US3231659A

US3231659A - Volume control device for electric musical instruments

Info

Publication number: US3231659A
Application number: US58235A
Authority: US
Inventors: Mabuchi Shigeaki
Original assignee: NIHON GAKKI SEIZO KK
Current assignee: NIHON GAKKI SEIZO KK
Priority date: 1960-04-06
Filing date: 1960-09-26
Publication date: 1966-01-25
Anticipated expiration: 1983-01-25

Description

Jan. 25, 1966 SHlGEAKl MABUCHI 3,231,659

VOLUME CONTROL DEVICE FOR ELECTRIC MUSICAL INSTRUMENTS Filed Sept. 26, 1960 Source of szynal United States Patent 3,231,659 VOLUME CONTROL DEVICE FOR ELECTRIC MUSICAL INSTRUMENTS Shigeaki Mabuchi, Hamamatsu-shi, Japan, assignor to Nihon Gakki Seizo Kabushiki Kaisha, Hamamatsu-shi, Japan Filed Sept. 26, 1960, Ser. No. 58,235 Claims priority, application Japan, Apr. 6, 1960, 35/20,14'4 2 Claims. (Cl. 84-109) The present invention relates to a volume control device for electric musical instruments.

In prior electric musical instruments, volume control has been effected by means of a variable resistor or an attenuator. However, since the volume of an electric musical instrument is very frequently and quickly changed, the former has short operating life and the latter is disadvantageous in that it is inevitably accompanied by noise because it changes the volume discontinuously. While in some cases variable condensers have been used, they are not suitable for use in electric musical instruments because of their narrow range of volume control.

It is the principal object of the present invention to provide, for electric musical instruments, a long life circuit arrangement for volume control having a Wide range of volume control without the accompaniment of the above-mentioned disadvantages.

Further objects and advantages of the present invention will become apparent, and this invention will be better understood from the following description, taken in connection with the accompanying drawing, in which:

FIG. 1 is a connection diagram showing one embodiment of the present invention;

FIG. 2 shows a block diagram of the embodiment of FIG. 1.

Referring now to the accompanying drawing, more particularly to FIG. 2, an electric circuit utilizing a fixed resistor as an impedance Z, and a fixed condenser as an impedance Z is known in the art as the Millers integrating circuit. According to a feature of the present invention, variable condensers are used as said impedances Z and Z and also said condensers are connected to operate difierentially.

Referring to FIG. 1, let it be assumed that resistances R R and R are sufficiently larger than 1/wC and l/wC and R is approximately equal to R and that the amplification factor of the vacuum tube is sufliciently large. Then, the following relation exists between the input voltage E and the output voltage E Further, let it be assumed that in the case when the capacitance of the condenser C is changed from a value of C to a value of C capacitance of the condenser C differentially changes from a value of C to a value of C 3,231,659 Patented Jan. 25, 1966 ice and that, in a particularly ideal case the values, C =C which means that the sound volume would change in proportion to the square of the change in the capacitance.

Thus, for instance, when a differential condenser which can vary from 10 pi. to pf. is used, the volume will be changed by 100 times (40 db), said range being sufficiently Wide for practical use.

The variable condenser utilized in the present circuit may be a condenser which is formed by slightly modifying a conventional variable condenser, or it may be designed to have small angle of rotation especially suitable for electric musical instruments.

In addition to the above, this invention is also characterized by the fact that the constant of the circuit can be varied in accordance with the frequency sensitivity curve of the ear by suitably selecting the resistances R R and R Thus, it is possible to effect so-called loudness control. Since apparent impedances of various portions are considerably low, it becomes possible to prevent noise from entering by suitable care. It is desirable that the capacitances of the variable condensers utilized in the present circuit be linearly variable.

While the invention has been explained by describing a particular embodiment thereof, it will be apparent that improvements and modifications may be made without departing from the scope of the invention as defined in the appended claims.

