US1754506A - Sound amplifier - Google Patents

Description

C. C. FLYNN SOUND AMPLIFIER April 15, 1 930.

Filed May 14, 192s JNVENTOR. Ckawes C. Flynn.

ATTORNEY.

Patented Apr. 15, 1930 CHARLES G. FLYNN, OF DETROIT, MICHIGAN scum) mamma Application med May 14,

My invention relates to a new and useful improvement in a sound amplifier or sounding chamber used on various articles such as loud speakers for radios, phonographs, and

so forth.

It is an object of the invention to provide a sound amplifying device of this class in which the sound led thereinto will be deflected and directed at opposite sides of the entry into a plurality of sound conducting cham-V bers so that at op osite sides of the entry there shall be provided a plurality of sound outlets.

lt is another object of the invention to provide reecting and dedecting surfaces in these sound conducting chambers co-ordinated with eachother so that as the sound issues from the various sound conducting chambers a harmonious blending of these sounds will result, accomplishing the4 amplifying desired and effecting an increasing'in volume anda mollifying ofthe tone so that a mellow, soft and smooth tone may result from the use of the amplifying device.

It is another object of the invention to provide a sound amplifying device in which a plurality of sound conducting chambers are so arranged and co-ordinated that a wide range of sound may be clearly andin a material manner transmitted therefrom thus affording 'an amplifying device in which the lower notes of the scale and the high notes will be equally distinct.

Dther objects will appear hereinafter.

The invention consists inthe combination and arrangement of parts hereinafter described and claimed.

'The invention (will be best understood by a reference to the accompanying drawings which form a part of this specification and in which,

Fig. 1 is a central longitudinal horizontal sectional view of the invention with parts broken away.

Fig. 2 is a sectional view taken on line 2-.2

of Fig. l. p

Fig. 3 is a secional view taken on line 3-3 of Fig. 4:.

Fig. 4:, is a fragmentary sectionall view taken on line li-Jl of Fig. 1.

1928. Serial No. 237,467.

lnsound amplifying devices such as those of the folded horn type, the generally accepted theory of design is based on rate of increase in area in values of an exponential equation or combinations ofV exponential curves and straight lines to-allow for rates of expansion along these predetermined lines. For sound amplifying devices basedon the theory of sound vibration lbeing in line with the direction of propagation, the design may be such .G0 that thel sound passages increase in width along dimensions which are plotted as harmonic means between the initial and nal openings as distinguished from harmonic sound passages. G5

In the present invention the rate of increase in width is along the continuous curve from the initial to the inal opening. In this folded type, the first section is initially a complete individual horn with width increasing as harmonic means between the initial and final opening. This section then opens into another section having for its initial opening the outlet opening of the first section and its width progressing from the inlet to the outlet increases in width as harmonic means so that there is virtually provided one horn opening into another.

ln types of` sound amplifiers now in use, the amplifying of both high and low frequencies occur. in the same space and the higher harmonics or chords are lost or smothered b-y interference.' By having one section opening into a pair ofdouble sections, one of a smaller rate of increase of area than the other, te handle the notes of higher frequencies of vibration and the other to take care of notes of lower frequencies of vibration, the interference of the harmonics of higher pitch with the harmonics of lower pitch is reduced toa minimum. 4

l A further reduction of this interference is edected by providing in the larger section a greater space of travel for the sound waves of notes of lower pitch so that the time of travel from the inlet to the outlet inthe amplifying device is variedin the different passages rovided. This also results in a blending o the sounds which produces the mellow mollied effect. The four separate outlet openings of 10@ the amplifier also produces the effect of solidity or depth or of space which cannot be obtained when a single outlet is used. l

The sound amplifier 4illustrated to accomplish these results comprises side walls 7 and 8 which m'ay be made of wood or other suitable material, preferably resonant. Mounted on the inner surface of the walls 7 and 8 at opposite positions are supporting plates 9 and 10. Extending between 'the plates 7 and 8 atthe lower edge and at opposite ends thereof are connecting blocks 11 and 12 which are secured at their opposite ends to the walls 7 and 8. Engaging the edges of the walls 7 and 8 and the upper surface of the blocks 11 and 12 is a cover 13 preferably made from light material such as parchment and the like. Formed in the cover 13 preferably centrally thereof ois an opening 14 extended through which is a collar 15 connected by a screw 16 to passage forming walls 17 and 18. Secured by these passage forming walls 17 and18 at the upper ends thereof are wedges 19 and 20 which extend as shown in Fig. 1 inwardly of the housin formed by the cover 13 and the side walls g and 8 beyond the upper edge of the securing plates 9 and 10. As shown in Fig. 1 the outer faces of these wedge members 19 and 20 lie in planes parallel to each other.

