Patent GB-301922-A (GB)
Title: Device for reproducing sounds
IPC: H04R1/28
Filed: 1928-12-07
Abstract: 301,922. Hoenigmann, V., (Assignee of Walter, B.). Dec. 9, 1927, [Convention date]. Loud-speakers ; magnetic instruments; diaphragms.-A sound reproducing device, more particularly a loud-speaker, comprises a number of resonant bodies, each of which is hollow and comprises a casing having a diaphragm covering one or each end thereof, the bodies being arranged one within the other and operated by one or more actuating devices. Fig. 1 shows a construction in which a conical diaphragm 3 has its periphery secured to a rectangular frame 2 glued to the resonance box 1. A resonance member 4, such as the body of a violin, viol, mandoline or other musical instrument has its top and bottom sides mounted on blocks 4a secured by bolts 5 to soundbars 6 mounted across the casing 1. A long rod 13, screwed to supports 10, 11 on the blocks 4<a>, carries the actuating means M, such as a magnet system. A pin S connects the means M to the diaphragm 3 and member 4. The inclined face 21 of a felt damper 20 is adapted to be brought into and out of contact with the back of the member 4 by means of n handle 23 guided in the support 11 and projecting through the casing 1. A screen 25 is arranged behind the diaphragm 3. The casing 1 and diaphragm 3 constitute a resonance member having a low natural frequency whilst the resonance member 4 has a high natural frequency. Various arrangements of the resonance members are described. Thus, as shown in Fig. 3, the member 4 provided with the small conical diaphragm 3a is mounted. together with the means M, on a sound bar 26, bridging the casing 1, whilst in the construction, Fig. 4, the member 4 is slidably adjustable on a guide 28 in the casing 1, the diaphragms 3. 3a being operated bv separate magnet systems M, M<1>. According to a further modification, the member 4 is suspended from the diaphragm 3. the means M being connected to the front of the member 4. Fig. 6 shows the member 4 mounted on blocks 41 secured to the casing 1, the means M being either arranged within the member 4 as shown in dotted lines or outside thereof as shown in full lines. In a modified arrangement, Fig. 7, the means M is attached by members 50 to the curved front D of the casing 1, a part of the back B of which constitutes the front of the member 4. According to the further modification shown in Fig. 8, three resonance members 1, 4a, 4b having different natural frequencies may be simultaneously operated by a magnet system M, the members 4<a>, 4<b> being arranged within the member 1 as shown. The Specification as open to inspection under Sect. 91 (3) (a) comprises also a modified arrangement of the construction shown in Fig. 7 according to which the member 4 is disposed on the outside of the back B. Fig. 8 (Cancelled) shows a construction in which the means M is mounted on rods 60 fixed to the back B, the pins S being connected to the front D and back B as shown. A small concave diaphragm may be stretched across a central opening in the front D. According a further modification. two or more magnet systems are attached to the front and back of the casing 1, all the systems being arranged outside the casing or some inside and others outside. Fig. 10 (Cancelled) shows a further construction in which the resonance members 1, 4 are arranged immovably or adjustably with .respect to one another on a base 70. The means M may be suspended by rods 71 in either of the members 1, 4 or between them. It is also stated that the actuating means M may be in the form of a gramophone sound-box. This subjectmatter does not appear in the Specification as accepted.