US1981347A - Radiocabinet - Google Patents

Description

Patented Nov. 20, 1934 UNITED STATES 1,981,347 RADIOCABINET Edward T. Dickey, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware 1 Application October 25, 1928, Serial No. 314,876

' Claims. (Cl. 181-31) This invention relates to radio cabinets and especially to cabinets in which loud speakers are to be supported.

At present, radio cabinets which support loud 5 speakers are designed so as to practically completely enclose the supported loud speaker. From the acoustic point of View such a construction is poor for the reason that the enclosed airspace in the rear of the loud speaker has a certain definite resonant period. Becauseof this, certain notes are emphasized more than others which in turn results in a so-called boomy characteristic, especially so at lower audio frequencies. The best way to avoid this boominess would be to mount the loud speaker on a flat board of the proper dimensions having a hole in its center to fit the loud speaker opening. However, from the artistic or decorative point of view this arrangement does not fulfill present day household rem quirements.

Accordingly, an object of this invention is to provide a loud speaker cabinet mounting which will not have resonant air columns to emphasize certain low notes and which will also be beautiful 5; in appearance. Briefly, the manner in which this is done is by mounting the loud speaker on a support having a polyhedronal configuration and having a plurality of open faces. In order to still further improve the acoustic qualities of my loud 9; speaker and cabinet combination, I mount the loud speaker in the cabinet as high as possible without unduly reducing baflle action at the top of the cabinet. This baiile action may be explained as follows:

- Cone type of loud speakers produce alternate compressions and rarefications of the air in front and in back of their diaphragms. Thus when the cone moves forward a compression wave is produced in front of it and a rarefied wave in the rear. For high frequencies, that is, frequencies whose wave length is small compared to the area of the cone, there is little possibility of these two waves annulling each other around the edge of a the cone. In the case of the longer waves produced by the lower audio frequencies, however, there is considerable possibility of the two waves neutralizing each other around the cone edge. To prevent this action it is usual to employ a bafile around the cone whose area is large compared to that of the cone itself. Such bafile board action is obtained by means of the various areas provided by the front and sides of the cabinets described in this application.

I shall now describe my invention in greater detail with the aid of the accompanying drawing in which, I

Figs. 1 and 2 are diagrammatically and in perspective, front and rear elevational views respectively of oneform of my invention; and,

Figs. 3 to 5 inclusive, show in perspective front elevational views of other embodiments of my invention.

Turning to Fig. -1, number 1 indicates a radio cabinet. In the upper part 2, as shown more clearly in Fig. 2, there is mounted by any suitable. means, such as a shelf 3, a loud speaker 4. The upper portion 2 of the cabinet has a polyhedronal configuration and has a plurality of faces left entirely open. More specifically, the polyhedro- (0 nal configuration of Figs. 1 and 2 is prismoidal having the back and top faces removed. The purpose of such removal is, as indicated before, to prevent the formation of resonant air chambers which would inevitably result if the back and top of the upper portion 2 were added to the cabinet l.

A grille 5 may be provided to hide the loud speaker. The receiving set, loop, power supply and the like are preferably mounted in the lower 8ov portion 1 of the cabinet.

In Fig. 3 another form of my invention is shown in which the support for the loud speaker is also of a prismoidal configuration. The oval 6 indicates the opening behind which the loud speaker is to be placed. In this modification the lateral faces 7 are cut away to still further reduce the possibility of resonant air columns. It is to be noted that here also the top of the prismoidal support and the lateral face to the rear of the loud speaker are omitted. To still further improve the support acoustically the portion of the midsection dividing member 12 behind the front face 13 and between the lateral faces 7, may be removed.

In Fig. 4, the polyhedronal support 9 supporting the loud speaker may be a section of either an octagonal or a hexagonal prism.

In Fig. 5, the polyhedronal support 10 supporting the loud speaker and radio apparatus takes the form of a rectangular parallelepiped. As in the other modifications just described, the loud speaker is placed in the upper portion of the cabinet 10 behind the oval opening 11 and as in the other cabinets the top and rear have been removed or rather not provided for, for the purpose of eliminating resonant air spaces. To still lessen the resonant air column objection the midsection dividing member, indicated in Figs. 2,

3 and 4 by the numeral 12 may also be removed. 11

The back and top portions being entirely open, very nearly the same advantages as that of a plain flat baffle board are obtained. This, of course, is also true of the modifications of my invention shown in Figs. 1 to 4, although in the latter modifications, to improve still more the tone qualities of the cabinet the portion of thedividing member 12 behind the speaker support may also be removed.

It is also to be, noted that the sides 10 of Fig. 5 may be hinged to the front at the front corners, so as to make it possible to swing the sides at an angle greater than 90 to the front panel to assist in producing desired acoustic results.

It will thus be seen that I have provided 'a combination loud speaker and radio cabinet which combines the feature of beauty, and, because of the elimination of resonant air chambers and by the advantageous high placing of the loud speaker, the feature of acoustic excellence.

It is to be understood that when I use the expressions polyhedronal, prismoida and similar geometric terms, that such terms are not strictly employed, but that they are rather used to avoid undue surplus of descriptive terms. Strictly speaking the device disclosed herein might also be described as a screen, shield, or bafiie having a front wall and at least two side walls, the latter being hinged if desired to the front wall, the front wall having a loud speaker mounted upon the back of, and adjacent to an opening provided in, the'front wall. However, it will be readily recognized that the reference to a support of polyhedronal configuration provided with an open top and rear face, and having a speaker mounted on the back of the front face adjacent an opening in the.latter is a practically synonymous description.

Having thus described my invention, what I claim is:--

and adjacent the opening in, the front wall.

3. In combination, a baffle wall provided with an opening in proximity to the top edge thereof, two side walls extending from the plane of the baflie wall to the rear thereof, and a loud speaker disposed between the side walls and in registration'with said opening, the space above and to the rear of the speaker being acoustically unconfined.

4. In combination, a bafiie wall provided with an opening in proximity to the top edge thereof, two side walls extending from the plane of the baffle wall to the rear thereof, and a loudspeaker disposed between the side walls and in registration with said opening, the space above and to the rear of the speaker being acoustically unconfined, said side walls being adjustable with respect to said baffle wall.

5. A baflie for acoustic apparatus and the like.

comprising a fiat panel having an opening therein adapted to be placed adjacent the diaphragm of the acoustic device and a plurality of additional bafiie sections hinged to the edges of said flat panel. 7

- EDWARD T. DICKEY.

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