US2062515A - Tremolo device - Google Patents

Description

Dec. 1, 1936. F. A. HoscHKE 2,062,515. TREMOLQA DEVICE Filed Feb. ,26.- 1935 Patented Dec. ,1, 1936 UNITED sTAfTEs PATENT ori-*ICE 2,062,515 TREHOLO DEVICE Frederick A. Holehkc, South Haven, Mich.; Wilhelmina Frederick A. Hoschke,

Hoachke executrlx of ldd appucmon'renmy ze, 193s, serai N0. am

s claim. (ci. isi-21) l disclosed iny my priorA application, Serial No.

'I19,396,.led April 6, 1934, although it can be used in connection with any loud speaker where tremolo effects are desired. i A further object is to provide a tremolo device l which may be operated by the usual organ stop and which consists of 'relatively simple mechanism as compared with other tremolo devices for organs.

A further object is to provide a tremolo device which puts an air load on the cone of the loud speaker so as to make the latter act more like a true piston than it does if the speaker weredelivering into the open air. The means for accomplishing this will be fully disclosed hereinafter. Other objects and advantages will appear in the following specification and the novel features of the invention will be particularly .pointed out in the appended claims.

My invention is illustrated in the accompanyl0 ing drawing forming part of this application, in

which:

.Figure 1 is a sectional view of the apparatus,`

the loud speaker being shown in elevation.

Figure 2 is a view showing a stop which con- 85 trols the circuit of an electric motor, and,

Figure 3 is a fragmentary sectional view showing a modified form of mechanism.

The tremolo device may be located in any suitable position. In practice I prefer to locate it i0 within the container that may be used for the organ bench, the tone being projected forwardly (to the rear of the organist) into the room or hall in which the device is placed. In Fig. 1 a portion ofthe framework of the bench is shown at 4.

.45 Underneath this is a conventional loud speaker 5 having a cone 6, the loud speaker being mounted on a shelf 1. A partition 8 is provided which extends from the member 4 to a bottom member 9 of the framework or housing, and this partition is provided with an opening I0. The front II of the cone fits tightlyagainst the partition 8, the latter being preferably made of some soundabsorbing material, such as cellular wall board.

Centrally disposed with respect to the cone and the opening Il, is a flare-hom I2r In the present instance this flare-hom is shown as a hollow truncated cone. -The interior surface of this cone is roughened, and to this end -I preferably coat the interior of the flare-'horn I2 with glue, A to which is applied coarse sawdust, so as to give 5 the interior of the flare-horn a coating I3, which is rough.

Within the flare-horn is disposed a transverse shaft- I3, which is journaled at its ends in bearings I5 in the sides of the nare-horn, and is pro- 10 vided with a pulley I6 which is rigidly secured thereto. The shaft I4 also bears fan blades I1 which are rigidly secured to the shaft. In the present instance I have shown two blades. Any suitable number may be used. A'belt I8 passes 15 over the pulley I6, thence through openings I9 in the flare-horn, and around the pulley 2l, on an electric motor 2| `carried on the base 9.

Connections 22 and 23 respectively lead from the motor 2| to a. source of current. not shown. 20 The conductor 23, as shown in Fig. 2, is connected to the source of current through the means of a switch S. A conventional organ stop "24 is provided which can be pulled out so as to close the switch and thus complete the circuit 25 through the motor, or to open thev switch,when it is pushed in,` to de-energize the motor.

, A grille cloth 25 is disposed at the larger end of the flare-horn covering an opening 26, while' a smaller grille cloth 21 covers an opening 2l in 30 the rear of the loud speaker.

From the foregoing description ofthe various parts of the device, the operation thereof may be readily understood. When it is desired to produce a tremolo effect the stop 24 is pulled out- 35 wardly, thus closing the circuit to the motor. The latter, through the medium of the belt Il and the pulley I6 revolves the blades Il. 'I'he roughened surface of the interior of the arehorn I2 tends, together with the grille cloth 25, 40 to provide. an air resistance column in front of the loud speaker. With they fan in operation there is a. variation in the pressure or air load on the loud Speaker cone, and this variation of pressure causes an effective tremolo which is 4I made much more effective by the roushe'ning of the interior surface of the flare-horn than if this interior surface were smooth.

My invention contemplatcs the use of a pneumatic motor instead of an electric motor when- 50 it is desired to do 'In Fig. 3, I have shown, diagrammatically, a pneumatic motor at 29, having a supply pipe 30 leading to any suitable source of air pressure, not shown.

used in combination with a bench it will be understood that the tremolo device may be'placed in any suitable position without departing from the spirit of this invention.

I am aware that it is not broadly new to employ a fan for producing a tremolo, but I am not aware of any device heretofore in which a fan is ernployed in connection with a loud speaker where such fan is enclosed in an air column within a flare-horn having its inner surface roughened to increase the air load.

I claim:

1. A tremolo device for loud speakers having a cone, comprising a flare-horn for conducting the sound from the cone, a grille cloth covering one 4 end of said flare-hom, a fan disposed within the nare-horn between the grille cloth and the cone, and means for actuating the fan at will.

2. A tremolo device for loud speakers having a cone, comprising a dare-horn for conductingy the sound from the cone, said are-horn having a rough interior surface, a grille cloth covering one end of said are-horn, a fan disposed within the flare-horn between the grille cloth and the cone, and means for actuating the fan at will.

3. A tremolo device for loud speakers having a cone, comprising a sound absorbing partition having an opening arranged to register with the end of the cone, a flare-horn having one end disposed against said sound absorbing partition, a Vgrille cloth covering t-he opposite end of the flarehorn, a fan disposed within the dare-horn between the grille cloth and the cone, and means for actuating the fan at will.

4. A tremolo device for loud speakers having a cone, comprising a flare-horn for conducting the sound from the cone, said flare-horn having openings in its walls, a grille cloth covering one end of said nare-horn, a fan disposed within the flare-horn between the grille cloth and the cone, a motor disposed outside of the flare-horn, a belt for said motor extending through the openings in the flare-horn, a shaft for rotatably mounting the fan, and a pulley disposed on the shaft and driven by the belt from the motor.

5. A tremolo device for loud speakers having a cone, comprising a flare-horn for conducting the sound from the cone, said flare-horn having openings in its walls, a grille cloth covering one end of said are-horn,:a shaft rotatably mounted, in the walls of the flare-horn and extending therethrough, a fan carried by said shaft within the flare-horn between the grille cloth and the cone, a pulley carried by the Shaft, a belt for said pulley extending through the openings in the flare-horn, an electric motor disposed outside of the flare-horn for driving the belt, electrical connections for actuating the motor including a switch, and an organ stop for opening and closing the switch at will.

FREDERICK A. HOSCHKE.

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