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Show lEdlted by G. Douglas Wardrop, Editor of Radio Merchandising.) By PAUL G. WATSON A great many designs of foud-spenk-kig receivers are on the market today, all with metal horns of some form or other. With practically no exceptions, these devices reproduce music and voice with a harsh, metallic sound similar sim-ilar to old models of the phonograph.' j The present models of loud speakers are somewhat smaller in size than the wooden horn here described. They nre designed to be placed on a table or stand, while this wooden horn is of sufficient size to stntid on the floor In I the parlor or places where a finished piece of apparatus Is desirable. .This j horn described will stand from 36 j Inches to 40 Inches high, and requires a floor space about 10 inches square. The reproducer unit Is a Baldwin ! type "C" mica diaphragm telephone. i It Is mounted in the box at the base of the horn, as shown In the cross-sectional drawing of the base. The receiver Lj4 ItM Tfis cW son iJtttr tat J'rrf , ?una ntoa tveotr 3ertw3 fyr mouniny irr cast Mounting of the Telephone Receiver In the Base. unit Is clamped against the top of the base by a wooden strip, held In place by two long wood screws passing through the strip Into the top of the box. Pads of rubber are placed wherever wher-ever the receiver case touches the base. Pieces of an automobile inner tube will serve this purpose. The phone should be mounted firmly, but not tight enough to crack the case. The dimensions of the base are of minor Importance, as long as the base la large enough to keep the horn upright, up-right, a size from nine to ten Inches square being about right for the horn described here. The height of this box, or base, should be about six or seven Inches. Construction of the Horn. The feature hardest to construct Is the bending of the front and back panels at the horn. The proper way tf FRONT XTl r i r8i'i rM j -J U-lj MATERIAL- HARCW00D Shape and Dimensions of the Pieces Needed for the Construction of the Horn. to do this Is to boll the parts to be bent In water for several hours and then bend them over a form, on which they are allowed to dry. Much of the tendency to spring out of shape is eliminated by this method of bending. The cleats shown In the assembly drawing prevent the thin material from bending or warping after It has been put In place. They should be fastened with small brass wood screws and glue. Only cleats necessary for strengthening the horn are shown In 4. The Complete Horn. the drawing. A much neater appearing appear-ing horn can be had by working these cleats Into a system of paneling. To bring out the points where strength I was needed the remainder were omlt- 1 ted. The cleat passing under the front panel, having the short bend, should have Its upper side rounded to fit this bend, and should be glued and screwed , In place. Where cleats are added, they must be on the outside, to give a clear : passage for the sound. The four pieces of the horn are fastened together after bending and ; drying, with small nails and glue. The : joints In the straight section of the hern can be strengthened by the addl- j tion of triangular blocks, glued In the corners. A small brass bracket can be placed under the cleats at the large end of the horn to hold the Joint together to-gether If necessary. The lower end of the horn should be squared off, and Is fastened to the base by four triangular wooden blocks mltered around the lower end of the horn. These blocks should be screwed and glued to the horn, and then fastened to the baseboard base-board In a like manner, making a very rigid joint The remainder of the base Is put together to-gether with round-head screws and has no complicated details, being only a simple wooden box, made of one-half-inch stock, while the bottom or base board Is made of three-quarter-Inch stock. A small hole is drilled In one side for the phone cord to pass, or, if desired, a pair of binding posts can be placed on the top of the base. Gives Clear Reception. I have found this loud speaker to give much clearer reception, when handling strong signals, than any other phone I was able to get. It is particularly desirable to have a clenr phone if voice, such as a radio sermon, ser-mon, is being reproduced, and in this case this loud speaker is fine, for a talk to an audience. The ifinish of the piece can be of any desired color or nature. It Is well to give the inside of the horn several coats of good varnish to produce a clear, smooth surface for the sound to travel over. It might be well to bring out the principle Involved In a loud-speaking receiver or any horn. There is no amplification In the horn. The horn serves as the connecting link between the small volume of air, which vibrates vi-brates with the receiver diaphragm, and tli e outside air of the room. Any increase of sound, which might seem to the layman as amplified in the horn, is only the result of a better connection, connec-tion, through the horn, between the small volume of air in the receiver and that In the room. ( Radio News.) |