Improving Small Cone Speakers.

Radio Record, Volume II, Issue 10, 21 September 1928, Page 29

Improving Small Cone Speakers.

"THE following method of improving cone speakers of small size is taken from "Radio News," and will doubtless interest many owners of such speakers. "In this day of high-quality broadcasting, the listener using a speaker

that does not reproduce the entire musical scale, or nearly so, is missing a great part of the joys of radio. The broadcasting stations have improved the quality of their transmitters, and radio reproduction is excellent-provid-ing the receiver and reproducer are of the proper design. "The large cone speaker is capable of ] }eproduction of the highest order. and when driven by a good radio receiver, _ will please the most critical. The users of the thousands of small, free-edge cone speakers sold during the past two years will be interested in learning of a simple, inexpensive way to transform these speakers into reproducing mediums that will compare very favourably with any of the speakers recently placed on the. market.

"mhe drawing will serve to show the constructional details of the small cone speakers referred to, all of them being constructéd in this". manner, or one similar. In all instances, the paper cone is as large as permissible, extending down to the base of the speaker. At first thought it would seem the cone could not be made larger, because of this fact. However, by using a cone of the eccentric type, this obstacle can be overcome. With the. peculiar shape of the eccentric cone, it need not bé. as large as. the usual circular cone to achieve the same result from a musical standpoint. "In the table below the dimensions for any desired size of cone are given. As the "short" side of the cone can extend down only to the base of the speaker, the cone conforming to this limitation should, be chosen. For best results, the cone should be constructed of the special paper made for this purpose. However, any paper heavy enough to be self-supporting will serve quite well. "lhe naner should be spread out on

a smooth surface, and secured by a tack in each corner. The circular outline ‘D’ is then drawn with a pencil, using a piece of string as the compass. The circle ‘HE’ is scratched on the surface of the paper, using a large bluntpointed nail as the scratching tool. — This line must be scratched quite deep: care being taken to see that the paper is not cut through, however. The paper is glued together along lines ‘A’ and ‘B,’ and the outer edge of the resulting cone is then bent back to about a 45degree angle along line ‘EH,’ thereby making it self-supporting. Finally, the small cone ‘¥’ is glued to the apex of the large cone, which will then be ready for use. "The following dimensions will be found suitable for the respective sizes of speakers :-

"The distance from ‘FH’ to ‘)’ is halfinch regardless of the size of the cone: and the small apex cone ‘I’ is also of the same dimensions in all cases. "The improved reproduction obtained by the use of the larger cone will repay the builder many times over for the time spent in remodelling the speaker."

Diam. Line Lines Cone. ‘EV’ to ‘G.’ ‘A-H’ and ‘B-H.’ Inches. Inches. Inches. 20 8 2 22 8} 2} 240° 93 24 26 10: 23 28 11} 3