US1755931A - Sound-amplifying horn - Google Patents

Description

April 1930- H. cl MUELLER 1,755,931

SOUND AMPLIFIIING' HORN Filed April 8, 1929 INVENTOR.

MM/M

A TTORNEYS Patented Apr. 22, 1930 PATENT OFFICE HERMAN C. MUELLER, OF MILWAUKEE, WISCONSIN SOUND-AMPLIFYING HORN Application filed April 8,

This invention relates to improvements in sound amplifying horns. v

It is the object of the invention to improve the tone quality of sound projected through a 6 horn and particularly through a horn having angularly related portions.

It is a further object of the invention to provide a novel and improved mechanical construction for an amplifying horn adapted 10 to facilitate its assembly while avoiding vibration or rattle such as might influence the sound output thereof.

In the drawings- Figure 1 is a front elevation of a horn em- 15 bodying this invention;

Figure 2 is a side elevation thereof;

Figure 3 is a plan view of the horn;

Figure 4: is an enlarged fragmentary detail in axial section.

Like parts are identified by the same reference characters throughout the several views.

The component parts of the horn comprise a sound reproducing unit 5 to which is connected an elongated tube 6 of gradually in- 25 creasing diameter. An extension 7 of similarly increasing diameter serves as a means,

of connecting the tube 6 to the discharge bell 8 of the horn and also provides a special sound reflector hereinafter to be described.

The tube 6 may be of'any desired construction but is preferably made to conform in an approximate way to the well known proportions of an exponential horn.

The output bell 8 is preferably made of wood and may be rectangular in cross-section as illustrated. It also may be of any desired construction.

The present invention is concerned primarily with the connecting device 7 which is designed for detachable connection with the tube 6 and the output bell 8 of the horn and must be constructed to avoid vibration and rattle, while at the same time providing for the effective and undistorted transmission of sound waves notwithstanding a change of direction which, in the present device, approaches a right angle.

In order to fulfill these requirements, the connecting device 7 comprises two parts 9 and 10 which are desirably so designed as to 1929. Serial No, 353,310.

be divided approximately at the median line of the fitting at the end thereof which clamps about tube 6 but which are of such unequal size that the portion thereof alone provides an anchorage to the output bell 8. The plane of union between the two parts 9 and 10 of the fittings runs out at the side thereof immediately adjacent the connection of fitting 10 with the output bell, as clearly shown in the drawings. j

The component parts 9 and 10 of the fitting are provided with complementary bosses at 11 and 12 and at 13 and 14, such bosses being bolted together to clamp the parts 9 and 10 of the fitting upon a suitable gasket 15 which may comprise a cord or a strip of rubber or any other well known yieldable gasket material for maintaining the parts 9 and 10 out of contact while permitting them to be clamped comparatively firmly together.

A flange 16 extending peripherally about the top and sides of the part 10 of the fitting is apertured to receive screws 17 whereby part 10 is screwed to the wooden bell 8 of the horn. t

One of the principal features of the invention consists in the formationof the fitting 7 to provide for proper reflection of sound waves from tube 6 into the hell 8. It is well known that irregularities or recesses out of the path of the sound waves traversing a horn tend to produce abnormalities and distortions in the tone thereof both by reason of their possible resonance and alsoby reason of their interference with the proper development of thesound waves in traversing the horn. Notwithstanding this knowledge, however, ithas been customary heretofore to provide either a plane or a concave surface for the reflection of sound waves at an angle in a horn in which such waves are propagated.

The present invention seeks to eliminate distortion resulting from the practices referred to by providing a convex reflecting surface which is preferably so designed as to offer very little interruption to the uniform propagation of sound waves. In attaining this objective, the convexity and position of the reflecting surface in the angle between the portions 6 and 8 of the horn are preferably so chosen that waves incident upon the reflecting surface along lines approximately parallel and adjacent to the divergent side margins of tube 6 will be reflected along lines immediately adjacent to and parallel with the sides of the bell 8. In other Words, the convexity of surface 20 is determined with reference to the divergence of the opposite sides of tube 6 and also with reference to the divergence of the walls of the mouth-piece 8. The posit-ion of the reflecting surface ZO'at the angle between the component parts of the her is preferably such that a linenormal the center of the reflecting surface will xubstantially bisect the angle between the axes of the angularly relat portions of the horn.

The fitting 7 and reflecting surface 20 thereof may be made of any desired materials but it has beenfound perfectly satisfactory to make these parts of castmetal, such as aluminum or the like, the weight of the metal preferably being such that its naturalperiod of vibration, if any, will not reinforce any audible frequencies.

