Amplifiers – With plural diverse-type amplifying devices
Reexamination Certificate
1998-11-24
2001-01-16
Mottola, Steven J. (Department: 2817)
Amplifiers
With plural diverse-type amplifying devices
C330S195000
Reexamination Certificate
active
06175271
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to an amplifier for electronic musical instruments and audio systems, and more particularly to an output signal converter for tube amplifiers, which is installed on the rear side of a tube amplifier and which is capable of amplifying or attenuating output signals while advantageously maintaining the output properties of tube amplifiers.
Because of progress in the field of semiconductor technology, vacuum tube amplifiers for electronic musical instruments and audio systems have been replaced by amplifiers based on semiconductor devices, such as transistors. However, tube amplifiers have particular output properties which cannot be reproduced exactly by amplifiers using only semiconductor devices and thus have persistent popularity so that a small number of tube amplifiers are still being produced, sold and used.
The disadvantages of vacuum tubes are well known. They have comparatively short lives, are broken more easily, are less reliable, bigger and more inconvenient to install than corresponding semiconductor devices. They are comparatively heavy, produce more heat and are more expensive than similar semiconductor devices. In many cases amplifiers based on semiconductor devices must be used because the corresponding vacuum tube amplifier is not available.
Many types of amplifiers which mimic to some extent the output properties of tube amplifiers by using semiconductor devices have been devised and used in practice.
However, one output property that can be obtained by using tube amplifiers is the one obtainable under interactive relation when magnetic saturation in an output transformer installed on the backside of a tube amplifier and counter electromotive force generated in a speaker affect the performance of the tube amplifier. Therefore, in the prior art there is a limit to the ability of semiconductor devices to reproduce the output properties of tube amplifiers due to the interactive relation. In fact, no amplifiers which can accurately imitate the output properties of tube amplifiers are known in the prior art.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an output signal converter for tube amplifiers from which output signals of a predetermined power level can be obtained from those of a tube amplifier containing a minimum number of vacuum tubes by converting the output signals of the tube amplifier by means of semiconductor devices while maintaining tube amplifier output properties including transformer and speaker properties obtainable when using tube amplifiers.
According to one embodiment of the invention the output signal converter for a tube amplifier comprises semiconductor devices for amplifying or attenuating an output signal of the tube amplifier while maintaining output properties of the tube amplifier. The output signal converter comprises an output transformer connected to the tube amplifier and having two output terminals; a circuit branch consisting of a current amplifier and a voltage amplifier connected in series with each other via a node, wherein the circuit branch is connected across the output terminals of the output transformer, the current amplifier has a current amplification factor and the voltage amplifier has a voltage amplification factor; and a speaker including two input terminals, wherein one of the input terminals of the speaker is connected to the node between the current amplifier and the voltage amplifier while another of the input terminals of the speaker is connected to ground. Furthermore the current amplification factor of the current amplifier and the voltage amplification factor of the voltage amplifier are related according to the following equation: Ac*Av=−k, wherein k is a constant.
According to another embodiment of the invention the output signal converter for a tube amplifier comprises semiconductor devices for amplifying or attenuating an output signal of the tube amplifier while maintaining output properties of the tube amplifier. The output signal converter comprises an output transformer connected to the tube amplifier and having two output terminals; a loop circuit in which a voltage amplifier, a speaker and a current amplifier are connected in series with each other and with a node between the voltage amplifier and the current amplifier, wherein the node is connected to one of the output terminals of the output transformer, the current amplifier has a current amplification factor and the voltage amplifier has a voltage amplification factor; and wherein another of the output terminals of the output transformer is connected to ground and the current amplification factor of the current amplifier and the voltage amplification factor of the voltage amplifier are related by the following equation: Ac*Av=−k, wherein k is a constant.
According to a further embodiment of the invention the output signal converter for tube amplifier comprises semiconductor devices for amplifying or attenuating an output signal of the tube amplifier to be supplied to a speaker while maintaining output properties of the tube amplifier. The output signal converter comprises an output transformer connected to an output terminal of a tube amplifier and including two output terminals; a first voltage amplifier connected between the output terminals of the output transformer and having an infinite amplification factor; a first impedance circuit; a second voltage amplifier having an infinite amplification factor; a series connecting circuit with a coefficient multiplier; and a second impedance circuit connected in parallel with the first voltage amplifier; and wherein the speaker is connected in parallel to the second voltage amplifier.
The above-described embodiments of the output signal converters according to the invention for a tube amplifier comprise semiconductor devices and amplify or attenuate the output of a tube amplifier containing a minimum number, preferably one, vacuum tube while maintaining tube amplifier output characteristics. In this way the disadvantages of a tube amplifier containing a large number of vacuum tubes, that have comparative short lifetimes, are easily broken and inconvenient to install are avoided, while still maintaining the desirable output characteristics of a vacuum tube amplifier.
REFERENCES:
patent: 4439742 (1984-03-01), Sondermeyer
patent: 4809336 (1989-02-01), Pritchard
patent: 4937874 (1990-06-01), Pittman et al.
patent: 4995084 (1991-02-01), Pritchard
patent: 5032796 (1991-07-01), Tiers et al.
patent: 5131044 (1992-07-01), Brown, Sr. et al.
patent: 5133014 (1992-07-01), Pritchard
patent: 5434536 (1995-07-01), Pritchard
patent: 5524055 (1996-06-01), Sondermeyer
patent: 5619578 (1997-04-01), Sondermeyer et al.
patent: 5636284 (1997-06-01), Prichard
patent: 5668499 (1997-09-01), Albert et al.
patent: 5789689 (1998-08-01), Doidic et al.
patent: 5805713 (1998-09-01), Pritchard
patent: 5909145 (1999-06-01), Zimmerman
Mieda Fumio
Mitoma Hirofumi
Mori Yasuhiko
Korg Inc.
Mottola Steven J.
Striker Michael J.
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