The invention relates to a loudspeaker system for omni-directional sound emission consisting of a elongate member forming an air column and a plurality of annular speaker units mounted in axially spaced relationship on the elongate member. Diffusors also mounted on the elongate member are provided with conical surfaces facing the speaker units. Electrical wiring and auxiliary speaker components such as crossover networks may be mounted in the elongate member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention, in general, relates to a transducer for converting 
electrical energy into acoustical signal energy and, more particularly, to 
a loudspeaker-diffusor combination for emitting sound in every direction 
substantially normal to a given axis. 
2. The Prior Art 
It is known in high-quality loudspeaker systems to combine two or more 
speakers covering different frequency ranges so that they may correspond 
as closely as possible to the frequency range of human audio perception, 
typically from about 20 to about 20,000 hertz. The same is also true of 
loudspeaker-diffusor combinations designed for 360.degree. sound emission, 
wherein an appropriate diffusor element is provided for the specific 
frequency range of substantially every speaker membrane. It is common 
practice in such speaker systems to position such diffusor elements 
opposite their associated membranes (see, for instance, DE 8,529,497.7; 
4,331,059 and WO 9,007,103). 
The draw-back of such systems is that their speaker and diffusor elements 
are statically connected to each other by external braces. The braces are 
thus positioned between the active surfaces of the membranes and the 
diffusors on one side and a listener on the other. 
In addition to the further disadvantage inherent in the complexity of the 
assembly of these braces and the electrical wiring of the loudspeakers 
supported in or by the braces, measurable acoustic distortions of the 
sound emission occur as a result of the shadow effect of the braces. 
Moreover, appearance and design of such speaker systems usually are 
aesthetically unpleasing. 
OBJECTS OF THE INVENTION 
Therefore, it is a general object of the invention to provide a 
loudspeaker-diffusor combination which requires no structurally unpleasant 
external braces. 
It is also an object of the invention to provide a loudspeaker-diffusor 
combination which emits sound substantially without distortions in every 
direction. 
Another object resides in the provision of a loudspeaker-diffusor 
combination the sound emission of which is substantially free of any 
shadow effect. 
Still another object of the invention is to allow a statically stable 
assembly and electrical connection of such loudspeaker-diffusor 
combinations into a speaker system. 
Other objects will in part be obvious and will in part appear hereinafter. 
BRIEF SUMMARY OF THE INVENTION 
In accordance with the invention, there is provided a novel transducer 
comprising a speaker-diffusor combination for emitting sound in every 
direction, in which all requisite speaker elements such as diaphragms, 
dust covers, speaker cones and speaker chassis as well as the diffusor are 
assembled in a statically stable manner around an air column, hereinafter 
sometimes referred to as a hollow axis, by means of an elongate hollow 
center member, the hollow member extending concentrically through an 
annular magnetic coil, an annular dust cover and an annular diaphragm and 
supporting a diffusor substantially concentrically. 
Alternatively, a plurality of speaker-diffusor combinations may be arranged 
to surround an air column in sequential alignment with each other, the 
speaker-diffusor combinations being mounted on an elongate hollow member 
or the speaker chassis and diffusors being selectively assembled together, 
the diffusors being structured as statically connected hollow support 
members and supporting, in their otherwise empty interiors, electrical 
wiring for the speakers and other electrical components such as crossover 
networks (frequency dividers) or additional speakers provided with annular 
speaker elements. 
Advantageously, all requisite speaker elements, diaphragms as well as 
diffusors are arranged around an elongate hollow center member. In one 
advantageous arrangement in accordance with the invention, diaphragms, 
dust covers and magnetic coil members are preferably of annular 
configuration and concentrically surround the hollow member. Electrical 
connecting wires such as wiring harnesses for individual speakers are 
disposed within the hollow elongate member. The external shape of the 
hollow member may be such as to function as a diffusor, and its hollow 
interior may be utilized for housing crossover network and other 
electrical components. The hollow member may be structured as a 
substantially straight tube or as a tube provided with a plurality of 
radially flaring sections of selective exterior configuration to 
accommodate the frequency emissions of their associated speakers and 
spaced sequentially to mount a plurality of speakers to form an equal 
number of speaker-diffusor combinations aligned relative to a common air 
column formed by an elongate hollow member. It is important that the 
connections between the speakers and diffusors is statically stable 
relative to the elongate hollow member. 
