1. Field of the Disclosure
The present disclosure relates generally to audio amplification and more particularly to use of a general-purpose computer for pre-amplification in an audio signal path.
2. Background Information
In a typical high-end audio system, audio data from an audio source passes through several devices along an audio signal path, before being heard by a listener. Audio signals generally originate from a playback device, such as a compact disk (CD) player, Digital Video Disc (DVD) player, turntable, portable mp3 music player; or a receiver device, such as radio tuner or Internet interface. The audio signals may be analog or digital depending on the particular playback or receiver device used. The audio signals often pass to a pre-amplifier, which may be a discrete device or a portion of an Audio/Video receiver. A function of the pre-amplifier is to amplify possibly low-level, high impedance analog audio signals to “line-level,” an accepted signal strength usually stated in terms of decibel volts (dBV). Most commonly used consumer audio equipment has been adapted for, and work best with, a line-level of about −10 dBV, which corresponds to signals of about 0.3162 volts RMS.
In addition to converting analog audio signals to line-level, pre-amplifiers often apply equalization, tone control, and mixing/effects to both analog and digital audio signals. Equalization refers to the process of amplifying or reducing the level of audio signals in different frequency ranges, to remove irregularities introduced by components in the audio signal path. Such equalization may be implemented with a combination of low pass, high pass, band pass, and/or band stop filters. Tone control similarly involves changing the level of audio signals in selected frequency ranges, yet rather than attempt to correct for irregularities, tone control attempts to enhance audio sound by adding more of a desirable tone (amplifying the signal strength in those frequency ranges), or by reducing undesired tones (reducing the signal strength in those frequency ranges). Well known bass, treble, and graphic equalizer adjustments are examples of tone control. Finally, mixing/effects encompass a wide variety of simulated surround sound, environmental effects, soundscapes, and other complex manipulations of audio signals common in modern audio systems.
After pre-amplification, the audio signals are generally passed through an A/V Receiver, where switching functions are performed, as well as digital to analog conversion functions, if necessary. Then, the audio signals are passed to a power amplifier, which may be part of the A/V receiver, or, especially in high-end systems, a separate unit dedicated to power amplification. The power amplifier provides a current gain to the now analog audio signals, bringing the signals to a level of tens, or hundreds, of watts, so they may drive loudspeakers or other sound delivery devices. After this amplification, the analog audio signals are generally ready to be delivered to, and drive, sound delivery devices.
One shortcoming of a conventional audio signal path is its inflexible nature. Audio devices are generally purpose built and offer the user little possibility for customization or upgrade. For example, a conventional pre-amplifier may be configured to provide certain types of equalization and tone control, and a user may be able to select from among the types provided. Yet most conventional pre-amplifiers offer little opportunity to upgrade the device to obtain additional functionality, for example, via a software download from the Internet. Instead, a user must generally purchase a new pre-amplifier that has been hard-wired with the additional functionality. Similarly, many pre-amplifier have a variety of dials, readouts, and controls on a physical control panel, often the front panel of the unit. These are generally single purpose hardware devices. A user who purchases the pre-amplifier must accept their appearance and functionality, and may not customize or alter them in any way. Finally, conventional pre-amplifiers generally lack the ability to output audio-interactive graphics and images for display to a user. Many users find such graphics and images entertaining, and a desirable addition to their listening experience. While some users accept these limitations, other users desire greater flexibility, customizability, and graphics display in the pre-amplification stage of the audio signal path of their audio system.
In brief summary, the present disclosure details the incorporation of a general-purpose computer into the audio signal path of an audio system, to provide or to enhance pre-amplification functions.
According to a first embodiment, audio signals are passed from a first output of a conventional pre-amplifier to a programmable multimedia controller that includes the general-purpose computer. The general-purpose computer in the programmable multimedia controller interprets and analyzes the audio signals. In response thereto, the programmable multimedia controller generates control commands and passes these control commands via a signal path back to the pre-amplifier. By sending appropriate control commands, particular equalization, tone control, and mixing/effects are implemented with the pre-amplifier. Since the programmable multimedia controller monitors the audio signals in real-time, the control of the pre-amplifier, in some configurations, is dynamically responsive to changes in the audio stream. This permits advanced pre-amplification functions beyond those that could be provided by a conventional pre-amplifier in isolation. In other configurations, in addition to control information, audio signals are passed back from the programmable multimedia controller to the pre-amplifier. Such audio signals are combined (i.e. mixed) at the pre-amplifier with the audio signals from the audio source to create environmental effects or other types of special effects. After pre-amplification, the audio signals are passed from a second output of the pre-amplifier to a power-amplifier, and thereafter to a sound output device.
According to a second embodiment, rather than control a separate pre-amplifier, the programmable multimedia controller, using its included general-purpose computer, implements the pre-amplification functions itself. The programmable multimedia controller includes executable program code that when executed on the general-purpose computer implements equalization, tone control, and mixing/effects on the audio signals while they are in digital form at the programmable multimedia controller. After equalization, tone control, and mixing/effects are applied, the audio signals are output to a digital to analog (D/A) converter and then passed to a power amplifier and sound delivery devices.
