 1B] One or more USB-C PD-powered phono preamplifiers according to one or more embodiments are illustrated below.

[0017] [Figure 2] This is a block diagram showing the connection of a USB-C PD powered phono preamplifier in a sound system according to one or more embodiments.

[0018] [Figure 3] This is a block diagram illustrating the system architecture of a USB-C PD-powered phono preamplifier according to one or more embodiments.

[0019] [Figure 4] This is a circuit diagram illustrating the operational amplifier power circuit of a USB-C PD-powered phono preamplifier according to one or more embodiments.

[0020] Similar or identical reference numbers are used to identify common or similar elements. [Modes for carrying out the invention]

[0021] Various embodiments disclosed herein relate to a phono preamplifier for processing audio output signals from a turntable powered by a variable voltage adapter, such as a USB-C PD ("Powered Device") power adapter.

[0022] In recent years, USB-C PD power adapters have become available. Because they conform to industry standards, many manufacturers can produce USB-C PD adapters in large quantities at a lower cost than conventional linear power adapters commonly used in high-end phono preamplifier devices. USB-C PD adapter devices can distribute 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 powered device. USB-C PD standard power supplies can be used to reduce costs without compromising audio performance. New USB-C PD supplies use more modern switch-mode power supply circuits than the previous USB 2.0 generation, and devices in each embodiment are designed to substantially reduce or eliminate the remaining switch-mode power supply noise of USB-C PD devices.

[0023] FIG. 1A illustrates a USB-C·PD powered phonopreamplifier 100 according to one or more embodiments. FIG. 1B shows specific internal components of the preamplifier 100.

[0024] FIG. 2 is a block diagram showing the connection of the USB-C·PD powered phonopreamplifier 100 in a sound system according to one or more embodiments. The phonopreamplifier 100 is powered by a USB-C·PD power adapter 102. Then, it receives an audio output signal from a turntable 104, amplifies and adjusts the audio signal. The processed audio signal is transmitted by the phonopreamplifier 100 via a wired or wireless network for reproduction by one or more speaker devices 106.

[0025] FIG. 3 is a block diagram illustrating the system architecture of the USB-C·PD powered phonopreamplifier 100 according to one or more embodiments. The phonopreamplifier 100 includes an electrical circuit board assembly 108 powered by one USB-C·PD power adapter 102. The circuit board assembly 108 includes a dedicated USB-C power controller chip 110 and a microprocessor module 112 that executes software. The microprocessor software communicates with the USB-C·PD power controller chip 110. A USB-C socket 114 on the circuit board enables the 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. Then, the software configures the power controller chip 110 to request a 12VDC voltage from the external power adapter 102.

[0026] The power controller chip 110 notifies the microcontroller's software that 12VDC is available from the USB-C·PD external power adapter 102. The 12VDC power is applied to a dedicated op-amp power circuit 116, where one resistor divides the 12VDC into two equal power rails. This effectively supplies the op-amp with split ±6VDC rails, enabling the op-amp to operate with optimal signal performance. Other electronic component values connected to the op-amp allow the op-amp to apply gain and frequency equalization to the input turntable signal received at port 120. The adjusted audio output signal is applied to the input of a high-quality analog-to-digital converter (ADC) 118. The microprocessor 112 receives the digital bitstream output of the analog-to-digital converter 118 for transmission via the wired or wireless LAN to which the phono preamplifier device 100 is connected. The digital bitstream is output to a wired network via the phono preamplifier's network port (e.g., Ethernet port 122 - Figure 1B) or to a wireless network via the wireless network interface of the phono preamplifier 100 (e.g., WiFi module 124 - Figure 3). In one or more embodiments, the phono preamplifier 100 does not include other audio outputs.

[0027] In the illustrated embodiment, the USB-C·PD powered phono preamplifier 100 consists of 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.

[0028] While several embodiments have been illustrated and explained above, it is natural that anyone with ordinary skill in the art will readily conceive of various changes, modifications, and improvements. Such changes, modifications, and improvements are intended to form part of this disclosure and to remain within the spirit and scope of this disclosure. Some of the examples presented herein involve specific combinations of functional and structural elements, but it should be understood that these functions and elements may be combined in other ways in accordance with this disclosure to achieve the same or different purposes. In particular, the functions, elements, and properties described in relation to one embodiment are not intended to be excluded from similar or different roles in other embodiments. Furthermore, the elements and components described herein may be further divided into additional components or combined to form fewer components to perform the same function.