In the drawings I have shown diagrammatically by means of. three lines traversing the component portions Band 8 of the horn how sound waves traveling along such lines will be'reflected at an angle equal to their angle of incidence upon surface 20 and will therebybe delivered from the horn without material interference or obstruction tending to produce distortion.

It will be obvious that due to the increased angularity between the walls of horn portion 8 as. compared withthe elongated portion 6 thereof,-sound waves would not be uniformly propagated in the bell portion but for the convex reflecting surface at 20. If the reflecting surface were concave, as is customarily the case in horns of this general type, the resultwould be the crossing of the lines representing the reflected sound waves with a re sultant series of oblique reflections from the wall of the bell 8 destroying uniformly of propagationand resulting in a confused and distorted emission of sound fromthe bell.

I claim:

1. In a horn having angularly related portions, the. combinationwith said portions of a sound reflector positioned in the angle at the juncture of said portiens, the area of said reflector being greater than that of a cross section of one of the portions and angularly disposed to intercept substantially all portions of a sound wave propagated through said portion and to reflect said sound wave into the other of said portions substantially symmetrically with reference to the axis thereof.

2. In a horn, the combination of a plurality of angularly related portions and a reflector angularly positioned in the unction between two said port-ions whereby the axes of said portions intersect substantially at the surface of said reflector and at substantially equal angles with respect to a line normal to the surface of said reflector at the point of intersection of said axes.

3. In a horn, the combination of two angularly related portions and a reflector positioned in the angle between said portions and provided with a surface contour such that divergent lines paralleling the sides of one of said portions and corresponding divergentlines parallelingthe sides of the other of said ortions will respectively intersect substantially at the surface of said reflector and at substantially equal angles to a line drawn normalto said surface at each point of intersectioir, 7

l/In a horn, the combination with .two

angularly related portions, of a convex re flectordisposed .in the angle between said portions:

5;In a horn, the combination with two angularly related portions, of a convex reflector disposed inlthe angle between said portions, the sides of one of said portions being more widely divergent than the sides of the other and the convexity of said reflector being an-v gularly disposed to reflect sound waves propagated in said last mentioned portion into the portion having more widelydlvergent sides for substantially uniform. and undis gularly relatedportions,of a convex reflector disposed inthe angle betweensaid portions in a positionito reflect axially ofone of said portions asoundwave propagatedaxially of the. other, one. of said horn portions'being provided with sides more rapidly divergent thanthe other of said horn portions and the convexityof the reflecting surface therebetween reflecting the soundwaves between said portions for propagation substantially uniform in accordance with/the divergence'of thesides ofthe horn portion into which sound waves are reflected.

8. In adevice of the character described,

the combination-with a horn portion having sides of relatively low divergence, and a second horn portion substantially at right angles to the: first and having sides of relatively greater divergence, of, a convex'refiector .disposed 1n the angle between said horn portions, having an extent substantially adequate to receive all portions of the sound wave propagated ineither of saidportions and to r so lid

reflect said sound Wave into the other of said portions, the convexity of said reflector being so determined that lines representing the included angle between the sides of one of said horn portions and lines representing the included angle between the sides of the other of said horn portions approximately intersect at the surface of said reflector and at like angles to imaginary lines drawn normal to said surface at the point of intersection.

9. In a device of the character described, the combination with a horn passage member and a bell angularly related to each other, of a connecting fitting rigidly anchored to said bell and provided with an adjustable portion in clamping engagement With said horn member.

10. In a device of the character described, the combination with a horn passage member and a bell angularly related to each other, of a connecting fitting rigidly anchored to said bell and provided with an adjustable portion in clamping engagement with said horn member, said fitting including a convex reflector in the angle between said horn memher and bell and substantially symmetrical with reference to the axes thereof.

11. In a device of the character described, the combination with a horn member and bell, of a fitting uniting said member and bell substantially at right angles and comprising a casing anchored at its margin to said bell and having an angularly related arm divided on an obliquely disposed plane r and provided with clamping means for pressing its component parts upon said member, sald plane intersecting the axls of sald arm substantially at its point of clamping engagement with said member and running thence laterally toward the point of engagement of said fitting with said bell.

12. In a device of the character described,

the combination with a horn member and a.

bell, of a fitting angularly connecting said horn member and bell and comprising a first part extending approximately 180 about said member and secured to said bell, and a second part extending approximately 180 about said member and abutting said first a part upon a plane oblique to the axis thereof and terminating adjacent the point of connection of the first part with said bell, said first part providing a convex reflector symmetrically disposed about a point substan- 5 tially at the intersection of the axes of said member and bell.

HERMAN G. MUELLER.

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