According to a third embodiment, rather employ a general-purpose computer incorporated in a programmable multimedia controller to implement the pre-amplification functions, a general-purpose computer is incorporated into a power amplifier to perform these functions. In such an embodiment, the programmable multimedia controller may be employed solely to send control signals to other devices, or may be absent from the system. The general-purpose computer in the power amplifier implements equalization, tone control, and mixing/effects on the audio signals, and these signals are output to sound delivery devices.
Furthermore, a virtual control panel on a display screen is provided in the first, second, and third embodiments for controlling pre-amplification of the audio signals. In the first and second embodiments, the display screen is coupled to, or incorporated into, the programmable multimedia controller, while in the third embodiment, the display screen is coupled to, or incorporated into, the power amplifier. The virtual control panel displayed on the display screen is a graphical user interface that simulates, replicates, or replaces with an alternate arrangement, the physical controls and readouts found on a physical control panel of a physical device. In one configuration, the dials and other indicators found on the physical control panel of a pre-amplifier are simulated as graphic representations on the virtual control panel, permitting the user to manipulate the virtual control panel rather than the physical control panel. In another configuration, the virtual control panel contains readouts and controls different from, or beyond, those provided by a conventional pre-amplifier, to allow for advanced control schemes. A user may readily change the configuration of the virtual control panel, including which readouts and controls are displayed, their locations, and certain aesthetic characteristics, such as their colors and designs.
In addition to displaying a virtual control panel, the display screen is further adapted to display audio-interactive graphics, images, and artwork. Such graphics, images and artwork are responsive to the rhythm of the audio signals and/or to the amplitude of the audio signals in certain frequency bands. Furthermore, the graphics, images and artwork are related to a particular user profile of a particular user. Accordingly, depending on the user currently controlling the system, different graphics and images may be shown.
The description below refers to the accompanying drawings, of which:
As used herein, the term “programmable multimedia controller” should be interpreted broadly as a device capable of controlling, switching data between, and/or otherwise interoperating with a variety of electronic devices, such as audio, video, telephony, data, security, motor-operated, relay-operated, and/or other types of devices. By interacting with these devices, a programmable multimedia controller implements an integrated multimedia control solution. Further details regarding the design and function of a programmable multimedia controller are provided in U.S. patent application Ser. No. 11/314,664, entitled “System and Method for a Programmable Multimedia Controller,” by Robert P. Madonna, et al., the teachings of which are expressly incorporated into this disclosure by reference.
An audio source 110, for example a playback device (such as a CD player, DVD player, or turntable) or a receiver device (such as a radio tuner or internet interface) originates audio signals. These audio signals are passed to a conventional pre-amplifier, which in this example is a separate audio component, but alternately may be a portion of an A/V Receiver or other audio device. The pre-amplifier 120 works in conjunction with, and under the control of, the programmable multimedia controller 150 to provided advanced pre-amplification functions and control beyond the ordinary capabilities of the conventional pre-amplifier 120. Such additional capabilities are facilitated by passing audio output signals from the conventional pre-amplifier to the programmable multimedia controller 150. The audio output signals may take the form of digital signals transmitted on a digital pathway 156, or analog signals transmitted on a analog pathway 158. If analog signals are employed, the signals are passed through an analog to digital (A/D) converter 130 to produce a digital signal. While the A/D converter 130 is shown in
The programmable multimedia controller 150 includes one or more general-purpose computers 155. As used herein, the term “general-purpose computer” refers to any computing system capable of executing a general-purpose operating system, for example an OS X™ operating system or a Unix™ operating system. A general-purpose computer may take the form of a CPU card, a Single Board Computer (SBC), a PC/104 processing module, a conventional ATX form factor motherboard and CPU, an “off-the-shelf” small form factor computer, and an “off-the-shelf” large form factor or rack-mount computer. Further details regarding the use of a general-purpose computer 155 in a programmable multimedia controller 150 are provided in “System and Method for a Programmable Multimedia Controller,” by Robert P. Madonna, et al.
In one embodiment, once the audio signals are received at the programmable multimedia controller 150, they are interpreted by the general-purpose computer 155, and control commands for the pre-amplifier 120 are generated in response thereto. These control commands are sent along a pathway 154, which may be a wired link, such as RS232 connection, or a wireless link, such as a WI-FI connection. By sending appropriate control commands along the pathway 154, particular equalization, tone control, and mixing/effects schemes are implemented with the pre-amplifier 120. For example, in response to user preferences, the programmable multimedia controller may measure the amplitude of the audio signals in selected frequency bands, and then command the pre-amplifier to adjust the amplitude in each frequency band to a desired level. The programmable multimedia controller 150 may thereafter monitor the audio signals generated by the pre-amplifier to verify that the appropriate adjustments have been made.
