US1768226A - Sound amplification - Google Patents

Description

June 24, 1930. w s 1,768,226

UND AMPLIFICAT Patented June 24, 1930 U ITED STATES PATENT OFFICE SELDEN '1. WILLIAMS, OF WOODBURY, NEW JERSEY, ASSIGNOR TO VICTOR TALKII ING MACHINE COMPANY, A CORPORATION OF NEW JERSEY SOUND AMPLIFICATIOE" Application filed February 12, 1927. Serial No 167,785.

This invention relates to sound amplifica- I tion, and more particularly to a novel sound amplifier and manner of constructing the same.

It is an object of this invention to provide a novel sound amplifier. which will enable the radiation of large quantities of sound energy without overloading and without substantial distortion.

desired extent.

Another object of this invention is to rovide anovel sound amplifier compose of a plurality of units to the end that the energy handled may be multiplied and the composite amplifier still conform to a basic design and predetermined low-frequency Another object of this invention is to provide a sound amplifier adapted to handle relatively large quantities of sound energy and having a relatively large outlet area and which at the same time is convenient to construct, transport and install.

Another object of this invention is to provide a method of amplifying sound and of producing sound amplifiers whereby large quantities of sound energy may be handled without overloading and without substantial distortion, whereby a predetermined low-frequency cut-off and a predetermined basic design may be maintained while shortening the overall length of the amplifier "and with or Without the use of a plurality of sources of sound, and whereby the construction, transportation and installation of the amplifier may be facilitated, particularly when it is designed to handle sound energy from a plurality of sources and have a relatively large mouth area cortrating other embodiments of the responding with a relatively low-frequency cut-off.

Other objects pertaining both to the amplifier and the method of constructing and using the same will appear from the description. of the invention. I

The invention is capable of being carried out 1n a variety of,.ways and of being embodled in a variety of mechanical constructions, some of which are shown on the accompanying drawings, but it is to be ex pressly understood that the. drawings are for purposes of illustration only, and are not to be construed as a definition of the limits of the invention, reference being had to the appended claims for that purpose.

Referring in detail to the drawings, wherein the same reference'characters are employed to designate corresponding parts in the several figures, r

Fig. 1 is a diagrammatic view to illustrate apredeter'mined basic horn design;

Fig. 2 is a schematic View illustrating the use of a plurality of sources of sound with a retention'of the basic design of Fig. 1;

Fig. 3 is a perspective view of a multiple unit horn embodying the present invention; Fig. 4 is a diagrammatic view ofanother embodiment of the present invention; and

Figs. 5 and 6 are schematic views illusinvention.

The present invention is capable of embodiment in conjunction with sound amplifiers of any desired design and while, for

purposes of illustration, a basic design which flares or tapers in accordance with an exponential equation has been selected, it is to be expressly understood that the invention is not restricted thereto, as it is equally applicable to any other basic design whether the change in cross section conformswith a straight line or a curved line function, and whether it be uniform or variable in character, and whether the horn be straight, curved, reentrant or otherwise. Consider a basic design of the character dia rammatically illustrated in Fig. 1 and let its equation, for purposes of illustration, be assumed to be present.

J! section (3-;

om the the end, and

1 he design sound ampli "e, and there the per'rormance acoustic charac-ze cs or the amplifier,

e detcy ined by ove aquatic ii "and desired. cutcns it becomes apicng'fi e: 1e amp er forms chara Jeiistics, because the performance 1 acteristics of the amplifier de upon the rate of flare as ab e indicated, and the low-frequency cut-oil is determined by the area at the outlet or mouth end of the amplifier. Therefore the amo ifier may be shortened by cutting oil the in section L Withoutv in any respect modif;v ng the performance and characteristics of the amplifier or its low-frequency cut-off.

it is frequently desirable to increase the quantity of sound energy handled, and experience has demonstrated that there is fairly definite optimum size of sound box, electrical sound receiver, or other sound producing unit, Which may be satisfactorily used, because with the increase in the size of such. sound producing units, there is an in crease in the mass and inertia effects, which produce distort-ion. On the other hand, any given unit can handle onlya given maximum amount of mechanical or electrical energy Without producing the consequences of overloading. The present invention enables the use of a plurality of sound producing units so as to multiply the sound energy to be handled, each unit being supplied with only so much energy as it can handle properly Without overloading, and each unit being of a size and design so that it can produce the desired sound Without substantial distortion, and at the same time adherence to the desired low-frequency cut-ofi' and acoustic characteristics and performance of the predetermined basic design. By taking advantage of the principles above discussed, this is effected, not only to enable the use of a plurality of sound producing units without modification of the basic design or the low-frequency cut-off, but also to effect a shortening of the overall length of the .basic design and facilitate the construction, transportation and installation of the amplifier.

