US2029523A

US2029523A - Tone compensated volume control

Info

Publication number: US2029523A
Application number: US743534A
Authority: US
Inventors: Leslie F Curtis
Original assignee: American Bosch Arma Corp
Current assignee: Ambac International Corp
Priority date: 1934-09-11
Filing date: 1934-09-11
Publication date: 1936-02-04
Anticipated expiration: 1953-02-04

Description

Feb. 4, 1936. 1.. F. CURTIS TONE COMPENSATED VOLUME CONTROL Filed Sept. 11, 1934.

- INVENTOR [Ail/f [Cher/5 ATTORNEY Patented Feb. '4, 19 6 2,029,523.

UNITED STATES PATENT OFFICE y 2,029,523 TONE COMPENSATED VOLUME CONTROL Leslie F. Curtis, Springfield, Mass., assignor to United American Bosch Corporation, Springfield, Mass., a corporation of New York Application September 11, 1934, Serial No. 243,534

' 9 Claims. (Cl. 179-1) This invention relates to a volume control for H3 in the cathode circuit, shunted by a bypass radio or allied electrical equipments, and more condenser M. particularly to a tone compensated volume con- As earlier mentioned the human ear does not trol. It is well known that the response of the have a flat response at low volume levels, but

ear to the audio frequency band is not proporfavors the middle audio'frequencies at the extional at different volume levels. The middle pense of the higher and lower frequencies. If frequencies have an apparent response greater an amplifier has a flat frequency response and than that of the lower frequencies at the volume repr u music at the Original Studio Volume level of average home entertainment. To' comlevel, 110 Compensation is needed- The 11511811 10 pensate for this non-linear response, thelower home entertainment level is, however, but afrac- 10 frequencies should be reduced in less degree than tion of the studio level and req bass the remaining frequencies in order to produce an p at on to achieve netllrelism- With a Studio effect of realism at low volume levels. level of 60 decibels at 1,000 cycles which is to Therefore one object of the invention is to be reproduced at a level 35 decibels lower, a 100- provide a tone compensated volume control cycle tone should be reduced only about 17 deci- 5 which reduces the middle and higher frequencies ,bels in order to compensa for the peculiarities proportionately more than the lower frequencies. of the ear, a d t Present/eh effect of realism Hit A u ther object'is to provide a combined volthe lower level. The difierential between the ume and tone control. necessary energy level of the IOU-cycle and the 20 Other objects and advantages will in part be IOOO-cycle tones varies according to the level of 20 stated and in part be apparent when the followreproduction as' contrasted with the original ing specification is read'in connection with the u ie le e T ci cu ShOWn in the drawing drawing in which the figure'is a diagrammatic ay b adjusted to automatically r u t t is representation of the volume control showing it difie n al a e d g t0 the requirements of the applied to an audio circuit. diiferent volume levels. In case the maximum 5.

Referring to the drawing more in detail, the output of the amplifier does not equal the studio numeral I represents a vacuum tube comprising level, the resistance 6 is inserted into the circuit the first audio stage of an amplifier. The tube I and ha a value determin d by h diff rence has in the cathode circuit a biasing resistor 2 between these levels. Thus in most home inwhich is shunted by a bypass condenser 3, The stallations some initial compensation is required 3 plate potential is fed through a plate coupling v t ful V me of the amplifier- With f resistor 4, and a coupling condenser 5 transmits amplifier Volume equal to the Studio level, 0011- audio frequencies to the next amplifier stage. "denser Of and P f 500,000 Ohms, it A fixed resistance 6 is serially connected with the a e f u d that resistanqe 8 should v y p- 85 resistance element R of a volume control popr ximat y nv s ly s h square r t of the tentiometer'P, the other end of the resistance r a ce R" yi below the potentiometer element being grounded. For the sake of clarity ch va at o is ubs a y t e a e a the resistance element R is divided into a secthat in direct proportion to the Square root of tion -R' lying above the movable potentiometer the ratio between the original, and the reduced 40 arm I, and a sectionR" whichhes below the v m v l at 1000 cycles. This may be ex- 40 potentiometer arm. A variable tone control repressed math m t a y as resistance va i a sistance B has an end connected to the coupling 1 condenser 5 and the other end free. Resistance 8 has a slidable contact 9 which is connected to a tone control condenser II) which may be varior resistance 8 varies as 45 able, although the invention will operate successfully with a fixed condenser. A common shaft 29 may control both the arm 1 and contact 9, but it is not essential to obtain the improved perwhere E0 is the greatest available signal voltage formance of the invention. The other side of and Eg is the voltage across the input of tube 50 condenser I0 is connected to the potentiometer I2. If resistance 8 is fixed, the low frequencies arm I. The signal is taken from a point=beare quickly reduced as the volume is initially tween condenser l0 and slidable contact 9 and is lowered, and thereafter they remain constant, led to the input circuit of tube l2 of the second independent of any further volume-level. This audio stage. Tube I! also has a biasing resistor has been the case with prior controls. For re- 55 production in rooms of different acoustic properties, it may be desirable to have the bass compensation adjustable at will. This is readily accomplished by making the condenser III ndependently variable or adjustable, as shown in Fig. l. The resistance 8 under this condition is varied proportionally with the potentiometer resistane R exactly as before.

