Amplifiers – With control of power supply or bias voltage
Reexamination Certificate
2002-11-21
2004-07-06
Nguyen, Patricia (Department: 2817)
Amplifiers
With control of power supply or bias voltage
C330S123000
Reexamination Certificate
active
06759901
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is related to voltage sensing regulators, and more particularly to an application of such a regulator in music amplifier systems.
Of primary importance to guitar players is the sound of the guitar amplifier, considered to be an integral part of the artists instrument, that instrument being comprised of the guitar, the amplifier, speakers, and any other sound modifier or signal processors included in the signal chain. Traditionally, the guitar amplifier, in general, and the tube amplifier, in particular, not only amplifies the signal from the guitar, but also adds additional sonic characteristics, such as adjustable treble and bass enhancements and harmonic distortion generated by overloading the vacuum tubes, transformers, and speakers.
In a vacuum tube guitar amplifier, pleasing distortion components are added to the amplified sound in varying degrees, based upon the settings and preferences of the user. As amplifier technology has become more sophisticated, the range of tonal variation has become significantly enhanced. There are other more subtle characteristics of guitar amplifier behavior to be explored and brought under control of the user.
One such behavioral characteristic of particular interest is actually more of an anomaly or artifact of an amplifier being purposely overloaded with respect to its power supply. A self-contained, or integrated amplifier is composed of three main blocks: the preamplifier (also denoted as “preamp”), which amplifies the very low level guitar signal to a level, required by the next block; the power amplifier, which amplifies the low level signal output of the preamplifier to a higher level sufficient to drive the speakers; and the power supply, which provides the voltage and current needed for the other component parts to operate according to design requirements. The power supply is part of the amplifier that converts AC input voltage to DC voltages required by the various components and amplifier circuits. As the amplifier volume is increased past normal operating parameters, the power supply becomes unable to meet the demands placed on it by the amplifier circuit. This causes the amplifier power supply voltage to drop below its normal reserve. In response, the amplifier output signal causes the audio output from the speakers to sound compressed or “spongy”. In addition, constant fluctuation of the power supply potential introduces Inter-modulation Distortion (IMD) into the audio signal-and produces a sonic artifact commonly referred to as a “ghost note.” Ghost notes are a phenomenon that occurs when the frequency of the IMD component modulates or beats against the fundamental audio signal being amplified, creating a harmonic undertone, which is perceived as an additional tone or note. While these artifacts may be undesirable from a technical standpoint, and are easily eliminated, they are part-and-parcel to the playing experience of the musician.
A third important artifact produced by overloading a conventional vacuum tube amplifier system is Output Transformer Core Saturation. This occurs when the output transformer, the component that couples the high impedance of the output tube(s) to the low impedance speaker load, has surpassed its capability to faithfully transfer the output signal from the power tube to the speaker load, due to the limitation of the magnetic flux created in the transformer core. Transformer saturation produces a subtle but audible form of compression of the output signal.
In component-based systems where the preamplifier and amplifier are each constructed in an individual chassis, the preamplifier operates independently of the power amplifier insofar as each chassis provides a power supply that supports only the circuits contained within that chassis. Because of this independence, the “floating” preamplifier voltages and attendant artifacts are eliminated, causing the preamplifier to output clearer signals, which sound dry, brittle, and lifeless compared to the integrated amplifier system.
Although many other manufacturers have offered preamplifiers to the market, there has always been a missing element that prevents these products from being widely accepted as “the real thing” in terms of their being able to replicate all of the various characteristics of integrated guitar amplifiers, especially with respect to the aforementioned artifacts.
Preamplifier circuitry as currently understood, is incapable of producing genuine power supply induced behavioral artifacts due to the nature of the preamp tubes themselves. Preamp tubes operate in Class A mode, a term used to describe the difference in power consumption under zero signal condition versus maximum signal condition. In Class A mode, there is no significant difference in power consumption between the aforementioned conditions of operation and therefore the power supply voltage stays constant. An integrated vacuum tube guitar amplifier consists of preamp tubes and power tubes. The power tubes are responsible for delivering the fully amplified sound to the speakers and therefore do all the “work”. This means they also consume 95% of all the available power in the power supply. Mostly, power tubes operate in Class AB mode. This simply means that very little demand is made upon the power supply under zero signal condition and maximum demand is made upon the power supply during maximum signal condition. The artifacts described above are caused by the radical fluctuation in power requirement between the zero signal and maximum signal condition. Because the preamp tubes are operated from the same supply source as the power tubes in an integrated amplifier, the preamp section “floats” along with the constantly shifting voltage potential of the power supply during conditions of rigorous operation.
What is needed is an architecture that emulates the desirable tonal artifacts in component-based guitar amplifier systems that were previously produced in integrated guitar amplifier systems.
SUMMARY OF THE INVENTION
The present invention disclosed and claimed herein, in one aspect thereof, comprises a power supply control circuit in a preamplifier component. The component comprises a power supply for providing a power signal. A regulator circuit receives the power signal and a regulator control signal, and provides a regulated output signal. An amplifier circuit operates from the regulated output signal, receives an input signal, and outputs an amplifier output signal. A converter receives the amplifier output signal and converts the amplifier output signal to a control voltage. A variable control circuit receives the control voltage, and varies the control voltage to output the regulated control signal to the regulator circuit. When a signal fluctuation occurs in the input signal, a corresponding signal fluctuation is induced in the regulated output signal in response thereto causing a random distortion in the amplifier output signal that is perceived by a listener as audio artifacts in the amplifier output signal.
REFERENCES:
patent: 4392103 (1983-07-01), O'Sullivan et al.
patent: 4816741 (1989-03-01), Ekstrand
patent: 5635872 (1997-06-01), Zimmerman
patent: 5761316 (1998-06-01), Pritchard
patent: 5777519 (1998-07-01), Simopoulos
patent: 5909145 (1999-06-01), Zimmerman
patent: 5977474 (1999-11-01), O'Brien
patent: 6350943 (2002-02-01), Suruga et al.
Amin & Turocy LLP
Jorgenson Eric D.
Nguyen Patricia
VHT Amplification, Inc.
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