Output signal converter for ampliciation or attenuation of...

Amplifiers – With plural diverse-type amplifying devices

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C330S288000

Reexamination Certificate

active

06229387

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field 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 capable of amplifying or attenuating output signals while maintaining advantageous output properties of tube amplifiers.
2. Prior Art
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the field of semiconductor technology, vacuum tube amplifiers for electronic musical instruments and audio systems have been replaced by amplifiers based on semiconductor devices, such as transistors.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 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 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 a 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. 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 a preferred embodiment of the invention an 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 having an input terminal; a first circuit branch connected between the input terminal and an output terminal of the tube amplifier and a second circuit branch connected to the input terminal of the output transformer and also connected in parallel to the first circuit branch. The second circuit branch includes means for generating an electric current proportional to a current level in the first circuit branch. The first circuit branch and the second circuit branch are located between the tube amplifier and the output transformer and comprise semiconductor devices so that the output signal from the tube amplifier is amplified while maintaining the output properties of the tube amplifier.
In a particularly preferred embodiment of the output signal converter the first circuit branch consists of a first resistance and a first transistor connected in series with each other, the second circuit branch consists of a second resistance and a second transistor connected in series with each other, the first transistor has a base terminal connected to a node between the second resistance and the second transistor and the second transistor has a base terminal connected to a node between the first transistor and the output terminal of the tube amplifier.
In another embodiment similar to the above-described embodiments a third transistor is connected in series between the second resistance and the second transistor and also connected to the base terminal of the first transistor to form a mirror circuit portion together with the first transistor.
In an additional embodiment similar to the above-described embodiments a diode is connected between the second resistance and the second transistor.
Preferably the second resistance is a variable resistance.
According to another preferred embodiment 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, while the tube amplifier comprises a first vacuum tube and a second vacuum tube. The output signal converter comprises an output transformer having a first input terminal and a second input terminal; a first circuit branch connected between the first input terminal and an output terminal of the first vacuum tube; a second circuit branch connected to the first input terminal of the output transformer and in parallel to the first circuit branch and including means for generating an electric current proportional to a current level in the first circuit branch; a third circuit branch connected between the second input terminal of the output transformer and an output terminal of the second vacuum tube; a fourth circuit branch connected to the second input terminal of the output transformer and in parallel to the third circuit branch and including means for generating an electric current proportional to the current level flowing in the first circuit branch; wherein the first circuit branch, the second circuit branch, the third circuit branch and the fourth circuit branch are located between the tube amplifier and the output transformer and comprise semiconductor devices so that the output signal from the tube amplifier is amplified while maintaining the output properties of the tube amplifier.
In a particularly preferred embodiment the first circuit branch consists of a first resistance and a first transistor connected in series with each other, the second circuit branch consists of a second resistance and a second transistor connected in series with each other, the third circuit branch consists of a third resistance and a third transistor connected in series with each other, the fourth circuit branch consists of a fourth resistance and a fourth transistor connected in series with each other, the first transistor has a base terminal connected to a node between the second resistance and the second transistor, the second transistor has a base terminal connected to a node between the first transistor and the output terminal of the first vacuum tube, the third transistor has a base terminal connected to a node between the fourth transistor and the fourth resistance and the fourth transistor has a base terminal connected to a node between the third transistor and the output terminal of the second vacuum tube.
In another embodiment similar to the embodiment described immediately above a fifth transistor is connected between the second resistance and the second transistor and is also connected to the first transistor to form a current mirror circuit portion and a sixth transistor is connected between the fourth resistance and the fourth transistor and is also connected to the third transistor to form another current mirror circuit portion.
In addition embodiment similar to the above-described embodiments a first diode is connected between the second resistance and the second transistor and a second diode is connected between the fourth resistance and the fourth transistor.
Preferably the second resistance and the fourth resistance are each variable.
The above-described embodiments of the output signal converter for a tube amplifier comprise semiconductor devices that amplify or a

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Output signal converter for ampliciation or attenuation of... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Output signal converter for ampliciation or attenuation of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Output signal converter for ampliciation or attenuation of... will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2494697

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.