Referring to Fig. 2 and takin as the simplest example the doubling of t e sound,

dance of the sound bor;

ons o t e cross sctnon at rea o; eacl Q home /e amplifier i, i. e.

This inlet area is therefore improper to balance the impedance of the sound producn f u it conformity With the present invention the amplifiers 2 and 3 are shortened to such a point that the area 1 in the basic design equal to 2 A Therefore each of the two horns, 2 and 3, is provided with an inlet area, i whereby its impedance is properly balanced with the impedance of the sound producing unit, and at the same time the low-frequency cut-off and the performance and characteristics or the combined two amplifiers Q and 3 are retained the same as those of the basic horn 1. Therefore the sound energy handled has been doubled and the overall length of the amplifier has been decreased Without changing the performance and characteristics or the low-frequency cutoff selected for the basic design employing a single sound producing unit.

The same principles may be employed in conjunction with any suitable multiplication of the sound energy to be handled. Thus let at equal the multiple by which the sound energy from a selected sound producing unit is to be multiplied, any given basic design having a given low-frequency cutoflt' may be retained and the amplifier may be divided into n units each of Which has an outlet area equal to the outlet area of the basic design divided by a, and each having a cross section at any point equal to the cross section at the corresponding point in the basic design divided by a, but each having a sound inlet equal to the sound inlet of the basic design. The condition to be obtained is that the sum of the cross sectional areas of the separate units at any point shall equal the cross sectional area of the basic design at the corresponding point, Whatever may be the number of units or the relative sizes of the individual units. Therefore, it will be perceived that the separate units may be of equal fractional parts of the basic design, or may be of unequal providing the aforesaid condition be maintained.

At the same time, the overall length of the multiple unit amplifier is decreased by that length of the basic design extending between its inlet and that cross section of the basic design where its area is equal to n times the area of the inlet section ofthe basic design, or between its inlet and that cross section of the basic design where the area of the latter is equal to the sum of the inlet areas of the separate units. The larger the number n, the shorter is the amplifier,

but whatever isthe number n or the relative cut-off of the basic design, while the sound i energy handled is n times the energy of the single unit. As this enables each unit to be used without increasing the .mechanical or electrical energy supplied thereto, there is no overloading, and as there is no increase in the size of the unit, the unit can be made of such size and design as to minimize the effects of mass and inertia action in tending to distortion. Therefore the present invention enables thehandling of any desired quantity of sound energy without overloading or substantial distortion and .at the same time the multiple sections of the amplifier taken together function the same and have the same low-frequency cut-offas the desired basic design. Y The subdivision of the amplifier into a plurality of units inconformity with the present invention furthermore possesses the advantage that each of said units maybe separately constructed, transported and installed, and this is of relatively great importance when it is desired to have the lowfrequency cut-ofl' relatively low, because the area of the mouth or outlet cross section increases rapidly as the low-frequency cutoff is decreased. Thus a low-frequency cutoff at forty cycles should have a mouth area on the order of 5,630 square inches, or an outlet more than six and one-half feet. square. In conformity withthe present in: vention this amplifier, as illustrated inFig. 3, maybe composed of nine sections 4, for example, each having a mouth "twenty-five inches square, and thereby obtain the lowf'requency cut-off at forty c cles, as well as the desired performance an characteristics, while handling nine times as-much energy and, at the same time, greatly decreasing the overall length of the amplifier.

The present invention may in amplifiers of a wide variety of constructions and using a wide variety of arrangebe embodied ments of sections as well as numbers of sections. For example, an amplifier composed of two sections 5 each of the reentrant type is ;shown in Fig. 4. In Fig. 5 the amplifier is shown as composed of eight secmon plane as shown in Figs. 3 and 4, or in a common curved surface as shown in Figs. 5 and 6. Where the mouths of the sections are not immediately contiguous,the intervening spaces should be closed by bafiles 8, as illustrated in Fig. 5.

While it is preferred to employ the-entire number of sections designed as heretofore described, the present invention also affords some flexibility in permitting a variation in the number of sections used. So long as the number of sections used as compared with the designed number of sections does not vary by a greater ratio than two to three, the number of sections used and therefore the quantity of sound energy handled may disclosed. If it were desired to reduce the 7 energy handled to five-ninths, however, so that only five of the sections would be employed, a supplemental mouth section should be'added to the! multiple uni-t amplifier,-

To provide said supplemental mouth section having an inlet equal to the combined areas: of the mouths of the sections used and having an outlet equal to the outlet of the basic horn design as determined by the low-frequency cut-oil. This supplemental mouth-piece will then supplement the sections used so that the amplifier as a whole will have the performance and" characteristics of the basic design.