What I claim is:

1. A volume controlled amplifier stagefor electronic musical instruments wherein tones are generated by appropriate oscillator and filter circuits, said amplifier stage comprising an electronic valve having a control electrode and a first and a second conductive electrode, an input terminal for applying a generated tone to said control electrode, :an output terminal, means for connecting a load impedance across said first and second conductive electrodes and to said output terminal, a first resistor connected between said input terminal and said control electrode and adapted to apply saidinput signals to said control electrode, a second resist-or connected between said output terminal and said control electrode to feed output signals back to said control electrode, one end of each of said first and second resistors being connected together and to said control electrode, a third resistor connected at one end to the junction of said first and second resistors and said control electrode and at the other end to said second conductive electrode and providing means in which the input signal and the feedback signal combine algebraically, said feedback signal being in phase opposition to said input signal across said third resistor, a first capacitor connected across said first resistor, a second capacitor connected across said second resistor, and means for simultaneously varying the capacitances of said first and second capacitors in opposite directions to modify the relative impedances of the first and second resistorcapacitor combinations to modify the amount of feedback signal applied to said third resistor in relation to the amount of said input signal applied to said third resistor to determine "the amount of cancellati-onof'said input signal and the References Cited by the Examiner UNITED STATES PATENTS 2,106,336 1/1 9318 .Andersonet-a'l. ,330 155 X 2,113,332 4/1938 ,Morseet a1. 330-1 55 2,202,522 5/1940 Gloess ..'3'30-97 X Hammond et a1. 841.26 X Firestone. Beanan et a1. 331-135 Burwen 330107 X Meyer 841.25

OTHER REFERENCES Electronic Ana-log Computers, Kern and Korn, 1952, published by M-cGraW-Hill Book 00., Inc, New York 10 (pages 1211 and 150 relied on).

GEORGE N. WESTBY, Primary Examiner. CARL W. ROBINSON, ARTHUR GAUSS, Examiners.

Claims

1. A VOLUME CONTROLLED AMPLIFIER STAGE FOR ELECTRONIC MUSICAL INSTRUMENTS WHEREIN TONES ARE GENERATED BY APPROPRIATE OSCILLATOR AND FILTER CIRCUITS, SAID AMPLIFIER STAGE COMPRISING AND ELECTRONIC VALVE HAVING A CONTROL ELECTRODE AND A FIRST AND A SECOND CONDUCTIVE ELECTRODE, AN INPUT TERMINAL FOR APPLYING A GENERATED TONE TO SAID CONTROL ELECTRODE, AN OUTPUT TERMINAL, MEANS FOR CONNECTING A LOAD IMPEDANCE ACROSS SAID FIRST AND SECOND CONDUCTIVE ELECTRODES AND TO SAID OUTPUT TERMINAL, A FIRST RESISTOR CONNECTED BETWEEN SAID INPUT TERMINAL AND SAID CONTROL ELECTRODE AND ADAPTED TO APPLY SAID INPUT SIGNALS TO SAID CONTROL ELECTRODE, A SECOND RESISTOR CONNECTED BETWEEN SAID OUTPUT TERMINAL AND SAID CONTROL ELECTRODE TO FEED OUTPUT SIGNALS BACK TO SAID CONTROL ELECTRODE, ONE END OF EACH OF SAID FIRST AND SECOND RESISTORS BEING CONNECTED TOGETHER AND TO SAID CONTROL ELECTRODE, A THIRD RESISTOR CONNECTED AT ONE END TO THE JUNCTION OF SAID FIRST AND SECOND RESISTORS AND SAID CONTROL ELECTRODE AND AT THE OTHER END TO SAID SECOND CONDUCTIVE ELECTRODE AND PROVIDING MEANS IN WHICH THE INPUT SIGNAL AND THE FEEDBACK SIGNAL COMBINE ALGEBRAICALLY, SAID FEEDBACK SIGNAL BEING IN PHASE OPPOSITION TO SAID INPUT SIGNAL ACROSS SAID THIRD RESISTOR, A FIRST CAPACITOR CONNECTED ACROSS SAID FIRST RESISTOR, A SECOND CAPACITOR CONNECTED ACROSS SAID SECOND RESISTOR, AND MEANS FOR SIMULTANEOUSLY VARYING THE CAPACITANCES OF SAID FIRST AND SECOND CAPACITORS IN OPPOSITE DIRECTIONS TO MODIFY THE RELATIVE IMPEDANCES OF THE FIRST AND SECOND RESISTOR-CAPACITOR COMBINATIONS TO MODIFY THE AMOUNT OF FEEDBACK SIGNAL APPLIED TO SAID THIRD RESISTOR IN RELATION TO THE AMOUNT OF SAID INPUT SIGNAL APPLIED TO SAID THIRD RESISTOR TO DETERMINE THE AMOUNT OF CANCELLATION OF SAID INPUT SIGNAL AND THE AMPLITUDE OF SAID OUTPUT SIGNAL AT SAID OUPUT TERMINAL.