It will be apparent that many changes and modifications may be made in this invention by any one skilled in the art without departing from the scope and true spirit of the invention as defined in the following claims.

What is claimed is:

audio source, a potentiometer having a resistance connected across said source, a variable resistance connected in series with said source, a slider arm on said potentiometer, a movable contact on said variable resistance, a condenser connected between said slider arm and said movable contact, and an output connection between said condenser and said movable contact.

2. In a compensated volume control circuit, an audio source, a series circuit comprising a fixed resistance and a potentiometer resistance connected across said source, a variable resistance connected in series with said source, a slider arm on said potentiometer, a movable contact on said variable resistance, a condenser connected between said slider arm and said movable contact, and an output connection between said condenser and said movable contact.

3. In a compensated volume control circuit, an audio source, a potentiometer having a resistance connected across said source, a variable resist-,

ance connected in series with said source, a slider arm on said potentiometer, a movable contact on said variable resistance, a variable condenser connected between said slider arm and saidmovable contact, and an output connection between said condenser and said movable contact.

4. In a compensated volume control circuit, an audio source, a series circuit comprising a fixed resistance anda potentiometer resistance connected across said source, a variable resistance connected in series with said source, a slider arm .on said potentiometer, a movable contact on said variable resistance, a variable condenser connected between said slider arm and said movable contact, and an output connection be-' tween said condenser and said movable contact.

5. In a compensated volume control circuit, an audio source, a potentiometer having a resistance connected across said source, a variable resistance connected in series with said source, a sliderarm arm on said potentiometer, a movable contact' on said variable resistance, a mechanical drive connection between said slider arm and said mov- 1. In a compensated volume control circuit, an...

able contact, a variable condenser electrically connected between said slider arm and said movable contact, and an output connection between said condenser and said movable contact.

'7. In a compensated volume control circuit, an audio source, a series circuit comprising a fixed resistance and a potentiometer'resistance connected across said source, a variable resistance connected in series with said source, a slider arm on said potentiometer, a movable contact on said variable resistance, a mechanical drive connection between said slider arm and said movable contact, a condenser electrically connected between said slider arm and saidmovable contact, and an output connection between said condenser and said movable contact.

8. In a compensated volume control circuit, an audio source, a series circuit comprising a fixed resistance and a potentiometer resistance connected across said source, a variable resistance connected in series with said source, a slider arm onsaid potentiometer, a movable contact on said variable resistance, a mechanical drive connection between said slider arm and said movable contact, a variable condenser electrically connected between said slider arm and said movable contact, and an output connection between said condenser and said movable contact.

9. In a compensated volume control circuit, an audio source, a potentiometer-having a resistance connected across said source, a variable resistance connected in series with said source,'a slider arm on said potentiometer, a movable contact on said variable resistance, a mechanical drive connection between said slider arm and said movable contact, a condenser electrically connected between said slider arm and said movable contact, and an output connection between said condenser and said movable contact, whereby said variable resistance increases as said slider arm moves toward low volume position.

LESLIE F. CURTIS.