It will be observed that, in-conformity with the present invention, each of the sections of which the amplifier is composed is by itself incapable of having the characteristics, performance and low-frequency cut off of the basic design. If the design ofeach section should be superimposed upon the basic design, its inlet section would extend to the left of A (as viewed in Fig. 1) to that point in the design projected where the cross section contracts to where n is the number of units employed, or where the desired inlet area for any given section is reached. lit the same time its outlet would fall to the left of the outlet of the basic design (as viewed in Fig. l) at that point where the cross section of the basic design is equal to or the proper fractional portion of the outlet of the basic design selected for that section. Each section, thereiore, as compared with the basic design, corresponds with a section adjacent the inlet end of the basic design, and the greater is a the shorter is the section of the basic design used for each section. in case the individual units are of unequal size, the cross section of their inlets may vary either above or below with the result that the design of the individual section would have to be shifted either to the right or to the left respectively in order to be superimposed upon the basic design.

It will therefore be perceived that a novel amplifier and manner oi constructing the same have been provided whereby the quantity of sound energy to be handled may be multiplied to any desired extent without overloading and without substantial distortion. At the same time this is effected while adhering to the desired low irequency cutoff and the predetermined characteristics and performance of the basic design. Therefore a multiple unit amplifier has been provided which, as a whole, conforms in its ,characteristics, performance and low-ire quency cut-off to the basic design for a single sound producing unit, while the sound energy handled may be multiplied to any desired extent without overloading or substantial distortion. In addition, the present invention possesses the further advantages that its application enables the sound amplifier to be decreased in length to any desired extent and at the same time divided up into a plurality of units which are easy to construct, transport and assemble, but which, when combined, assure the desired performance and characteristics of the basic amplifier design.

The present invention also affords some flexibility in varying the quantity of sound energy handled by varying the number of units employed, and also provides for the use of any desired number of units when a supplemental mouth section is employed.

Nhile the invention has been described as employing a plurality of sound producing units of the same size and character as that intended for use with the basic design, this is not essential, as the present invention enables the use of a plurality of smaller units, in which event the sound energy handled will be less than that of the capacity of the unit corresponding to the basic design multiplied by the number of units employed. Also larger units may be employed and the advantages of the present invention obtained without the use of many amplifier sections. It is also to be expressly understood that any suitable sound producing units may be used in conjunction with the present invention, although the invention lends itself particularly to the use of a plurality of electrical receivers or loud speaking units where the quantities of sound energy desired to be handled are relatively great.

Vhile certain applications and embodiments of the invention have been described with considerable particularity, it is to be e zpressly understood that the invention is not restricted thereto as the same is capable of other applications and exemplification in other constructions without departing from the spirit of this invention. Reference is therefore to be had to the claims hereto appended for a definition of said invention,

What is claimed is:

1. The method 01": multiplying the sound energy adapted to be handled by a predetermined basic amplifier design which consists in multiplying the number of sound producing units employed to the number required to obtain the desired energy without overloading of the individual units and amplifying the sound produced by each unit by an amplifier-section the cross sectional area of which throughout its length corresponds with the cross sectional areas of a section of equal length adjacent the inlet end of the basic design and the inlet area of which is determined by the outlet of said unit.

2. The method of multiplying the sound energy adapted to be handled by a predetermined basic amplifier design which consists in multiplying the number of sound producing units employed and amplifying the sound produced by each unit by an amplifier-section the inlet of which is equal to the inlet of the basic design and the outlet of which is equal to the area of the outlet of the basic design divided by the number of sound producing units employed.

3. The method of multiplying the sound energy adapted to be handled by a predetermined basic amplifier design which consists in multiplying the number of sound producing units employed and amplifying the sound produced by each unit by an amplifier-section the inlet of which is equal to the inlet of the basic design and the outlet of which is equal to the area of some inter mediate section of the basic design.

4. The method of multiplying the sound energy adapted to be handled by a predeproducing units employed and amplifying termined basicamplifier design which consists in multiplying the number of sound the sound produced by each unit by an amplifier-section the inlet of which is greater than the area of the inlet of the basic design divided by the number of sections employed and the outlet of which is equal to the area of some intermediate section of the basic design.

5. The method of constructing a multiple unit amplifier to conform with the characof which is equal to the area of some inter includes providing a plurality of units the v teristics of a basic amplifier design which includes providing a plurality of amplifier units the inlet of each of which is equal to the inlet of the basic design and the outlet mediate section of the basic design.