Secured to and engaging at their opposite ends the plates 9 andlO are blocks 21 and 22, the upper edge of these blocks 21 and 22 extending slightly above the lower edges of the wedges 19 and 20. The inner faces of these blocks 21 and 22 are planar surfaces which l engage the edges of the passage forming members 17 and' 18 and extend downwardly below the lower ends thereof. Projecting between and connected to at opposite ends the plates 9 and 10 at, the lower edges thereof is a reflecting block 23 which is spaced as shown in Fig. 3 and Fig. 1 below the lower edges of the passage forming members 17 and 18, the outer face of the block 23 lying flush with the lower ends of the blocks 21 and 22 and the lower edges of the plates 9 and 10. The upper surface of the block 23 is provided with recesses 24 and 25 which are curved from the point 26 which lies in the longitudinal axis of'the'passage formed by the members 17 and 18 and the wedges 19 and 20.

Engaging the surfaces of the plates 9 and 10 is a cover 27' formed from light material such as wood, parchment,and the like. Re- Ataining blocks 28 and 29 engage the outer surface ofthe cover 27 at its lower edge and serve to reinforce the `housing, the ends of the members 28 and 29 being secured at the side walls 7 and 8. A screen 30 is mounted 0n the forward or open side of the housing.

In operation, the sound waves entering the housing through the collar 15 will pass downwardly between the passage Iforming members 17 and 18 and outwardly at the ends thereof being deflected by the recesses 24 and 25 thence upwardly in the passages 31 and 32, these passages progressing in cross sectional area from the inlet to the outlet end. The Sound when reaching'the outlet end of the passages 31 and 32 is-free to pass over the upper edges of the blocks 21 and 22 and outwardly in the passages 33 and 34. It is also free to pass between the edves of the cover forming members 27 and 2 outwardly in the assages 35 and 36.

T ese passages 33 and 34 also progress in cross sectional area, increasing in size from the inlet end to the outlet end, ,the inletend in cross sectional area being equal to the outlet end of the passages 31 and 32 in cross sectional area. The passages 35 and 36 also increase in cross sectional area from the inlet end to the 'outlet end and this increase in cross sectional area is on a predetermined ratio, the increase being along dimensions which may be plotted as harmonic means. In this way the passages outlined herein are produced in a practical working device. Experience has shown that the notes of higher pitch will ordinarily be transmitted outwardly through the passages 33 and 34 and that the notes of lower pitch or of greater wave length will be transmitted outwardly through the passages 35 and 36. The dierence in length of these passages is evident from Fig. 1 and this difference in length compensates for the difference in the length of the sound waves and elfects a harmonious blending of the sounds issuing from the outlet ends of the passages 33, 34, 35, and 36.

' While I have illustrated and described the preferred form of my invention, I do not wish to limit myself to the precise details of structure shown, but desire to avail myself of such variations and modifications as may comewithin the scope of the appended claims. Having thus described my invention what I claim as new andydesire to secure by Letters Patent is: l

1. A sound amplifier of the class described, comprising: a housing having side walls sup-v porting plates mounted on said side walls; a covering for said side walls; a sound passage extending inwardly of said housing, projecting beyond said supporting plates; a pair of coverings, each positioned on said supporting plates at opposite sides of said passage, said supportin plates cooperating with said sound passage or dividing said housing into a plurality of pairs of outlet passages. 2. A sound ampler of the class described, comprisin a housing having side walls; a covering` or said housing; a sound passage projecting inwardly of said housing; supporting plates mounted on the inner surface of each of said side walls projecting laterally pairs of sound conduits .in communication with each other and in communication with said sound passage.

3L A device of the class described, compris- 5 ing: a housing having side walls; a covering for said side walls; a sound passage projecting inwardly yof said housing; supportin plates mounted on the inner surface of sai side walls; partition plates engaging at opposite ends said supporting plates and at their facessaid sound passage; a pair of coverings, each engaging the edges of said supporting plates at opposite sides of said sound passage; cross hars engaging said side walls and the outer surface of said pairs of coverings adjacent the lower edge thereof.

4. A device of the class described, comprising: a housing having side walls; a covering for said side walls; a sound passage projecting inwardly of said housing; supporting plates mounted on the inner surface of said side walls; partition plates engaging at opposite ends said supporting plates and at their faces said sound passage; a pair of coverings,

each engaging the edges of said supporting plates at opposite sides of said sound passage; cross ars engaging said side walls and the outer surface of said pairs of coverings adjacent the lower edge thereof; and a sound reflecting block engaging said supporting plates adjacent the lower edge thereof at the end of said sound passage, said sound pas- `sage communicating around its sides and between said pairs of coverings with a plurality of sets of outlet passages.

In testimony whereof I have signed the foregoing specification.

' CHARLES C. FLYNN.

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