The advantages of the invention are that signals emitted from 
speaker-diffusor combinations in accordance with the invention are free of 
acoustic distortions, and they are omni-directional without interference 
from braces. The quality of the emitted sound is thus significantly 
improved relative to known prior art systems. 
Also, because external braces are no longer required, speaker-diffusor 
combinations in accordance with the invention can be designed which are 
more esthetically pleasing than hitherto known similar apparatus. 
Electrical wiring harnesses may be installed within the speaker-diffusor 
combination, hidden from the viewer's or listener's view. Several such 
speaker-diffusor combinations may without technical complexity be combined 
to form a compact speaker system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
In FIG. 1, there is shown a loudspeaker system comprising, at one end 
thereof, a chassis 7 of a midrange and low frequency speaker surrounding 
an air column 4 formed by an elongate tubular member 11. The chassis 7 
includes a speaker cone 12, magnet system 10, diaphragm 8, and dust cover 
9 all of which are positioned concentrically around the tube 11 and, 
hence, the air column 4. At the other end of the tube 11, there is mounted 
a high frequency speaker or tweeter 1 including an annular membrane 2 and 
a dust cover 3. 
The midrange and low frequency speakers as well as the tweeter are disposed 
concentrically around the tube 11. To this end the magnetic system of the 
tweeter 1 is provided with a central bore and is mounted at one end of the 
tube 11. The magnetic system 10 of the midrange and low frequency speaker 
(woofer) is also provided with a central bore and is mounted at the other 
end of the tube 11, flush with the end thereof. Between the tweeter 1 and 
the midrange and low frequency speaker 10, a diffusor 5 is concentrically 
mounted on the tube 11. The diffusor is, in fact, a double diffusor having 
two coaxial substantially conical sections facing in opposite directions 
towards the tweeter 1 and woofer 10. Advantageously, the surface 
structures of the conical sections are designed to accommodate the 
frequency spectrum or desired acoustic emission characteristics of their 
associated speakers. Thus, as shown by way of example, while the cone 
facing the tweeter 1 has a substantially planar surface the cone facing 
the lower frequency speaker 10 is substantially convex in its 
configuration. 
The speaker chassis 7 is provided with a plurality of screw holes 6 to 
facilitate its mounting in a speaker box (not shown) which is preferably 
of the kind accommodating low frequencies. As shown, the air column 4 
serves to provide a conduit for electrical wiring 22 connected to the 
tweeter 1. The tube may also serve to mount a cover (not shown) over the 
tweeter 1. 
In FIG. 2, there is shown an alternative embodiment of a speaker-diffusor 
combination incorporating the principles of the instant invention. As 
shown in FIG. 2, the speaker system includes three speaker-diffusor 
combinations, viz.: a woofer 18, a midrange speaker 14 and a tweeter 13. 
The speakers are connected to each other in a statically stable manner by 
a double diffusor 17 placed between the midrange speaker 14 and the woofer 
18, a diffusor 16 associated with the tweeter 13 and by a speaker cone 20. 
The three speakers are sequentially and concentrically mounted relative to 
an air column 19 formed by the multi-section diffusor, the tweeter 13 
being positioned above the diffusor 16. A recess or cavity 15 formed by 
the diffusor 16 functions as a midrange frequency box for the midrange 
speaker 14 mounted therein. 
Electrical wiring for energizing the midrange speaker 14 and the tweeter 13 
is placed within the diffusors 16 and 17, and as schematically shown, a 
crossover network or frequency divider 21 is mounted within the diffusor 
17.