6. The method of constructing a multiple inlet of each of which is greater than the area ofthe inlet of the basic design divided by the number of units employed and the outlet 'of which is equal to the area of some intermediate section of the basic design. I

8. The method of constructing a multiple unit amplifier to conform with the characteristics of a basic amplifier design which includes providing a plurality ofv units including units of difi'erent cross sectional size tion of the basic design and each of which corresponds with a seeadjacent the inlet end thereof. i

9. The method of constructing a multiple unit amplifier to conform with the characteristics of a basic amplifier design which includes providing a plurality of units including units of different cross sectional slze and each of which corresponds throughout its length with a fractional length of the basic design.

10. The method of amplifying relatively large quantities of sound energy in, accordance with the characteristics of a basic am plifier design which consistsin providing a plurality of sound producing units including units of different size and amplifying the sound from each of said units by an amplifier-section the crosssection of which throughout its length corresponds with a fraction of the corresponding cross sections of an e ual length of the basicdesign.

" 11. Tie. method of amplifyingrelatively large quantities of Sound "energy 111 accordance with the characteristics of a basic amplifier design which consists inproviding a plurality 0 sound producing units and amplifymg the sound from each of said units y an amplifier-section which has an inlet equal to the inlet'of the basic design and an outlet equal to the area of some intermediate section of the basic design.

12. The method of amplifying relatively large quantities ,of sound energy in accordance with the characteristics of a basic amplifier design which consists in providing a plurality of sound producing units and amplifying, the sound from each of said units by an amplifier-section which has an inlet section equal to the inlet section of the basic design and an outlet section equal to the area of the outlet section of the basic design divided by the number of sections employed.

13. The method of,amplifyi'ng relatively large quantities of sound energy in accordance with the characteristics of a basic amplifier design which consists in providing a plurality of sound producing units and amplifying the sound from each of said units by an amplifier-section which has an inlet section greater than the area of the inlet section of the basic design divided by the number of sections employed and an outlet section. a

equal to the area of some intermediate section of the basic design. 7 v

14. A method of constructing a multiple unit sound amplifier in conformity .with a basic design which consists in constructing each unit of the amplifier so as to have ,an inlet equal tcT the inlet of the basic design and an outlet equal to some intermediate sec tion of the basic design.

15. A method of constructing a multiple unit sound amplifier in conformity with a basic design which consists in constructing each unit of the amplifier so as to have an inlet equal to the inlet of the basic design and an outlet equal to the area of the outlet of the basic design divided by the number of units employed. I

.16. A method of constructing a multiple unit amplifier in conformity with a basic desi n which c onsistsin constructing each unit 0 the amplifier so as to conform with a section at the inlet end of the basic design.

17. The method ofamplifyingv relatively large quantities of sound energy inconformity with a basic amplifier design which consists in providing a plurality of sound producing units, providing each unit with an amplifier whose inlet corresponds with the size of the sound producing unit and whose .outlet corresponds with the area of the outlet of the basic design divided by. the number of units employed, and varying the number of sound producing and amplifying units in accordance with the quantity of sound energy to be handled.-

18. The method ofamplifying relatively large quantities of sound energy in con tormity with a basic amplifier design which consists in providing a plurality of sound producing units, providing each unit with an amplifier whose inlet corresponds with the size of the sound producing unit and whose outlet corresponds with the area of the outlet of the basic design divided by the number of units employed, varying the number of sound producing and amplifying" units in accordance with the quantity of sound energy to be handled, and supplementing the units employed with an amplifying mouth section whose outlet substantially corresponds with the outlet of the basic design.

19. A multiple unit amplifier adapted to have the characteristics of a basic amplifier design, said amplifier being composed of a plurality of sections the sum of the cross sections of which at any point in their length is equal to the cross section or" the basic design and the inlet of each of said sections being equal to the inlet or" the basic design. 7

20. multiple unit amplifier adapted to have the characteristics of a basic amplifier design, said amplifier being composed of a plurality of sections each of which corresponds with an intermediate section of the basic design and a supplemental mouthpiece whose inlet is equal to the sum of the outlets or" said sections and whose rate of flare tol lows said basic design.

21. A multiple unit amplifier adapted to have the characteristics of a basic amplifier design, said amplifier being composed of a plurality of sections each of which has cross sections throughout its length conforming to the cross sections of a corresponding length at the inlet of the basic design.

22. A multiple unit amplifier adapted to have the characteristics of a basic amplifier design, said amplifier being composed of a plurality of sections each of which has an inlet equal to the inlet or" the basic design and an outlet equal to the area of some cross section intermediate the length of the basic design.

23. multiple unit amplifier adapted to have the characteristics of a basic amplifier design, said amplifier being composed of a plurality of sections each of which has an inlet greater than the area of the inlet of the basic design divided-by the number of sections employed and an outlet equal to the area of the outlet of the basic design divided by the number of sections employed.

In testimony whereof I have signed this specification.

SELDEN T. WILLIAMS.

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