Index of content:
Volume 14, Issue 3, January 1943
14(1943); http://dx.doi.org/10.1121/1.1916216View Description Hide Description
Last fall this writer described two designs for a low frequency horn adapted to operate in the corner of a room. The data presented consisted of experimental and computed performance on an experimental model and the computed performance of an improved design. The present paper describes the measured impedance of the new design and shows that this new design is a practical answer to the requirements of a speaker of this type. Minor discrepancies between the computed and measured performance are explained. Such discrepancies as exist are more of academic than practical interest. The improved design possesses all the characteristics which are desirable in a device of this class. This speaker, which is about the size of an ordinary radio console, has good response down to 40 cycles and an average efficiency from 40 to 400 cycles of about 30 percent, and a maximum variation of efficiency in this frequency range of only 2 decibels. Its normal environment, a room corner, utilizes room space which is ordinarily wasted. Observers have commented favorably upon both the artistic use of the space in the corner of the room and the acoustic performance of the instrument. With its high efficiency it is suitable for large scale sound reproduction.
14(1943); http://dx.doi.org/10.1121/1.1916217View Description Hide Description
The general problem of mechanical‐electrical analogies is discussed. The advantages of Firestone's mobility system over the older analogy is clearly demonstrated especially when used with the powerful methods of circuit analysis presented. Torsional and geared, as well as linear systems are discussed. It is shown that the choice of analogy to be used is usually one of convenience, but that certain systems intrinsically make only one analogy possible. It is further shown that the use of a mechanical‐electrical analogy in a system involving both electromagnetic and electrostatic coupling is fundamentally impossible as the resulting circuit could not satisfy Maxwell's equations.