US1809314A - Sound amplifying device - Google Patents

Description

June 9, 1931. Q E, oss

SOUND AMPLIFYING DEVICE Filed May 21, 1928 Carmen E. Ross.

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Aff'orne Patented June 9, 1931 UNITED STATES PATENT OFFICE CARMEN E. ROSS, OF VANCOUVER, BRITISH COLUMBIA, CANADA, ASSIGNOR TO W. WYLLIE JOHNSTON, TRUSTEE, OF VANCOUVER, CANADA SOUND AMPLIFYING DEVICE A plication filed May 21, 1928, Serial No. 279,476, and in Canada March 28, 1928.

This invention relates to sound amplifying devices, such as are used in connection with radio apparatus as loud speakers, or with phonographs and the like, for increasing and concentrating the sound whilst retaining the original clarity and distinctiveness of the tone values.

The primary object of the invention is to provide a device of this character which will transmit and amplify sonorous vibrations over a wide range of scale without confusion or impairment of their tonal characteristics.

I effect this by utilizing a tube having a gradually increasing cross sectional area proportioned in reference to its length and the size of its apertures on well known acoustic principles. This I curve (over a portion of its length) into a convenient volute form in a plane which is substantially right-angular to the axis of its bell-mounted outlet, the en tire tube or tubular cavity as the case may be being embedded in or encased by some suitable solid medium.

By this construction the direction of the impulse of the sound waves in one portion of the device is right-angular to the same in another part and possibly secondary vibrational effects which might be set upwithin the body of the enclosing material are neutralized, thus effecting or maintaining the clarity of tone obtained by my device.

A preferred embodiment of my device is shown in the drawings herewith forming a part of this application, in which:

Fig. 1 is a vertical section through the centre line of the bell-mouthed aperture shown in Fig. 3. V

Fig. 2 is an end view of Fig. 1.

Fig. 3 is a plan.

Fig. 4 is a section on line A-A of Fig. 1 looking in the direction of the right hand arrow points.

Fig. 5 is a section on line BB of Fig. 1.

Fig. 6 is a section on line A-A of Fig. 1 looking in the direction of the left hand arrow points.

In these drawings it will be observed that the device is by preference, formed in and by a solid wood block, say of pine or spruce, which for convenience is divided into three sections 7 8, 9 to facilitate the carving of the internal tubular passage.

These sections 7 8, 9 are dowelled together and finally glued so as to effect substantially a solid block. The intake aperture 10 is adapted to receive or be connected to the usual microphone unit or other device providing the initial sonorous vibrations from a pulsatingr diaphragm.

he tube 11 leading from the aperture 10 is continued to form the convolution terminatin at 12 where its direction makes a curving right-angular change as shown at 13 through sections 8 towards section 7 where it turns upwardly at 14 and thence by a third rounded bend through another rightangular turn into the trumpet-shaped portion 15 to the flared exit aperture at 16.

In operation the sound. impulses enter at 10 pass around the volute 11 changing their direction by three right-angular turns into the trumpet-shaped exit at 16. These curved but otherwise abrupt turns in the tubular path produce a resonance efiect which adds to the amplifying qualities of the tube, their external vibrational efi'ects being absorbed by the surrounding wood block and any directional effect being neutralized by the right-angular flow of their transmission.

Having now particularly described my in- Vention, what I claim as new and desire to be protected in by Letters Patent, is:

A sound amplifying device comprising a series of three corresponding and adjacent rectangular blocks, one surface of the middle block in said series and the adjacent surface of the outer block of said series being channeled in convolutionary form whereby a tubular cavity of circular cross section is formed by the combination of the two blocks, the extremities of said tubular cavity being connected with surface apertures in the said blocks and in planes which are right-angular to each other, central and correspondingly connected apertures transversely of said. convolutionary cavity in both said blocks, the other surface of the said middle block and that of the other outer block adjacent thereto being similarly channeled to connect the said central aperture and one of the said extremities, whereby a continuous tapered tubular cavity is produced Within the said three blocks, the said oavity'being so formed that a convolution around a straight portion is obtained.

In testimony whereof I aflix my signature.

CARMEN E. BOSS.

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