Since the programmable multimedia controller 150 monitors the audio signals in real-time, its control of the pre-amplifier 120, in some configurations, is dynamically responsive to changes in the audio stream. This permits advanced pre-amplification functions beyond those that could be provided by the conventional pre-amplifier 120 in isolation. For example, using the programmable multimedia controller 150, a user may select particular equalization and tone control schemes for differing types of music, or for audio with different audio quality. In this manner, the user may select that classical music is equalized in one manner, while bass-heavy rock music equalized in another. Similarly, the user may select that a low quality audio signal, such as that generated from a low bit-rate Internet audio feed, is subjected to extensive equalization and tone-control, to improve (to the extent possible) the listening experience, while a high-quality audio signal is subject to minimal equalization and tone-control. The computational power of the general-purpose computer 155 is used to implement these dynamic pre-amplification functions.
In another embodiment, in addition to control information, the pathway 154 to the pre-amplifier 120 passes audio signals from the programmable multimedia controller 150 to the pre-amplifier. Such audio signals may be used in a variety of manners, depending on the configuration of the programmable multimedia controller 150 and the pre-amplifier 120. For example, in one configuration the audio signals from the programmable multimedia controller 150 are combined (i.e., mixed) with the audio signals from the audio source 110 to create environmental effects or other special effects. In another configuration, the audio signals from the programmable multimedia controller 150 are used in place of the original audio signals. That is, they are passed to additional outputs of the pre-amplifier 120 that drive the rest of the audio signal path.
The programmable multimedia controller is coupled to a display 180, such as a touch sensitive LCD screen, or a television screen, to facilitate user control. In one embodiment, the display is arranged as the front panel (front face) of the programmable multimedia controller, while in another embodiment the display is a separate unit, such as a table top display screen, interconnected to the programmable multimedia controller by a wired or wireless connection. The display is adapted to show a virtual control panel for pre-amplification functions, among other functions. A virtual control panel is a graphical user interface that simulates, replicates, or replaces with an alternate arrangement, the physical controls and readouts found on a physical control panel of a physical device. For example, the dials and other indicators found on the physical control panel of the pre-amplifier 120 may be simulated as graphic representations on the virtual control panel display. Similarly, the control knobs and buttons of the physical control panel may be shown on the virtual front panel, and their manipulation used to control pre-amplification.
Since the virtual control panel is a graphical construct, it may also be designed quite differently from any physical control panel, and may contain readouts and controls beyond those provided by physical units. In this manner, the virtual control panel may provide advanced control schemes using the graphics capabilities of the general-purpose computer 155. For example, the virtual control panel itself may be responsive to the beat or tones of the music in the audio stream, such that its appearance changes in response thereto. Further, a user may readily change the configuration of the virtual control panel, choosing which readouts and control are to be displayed, their locations, and aesthetics such as their colors and designs. Such flexibility allows the user to modify their system as their preferences change, absent the purchase of new hardware devices. Further discussion of the virtual control panel is provided below in reference to
In addition to using the display screen to show a virtual control panel, the display screen is further adapted to display audio-interactive graphics, images, and/or artwork. Using the processing power of the general-purpose computer 155, the audio signals may be analyzed according to any of a number of algorithms to extract the rhythm (i.e. the beat) of the audio signals. Further, the amplitude of the audio signals in certain frequency ranges may be measured, as discussed above. In response to such characteristics of the audio signals, graphics, images and/or artwork are arranged to move, gyrate, or distort in response to the music, to create an audio-interactive display. The particular graphics, images, or artwork shown are in some configurations responsive to the preferences of a particular user, and may displayed only when that user is operating the system. One technique for determining when a particular user is operating the system is described in U.S. patent Ser. No. 11/520,328, entitled “Remote Control Unit for a Programmable Multimedia Controller”, by Robert P. Madonna, et al., the teachings of which are expressly incorporated into this disclosure by reference.
The programmable multimedia controller 150 is also connected via a network connection to the Internet 190, or another wide area network (WAN) or local area network (LAN). Via the network connection, pre-designed virtual control panels may be downloaded as executable program code. Similarly additional equalization, tone-control, and effects may be downloaded as executable program code. As the programmable multimedia controller includes a general-purpose computer 155 with a general-purpose operating system, such executable program code may readily be executed to modify the system's configuration, function, and appearance on the display 180.
Returning to discussion of the audio signal path, the pre-amplifier 120 passes analog audio signals via an output to a power amplifier 160, which provides a current gain to the signals, bringing the them to a level sufficient to drive at least one sound deliver device 170, such as a loudspeaker. The power amplifier 160 further receives control commands from the programmable multimedia controller 150 along a path 152, for example, control commands to adjust volume. While only a single sound delivery device is shown in
Further, while the power amplifier 160 is shown in
After equalization, tone control, and mixing/effects are applied, the audio signals are output to a digital to analog (D/A) converter 210, and then passed to a power amplifier 160. The power amplifier 160 is further controlled by control signals from the programmable multimedia controller 150 over pathway 152. Finally, the audio signals are passed to at least one sound delivery device 170.
The foregoing description has been directed to several example embodiments. It will be apparent, however, that other variations and modifications may be made to the described embodiments, with the attainment of some or all of their advantages. Additionally, the procedures or processes discussed above may be implemented in hardware, software, embodied as a computer-readable medium having program instructions, firmware, or a combination thereof. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.
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Number | Date | Country | |
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20080075305 A1 | Mar 2008 | US |