[0029] Therefore, the above description and accompanying drawings 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 the audio output signal from a turntable, An audio input port configured to be connected to the turntable by a cable in order to receive an audio output signal from the turntable, A power input port configured to be connected to the variable voltage adapter by a cable in order to receive power from the variable voltage adapter, A power controller subsystem connected to the aforementioned power input port and configured to manage the power received by the aforementioned power input port, A microprocessor subsystem connected to the power controller subsystem and controlling the operation of the power controller subsystem, An operational amplifier circuit connected to the aforementioned audio input port and the aforementioned power controller subsystem amplifies and adjusts the audio output signal from the turntable, An analog-to-digital converter connected to the operational amplifier circuit, which converts the amplified and adjusted audio output signal from the operational amplifier circuit into a digital bitstream output, Includes, The microprocessor subsystem is connected to the analog-to-digital converter and receives and processes the digital bitstream output for transmission via a wired or wireless network for playback by one or more speaker devices. The power controller subsystem and the operational amplifier circuit further include an operational amplifier power circuit connected to the operational amplifier circuit, The operational amplifier power circuit is configured to divide the output voltage of the power received from the power controller subsystem into two power rails of equal voltage but opposite polarity, and to supply power to the operational amplifier circuit. Phono preamplifier.

2. The phono preamplifier according to claim 1, wherein the variable voltage adapter includes a USB-C power supply device power adapter.

3. The phono preamplifier according to claim 1, wherein the output voltage is 12VDC and the two equivalent power rails consist of ±6VDC rails.

4. The phono preamplifier according to claim 1, wherein the operational amplifier circuit performs high-gain amplification and standardized frequency equalization on the audio output signal from the turntable.

5. The phono preamplifier according to claim 1, wherein the variable voltage adapter supplies power to the phono preamplifier at a sufficiently high output voltage to reduce the effects of electrical noise and prevent saturation at loud sections of music.

6. The phono preamplifier according to claim 5, wherein the variable voltage adapter supplies power to the phono preamplifier with an output voltage of 12VDC.

7. The phono preamplifier according to claim 1, wherein the variable voltage adapter includes a switch-mode power supply circuit.

8. The phono preamplifier according to claim 1, wherein the microprocessor subsystem is configured to request a 12VDC voltage from the variable voltage adapter, the power controller subsystem.

9. The phono preamplifier according to claim 1, wherein the phono preamplifier is incorporated into the housing of the turntable.

10. The phono preamplifier according to claim 1, wherein the phono preamplifier outputs the digital bitstream to a wired network via the network port of the phono preamplifier or to a wireless network via the wireless network interface of the phono preamplifier, and the phono preamplifier does not include any other audio outputs.

11. A method of supplying power to a phono preamplifier that processes the audio output signal from a turntable using a variable voltage adapter, The steps include receiving an audio output signal from the turntable, The steps include receiving power from the aforementioned variable voltage adapter, The steps include managing the power from the aforementioned variable voltage adapter, The steps include: amplifying and adjusting the audio output signal from the turntable using power from the variable voltage adapter; The steps include converting the amplified and adjusted audio output signal into a digital bitstream output, The process includes the step of processing the digital bitstream output for transmission over a wired or wireless network for playback on one or more speaker devices, The further step includes dividing the output voltage of the power received from the variable voltage adapter into two power rails of equal voltage but opposite polarity, and supplying power to an operational amplifier circuit for amplifying and adjusting the audio output signal. method.

12. The method according to claim 11, wherein the variable voltage adapter includes a USB-C power supply device power adapter.

13. The method according to claim 11, wherein the output voltage is 12VDC and the two equivalent power rails consist of ±6VDC rails.

14. The method according to claim 11, wherein the step of amplifying and adjusting the audio output signal includes performing high-gain amplification and normalized frequency equalization on the audio output signal from the turntable.

15. The method according to claim 11, wherein the variable voltage adapter supplies power at a sufficiently high output voltage to reduce the effects of electrical noise and prevent saturation at loud sections of music.

16. The method according to claim 15, wherein the variable voltage adapter supplies power with an output voltage of 12VDC.

17. The method according to claim 11, wherein the variable voltage adapter includes a switch-mode power supply circuit.

18. The method according to claim 11, further comprising the step of negotiating the voltage level of the power received from the variable voltage adapter.

19. A USB-C PD powered phono preamplifier that processes audio output signals from a turntable, An audio input port configured to be connected to the turntable by a cable in order to receive an audio output signal from the turntable, A power input port configured to be connected to a USB-C power device adapter by a cable in order to receive power from the USB-C power device adapter, A power controller subsystem connected to the aforementioned power input port and configured to manage the power received by the aforementioned power input port, A microprocessor subsystem connected to the power controller subsystem and controlling the operation of the power controller subsystem, An operational amplifier circuit connected to the aforementioned audio input port and the aforementioned power controller subsystem amplifies and adjusts the audio output signal from the turntable, Includes an analog-to-digital converter connected to the operational amplifier circuit, which converts the amplified and adjusted audio output signal from the operational amplifier circuit into a digital bitstream output, The microprocessor subsystem is connected to the analog-to-digital converter and receives and processes the digital bitstream output for transmission via a wired or wireless network for playback by one or more speaker devices. The power controller subsystem and the operational amplifier circuit further include an operational amplifier power circuit connected to the operational amplifier circuit, The operational amplifier power circuit is configured to divide the output voltage of the power received from the power controller subsystem into two power rails of equal voltage but opposite polarity, and to supply power to the operational amplifier circuit. USB-C PD powered phono preamplifier.

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